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Advances in Space Imaging

Advances in Space Imaging. Russell A. Howard Naval Research Laboratory NSF Workshop on Small Missions, 15-17 May 2007. Outline. Overview of the STEREO Mission Overview of SECCHI instrument and its capabilities Some early observations/results

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Advances in Space Imaging

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  1. Advances in Space Imaging Russell A. Howard Naval Research Laboratory NSF Workshop on Small Missions, 15-17 May 2007

  2. Outline • Overview of the STEREO Mission • Overview of SECCHI instrument and its capabilities • Some early observations/results • Thoughts on miniaturizing this type of instrumentation

  3. STEREO Science Objectives • Understand the origins and consequences of CMEs • Determine the processes that control CME evolution in the heliosphere • Discover the mechanisms of solar energetic particle acceleration • Determine the 3-D structure and dynamics of corona and interplanetary plasmas and magnetic fields

  4. STEREO Instruments • Remote Sensing • Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) PI: Russell Howard, Naval Research Laboratory • STEREO/WAVES (SWAVES) PI:Jean Louis H. Bougeret, Centre National de la Recherche Scientifique, Observatory of Paris • In Situ • In situ Measurements of Particles and CME Transients (IMPACT) PI: Janet G. Luhmann, University of California, Berkeley • PLAsma and SupraThermal Ion and Composition (PLASTIC) PI: Antoinette Galvin, University of New Hampshire

  5. STEREO Spacecraft (Behind) SCIP SWAVES Boom (3x) Plastic HI SWAVES Boom (3x) SWAVES Boom (3x) IMPACT Boom

  6. STEREO Orbits 4 yr. 3 yr. 2 yr. Ahead @ +22/year 1 yr. Sun Sun Earth 1yr. Ahead Behind @ -22/year Earth 2yr. 3 yr. Behind 4 yr. Heliocentric Inertial Coordinates (Ecliptic Plane Projection) Geocentric Solar Ecliptic Coordinates Fixed Earth-Sun Line (Ecliptic Plane Projection)

  7. SECCHI Science Overview 021104-06SECCHI_CDR_Science.8

  8. COR/HI Overlap Regions

  9. Fields of ViewCOR2 (Black)HI-1 (Red) and HI-2 (Blue)

  10. SECCHI/EUVI First Light ImagesFe IX, Fe XII, Fe XV, He II

  11. EUVI Enhanced Images • This is an example of wavelet enhanced EUVI (Fe XV, 284A) images of a solar rotation in March • They reveal the off-limb structures out to the edge of the field of view (1.7 Rsun) • Similar movies in Fe X and Fe XII also show the XUV structures to the FOV edge • This enables us to couple the white light structures in the COR1 coronagraph with an inner limit of 1.4 Rsun to the disk.

  12. SECCHI/COR2 and LASCO/C2/C3

  13. Image of Moon from SECCHI/HI-2 During STEREO-A Flyby 12/15/2006

  14. Comet McNaught Movie HI-1

  15. HI-2B Comet McNaught Receding Milky Way Earth’s Moon (Saturating The CCD Pixels) Stray Light From Earth TO SUN Comet McNaught Earth Occulter

  16. HI 1A: 2007 Feb 1-15 Streamer relocates to a higher latitude Mercury Venus and optical system ghost artifact

  17. Putting All the A-Telescopes Together 4º 15 R 0 65º 260 R 24º 96 R 90º 360 R 4R ≈ 1º

  18. CME observed in All Telescopes (24 Jan 2007) 0 4 24 55 90 DEGREES Ecliptic Plane

  19. EUVI, COR1, COR2: 9 Feb 2007 Outer Limit = 15 Rsun Cropped on West Limb

  20. COR2, HI-1, HI-2: 9 Feb 2007Running Differences & Additional Filtering

  21. SECCHI – Early Results:COR2 Observations • Apparent limiting magnitude: at least m11 • Lots of stars • Observed comets: • Surprisingly few! • Over 40 “SOHO” Kreutz have passed through COR2 • We have seen just four of them • This is due to the bandpass of COR2 relative to LASCO/C2

  22. Comet Encke

  23. Miniaturization Thoughts (1) • NRL/Solar Physics has been involved in all classes of instruments from small rocket payloads to very large shuttle class instruments. • Solar Imaging requirements • Pointing system to point the payload at the Sun. The trend now is for very accurate pointing with low jitter (sub arc sec pointing) • Spinners are possible but 3-axis stabilized platforms much better • Large apertures/long focal lengths for highest resolution, shortest exposure times • Monitoring instruments (e.g. for space weather) could relax these requirements, thereby reducing the size/mass. • If cadence permits, images can be summed on-board to increase the number of photons collected. The SECCHI/HI-1/2 accumulate respectively 50/100 images to achieve ~30/60 minutes of exposure • The size of the SOHO/LASCO was reduced to save mass, but C3 reduction hit practical limits in the size of overlap and could not be reduced any further.

  24. Miniaturization Thoughts (2) • Can any of the STEREO be minimized? • Consisted of 2 spacecraft, • Each S/C ~450 kg dry mass, ~500 kg wet. • Instrument complement • ~95 kg each S/C • SECCHI • 5 telescopes, electronics box, interconnect harness ~50 kg • One subsystem: Heliospheric Imager (HI) ~12 kg shown on left. Most of the mass is the CCD passive cooling system • The optical system itself is quite small.

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