MATS Mission Definition Phase Report

Transcription

1 MATS Mission Definition Phase Report Public Summary Lead authors: J. Gumbel 1, N. Ahlgren 2, N. Larsson 2, F. v. Schéele 3 1 Department of Meteorology Stockholm University Stockholm Sweden 2 OHB Sweden AB P.O. Box Kista Sweden 3 Omnisys Instruments Solna Strandväg Solna Sweden

2 Table of Contents Introduction 3 Scope of this repoort 4 Scientific background 4 The InnoSat/MATS spacecraft 5 Project structure 9 Project organization 10 Project schedule 11 Scientific requirements 13 Limb imaging 14 Nadir imaging 18 Pointing and orbit 20 General operation 22 Platform development 23 Introduction 24 Spacecraft performance and configuration 25 Functional architecture 29 Failure detection, isolation and recovery 31 Subsystems 32 Development approach 42 Science and payload development 45 Responsibilities 46 Payload concept 46 Research group activities 51

3 Introduction Introduction MATS Mission Definition Phase Report page 3

4 Introduction 1. Scope of this report The MATS satellite concept has been proposed in response to a Call for Ideas on "Innovative low-cost research satellite missions" issued by the Swedish National Space Board (SNSB) in Behind MATS is an instrument consortium comprising Stockholm University, Chalmers, KTH and Omnisys Instruments. In parallel, the spacecraft concept InnoSat has been developed by a platform consortium comprising OHB Sweden and ÅAC Microtec. In May 2014, SNSB decided to fund a Mission Definition Phase (MDP) for an InnoSat/ MATS satellite mission. Major objectives for this Mission Definition Phase were to agree on the project organization, including the responsibility and work split between the platform and instrument teams, to establish and agree on the InnoSat/MATS schedule and milestones, for the MATS payload, to provide updated proposals, comprising payload design, development and verification, as well as scientific analysis, for the InnoSat platform, to provide updated proposals, including mission tuning and possible adaptations for MATS, to agree on the technical interface between the platform and the payload. The present report summarizes major outcomes of the Mission Definition Phase. 2. Scientific background Our atmosphere is full of waves. Similar to waves in our oceans, these waves can be generated by different mechanisms, propagate over long distances, break into turbulence, and strongly control local conditions. Waves in the atmosphere exist on many scales from local perturbation to global patterns. Recent research has revealed that waves can link together different parts of our climate system over long distances. An important goal of the MATS satellite mission is to investigate waves in the atmosphere. MATS focuses in particular on atmospheric altitudes between 50 and 100 km, the so called mesosphere. In many ways, the mesosphere can be regarded as a transition region between the "usual atmosphere" around us and the "space" that takes over at higher altitudes. Here waves originating from the lower atmosphere can grow to large amplitudes and strongly affect everything from global wind patterns to local temperatures. In order to understand the atmosphere as a whole, we need to learn more about this transition region and its coupling to atmospheric conditions below and above. The acronym MATS stands for "Mesospheric Airglow/Aerosol Tomography and Spectroscopy". What is behind this name? From its orbit about 600 km above the Earth's surface, MATS uses optical measurement techniques to study the mesosphere. It does so by making use of optical phenomena that are specific for the mesosphere. One such phenomenon is light emitted from oxygen molecules, a process called airglow. Another such phenomenon is light scattered by aerosol particles in the form of "noctilucent clouds", the highest clouds in our atmosphere that can exist at altitudes MATS Mission Definition Phase Report page 4

5 Introduction Noctilucent clouds observed from Stockholm in the summer twilight sky. At altitudes around 80 km, noctilucent clouds are the highest clouds in our atmosphere. Their observation can provide us with important information about the physical state and the dynamics of the mesosphere. (Photo by Nathan Wilhelm.) around 80 km. In order to gain information about atmospheric structures and wave patterns from these phenomena, MATS applies tomography: by looking at the mesosphere from many different directions it is possible to reconstruct a threedimensional picture. Even more information can be obtained by combining tomography with spectroscopy: by analyzing the detected light at different wavelengths (colors) it becomes possible to draw conclusions e.g. about atmospheric temperatures, composition or cloud properties. By collecting data from the mesosphere over two years time, MATS will thus allow us to address a wide range of scientific questions about this remote part of the atmosphere. 3. The InnoSat/MATS spacecraft The MATS mission is based on the development of the InnoSat spacecraft concept. The InnoSat spacecraft is a small, capable and low-cost platform intended for a range of scientific research missions in Low Earth Orbit. It is designed to fit within a piggyback launch envelope, that is roughly 50 kg mass and cm size, and to provide high performances in terms of pointing, power and data downlink. The InnoSat Platform has been designed to utilize the most of the launcher volume available for a piggyback launch. The main drivers behind this are simply the power and volume needed for the payload. A key factor of being able to meet those demands is to baseline a dawn/dusk orbit or go to a sun pointing mode. Having the sun from one side reduces the amount of necessary solar panels in different directions, which allows for greater flexibility for the payload accommodation. All platform avionics will be accommodated into one module, called the Service Module. This module has a launch vehicle adapter on one side and a payload interface on the other side. MATS Mission Definition Phase Report page 5

6 Introduction Layout of the InnoSat/MATS satellite. Red structures mark the InnoSat platform, while grey structures show part of the MATS payload with the optical instruments. The MATS scientific payload has in turn been designed to make optimal use of the capabilities provided by the InnoSat platform. As the basis for the tomographic and spectroscopic analysis, MATS carries a total of seven imager channels that view the Earth's atmosphere in selected wavelength intervals. Six of these imager channels view the Earth's atmosphere in the limb direction (looking tangentially through the atmosphere), while one imager channels views in the nadir direction (looking downward). Measurements are based on optical emissions from altitudes km, and will be analyzed in terms of atmospheric wave patterns with horizontal wavelengths from tens of kilometers to global scales. Primary measurement targets are airglow emissions from oxygen molecules in the near infrared (the so-called Atmospheric band emission at wavelengths nm) as well as sunlight scattered from noctilucent clouds in the near ultraviolet ( nm). Tomographic and spectroscopic analysis of these measurements will reveal detailed information about the mesosphere in terms of composition, temperature and cloud microphysics. The limb instruments are based on sophisticated mirror optics to provide the necessary imaging quality. Fields of view at the distance of the Earth's tangent point are up to 50 km in the vertical and 300 km across track. Two mirror telescopes deliver images of the limb to infrared and ultraviolet spectrograph units inside the instruments. These units split the light into four and two spectrally separated images, respectively. The image detection is based on advanced CCD sensors with readout electronics that allows for flexible pixel binning and image processing. A critical challenge for the limb instruments is stray light. Sources of stray light are both direct sunlight and the bright lower atmosphere that is less than 1 from the instruments' nominal field of view. Telescope optics and interior instrument setup are carefully designed to suppress stray light effects. MATS Mission Definition Phase Report page 6

7 Introduction Of particular importance is the layout of the limb baffle system that is optimized by making use of the entire length of the InnoSat platform. Tomographic and spectroscopic retrievals are based on a co-analysis of limb data from the six spectral channels and from different locations along the orbit. This requires sequences of limb images together with appropriate information about pointing and geolocation. This need for image co-analysis thus defines requirements on fields of view, instrument alignment, and image quality. It also defines the requirements on the InnoSat platform in terms of accuracy and stability of the spacecraft's pointing and pointing reconstruction. In addition to this MATS limb analysis, the nadir imager takes pictures of Atmospheric band emissions from below the satellite. This provides complementary information on smaller spatial scales, albeit restricted to a single spectral channel. Because of the susceptibility of nadir measurements the lower atmospheric background light, these data will be restricted to the nighttime. The nadir instrument is basically a wide angle camera. Data are taken one row at a time, covering a horizontal distance of about 300 km across the footprint of the satellite path. In contrast to the limb instruments, simpler lens optics is used to image nadir structures on a CCD sensor. Again, baffling against direct sunlight is a critical driver of the instrument design. Other major constituents of the MATS payload are the mechanical structure including thermal control hardware and the star tracker interface, and the instrument power and control unit. Interfaces to the spacecraft platform regard telemetry, command, power, optical, thermal and mechanical aspects. Telemetry and commands are transferred over SpaceWire connections. Power is provided over 28V lines. Thermally the MATS payload is largely decoupled from the InnoSat platform structure. MATS Mission Definition Phase Report page 7

8 Introduction MATS Mission Definition Phase Report page 8

9 Project Structure MATS Project Structure MATS Mission Definition Phase Report page 9

10 Project Structure 1. Project organization The basic structure of the MATS project is governed by the separation of the project into a platform consortium and an instrument consortium. The platform consortium comprises OHB Sweden ÅAC Microtec The instrument consortium comprises the Department of Meteorology (MISU) at Stockholm University the Department of Earth and Space Sciences at Chalmers the Space and Plasma Physics Group at KTH Omnisys Instruments. The following meeting structure has been suggested in order to provide an efficient planning, coordination and workflow within the consortia and the overall project: Formal MATS progress meetings together with the Swedish National Space Board (SNSB) will be held every 6 months. A MATS steering group is established that consistists of (permanent) representatives from SNSB, OHB, MISU (PI and project manager), and Omnisys. Additional participants may be invited. This group should have the mandate to make overall decisions related to the MATS mission implementation. The group should meet every two months or on a case-by-case basis when the need occurs MATS coordination meetings assemble representatives from all six partners (OHB, ÅAC, MISU, Chalmers, KTH. Omnisys). These meetings provide the basic forum for information exchange and coordination between the consortia concerning ongoing and upcoming activities. The exact composition of the group varies depending on prevailing project needs. Meetings are held once per month. SNSB is invited to participate in these meetings. Instrument coordination meetings assemble representatives of the research groups and Omnisys. This group coordinates workflow and information exchange within the instrument consortium. Meetings are held once per month, typically one week prior to the MATS coordination meeting. With representatives from OHB and ÅAC, platform coordination meetings are the basis for coordinating activties within the platform consortium. These meetings are held at least once per month. The number of review meetings (Preliminary Design Review, Critical Design Review, Acceptance Reviews) are minimised in order to save cost for production and delivery of the review data packs. MATS Mission Definition Phase Report page 10

11 Project Structure In addition to the formal meetings above, ad-hoc groups will be formed temporarily depending on the needs of various activities. Beyond the above MATS consortia, a MATS Science Team has been established with Swedish and international scientists that are interested in contributing to MATS mission planning, instrument and method development, and/or scientific analysis. The MATS Science Team is also an important basis for establishing scientific collaboration between MATS and other projects and databases. The composition of the MATS Science Team will vary over time. Two meetings per year are anticipated. 2. Project schedule During the MATS Mission Definition Phase, detailed schedules have been developed for the payload design, development and verification (DDV) plan, and for payload and spacecraft assembly and integration test (AIT) plans. These schedules have been coordinated between platform consortium and instrument consortium. The MATS overall schedule is shown below. It assumes a mission kick-off in November 2014, and scientific measurements in orbit during Important milestones concern preliminary design review (PDR) for the payload, critical design reviews (CDR) for payload and complete spacecraft, and flight acceptance review (FAR). The scientific analysis will continue beyond MATS Mission Definition Phase Report page 11

12 Project Structure MATS Mission Definition Phase Report page 12

13 Scientific Requirements MATS Scientific Requirements MATS Mission Definition Phase Report page 13

14 Scientific Requirements 1. Limb imaging 1.1 Spectral selection Background The MATS scientific analysis applies spectral analysis of noctilucent clouds in the ultraviolet ( nm) and spectral analysis of O 2 Atmospheric Band airglow emissions in the near infrared ( nm). Spectral analysis of the noctilucent clouds is the basis for retrieving information about particle sizes and other microphysical cloud properties. Spectral analysis of the O 2 Atmospheric Band is the basis for retrieving atmospheric temperatures. The latter analysis also needs a characterization of background contributions in order to correct for atmospheric emissions/scattering as well as stray light. Scientific requirements Two ultraviolet channels are needed around 270 nm (UV channel 1) and 300 nm (UV channel 2) with a spectral width of about 3 nm. Wavelength intervals affected by airglow and auroral emissions need to be avoided. Exact filter bands will be decided as part of a deepened design study. Two Atmospheric Band channels are needed, one covering the entire 0-0 vibrational transition (IR channel 1, nm), another covering only the center of this band (IR channel 2, nm). Two background channels are needed covering adjacent shorter and longer wavelength intervals, around 756 nm (IR channel 3) and 772 nm (IR channel 4). Exact filter bands will be decided as part of a deepened design study. 1.2 Field of view and resolution Background The limb measurements are to provide sequences of limb images together with appropriate pointing information. Limb images of different spectral channels and from different locations along the orbit will be co-analyzed by the tomographic and spectral retrieval algorithms. This need for co-analysis defines requirements on the field of view, instrument alignment, accuracy of pointing information, imaging quality, signal-to-noise ratio etc. that will be discussed under later points. The optical setup and CCD sensor array also must provide margins to deal with a number of uncertainties and unknowns: the platform pointing uncertainty (see point 3.1) potential alignment errors in-between the instrument (see point 1.3) final choice of satellite orbit between 550 and 650 km. The vertical resolution of the limb imaging has to be consistent with CCD pixel size, requirements on imaging quality (point 1.4) and pointing reconstruction (point 3.3). The final choice of vertical and horizontal image resolution and pixel binning will depend on the choice of CCD sensor. Scientific requirements The vertical field of view for the IR imagers must comprise tangent altitudes km with margins 7.5 km at top and bottom. The vertical field of view for the UV imagers must comprise tangent altitudes km with margins 10 km at top and bottom. The horizontal limb field of all channels must comprise at least ±130 km across track from the orbit plane at the distance of the look point. The resolution of the limb images is expressed as object pixel size at the look point (horizontal vertical). For the tomographic analysis, required vertical resolution is 0.4 km MATS Mission Definition Phase Report page 14

15 Scientific Requirements or better in the UV, 0.5 km or better in the IR Atmospheric band channels, and 1.0 km or better in the IR background channels. Required horizontal resolution is 5 km or better in the UV, 10 km or better in the IR Atmospheric band channels, and 50 km or better in the IR background channels. 1.3 Instrument alignment Background All pointing requirements on the platform are defined and communicated in terms of orientation of IR limb imager channel 1 (see points 3.1, 3.3). The orientations of the other limb imager channels (IR and UV) are defined in terms of alignment relative to this IR limb imager channel 1. Misalignment must not be larger than what can be compensated by appropriate choice of pixels on the individual CCDs (point 1.2). Scientific requirements All four IR limb imagers need to image the nominal field of view km vertically and ±150 km horizontally, as defined under point 1.2. The two UV limb imagers need to image the nominal field of view km vertically and ±150 km horizontally. This means that the alignment of the four IR limb imager channels shall be better than The alignment of the two UV limb imager channels shall be better than Imaging quality Background Requirements on image resolution are moderate. Both in IR and in UV, there is an order of magnitude margin to the diffraction limit. Tomographic retrieval is particularly susceptible to distinct error features in the individual images. Effects like coma need to be avoided as they can lead to artifacts in the tomographic retrieval. Similar problems can arise from the presence of bad pixels on the CCDs. For the same reason, smearing effects in the images need to be minimized. From the instrument, smearing effects are connected to the image shifting during the CCD readout. From the platform, smearing effects are connected to unstable limb pointing during the image integration time. Scientific requirements Image quality in terms of 80% encircled energy must be achieved in consistency with the required image resolution. CCD read-out routines need to be developed that minimize image smearing. Complete frame readout of all CCDs needs to be applied at least once per month in order to identify bad pixels on the CCDs (see point 1.10). As part of the CCD read-out in nominal measurement mode, information from bad pixels needs to be removed before the pixel binning. 1.5 Sensitivity Background The MATS tomography and spectroscopy are based on the co-analysis of limb images that are obtained from the individual spectral channels and along the orbit. Errors in terms of MATS Mission Definition Phase Report page 15

16 Scientific Requirements signal-to-noise ratio will accumulate during the retrieval process. The airglow layers and noctilucent clouds addressed by MATS provide strong features in limb imaging. However, the analysis needs to subtract background like molecular scattering from these distinct emission layers. This quantification and subtraction of background defines the requirements in terms of signal-to-noise ratio. CCD dark counts need to be characterized both on the ground and in orbit as instrument degradation during the mission can lead to increases in dark counts. Scientific requirements In the IR channels, a S/N ratio exceeding 5 must be achieved over the entire limb image. In the UV channels, a S/N ratio exceeding 1 must be achieved for the molecular scattering background in the absence of noctilucent clouds. 1.6 Stray light suppression Background Stray light is light from outside the instrument's field of view that reaches the sensor through scattering at platform or instrument structure. Stray light causes an unwanted background that compromises measurement and analysis. There are two light sources that contribute to stray light for the MATS limb measurements: the "point source" Sun and the extended source of light scattered from the lower atmosphere and the Earth's surface. Baffle scattering is the most important cause that lets this light from outside the nominal field of view reach the sensor. Other causes are imperfections of the optical components and impurities (dust) on the optical components. Scientific requirements The CCD sensor signal due to stray light shall not exceed CCD sensor signals due to molecular Rayleigh scattering from the nominal field of view. Typical radiances of molecular Rayleigh scattering from the nominal field of view is 10 9 ph cm -2 s -1 str -1 nm -1 for the UV channels and ph cm -2 s -1 str -1 nm -1 for the IR channels. 1.7 Stray light characterization Background Stray light affects the analysis by adding an unwanted background to the measurements. As for the analysis of the IR channels, stray light can in principle be subtracted with the help of the two IR background channels. However, the spectral shape of the stray light in the O 2 Atmospheric band is dependent on the albedo conditions in the lower atmosphere. Therefore, the albedo needs to be characterized in terms of upwelling radiance within and outside the O 2 Atmospheric band. This is achieved by complementing the limb measurements with two small downward-looking albedo monitors. These monitors are based on photodiode sensors and use interference filters for spectral selection. In order to determine the spectral shape of the stray light in the limb measurements, these albedo measurements will be combined with detailed radiative transfer simulations. Scientific requirements Upwelling radiances need to be measured during daytime in spectral channels approximately corresponding to IR channels 2 and 3. The field of view of the measurements should be about ±3, the readout frequency about 1 per second. Typical upwelling radiances are of the order ph cm -2 s -1 str -1 nm -1. Basic baffling against direct sunlight is needed for solar positions down to 80 from the detector's optical axis. MATS Mission Definition Phase Report page 16

17 Scientific Requirements 1.8 Data rate Background The handling of the limb images on the payload needs to provide both a large dynamic range during read-out and a limitation of the data amount for telemetry transfer. CCD output in terms of pixel-binned images should be based on a dynamic range of ~16 bit. Image processing on the payload should keep this dynamic range while reducing the amount of data. This can be achieved by conversion into a 12-bit logarithmic scale and application of appropriate image compression algorithms. Scientific requirements Envisaged image sizes after on-board image processing are at least 4.0 kb for the UV images, at least 1.5 kb for the IR Atmospheric band images, and at least 0.2 kb for the IR background images. The total amount of limb image data must not exceed 9 MB per orbit in nominal science mode. Appropriate pixel binning (after removal of bad pixels) needs to be applied during CCD read-out. Subsequent image processing on the payload needs to provide appropriate image compression. 1.9 Data selection Background Limb images of the O 2 Atmospheric band concern both dayglow and nightglow emissions. These data will be transmitted during the entire mission. Measurements in the UV, on the other hand, concern noctilucent clouds that exist only during summer (about one month before summer solstice to about 1 month after summer solstice) and at high latitudes (beyond about 45 ). Transmission of UV data thus needs to be restricted in terms of season and latitude in order to limit the total amount of data. In this way, transmitted data amounts in ordinary science mode are kept within the InnoSat baseline specification. Scientific requirements Limb data on the O 2 Atmospheric band (IR channels) are needed throughout the mission. Limb data on noctilucent clouds (UV channels) are needed from latitudes poleward of 45 N from May 1 to September 10, and from latitudes poleward of about 45 S from November 1 to March Special operations Background All nominal measurements (science mode) apply pointing towards a fixed limb altitude (see point 3.1). All nominal measurement also apply data transfer in terms of pixel-binned compressed limb images of sizes up to 4.5 kb (see point 1.8). However, other modes of pointing and data collection are needed in order to characterize instrument behavior in orbit. These special operations can include reading the entire CCD frame without pixel binning, thus leading to significant larger image sizes of about 3 MB. Orbits applying these special operations will therefore benefit from increased data transfer as can be provided by multiple downlinks per day. Tests of pointing and alignment tests will use based on using the limb imagers as star MATS Mission Definition Phase Report page 17

18 Scientific Requirements sensors. With an integration time of 1 s very good signal-to-noise ratios can be achieved for the 40 brightest stars in the sky. An integration time of 1 s requires inertial (space-fixed) pointing towards the star over the integration time. Scientific requirements Operations of the platform and instrument must be possible that allow for instrument characterization in terms of alignment and pointing calibration by star imaging status checks of individual CCD pixels (identification of bad pixels) calibration by imaging of the Moon calibration by observing molecular scattering from lower tangent altitudes 2. Nadir imaging 2.1 Nadir imaging Spectral selection Background The MATS scientific analysis applies nadir imaging of the O 2 Atmospheric Band nightglow structures in the near infrared ( nm). Scientific requirements The nightglow below the satellite must be imaged integrated over a spectral range that covers the O Atmospheric Band 0-0 band ( nm). The filter must fulfill these requirements over the relatively large range of incident angles defined by the nadir field of view. The exact filter band will be decided as part of a deepened design study. 2.2 Field of view and resolution Background The nadir measurements are to provide a sequence of nadir images together with appropriate pointing information. The horizontal resolution of the nadir imaging has to be consistent with CCD pixel size, requirements on imaging quality (point 2.4) and pointing reconstruction (point 3.3). The final choice of horizontal image resolution and pixel binning will depend on the choice of CCD sensor. Scientific requirements The horizontal field of view for the nadir imagers must at least ±150 km across track from sub-satellite point. The horizontal resolution of the nadir imaging must be 5 km or better, as expressed in terms of horizontal distance at an altitude of 100 km above the ground, i.e. the approximate altitude of the O 2 Atmospheric Band nightglow layer. 2.3 Instrument alignment Background All pointing requirements on the platform are defined and communicated in terms of orientation of IR limb imager channel 1 (see points 3.1, 3.3). The orientation of the nadir imager in terms of alignment offset relative to the IR limb imager channel 1. Scientific requirements The nadir images should be centered around the sub-satellite path with an accuracy of 2 km. MATS Mission Definition Phase Report page 18

19 Scientific Requirements 2.4 Imaging quality Background Requirements on image resolution are moderate. There is substantial margin to the diffraction limit. Scientific requirements Image quality in terms of 80% encircled energy must be achieved in consistency with the required image resolution. CCD read-out routines need to be developed that minimize image smearing. Complete frame readout of all CCD needs to be applied at least once per month in order to identify bad pixels on the CCD. As part of the CCD read-out in nominal measurement mode, information from bad pixels needs to be removed before the pixel binning. 2.5 Sensitivity Background The scientific analysis of the nadir imager is based on a characterization of relative structures in the nightglow intensity. Signal-to-noise ratio is critical for the identification of such structures. CCD dark counts need to be characterized both on the ground and in orbit as instrument degradation during the mission can lead to increases in dark counts. Scientific requirements A S/N ratio exceeding 5 must be achieved over the entire nadir image. 2.6 Stray light suppression Background For the nadir nightglow imaging, the only source of stray light is the "point source" Sun. Baffle scattering is the most important cause that lets this light from outside the nominal field of view reach the sensor. Other causes are imperfections of the optical components and impurities (dust) on the optical components. Scientific requirements The CCD sensor signal due to stray light shall not exceed the CCD sensor signal from the nightglow layer. Typical radiances from the O Atmospheric Band nightglow are 10 8 ph cm -2 s -1 str -1 nm Data rates Background Requirements on dynamic range and data amount are moderate for the nadir nightglow measurements. Scientific requirements Envisaged image sizes after on-board image processing are at least 0.6 kb for an image size corresponding to km horizontal distance at 100 km. The total amount of nadir image data must not exceed 0.5 MB per orbit in nominal science mode. Appropriate pixel binning (after removal of bad pixels) needs to be applied during CCD read-out. MATS Mission Definition Phase Report page 19

20 Scientific Requirements 2.8 Data selection Background Nadir nightglow measurements will be restricted to nighttime conditions with solar zenith angles typically exceeding 105 at the sub-satellite point. Scientific requirements Transmission of data from a selected part of the satellite orbit (latitude range) needs to be chosen by telecommand on a weekly basis. 2.9 Special operations Background In contrast to the limb imagers, no special operations in terms of platform pointing are needed for the characterization of the nadir instrument. Read-out of the entire CCD frame will be applied to identify bad pixels. Scientific requirements Operation of the instrument must be possible that allow for status checks of individual CCD pixels (identification of bad pixels). 3. Pointing and orbit 3.1 Absolute pointing error Background The vertical limb field of view needed for the scientific analysis comprises tangent altitudes km for the IR imagers and km for the UV imagers (see point 1.2). The horizontal limb field of view needed comprises a distance of ±150 km across track from the tangent point. The limb instruments' field of view applies a margin of 5 km to account for uncertainties in the platform's limb pointing. This margin determines the requirements on the platform's pointing accuracy. In the following, the orientation of the IR limb imager channel 1 (total O 2 Atmospheric Band channel) is used as reference when describing the limb viewing geometry. All pointing requirements (absolute pointing error APE, absolute knowledge error AKE) on the platform are defined and communicated in terms of orientation of this IR limb imager channel 1. The pointing requirements of the MATS nadir measurements are less strict than those of the limb measurements. In the following, pointing requirements are therefore only defined in terms of the limb instruments. Meeting the limb requirements in terms of 3-dimensional APE will ensure that also the nadir requirements are met. Scientific requirements The limb imagers' vertical fields of view need to cover a tangent altitude range of km (IR) and km (UV), respectively. The limb imagers' horizontal fields of view need to cover a tangent range across track of ±150 km from the orbit plane. This coverage needs to be achieved with a confidence level of 2-sigma. MATS Mission Definition Phase Report page 20

21 Scientific Requirements 3.2 Pointing stability Background As the limb instruments are to point to a limb point at a fixed tangent altitude above the geoid (point 3.1), the platform needs to perform a continuous pitch rotation with 360 per orbit. While pointing towards a given tangent altitude, measurements are taken with integration times between 3 s and 5 s. Over this time interval, abrupt changes in platform attitude and deviations from the smooth pitch rotation will lead to significant smearing between the image pixels. This must be avoided. Unsmooth changes of the satellite attitude may occur due to lack of stars in the star sensor field of view, pixel effects in the star tracker, limited smoothness of the reaction wheels, or the need to correct erroneous pointing. In order to reduce effects of unsmooth attitude changes on the data analysis, the pointing reconstruction must make it possible to know the pointing with sufficient accuracy at each moment during the measurement (point 3.3). Scientific requirements Changes in platform attitude should be smooth. This applies in particular to the continuous pitch rotation. Acceptable are attitude changes that do not lead to significant smearing between image pixels. The tangent point towards viewed by the optical axis of the limb imagers should not shift by more than 0.4 km in altitude and 2 km across track over a time period of 5 seconds. The platform roll angle should not change more than 0.1 over a time period of 5 seconds 3.3 Absolute pointing knowledge Background The tomographic retrieval of the limb measurements requires a co-analysis of long sequences of limb images. This requires sufficient accuracy of the absolute pointing reconstruction (absolute knowledge error AKE) for individual limb images, but also a high level of confidence in the relative pointing reconstruction of the entire image sequence (relative knowledge error RKE). This is especially critical for the vertical pointing (pitch), both because of the higher image resolution in the vertical and because of the continuous pitch rotation of the platform. Attitude information must be made available at a rate sufficiently high to reconstruct the limb pointing with the desired accuracy at any time of the measurement. The requirements on AKE and RKE of the MATS nadir measurements are less strict than those of the limb measurements. In the following, pointing requirements are therefore only defined in terms of the limb instruments. Meeting the limb requirements in terms of 3- dimensional AKE and RKE will ensure that also the nadir requirements are met. Scientific requirements The relative limb pointing for a series of limb images needs to be reconstructed with an accuracy that corresponds to the limb image resolution. This information about the pointing reconstruction is needed in terms of the position of the look point (altitude and across track) of the limb imager channels. Any tilt of the limb images with respect to the optical axis of the imager must be known with an accuracy that corresponds to image resolution. Pointing reconstruction must be provided frequently enough to allow for interpolation of the pointing information with the above accuracy and confidence level to any point in time during the measurement. MATS Mission Definition Phase Report page 21

22 Scientific Requirements 3.4 Pointing and orbit Geolocation reconstruction Background For the limb measurements, accurate knowledge of the geolocation is needed in order to convert payload attitude information (pitch, yaw, role angle) into accurate information in terms of limb pointing (geolocation and altitude of the limb point). For the nadir measurements, accurate information about geolocation and pointing is needed in order to enable detailed comparison of nadir nightglow imaging with ground-based all-sky nightglow imagers. Scientific requirements Knowledge of horizontal location of nadir point with accuracy 0.5 km for nadir imager. 4. General operation 4.1 Mission duration Background The scientific aims defined for MATS concern atmospheric processes with a distinct seasonal dependence. It is therefore decisive to have an operational lifetime of at least 2 years in order to fully study the transitions between seasons, including an analysis of hemispheric differences in these transitions. Noctilucent clouds are a distinct phenomenon that occurs at summertime high-latitudes and that is connected to atmospheric dynamics on a global scale. We know that there are substantial variations between NLC seasons. A mission lifetime of two years will provide measurements during two summer seasons in each hemisphere. Scientific requirements An operational lifetime of 2 years, preferably comprising scientific measurements during two complete summer seasons (May-August, November-February) in each hemisphere. 4.2 Level-0 and Level-1a data Background The tomographic and spectroscopic analysis of the limb measurements requires a co-analysis of a large number of limb images. The tomographic retrieval also envisages a co-analysis with the nadir imaging. Opportunities to co-analyze with results from other missions are essential for the entire MATS project. Scientific requirements Scientific data from the imagers need to be provided in combination with synchronized information about pointing, geolocation, as well as platform/instrument performance (housekeeping and event data). MATS Mission Definition Phase Report page 22

23 Platform Development MATS Platform Development MATS Mission Definition Phase Report page 23

24 Platform Development 1. Introduction The InnoSat spacecraft is a small, capable and low cost platform intended for a range of scientific research missions in Low Earth Orbit. It is designed to fit within a piggyback launch envelope, that is roughly 50 kg mass and 60x70x85 cm size, and to provide high performances in terms of pointing, power and data downlink. It will serve as an observation platform for space science that will provide a 24/7 service to the end users. The need for routine engineering maintenance and support will be limited thanks to the high level of autonomy in the system. The first mission that has been analysed in detailed is the MATS scientific mission. The idea behind the MATS satellite mission is to analyse wave activity in the Mesosphere and Lower Thermosphere (MLT) over a wide range of spatial and temporal scales. Measurements are based on optical emissions from the altitude range km, which are analysed in terms of wave spectra with horizontal wavelengths from tens of kilometres to global scales. This document summarizes the preliminary platform design as well the additional MATSspecific analyses and descriptions of the required mission-specific adaptations of the InnoSat standard platform. MATS Mission Definition Phase Report page 24

25 Platform Development 2. Spacecraft Performance Factor and Physical Configuration 2.1 Key Performance Factors The key performance factors of the InnoSat spacecraft bus is summarized in the table below. Satellite mass Size Max payload mass <40 kg 70x65x85 cm Up to 15 kg Max payload power 40 W (orbit average, 06:00/18:00 LTAN SSO ) Design lifetime Downlink bitrate Pointing performance requirements Orbit determination Nominal attitude mode 2 years 3-5 Mbps Max 0.1 deg absolute pointing error Max 0.01 deg pointing knowledge error (reconstructed) On-board GPS Nadir/Forward-looking 2.2 InnoSat Platform The InnoSat Platform has been designed to utilize the most of the launcher volume available for a piggyback launch. The main drivers behind this are simply the power and volume needed for the payload. The following criteria had to be considered for the baseline design: Payload volume Payload power Payload shadowing The key factor of being able to meet those demands is to baseline a dawn/dusk (06:00 LTAN/LTDN) orbit or go to a sun pointing mode. Having the sun from one side reduces the amount of necessary S/A panels in different directions, which allows for greater flexibility for the payload accommodation. Another benefit of having the Sun from one direction is that the S/A panel works as a natural Sun shield for providing shadowing of the payload (of course with some seasonal effects). Figure 2-1: InnoSat standard configuration MATS Mission Definition Phase Report page 25

26 Platform Development The volume available to the payload instrumentation has been optimized using feedback from the science teams. It s evident that the piggyback launch configuration is already a quite heavy constraint for the instrument design. In addition, different missions have different requirements it terms of accommodation and clearances. To meet these needs all avionics will be accommodated into one module, called the Service Module. This module will have a launch vehicle adapter on one side and a payload interface on the other side. In the launch vehicle the payload will be standing on-top of the Service Module, on the sun facing side of the module a S/A panel will be fixed, expanding upwards i.e. the panel will be partly body mounted. The Service Module will ideally remain the same for different payloads, and the payloads simply scales upwards as far allowed by the launch vehicle envelope. In the same manner the S/A panel is scaled upwards for increased power if allowed by the launcher envelop. Figure 2-2: Service Module and payload accommodation volume If more power is needed, but there is no additional height clearance in the launcher envelope, the design supports two deployable panels on the sides of the Service Module. The service module is made not as wide as the launch vehicle envelope allows, thus leaving out enough space for the deploy mechanisms and hinges. However, the baseline configuration is a single partially bodymounted panel. Depending on the payload being an astrophysics or Earth observing instrument, the payload is directed to the zenith or nadir directions respectively, hereby called the payload to zenith and payload to nadir flight configurations. The needed reconfiguration of the service module is summarized as follows: S-band antennas: In the payload to zenith configuration the S-band antennas are placed on the same panel as the launch adapter. For an Earth observing payload the antennas are placed on the corners of the solar panel. MATS Mission Definition Phase Report page 26

27 Platform Development GPS Receiver Antenna: An antenna bracket compatible with both configurations is used; the placement is just a matter of where the mounting points are located on the anti-sun panel. Figure 2-3: Possible high power extension (with two deployable panels) Star tracker: The star tracker will be mounted so it points either to zenith or nadir with an angle. A universal bracket that by a 180 degrees turn can be used for this. Another alternative is to fly with the payload deck in the forward ram direction or in the backward wake direction. Observe that the preferred direction depends on the LTAN of the dawn/dusk orbit. The reconfiguration is as follows: S-band antennas: Mounted on the side panels pointing towards nadir and zenith. GPS Receiver Antenna: Mounted on the side panel pointing towards zenith. Star Tracker: Mounted on the anti-sun panel pointing towards zenith (similar as in the payload to zenith/nadir configurations) or mounted on the zenith side panel as the GPS and one of the S-band antennas. Three launch alternatives have been taken into account namely the Indian (ISRO) PSLV, Arianespace s Soyuz-ASAP and Spaceflight Inc. SSPS (Spaceflight Secondary Payload System) using the excess capacity of various launch vehicles, both American and Russian. The table below illustrates the available S/C envelop of the three launch vehicles and as well the IRF space simulator. PSLV Soyuz-ASAP SSPS IRF Space Simulator Dimensions (BxWxH): 600x700x850 mm 3 800x600x1000 mm 3 800x800x x800x800 mm 3 mm 3 (maximum) 500x500x500 mm 3 (illuminated) S/C mass: 100 kg 200 kg 300 kg TBD kg Table 2-1: Volume and Mass constraints for the InnoSat spacecraft MATS Mission Definition Phase Report page 27

28 Platform Development As seen in Table 2-1, in terms of launch vehicles the PSLV alternative is the more restricting one thus setting the maximum envelope for the S/C. If the S/C dimensions grows outside the space simulator envelop, the S/C will be tested without mounted solar panel (shorter dummy panel will be used) and payload, where heat contribution of the payload is emulated by a dummy heat source. As long all parameters in the space simulator is known, it will be possible to correlate the thermal model of the satellite without having to fit the whole craft inside the space simulator chamber. 2.3 MATS: Payload Accommodation and Bus Adaptations The MATS Payload will be mounted on the standard InnoSat payload panel but its Limb Imager baffle needs to be extended alongside the solar panel and the Service Module as depicted in Figure 2-4. This is made possible by a minor modification of the Service Module form factor. Figure 2-4: Preliminary configuration for MATS The Limb Imager needs to be kept pointing towards the Earth s limb about 2800 km ahead of the satellite with a high level of accuracy and stability. To optimize the pointing stability, the InnoSat Star Tracker will be mounted on the imager s optical bench, thus the thermoelastic effects between payload and Star Tracker is minimized. Figure 2-5: MATS nominal flight configuration MATS Mission Definition Phase Report page 28

29 Platform Development 3. Functional Architecture The functional architecture of the InnoSat spacecraft is divided into the classical subsystems The Electrical Power Subsystem (EPS) is responsible for power conditioning and distribution of 28 V unregulated power to on-board users and 5V power to the DHS. The Thermal Control Subsystem (TCS) is responsible for controlling the on-board temperatures and is designed with mainly passive methods and only a limited set of active heaters. The Data Handling Subsystem (DHS) is responsible for telecommand and telemetry handling, for commanding and monitoring of the on-board avionics as well as for executing the on-board software. The Attitude Control Subsystem (ACS) is responsible for controlling the attitude of the satellite using dedicated sensors and actuators. The Telemetry, Tracking and Telecommand (TT&C) Subsystem is responsible for communication with Ground using S-band RF communication. The Payload is the mission-specific instrumentation. 3.1 Operational Modes Figure 3-1: InnoSat Operational Modes MATS Mission Definition Phase Report page 29

30 Platform Development The Spacecraft mode architecture, depicted in Figure 3-1, is driven by the following needs: To protect the battery from excessive discharge using load shedding To provide soft-start capability when recovering from a low power situation To provide autonomous configuration into a safe mode of operation, where long-time survival of the spacecraft is guaranteed and where communication with Ground is made possible. 3.2 Control Hierarchy The on-board electrical system is divided into separate entities that constitute independent functions. Each function is related with the others and with the ground control via a hierarchical control structure, which is visualised in the following diagram. This control hierarchy strongly influences power and data distribution. MATS Mission Definition Phase Report page 30

31 Platform Development 4. Failure Detection, Isolation and Recovery (FDIR) The spacecraft FDIR strategy has the following objectives: To guarantee spacecraft survival in case of failures in non-critical functions. To recover from SEE-induced anomalies and intermittent software problems by equipment reset or power-cycling. To provide a controlled de-activation on on-board functions due to hardware or software failures. To provide extensive diagnostic information in telemetry to allow for ground-based contingency analyses. To provide a high level of controllability to allow for ground-based recovery actions. To provide a set of hard-wired TM/TC emergency functions to allow for Ground to restore the satellite to its original state. FDIR is performed at on-board level and at ground level as outlined below. At the on-board level: The satellite is able to detect and manage internal failures as follows: Level 1 - Protection: close to the hardware, aiming at avoiding any failure propagation over the satellite. Examples of implementations are: watchdogs; anti latch-up device; EDAC in DHS memory; triplication on software function. The effect on the rest of the system is limited to a temporary outage of sensor data. Level 2 - Restart: aims at restarting the equipment in cases where level 1 actions aren t sufficient. Level 3 - Reconfiguration: aims at managing the on-board redundancies. No redundant units are included in the InnoSat baseline but there might be some redundant interfaces that are managed at this level. Level 4 - Recovery: directly managed by the on-board software, which monitors the good health of the satellite and can trigger interruption of services or safe mode transition. At ground level: As soon as a satellite is in safe mode, the ground shall investigate with the help of the telemetry report, the anomaly characteristics and decide the way to recover the situation. The satellite will wait until an order is given to go back to the nominal mode. MATS Mission Definition Phase Report page 31

32 Platform Development 5. Subsystems 5.1 Structure and Mechanical Subsystem (SMS) Structure Concept The InnoSat platform structure will be based on the PRISMA Mango platform, shown below, which has proven to carry >50 kg of payload (Tango spacecraft supported on top panel during launch and commissioning, and additional payload hardware on-board Mango). Figure 5-1: Mango spacecraft configuration, showing anti sun-facing main radiator (left). Mango spacecraft, shown in launch configuration with 50 kg payload on top deck (right) This design builds on heritage from Odin and Smart-1 in terms of construction (joints, inserts, materials) and load paths. As for the Mango spacecraft, the InnoSat structure baseline will be aluminium honeycomb panels. Being substantially smaller than the Mango spacecraft, the thickness of the panels for InnoSat can be decreased and the inner shear panel adding stiffness to the Mango spacecraft is likely not to be needed. MATS Adaptations As mentioned previously in section 2.3, the following MATS-specific adaptations will be necessary: The width of the Service Module needs to be shortened to allow for the Limb Imager baffle to extend alongside the solar panel. The height of the Service Module needs to be increased slightly so that the Limb Imager s optics is aligned with the solar panel edge. The Star Tracker needs to be mounted on the Payload s optical bench (for increased pointing stability). MATS Mission Definition Phase Report page 32

33 Platform Development The GPS and S-band antennas need to be re-arranged for the MATS flight direction The placement of the antennas needs to be further refined in the detailed design phase. Figure 5-2: Tango body mounted solar panel Optical bench Star tracker Radiators Nadir baffle Power unit Limb baffle Connector plate Figure 5-3: MATS main components (18:00 LTAN configuration) 5.2 Thermal Control System (TCS) Thermal Control Concept Since no propulsion system is included in the InnoSat platform, the thermal control will be less complicated compared to PRISMA and many other satellite missions. Standard small satellite thermal control methods will be applied for the platform. The total power and operation modes of the payload and platform suggest that a simple system should MATS Mission Definition Phase Report page 33

34 Platform Development be sufficient (no heat pipes, louvers, etc.). A baseline setup of hardware including MLI, foil heaters, thermistors, thermostats, radiators and filler materials is assumed. Figure 5-4: PRISMA Mango with silver FEP tape radiator surface and black Kapton MLI (left). Typical heater/thermostat installation (battery in the centre) (right) Optionally self-regulated heaters can be used, such heater is designed to keep a constant temperature when powered i.e. no temperature feedback and control logic is needed. 5.3 Electrical Power Subsystem (EPS) Power architecture The InnoSat Power Subsystem includes the Solar Panel(s), the Battery (or Batteries) and the Main Power Distribution Unit (MPDU). The MPDU receives the incoming power from the solar panels and regulates the battery charging. It protects the battery from overvoltage due to overcharging and regulates the charging current. An isolated DC-DC converter generates the 5V which is then distributed to each of the DHS consumers. The high-power consumers connect directly to the unregulated battery 28V bus through an Latching Current Limiters (LCLs). 5.4 Attitude Control Subsystem (ACS) This section summarizes the design and design justification of the Attitude Control Subsystem. General Design Drivers For the generic ACS design, the following main drivers have been identified: Dawn/dusk SSO: The baseline orbit for the InnoSat spacecraft is a dawn/dusk sunsynchronous orbit at 550 to 650 km MATS Mission Definition Phase Report page 34

35 Platform Development Single solar array panel: The spacecraft will carry one single solar panel that needs to be oriented towards the sun. Autonomous, Low-Complexity Safe Mode: The spacecraft shall be able to survive indefinitely in a fully autonomous Safe Mode. In this mode, the on-board power consumption will be minimized and the payload will be switched OFF. The ACS design needs to be aligned with the overall power budget and energy budget so that enough solar power is generated also during worst-case conditions (for example at BOL after separation from L/V). The Safe Mode should utilize a minimal set of actuators and sensors as well as a simple and robust control law. Autonomous Nominal Mode: The nominal flight attitude shall be oriented towards forward/nadir with one 360º revolution per orbit. After LEOP and Commissioning, the satellite should never leave this configuration (even when not performing science operations). The only exception being a failure in a critical hardware unit when a fallback to a more minimalistic attitude control mode shall be triggered (Safe Mode). Mission-specific pointing control: Each InnoSat mission will carry a dedicated science payload that comes with specific ACS needs. It shall be assumed that, for any mission, the principal attitude mode shall be the forward/nadir looking mode but that the fine attitude control will be mission specific. Pointing performance: The detailed pointing performance requirements will be mission-specific but the baseline ACS performances shall meet the following requirements (SC-51): o Maximum 0.1 degrees Absolute Pointing Error (APE) at the Star Tracker mounting point, 2-sigma o Maximum 0.01 degrees Absolute Pointing Knowledge Error (AKE) at the Star Tracker mounting point (after á-posteriori attitude reconstruction) Single-string/low-complexity approach: For cost reasons, a single string approach has been adopted for the overall spacecraft design. This means that there will be no redundant units that can be utilized in case of equipment failure. To limit the risk for failure, complex ACS designs with a large suite of complex sensors and actuators shall be avoided. InnoSat ACS Design The design of the InnoSat attitude control system is summarized below: For rate damping, e.g. after L/V separation, a simple b-dot control law using magnetorquers and magnetometer shall be used in Safe Mode. In Safe Mode, a magnetic control law will be used to orient the solar panel towards the sun. In Science Mode, a Star Tracker / Reaction Wheels based design will be used to fulfil the fine pointing requirements. An on-board GPS will be used to support autonomous operations in Science Mode and to support the on-ground fine orbit determination algorithms. MATS Mission Definition Phase Report page 35

36 Platform Development MATS Specific Adaptations For the MATS mission, the following specific design drivers have been identified: Limb-viewing: The Limb Imager shall be the design driver for the ACS. The attitude control mode for the Limb Imager is defined as follows: o The Spacecraft shall, in Science Mode, control the attitude of the Spacecraft so that: The +Z SC axis is roughly pointing in the direction of motion. The +Z LI axis of the Limb Imager is continuously pointing towards a Look Point (LP) located h LP km above the horizon as defined by the WGS84 ellipsoid. The +Y LI axis of the Limb Imager is aligned with the WGS84 horizon at the Look Point. Pointing performance: The ACS shall be designed to meet the MATS pointing performance requirements. The conclusion for the MATS ACS trade-off is: The proposed baseline for the MATS Science Mode attitude control is the InnoSat baseline ACS with three Reaction Wheels and one Star Tracker, complemented with three Rate Sensors (Gyros). 5.5 Data Handling Subsystem (DHS) Overview The data handling subsystem (DHS) consists of the hardware and software infrastructure required for the satellite operation, but not detailing the S/C mission software. Specifically, it concerns the communication (intermodule and ground) of the S/C. Figure 5-5 shows an overview of how the DHS is organized into hardware modules and its connections to the DHS peripheral units. Between missions, there is a possibility to leave complete end nodes unaltered and have the mission specific software changes only in one node. This minimizes the changes between missions and reduces cost. There is also a possibility to add and remove hardware nodes. It would for example be possible to add a future propulsion end node which would be connected to the SpaceWire router and communicating over SPA, but with only minor changes to the rest of the system. MATS Mission Definition Phase Report page 36

37 Platform Development Figure 5-5: Data handling subsystem overview Figure 5-6 Current ÅAC Microtec µrtu FM product MATS Mission Definition Phase Report page 37

38 Platform Development 5.6 Telemetry, Tracking and Command Subsystem (TT&C) Introduction The TT&C subsystem is responsible for S-band RF communication for satellite control and monitoring as well as for science data downlink. Design Drivers and Trade-Offs Figure 5-7: TT&C functional block diagram The following design drivers for the TT&C subsystem have been identified: Downlink Bitrate: Bitrates between 100 kbps to several Mbps is desirable to cover both Safe Mode operations with unfavourable antenna orientation as well as maximum science data throughput using only a few daily ground station passages. RF Output Power: RF output levels ranging from 1 W to 2 W will allow for flexibility in the link budget depending on the satellite power budget (for a specific mission) as well as for different ground station antenna sizes. Antenna Pattern: The antenna pattern shall be optimized for science mode with forward/downward looking satellite attitude. Adequate antenna gain shall also be provided for other attitudes (in case of a contingency situation), but strict hemispherical coverage is not required. The satellite Safe Mode is designed to provide an earth-pointing attitude at high latitudes so a gap in the antenna pattern in the zenith direction is deemed acceptable. CCSDS Compatibility: CCSDS compatibility is a requirement if an external ground station is used. 5.7 On-Board Software (OBSW) Design Drivers The following main design drivers for the InnoSat On-Board Software have been identified: Distributed Processing: Three on-board processing units will be used for flight software deployment: Mission Controller, Spacecraft Controller and TT&C Controller (see section 3). Space Plug and Play: SPA shall be used for interconnectivity between the three processing units and for equipment access. MATS Mission Definition Phase Report page 38

39 Platform Development RAMSES Compatibility: The on-board software shall be compatible with the existing RAMSES Mission Control System and with a limited set of the ECSS PUS standard. ACS Software Integration: The ACS software will be developed using the existing MATLAB/Simulink-based approach and autocoding. ACS Software Scheduling: The ACS software shall be scheduled in a periodic and deterministic manner. ACS Software Diagnostics: The ACS software inputs and outputs must be observable in telemetry with the sampling synchronized with the ACS periodic scheduling. Equipment Check-Out: Raw equipment telemetry data shall be visible in telemetry. It shall be possible to send direct commands to any equipment from the RAMSES MCS. Software Patching: It shall be possible to update the on-board software when in orbit. Low-level software may be excluded from this requirement. System Simulator: Software validation is assumed to be performed on EM hardware for low-level software and on a System Simulator for application software. Thus, it must be possible to execute the application software in a virtual environment (Linux or Windows OS and with emulated SPA and equipment drivers). Space Plug and Play Avionics (SPA) The Space Plug-and-Play Architecture (SPA) standard was designed to help decrease the amount of time and money required to integrate a satellite and to ease the reuse of components between missions. As this is the current baseline for the Data Handling Architecture, it implies some consequences for the on-board software. SPA can be set up to interconnect everything from applications to sensors, but in InnoSat this has been restricted to the major components of the Data Handling System (DHS) which is set up as a SPA network. Each node on the network needs to have an Extensible Transducer Data Sheet (xteds), an xml file declaring its name and abilities to allow for rapid autoconfiguration of the network. The basis for the SPA network is a collection of software called the SPA Services Manager (SSM) which handles the interconnections of the different modules on the SPA network. Packet Utilization Standard (PUS) and SPARTAN The RAMSES Mission Control System has been developed by OHB Sweden for the PRISMA mission and re-use of this system for InnoSat is envisaged. RAMSES relies on CCSDS standards for the space/ground link and on the ECSS PUS standard for operational services. While RAMSES is implementing the PUS services on the ground side, the SPARTAN software stack will be providing the PUS implementation on the spacecraft. SPARTAN is derived from heritage projects at OHB Sweden and is portable in terms of operating system, processor hardware and OBSW framework. MATS Mission Definition Phase Report page 39

40 Platform Development 5.8 Payload Interface Electrical interface The electrical interface for the payload is summarized in Table 5-1 below. Function Primary Power Safe Power Command and Telemetry Auxiliary Attribute Unregulated 28 V Unregulated 28 V SpaceWire (10 Mbit/s) PPS and spare Table 5-1: Payload electrical interface. The payload power interface is assumed to be equivalent (from the S/C point of view) to the schematic as depicted in Figure 5-8. The payload shall utilize an isolating DC/DC converter for its secondary voltages. An exception is made for payload heaters which are allowed to be connected directly to the primary or safe power given that the minimum hysteresis control period is in order of seconds. If active control is used, the ON/OFF switching of the heaters shall be done through devices providing galvanic isolation (relay) or very high impedance between the primary power and source of payload thermal control (e.g. by the usage of MOSFETs). Communication interfaces (including PPS) shall utilize differential signalling. Figure 5-8: Schematic payload power interface. MATS Mission Definition Phase Report page 40

41 Platform Development Power consumption and control The maximum allowed power consumption of the payload is defined in Table 5-2 below. Average Power Nominal Mode 36W 72W Safe Mode 10W 18W Maximum Power Table 5-2: Average and maximum power consumptions. The lower power during safe mode is foreseen to be used for thermal control if so needed. A notice of mode change from nominal to safe will be sent from the platform to the payload via the communication interface, exceptions may apply during power emergency where primary power may be switched OFF without notice. Taking the instrument from safe to nominal mode will be a matter of switching OFF the safe power and switching ON the primary power. Communication interface SpaceWire is foreseen as baseline due to its high bandwidth allowing fast data transfer between payload and on-board mass memory. The payload needs to support both the ECSS PUS stack and the SPA-S stack. The latter allows the payload to communicate with and through the DHS, and the former is necessary for the space to ground segment. Mechanical and Thermal A number of inserts will be provided on the payload deck where the payload can be mounted. To limit the conductive heat transfer between the S/C and P/L, thermal washers are foreseen to be used for the bolts. MATS Mission Definition Phase Report page 41

42 Platform Development 6. Development Approach and Overall System Architecture 6.1 General Design Approach To be able to realise a mission based on the InnoSat architecture at very low recurring cost, an efficient industrial team with the ability to develop the system following a Design to Cost approach is necessary. The proposed approach can be summarized as follows: Simplified Design: The spacecraft design will be significantly simplified compared to the most recent Swedish satellite missions. In particular, this includes a single-string hardware configuration and a reduced ACS complexity. Generic System Specification: The science payload design and performance will be constrained by a System Specification and thus not allowed to drive cost excessively. The design-to-cost approach must also apply for the science team. Re-Usability: The spacecraft architecture will be re-usable on two levels: o Bus Level: Re-use of the complete satellite bus for science payloads that comply to the InnoSat system requirements. This allows for the lowest recurring costs. o Core Architecture Level: For missions that can t be constrained by the System Specification, adaptations of the InnoSat bus will be necessary. However, re-usability at the core architecture level (most notably in terms of interface electronics and software) will allow for adaptations and extensions of the InnoSat bus without a major re-design of the complete bus. The adaptation cost will depend on the new science requirements. Figure 6-1: InnoSat Top-Level System Architecture MATS Mission Definition Phase Report page 42

43 Platform Development Testing: Thanks to the reduced system complexity, unit-level testing can be reduced in scope and replaced with system-level testing. This will be in particular applicable to software testing, with combined software/system engineering and validation. Small Team: Thanks to the simplified design and the reduced verification programme, it will be possible to run the project with a small team and thus increase the labour efficiency. 6.2 System Architecture The InnoSat system is defined as all the parts and services needed to fully implement an InnoSat science mission, including the spacecraft platform, launch services and operations as depicted below. It is envisaged that the following core components can be re-used between different InnoSat science missions: InnoSat Core Spacecraft Components: A set of spacecraft infrastructure components (hardware and software) that in the InnoSat standard platform as well as in possible evolutions (such for multi-satellite missions). This includes mainly items developed and owned by the consortium members (i.e. ÅAC Microtec and OHB Sweden): o Main computer o Secondary processors and interface electronics o Mass memory o Data and power routers o Power conditioning unit o Flight software. InnoSat Mission Control Centre: A set of ground segment components (hardware and software) that can be used to operate an InnoSat mission: o Mission Control System (including flight dynamics system) o Automation Server In addition to the core components, there will be a baseline of externally procured equipment that is used in the InnoSat standard configuration and in the extension variants. ACS actuators and sensors TT&C transceiver and antennas Solar panels (sized for each mission) Batteries (sized for each mission) The core components and the equipment baseline constitute the InnoSat Generic System Architecture that can be used to build, or instantiate, a system for a specific mission. Even if several types of systems can be built using the generic system architecture, one baseline reference system has been assumed: MATS Mission Definition Phase Report page 43

44 Platform Development InnoSat Baseline: This is a 3-axis stabilized, nadir/forward-pointing spacecraft in day/night orbit. Possible extensions to the baseline configuration are: InnoSat SP (Sun Pointing): This is a sun-pointing spacecraft in SSO with arbitrary LTAN. Optionally, a slow spin can be employed for heat balancing and/or use of wire booms. InnoSat HT (High Torque): This is configuration is similar to the sun-pointing configuration but with larger reaction wheels to facilitate fast slews to target specific objects. These extensions are possible to realize with the same core components in the architecture but would require modifications in mainly the power subsystem, in the attitude control system and in the mechanical design. Figure 6-2: InnoSat System Development Approach MATS Mission Definition Phase Report page 44

45 Payload and Science Development MATS Payload and Science Development MATS Mission Definition Phase Report page 45

46 Payload and Science Development 1. Responsibilities MISU (Department of Meteorology, Stockholm University) has the overall responsibility for the MATS science, as well as instrument concept, trade-off decisions, development plan, procurement of optical components, and calibration. Development of MATS will be carried out for MISU by Omnisys Instruments, responsible for detailed optical, mechanical, power and control design, and procurement of major instrument parts, integration and test of the various instrument models, and interfaces to both the detectors and the spacecraft platform. Contributions to the development will be made by KTH (Royal Institute of Technology) and Chalmers University of Technology. KTH will be responsible for procurement of detectors and read-out electronics and development of software, A/D converters and an interface to the power and control units of Omnisys. Chalmers will be responsible for input to the optical design and retrieval algorithms. MATS payload product tree Structure Optical components Imaging detectors Albedo detectors Power and contol Test facilities GSE Optics housing CCD and read-out electronics ADC and digital interface EPS Assembly and Integration Test Alignment gear Baffles Read-out software Power interface Harness Optical Tests Transport equipment Thermal h/w ADC and digital interface CPU and control software Calibration Check-out and flight control software Star tracker interface Power interface Data compression software Environment test Time stamping software MATS payload top level payload tree. Colors mark the primary responsibility areas: blue - Omnisys; green - KTH; orange - MISU. 2. Payload Concept 2.1 Design MATS is a self-contained seven-channel imager in IR and UV wavelengths, four IRchannels and two UV channels observing in the limb direction and one IR channel basically nadir-looking. Two complementary photometers in the nadir are also foreseen in order to further support limb measurements. MATS Mission Definition Phase Report page 46

47 Payload and Science Development Table: Key performance parameters for the MATS limb imagers (6 channels). channels IR O 2 A-band IR background UV spectral ranges nm nm nm nm nm nm nominal field of view km km field of view with margins km km limb resolution km km km CCD pixels used CCD pixel binning binned super pixels = = = image size, uncompressed bit = bit = bit = 6.0 kb 0.5 kb 19.2 kb compression factor image size, compressed 2.0 kb 0.2 kb 6.4 kb readout interval 5 s 3 s images per orbit (entire orbit) (summer lat > 45 ) data per channel and orbit 2.2 MB 0.2 MB 3.2 MB total data per orbit 11.2 MB Table: Key performance parameters for the MATS nadir imager (1 channel). name IR O 2 A-band wavelength range nm time of day nightglow horizontal range (instantaneous field of view) km (field of view ±17 ) horizontal resolution (along track across track) 5 5 km dynamic range 12 bit (logarithmic) image size 6 kb image compression none integration time ~1 s readout rate every 45 s images per orbit 50 (assuming sufficient darkness along 40% of orbit) data per orbit 0.3 MB MATS Mission Definition Phase Report page 47

48 Payload and Science Development The major constituents of the instrument are the mechanical structure, including optical baffles, thermal control hardware and the star tracker interface, the relay optics, the CCD sensors with read-out and associated electronics, and finally the instrument power and control unit. Interfaces to the spacecraft platform regard telemetry, command, power, optical, thermal and mechanical aspects. Telemetry and commands are transferred over SpaceWire connections. Power is provided over 28V lines. Thermally MATS is largely decoupled from the spacecraft structure. Mechanical structure of the MATS limb imagers. Mechanical structure of the MATS nadir imager. A rapid first design iteration or assessment of critical parts of the instrument was performed during the MATS Mission Definition Phase. Mass, power and data budgets were established, as well as preliminary mechanical, electrical and thermal interfaces. First analyses of temperatures in orbit and structure resonance frequencies were carried out. Substantial effort went into assessing the optical requirements, properties and components, as well as verification methodology. The most critical optical items are MATS Mission Definition Phase Report page 48

49 Payload and Science Development the detectors, where the baseline choice is to use CCD sensors for both the IR and the UV channels. The optical desin has to fulfill three basic requirement: provide sufficient image quality provide sufficient stray light suppression provide acceptable range of incident angles for interference filters Preliminary optical design of the MATS ultraviolet imager. The mirror telescope delivers images of the limb to the ultraviolet spectrograph unit. Here, the light is split by a beam splitter (BS) into two spectrally separated images with spectral ranges defined by interference filters (IF). The image detection is based on CCD sensors. Baffle system and internal optics with field stops (FS) are designed to minimize effects of stray light. Preliminary optical design of the MATS infrared imager. The mirror telescope delivers images of the limb to the infrared spectrograph unit. Here, the light is split by beam splitters into four spectrally separated images with spectral ranges defined by interference filters. The image detection is based on CCD sensors. Baffle system and internal optics with field stops (FS) are designed to minimize effects of stray light. MATS Mission Definition Phase Report page 49

50 Payload and Science Development 2.2 Model philosophy The following test units will be manufactured as part of the MATS mission: Breadboards: Currently the following breadboards are planned: - Two KTH CCD read-out and associated electronics breadboards, one for internal use at KTH and one for use by Omnisys for (power &) control/communications interface verification. - Two Omnisys control breadboards, one for internal use and one for early inclusion into the OHB Avionics Test Bench (ATB) to develop and test the communications interface to the spacecraft. Here it is assumed that an interface model is provided by OHB early enough for the breadboard development. - One Omnisys baffle breadboard to verify the present concept of shutting out stray light and reflecting away sunlight. - A breadboard CCD mechanical mounting, according to instructions from the CCD supplier to KTH and Omnisys design considerations for optical components in general. Omnisys can provide the breadboard, if so agreed. Other breadboard items sets may be defined as we see fit during the design phase up to PDR. Prototype: An opto-mechanical structural prototype of MATS will be produced before CDR in order to test compliance of the structure design concept including test optics to the environmental requirements, like thermal-vacuum, vibration, and in particular shock, posed by the orbit environment and the chosen launcher. Structural Model (SM): The Structural Model will be delivered to OHB and used for mechanical verification and qualification on spacecraft system level. It shall be representative of the flight structure and equipped with real subsystems or mass dummies depending on type of test and availability of subsystems. Engineering Model (EM): The engineering model will be delivered to OHB and used on their ATB for verification of the electrical and communications interface to the spacecraft. It shall be electrically completely representative of the flight model, except for using down to only one imaging channel with a test CCD. Proto-Flight Model (PFM): The flight model is the final model to be delivered. This is the first complete model of the instrument and is therefore in fact a proto-flight model. It will be used for functional and performance testing as well as calibration before being delivered to system AIT. On system level it will be subjected to environmental qualification level testing with acceptance time durations. MATS Mission Definition Phase Report page 50

51 Payload and Science Development 3. Research group activities In the following, work packages of the three MATS research groups (MISU, Chalmers, KTH) are listed. As described above, Omnisys Instruments has a major responsibility for project parts concerning the MATS payload development. Work packages of the reserach groups have in this case a supporting function for corresponding work packages by Omnisys. 3.1 Management and coordination The MATS project builds on a broad involvement of research groups and space industry. Important organisational structures comprise the platform consortium, the instrument consortium and the general science team. This work package concerns management and coordination within and in-between these parts. Important for this process are the MATS steering group and the instrument consortium's coordination group. Documentation of the mission achievements is important in order to feedback to different parts of society and the scientific community. Science coordination Develop and consolidate MATS science objectives. Develop the MATS Science Team as a resource for mission definition, instrument and method development, and scientific analysis. Establish collaborations between MATS and complementary projects and databases. Collect and document mission outcomesfor feedback to different parts of society and the scientific community. Connect to outreach activities (WP R-11). Consolidate mission requirements Iterate mission requirements and measurement concepts in MATS Science Team. Refine mission requirements with particular emphasis on instrument design questions. Coordination of design, assembly and test activites Based on project organisation, coordinate workflow and interaction between MATS reseatrch and industrial groups. Define, coordinate and review the involvement of the research groups in activities led by Omnisys and OHB. Coordination of retrieval development and data production Define tasks and challenges in retrieval development. Establish collaboration with related/complementary retrieval projects. Coordinate definition and development of modular processing chains. 3.2 Sensor development Determine which Analog-to-Digital Converters to use (commercial or spacequalified) and verify by test that it meets the requirements. Design the Engineering Model electronics for control and readout of the CCDs. Develop and test the FPGA firmware. Manufacture Engineering Model units of the CCD control and readout electronics. Develop EGSE including software for tests of CCD and control/readout MATS Mission Definition Phase Report page 51

52 Payload and Science Development electronics. Test Engineering Model units of CCD and control/readout electronics, and update FPGA firmware software as needed. Test and characterize the flight CCDs, regarding response, noise, bad pixels, etc. Manufacture Flight Model units of CCD and control/readout electronics. 3.3 Design limb instrument MISU has the lead in defining the limb measurement concept and overall design strategies. Omnisys Instruments lead designing the MATS IR and UV limb imagers. Based on MRD and MDP design studies, the design will be finalized with particular regard to sensitivity, stray light suppression, imaging quality and spectral filtering. Verification and calibration procedures are developed in parallel. Define limb imager concept Define limb imager concept and overall design, based on conclusions of the design trade-offs. This concerns decsioons on size and grade of CCD, definition of the readout and control electronics interface, component requirements, observation geometry of, baffle designs, signal strength, cleanliness strategy, and thermal design. Support limb imager design Support a deepend design study of the MATS IR and UV limb imagers with particular regard to the requirements in terms of sensitivity, stray light suppression, imaging quality and spectral filtering. This work is coordinated with tests on a baffle prototype. After payload PDR, support finalization of IR and UV limb imager design. This work is coordinated with tests on the prototype model. Develop limb optics verification and calibration procedures Support the development of procedures for verifying and calibrating test and flight models in accordance with the MRD. Verification and calibration procedures comprise (1) absolute sensitivity (2) spectral response (3) stray light suppression (4) imaging quality (5) alignment Calibration procedures for (1) and (2) are developed for MISU's calibration facility. Verification procedures for (3), (4) and (5) are developed for Omnisys' optical test facility. Complementary procedures are developed for verifying (1), (4) and (5) during spacecraft AIT. 3.4 Design nadir instrument MISU has the lead in defining the nadir measurement concept and overall design strategies. Omnisys Instruments lead designing the MATS IR nadir imager. Based on MRD and MDP design studies, the design will be finalized with particular regard to sensitivity, stray light suppression, imaging quality and spectral filtering. Verification and calibration procedures are developed in parallel. WP R-4 also comprisies design MATS Mission Definition Phase Report page 52

53 Payload and Science Development work on the nadir-viewing albedo monitor to be employed in support of the limb measurements. Define nadir imager concept Define nadir imager concept and overall design, based on conclusions of the design trade-offs. This concerns decsions on definition of the read-out and control electronics interface, component requirements, observation geometry of, baffle design, signal strength, cleanliness strategy, and thermal design. Support nadir imager design Support a deepend design study of the MATS IR nadir imager with particular regard to the requirements in terms of sensitivity, stray light suppression, imaging quality and spectral filtering. After payload PDR, support the finalization of the MATS nadir imager design. This work is coordinated with tests on the prototype model. Design albedo monitors Perform a deepend design study on the nadir albedo monitors in support of the IR limb measurements. Consolidate the design of telescope optics, baffle, filter, and photodiode sensor. Develop nadir optics verification and calibration procedures Support the development of procedures for verifying and calibrating test and flight models in accordance with the MRD. Verification and calibration procedures comprise (1) absolute sensitivity (2) spectral response (3) stray light suppression (4) imaging quality (5) alignment Calibration procedures for (1) and (2) are developed for MISU's calibration facility. Verification procedures for (3), (4) and (5) are developed for Omnisys' optical test facility. Complementary procedures are developed for verifying (4) during spacecraft Assembly and Integration Test. 3.5 Instrument integration and testing Omnisys Instruments has the lead in manufacturing, integrating and testing MATS instruments and payload. MISU and KTH support this work work. As a starting point for this work, Omnisys' optical testing facility be installed and MISU's calibration facility will be updated. Subsequent test activities range from verification of instrument parts to extensive tests of payload models, in close iteration with the design work. Final step is the calibration of the Proto-Flight Model at MISU before delivery to the spacecraft Assembly and Integration Test. Update optical calibration facility Update and prepare MISUs calibration facility (darkroom) for the MATS calibration procedures. This concerns both absolute calibration and relative spectral calibration MATS Mission Definition Phase Report page 53

54 Payload and Science Development of the instrument channels. Also individual optical components (mirrors. beam splitters etc.) will be quality checked after purchase. Support development optical test facility Support the development and preparation of an optical test facility at Omnisys for the MATS testing and verification. This tests of imaging quality, stray light susceptibility and instrument alignment. Mobile equipment will be developed for tests of imaging quality and alignment on the assembled spacecraft. Order and characterize optical test components Based on results fromthe preliminary design study, order test versions of optical components (mirrors, beam splitters, filters, lenses). Characterize these at MISU's optical calibration facility after delivery. Support testing of limb baffle prototype Support the manufacturing and test of a prototype of the limb baffle system. Tests at Omnisys' optical test facility concern the stray light susceptibility for varying incident angles in both UV and IR. Support optical tests of electrical/optical prototype Support the optical tests on the electrical/optical prototype payload model. These tests Omnisys' optical test facility concern basic instrument functioning, imaging quality and mapping of stray light susceptibility. Support environmental tests of electrical/optical prototype Support the environmental tests on the electrical/optical prototype payload model. Imortant tests concern the functionality and optical properties of the instruments after undergoing shock tests and other mechanical/thermal stress. Order and characterize optical flight components Based on results fromthe preliminary design study, order flight versions of optical components (mirrors, beam splitters, filters, lenses). Characterize these at MISU's optical calibration facility after delivery. Manufacture and test albedo monitors Manufacture albedo monitor. Perform basic function tests and calibration at MISU's optical calibration facility. Omnisys prepares mechanical and electrical interface for payload integration. Support Proto-Flight Model integration and alignment Support the integration of the Proto-Flight Model. Support the alignment and alignment measurements of the instrument channels at Omnisys' optical test facility. Support Proto-Flight Model function, performance and acceptance tests Support the function and performance tests on the Proto-Flight Model. KTH and MISU support in particular tests and characterization of CCD performance and optical performance. Support Factory Acceptance Test and subsequent Factory Acceptance Review. MATS Mission Definition Phase Report page 54

55 Payload and Science Development Proto-Flight Model calibration Perform final calibration of PFM instruments at MISU's optical calibration facility. Calibration measurements concern both absolute sensitivity and relative spectral response of the instrument channels. 3.6 Spacecraft integration and testing OHB Sweden has the lead in integrating and testing the InnoSat/MATS spacecraft. Under WP R-6, MISU follows and supports this work. This concerns tests on the Structural and Engineering Models, Proto-Flight Model, as well as tests in connection with launch preparation activities. Support tests of structural model and engineering model Support OHB's tests of the structural model and engineering model. Together with Omnisys, evaluate the results of these tests and possible conclusionas for instrument performance and scientific mission. Support spacecraft Assembly and Integration Test Support OHB's test program during the system integration and environmental tests. Together with Omnisys, follow up on instrument status in connection with tests, including imaging quality and instrument alignment. Finally, go through Flight Acceptance Review, thus qualifying Proto-Flight Model to Flight Model. Support launch preparation Support OHB's test program and activities in preparation for launch. 3.7 In-orbit operations planning In orbit operations require active planning and implementation by telecommanding. Telecommanding routines are developed in collaboration with Omnisys and OHB. These are subsequently employed during commissioning phase, nominal science operation and calibration operations. Define operation modes Define in-orbit operation modes for commissioning, nominal science operations and calibration operations. Calibration operations concern - alignment and pointing tests by star imaging - characterisation of CCD pixels - calibration by imaging of the Moon - calibration by observing molecular scattering from lower tangent altitudes Together with Omnisys and OHB, define a set of telecommands necessary to contol nominal science operations and calibration operations. Support commissioning activties Support OHB during the post-launch commissioning phase. For the payload, commissioning comprises MATS Mission Definition Phase Report page 55

56 Payload and Science Development - commissining the instruments - commissioning the nominal science operations - commissioning calibration operations Science operation planning Define weekly operation planning for the nominal science activities. This concerns in particlar seasonal and latitudinal data selection from the instrumnent channels. Calibration operation planning In collaboration with OHB, decide on occassions for calibration activities. Define operation planning for the calibration activities. Calibration operations concern - alignment and pointing tests by star imaging - characterisation of CCD pixels - calibration by imaging of the Moon - calibration by observing molecular scattering from lower tangent altitudes 3.8 Retrieval development Modular algorithms are developed for the complete chain from Level-1a raw data to Level-2b scientific data, including error propogation. As part of this, simulation models are developed that also serve instrument and measurement planning. Requirements on operational software and hardware are defined. Development and testing continue throughout the MATS project, with a particular emphasis on the period when real data become available post-launch. Define retrieval requirements and data productes Define scientific goals of data retrieval. Define levels of data products. Break down retrieval tasks into modular retrieval development plan. Measurement simulations Analyze radiative transfer of the MATS measurements. Develop atmospheric forward models and instrument transfer functions. Continued testing and optimization of these algorithms throughout the project. Data reduction algorithms Define and develop algortithms converting Level-1a raw data to input to Level-2 retrieval algorithms. As part of this, develop algorithms for calibration and data correction (dark counts, stray light etc.). Implement error analysis. Continued testing and optimization of these algorithms throughout the project. Tomographic algorithms Test and decide on tomographic retrieval scheme. Develop and test retrieval algorithms. Implement error analysis. Define software and hardware requirements (computer cluster). Continued testing and optimization of these algorithms throughout the project. Airglow retrieval Develop and test retrieval algorithms for background correction, dayglow spectroscopy, nightglow spectroscopy, temperature derivation. Implement error MATS Mission Definition Phase Report page 56

57 Payload and Science Development analysis. Define software and hardware requirements. Continued testing and optimization of these algorithms throughout the project. Noctilucent cloud retrieval Develop and test retrieval algorithms for background correction, noctilucent cloud spectroscopy, microphysics retrieval. Implement error analysis. Define software and hardware requirements. Continued testing and optimization of these algorithms throughout the project. 3.9 Operational data retrieval With basic retrieval algorithms in place (WP R-8), operational retrieval is planned, implemented and tested in a modular way. Input and output data formats are defined. Routines are developed for handling input from in-orbit calibration operations. Reliable data production and distribution schemes are implemented, complemented by quality assurance routines. Define data flows and structure Analyze input raw data format and develop inout routines. Decide on data flows and structures. Define output format and distribution routines. Prepare documentation. Hardware implementation Decide on and plan hardware system (computer cluster). Order and implement computer hardware and basic software at MISU. Software implementation Optimize retrieval algorithms for operational use on computer cluster. Implement and test on computer cluster. Develop routines for handling input from in-orbit calibration operations. Establish data flows (Parallel data centre, end users, etc.) Data production Take in operational Level-1b raw data. Produce and distribute Level-1b, 2a and 2b data. Monitor retrieval and data flows. Provide documentation. Quality control and validation studies Verify and apply input from in-orbit calibration operations. Provide feed-back to planningof calibration operations. Establish collaborations for validation. Plan and carry out validation against ground-based and space-borne projects and databases Scientific analysis Based on Level-2 data products, and knowledge of the MATS instruments and operation, perform deeper scientific studies. In accordance with the MATS scientific objectives, these studies concerns primarily airglow (and related composition analysis), temperature fields, wave processes and noctilucent cloud microphysics. Coanalysis with scientific results from other missons is essential to maximize the scientific output. Collaborations are established within the MATS Science Team and beyond. MATS Mission Definition Phase Report page 57

58 Payload and Science Development Airglow studies Relate airglow data to airglow photochemical processes and species retrievals. Analyse seasonal and spatial variabilities. Relate to and co-analalyze with other projects and datasets. Co-analyze limb and nadir measurements. Atmospheric temperature and structure Analyze temperature fields from airglow retrieval. Analyze structures in airglow, retrieved species and temperature fields. Analyse seasonal and spatial variabilities. Relate to complementary data fields and missions. Atmospheric waves Analyze wave structures on different scales. Analyse seasonal and spatial variabilities. Relate to complementary data fields and missions. Invoke models (large scale models, case studies). Noctilucent cloud structure and microphysics Analyze microphysical parameters and processes. Analyse seasonal and spatial variabilities. Analyze wave structures in NLC. Relate to complementary data fields and missions. Relate to microphysocal and global modelling Outreach Outreach activities are central both for the InnoSat satellite concept and the MATS science mission. In collaboration with SNSB and indiustry, a broad range of tools and pathways will be utilized. It is important to make use of existing pathways and organisations. Create outreach material Define goals and target groups. Create information material for the internet. Coordinate activities with SNSB and industry. Plan, design and create website (both SNSB and Stockholm University). Create presentation material (ppt) and printed material for schools etc. Support SNSB in creation of media material. Create highprofile outreach material for politicians, lobby groups etc. Outreach activities In coordination with SNSB and industry, create and/or choose opportunities for outreach. Target school teachers as a primary target group. Utilize existing support infrastructure and organizations. Document results of outreach activities. MATS Mission Definition Phase Report page 58