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L1 and L2 Observatories in the Post-2010 Era

L1 and L2 Observatories in the Post-2010 Era. Warren Wiscombe & Jay Herman NASA Goddard Francisco Valero Scripps Oceanography. Multiple Vantage Points (from NASA’s Earth Science Vision). Polesitter. Molniya Orbit. GEO. balloons. L1 Observatories. L2 Observatories.

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L1 and L2 Observatories in the Post-2010 Era

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  1. L1 and L2 Observatories in the Post-2010 Era Warren Wiscombe & Jay Herman NASA Goddard Francisco Valero Scripps Oceanography

  2. Multiple Vantage Points(from NASA’s Earth Science Vision) Polesitter Molniya Orbit GEO balloons L1 Observatories L2 Observatories IGARSS 2002

  3. Lagrange Points L1 and L2: New Planets! L-1 L-2 At L1 and L2, the sum of the Earth’s and Sun’s gravitational fields gives a net gravitational pull equal to that at Earth. Therefore, a spacecraft at L1 or L2 must orbit the Sun with the same period as the Earth.

  4. L1...More to Scale IGARSS 2002

  5. Simulated L1 View of Earth and Moon IGARSS 2002

  6. L1 and L2 Observatories as Nerve Centers of the SensorWeb “Perhaps Triana’s most important contribution to Earth science observations is the potential for using L1 observations of Earth to integrate data from multiple spaceborne as well as surface and airborne observation platforms in a self-consistent global database for study of the planet and documenting the extent of regional and global change.” National Academy of Sciences report on Triana, March 2000 IGARSS 2002

  7. Unique L1/L2 Attributes • Relate and connect all other observational assets • Synoptic view (all times at once) • High time resolution (1 min or better) • Sunrise to sunset coverage • Stably pull out small, delicate effects over many years • Monthly Moon calibration opportunities • Looong integrations for higher accuracy • Assist field programs • Much simpler data processing compared to LEO, GEO • A true global change observing location! IGARSS 2002

  8. Low Earth Orbit (LEO) and L1 Views 45-min LEO swath Sunrise to sunset instantly LEO view of Earth takes ~45 min to paint one swath covering ~1/14th of the planet — 11 hr to paint whole planet. From L1, can do same in less than 1 min (over 600x faster). IGARSS 2002

  9. Geostationary (GEO) Satellite Views Each GEO takes 15-30 min to paint its covered area. IGARSS 2002

  10. LEO DOMAIN L1 DOMAIN Spatio-Temporal Domain of a LEO Satellite vs. an L-1 Observatory IGARSS 2002

  11. The Triana Satellite NISTAR Faraday Cup EPIC Electrostatic Analyzer /Magnetometer Boom IGARSS 2002

  12. NISTAR: Views Whole Earth IGARSS 2002

  13. EPIC Imager: 10 channels 8–km resolution at nadir IGARSS 2002

  14. Triana in Launch Configuration IGARSS 2002

  15. EPIC Science Objectives • Ozone • Aerosols • Cloud phase (ice, water) and particle shape • Column water vapor • UV at the surface • Stratospheric dynamics • “Hotspot” — vegetation direct backscatter IGARSS 2002

  16. Sun L2 Earth Atmosphere Solar-Occultation Imager Solar Occultation from Lagrange point L2 using Fourier Transform Imaging Spectrometer with 10 Meter telescope Wavelength Range: 1 – 4 mm Resolution: 5 cm-1 or better Spatial Resolution: 1–2 km in altitude Available Solar Flux ~ 12 - 15% of Total Sun L2–EASI IGARSS 2002

  17. Sun Eclipsed by Earth from L-2 Detector rotates around Earth limb – 2 km altitude resolution – 1 to 4 mm spectrum NightsideEarth 440 km in Earth coordinates; 53,500 km on Sun Exposed Sun: – 15% of solar area – 4% of solar radius IGARSS 2002

  18. L2–EASI: Science Goals • Measure greenhouse gases at sunrise, sunset... • CO2, CH4, H2O, O3, O2, N2O • and get their first 3-D Mapping with resolution • Height, 2 km: Latitude, 1o Longitude, 2o IGARSS 2002

  19. Limb View from L2, 1.5 to 2 mm IGARSS 2002

  20. Other L2 Science Goals • Magnetotail • Cosmic rays • Lightning • Aurora • Airglow • Incoming bolides IGARSS 2002

  21. L2 L1 L1 and L2 Synergy: Two Examples Day and night observations of clouds dynamic observations of solar disturbances outside of the bowshock and within the magnetotail IGARSS 2002

  22. Technical Challenges at L1 and L2 • Large apertures (10 meter) • Communications back to Earth (at all!) • Data rate back to Earth • Orbit design • Power at L2 • Rotation of Earth • Thermal control (L2) IGARSS 2002

  23. Backup IGARSS 2002

  24. Halo Orbits can have any radius (more fuel to insert into tighter orbit)... 26,000 km 14,000 km 400 km but period is always 6 months. orbits are 3D; planar projections are Lissajous figures (orbit evolves from one quasi-ellipse to another over several years) stationkeeping once/month or more IGARSS 2002

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