Remote Sensing for Space Exploration in 50 Years

1. Remote Sensing for Space Exploration in 50 Years Steven Beckwith Space Telescope Science Institute Johns Hopkins University

2. Investment Predictioning the Future • Most of the interesting science problems 50 years out are unknown, but we understand the limits of nature • (Almost) all technological breakthroughs that will change the nature of astronomical observations will be developed for other customers (not astronomers) NASA Space Science 1.5% NASA Other 16% NASA is a small fraction of the US space industry; space science is a small fraction of NASA Commercial Space 54% Military Space 28%

3. Earth Observations from Space • Benefits of HEO: • Long dwell times on target: continuous coverage • Large field of view on Earth ⇒ high information / image • Few satellites to cover surface • LEO ⇒ 90 satellites, 200 km FOV • GEO ⇒ 3 satellites, 10,000 km FOV • Surveillance: 10 cm (r0) • 41 mas @ LEO: ~2m (KH series) • 0.5 mas @ GEO: 160m (0.5 µm) • Earth Science: 5m • 28 mas @ GEO: 7m (1 µm) • 0.6 mas @ L2: 150m (0.5 µm) Defensible 0.4 ≲≲ 20 µm

4. The Natural Limits of Observation • Absorption-free wavelength coverage • Space: 10-14.5 µm (pair production) to 10 km (ISM absorption) • Ground: 0.3 µm - 25 µm (limited), 300 µm to ~10m + weather • Low foreground (background) radiation • Space backgrounds are typically orders of magnitude less than terrestrial backgrounds, expect in the range 0.4 - 0.6 µm • Wavefront stability • Space: • Diffraction-limited performance all  > 0.1 µm • Diff-limited entendue ~ 100 m2 deg2 (~1011 pixels) is easy • High contrast (~10-10) achievable, in principle • Ground: • Diffraction-limited performance all  > 1 µm, in principle • DL etendue < (30m x 0.03º)2 ~ 1 m2 deg2 (~108 pixels) is hard • Limited photometric contrast (~10-6?) The natural limits to observation are vastly smaller in space than on the ground for any technique.

5. Background Radiation AO corrected

6. DMT consortium http://dmtelescope.org/science.html Near Earth Objects Pan Starrs LST LSST

7. Survey Information Rates • Space vs. ground based telescope per image: • >30x deeper (lower background / pixel) • >40x information capacity / image, (resolution x depth) • LSST 30s / image: • 319 m2 deg2 • 2.5x108 pix/image • 24.5 AB mag AW/t 15 sec exposures 2000 exposures per field LSST in space would have 2x slower mapping speed but 20x faster information rate for a similar cadence (3 days/3) • 6.5m space, 30s: • 163 m2 deg2 • 1010 pix/image • 28.1 AB mag

8. 8m 4m 2m Mapping the Universe Dark energy: BAO, SN Ia, lensing Dark matter: lensing, structure of universe 1016 NEOs Asteroids KBOs Transients GRB-like Novae SN Moving obj. Microlens. 5 yr space mission all sky surveys 1014 1000x 4 sr with 0.5" seeing # Resolution elements LSST 1012 Pan-Starrs 30x SDSS Palomar Sky Survey 1010 108 Human eye HUDF 106 0 5 10 15 20 25 30 35 AB Magnitude

9. Massively Parallel Astrophysics From Tony Tyson's LSST talk, STScI 11/7/07 Science from a large sky survey: • Dark matter/dark energy via weak lensing • Dark energy via baryon acoustic oscillations • Dark energy via supernovae • Galactic Structure encompassing local group • Dense astrometry over 20000 sq.deg: rare moving objects • Gamma Ray Bursts and transients to high redshift • Gravitational micro-lensing • Strong galaxy & cluster lensing: physics of dark matter • Multi-image lensed SN time delays: separate test of cosmology • Variable stars/galaxies: black hole accretion • QSO time delays vs z: independent test of dark energy • Optical bursters to 25 mag: the unknown • 5-band 27 mag photometric survey: unprecedented volume • Solar System Probes: Earth-crossing asteroids, Comets, TNOs • Planetary transits

10. Exoplanet Atmospheres 's of interest

11. ExoPlanet Atmospheres & Telescope Size IWA = 25 mas (10m / Dtel) 75 pc OHZ IHZ Nobs ~ Dtel3.3 9 pc Life-bearing planets to study = Nsampleearth Sample sizes given above.

12. Space-Time Structure:Observing Black Holes Courtesy of Matt Mountain (2007) Image of accretion disk To observe the structure of Space -Time around a Schwarzschild Black Hole requires angular resolutions in the 10~50 arcsec. range Computations by Youri Dabrowski

13. HH30 Generation of Jets: stars to BH Need ~100 µas for nearby stars M87 0.05 AU 0.01 Alfven surface B field Super-Alfvenic flow critical equipotential dead zone: coronal gas, soft x-rays x-wind funnel flow uv hot spots disk Rx sonic surface Shu et al. 1994

14. Surfaces of Stars Betelgeuse with HST Computer Model

15. Technology Advances • Large optical facilities constructed & tested in space • Lifts today's limits on optical size • No data processing/transmission limits • Optical transmission; maybe optical/QC processing • Focal plane sampling limited by optics only • Essentially unlimited numbers of pixels (Moore's law) • Multiple customers for remote sensing • NRO/military reconniasance • Global Earth sensing from GEO • Real-time Earth imaging for commerce • In space servicing & maintanence allows long-term investment in very large telescopes

16. The Power of Resolution M87 BH Milky Way BH Winds & Jets Interferometers Filled apertures