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

2. 2 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) Commercial Space 54% Military Space 28% NASA Other 16% Investment NASA Space Science 1.5% NASA is a small fraction of the US space industry; space science is a small fraction of NASA

3. 3 Earth Observations from Space Surveillance: 10 cm (r 0 ) –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) 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 0.4 ≲ ≲ 20 µm Defensible

4. 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 m 2 deg 2 (~10 11 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 m 2 deg 2 (~10 8 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. 5 Background Radiation AO corrected

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

7. 7 Survey Information Rates 15 sec exposures 2000 exposures per field  LSST 30s / image: -319 m 2 deg 2 -2.5x10 8 pix/image -24.5 AB mag 6.5m space, 30s: -163 m 2 deg 2 -10 10 pix/image -28.1 AB mag Space vs. ground based telescope per image: ->30x deeper (lower background / pixel) ->40x information capacity / image, (resolution x depth) LSST in space would have 2x slower mapping speed but 20x faster information rate for a similar cadence (3 days/3  )

8. 8 Mapping the Universe Human eye Palomar Sky Survey SDSS Pan-Starrs HUDF 5 yr space mission all sky surveys 2m 4m 8m 10 6 10 8 10 10 12 10 14 10 16 05101520253035 AB Magnitude # Resolution elements Dark energy: BAO, SN Ia, lensing Dark matter: lensing, structure of universe LSST 4  sr with 0.5" seeing NEOs Asteroids KBOs Transients GRB-like Novae SN Moving obj. Microlens. 1000x 30x

9. 9 Massively Parallel Astrophysics 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 From Tony Tyson's LSST talk, STScI 11/7/07

10. 10 Exoplanet Atmospheres 's of interest

11. 11 ExoPlanet Atmospheres & Telescope Size  IWA = 25 mas (10m / D tel ) N obs ~ D tel 3.3 9 pc 75 pc Life-bearing planets to study = N sample  earth Sample sizes given above. D(m)Transit Planets Coronagraphic TotalSolar 2130 4112710 88521678 1668217261092 OHZ IHZ

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

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

14. 14 Surfaces of Stars Betelgeuse with HSTComputer Model

15. 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. 16 The Power of Resolution Winds & Jets M87 BH Milky Way BH Interferometers Filled apertures

17. 17 Exploration & Remote Sensing Distance for human explorers: –2 Myr BP to 1968: 40,000 km (Earth, NEO) –1969-1972: 400,000 km (Moon) –1972-2020: 40,000 km (NEO) –2040? 2 AU (Mars) Distance for robots –Currently >60 AU (Voyager) –Routinely: 10 AU (Voyager, Cassini, etc.) –Landing: 2 AU (Mars) Distance for telescopes –Currently from 1 AU to ~90 billion light years