Progress Towards the Solar Dynamics Observatory

Transcription

1 Progress Towards the Solar Dynamics Observatory Barbara J. Thompson SDO Project Scientist W. Dean Pesnell SDO Assistant Project Scientist Page 1

2 SDO OVERVIEW Mission Science Objectives The primary goal of the SDO mission is to understand, driving towards a predictive capability, the solar variations that influence life on Earth and humanity s technological systems by determining How the Sun s magnetic field is generated and structured How this stored magnetic energy is converted and released into the heliosphere and geospace in the form of solar wind, energetic particles, and variations in the solar irradiance. Mission Specs: April 2008 launch: GTO to GEO Inclined Geosynchronous Orbit (semiannual eclipse seasons) Five-year mission baseline 3-axis stabilized spacecraft Data transmission: continuous high rate data stream ~150 Mbps compressed data at Ka-Band Single ground station Mission development and management at GSFC Science Investigations Helioseismic and Magnetic Imager (HMI) PI Institution: Stanford University Images the Sun s helioseismic, longitudinal and vector magnetic fields to understand the Sun s interior and magnetic activity EUV Variability Experiment (EVE) PI Institution: University of Colorado Measures the solar extreme ultraviolet (EUV) spectral irradiance to understand variations on the timescales which influence Earth s climate and near-earth space Atmospheric Imaging Assembly (AIA) PI Institution: LMSAL Provides multiple simultaneous high-resolution images of the corona over a wide range of temperatures to determine magnetic structure and variability Page 2

3 SDO investigations in brief The science of SDO will be performed by its three investigations: EUV Variability Experiment (EVE, PI: Tom Woods, University of Colorado): Measure the EUV spectral irradiance from 0.1 to 105 nm at a cadence of 10 seconds. EVE will specify the spectral irradiance with a sensitivity that allows us to gauge the energy input into the complex processes of the Earth's atmosphere and near-earth space. Its temporal resolution will allow us, for the first time, to understand the flare-induced impacts on these processes. Helioseismic and Magnetic Field Investigation (HMI, PI: Phil Scherrer, Stanford University): Measure the Doppler shifts due to oscillation velocities over the entire visible disk. High-resolution measurements of the longitudinal and vector magnetic field over the whole visible disk of the Sun. HMI will observe "filtergrams" of the Sun which will be used to produce dopplergrams and magnetograms. Analysis of these measurements will allow us to understand the interior processes governing the transition from solar minimum to solar maximum, will be able to probe the dynamics of the near-surface shear layer to observe local strong flux regions before they reach the photosphere, and will measure the highly variable magnetic field. Atmospheric Imaging Assembly (AIA, PI: Alan Title, Lockheed-Martin Solar and Astrophysical Laboratory): Four multi-wavelength telescopes with the spatial resolution of TRACE but a full-sun field of view to provide chromospheric and coronal images at a 10-second cadence. AIA will capture the initiation and progression of dynamic processes, with the spatial resolution necessary to understand their connection to the magnetic field and the spectral coverage to infer the processes at multiple temperatures. Page 3

4 What SDO is designed to do In order to meet the needs of the Living With a Star program and determine the drivers and diagnostics of solar activity and variability which affect Earth and humanity, the Solar Dynamics Observatory must: Provide nearly continuous coverage of solar activity Provide coverage of the regimes (interior, photosphere, low corona) in which the activity occurs Provide sufficient data on the types of phenomena which impact Earth, near-earth space and humanity Observe over the relevant timescales (seconds to years) of solar variability Analyze the data and interpret the resulting inferences about the physical processes that govern the Sun-Earth system. Page 4

5 7 Science Questions of SDO The SDO Science Definition Team determined seven chief Science Questions, which are defined and documented in the SDO Level 1 Requirements. 1. What mechanisms drive the quasi-periodic 11-year cycle of solar activity? 2. How is active region magnetic flux synthesized, concentrated, and dispersed across the solar surface? 3. How does magnetic reconnection on small scales reorganize the large-scale field topology and current systems? How significant is it in heating the corona and accelerating the solar wind? 4. Where do the observed variations in the Sun s EUV spectral irradiance arise, and how do they relate to the magnetic activity cycles? 5. What magnetic field configurations lead to the CMEs, filament eruptions, and flares that produce energetic particles and radiation? 6. Can the structure and dynamics of the solar wind near Earth be determined from the magnetic field configuration and atmospheric structure near the solar surface? 7. When will activity occur, and is it possible to make accurate and reliable forecasts of space weather and climate? Page 5

6 Yohkoh present: TRACE demonstrated the power of high-resolution coronal imaging. However, its limited field of view kept us from understanding the global processes. EVE, HMI and AIA Heritage : The Yohkoh Mission taught us the power of continuous full-disk imaging at high energies. However, it was primarily a gauge of the high-energy corona present: The SOHO Mission was launched at solar minimum, prioritizing the fundamental processes of the Sun. It brought us a powerful helioseismology investigation (MDI) which revealed processes occurring in the solar interior, and full-disk and coronal imagers (EIT and LASCO) which revealed that even the solar minimum corona is a dynamic and even dangerous environment present: TIMED (and SOHO) established a foundation for our ability to connect the variations in the solar EUV irradiance with a number of fundamental effects at Earth. However, many effects require an understanding of spectral irradiance at a higher spectral resolution and time cadence present: SORCE is performing precise measurements of the total, UV, IR and X-ray solar irradiance to gauge the input of energy to various processes at Earth. However, many fundamental processes require EVE's sensitive spectral resolution of the EUV irradiance. Page 6

7 Significant Events Completed all S/C component/subsys. & Instrument Peer Reviews & PDRs, Ground System element level Peer Reviews. Successful Mission PDR held March 9-12, 2004 Liz Citrin replacing Ken Schwer as Project Manager beginning March 2004 AIA Investigation PDR concludes April 14-15, 2004 SDO Confirmation Review: June 2004

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