Mars: History of Exploration II

1. Geography 441/541 S/14 Dr. Christine M. Rodrigue Mars: History of Exploration II C.M. Rodrigue, 2014 Geography, CSULB

2. C.M. Rodrigue, 2014 Geography, CSULB Mars: History of Mars Exploration History of Earth-based Mars exploration The Spectral Analysis era: A New Mars Spectral analysis in this context is the study of absorbed, emitted, and scattered/reflected radiation A radiant object can emit wavelengths along the EMS at varying intensities: hot or dense objects emit across a continuous spectrum Substances in the radiant object or between it and the sensor can absorb certain wavelengths The wavelengths absorbed are diagnostic of particular minerals or elements or compound Substances and surfaces also reflect particular wavelengths

3. Mars: History of Mars Exploration • History of Earth-based Mars exploration • The Spectral Analysis era: A New Mars • The electromagnetic spectrum can be displayed by wavelength C.M. Rodrigue, 2014 Geography, CSULB

4. Mars: History of Mars Exploration • History of Earth-based Mars exploration • The Spectral Analysis era: A New Mars • Some reflectance spectra: • water • carbon dioxide • methane C.M. Rodrigue, 2014 Geography, CSULB

5. Mars: History of Mars Exploration • History of Earth-based Mars exploration • The Spectral Analysis era: A New Mars • Continuous spectra • Emission line spectra • Absorption line spectra C.M. Rodrigue, 2014 Geography, CSULB

6. C.M. Rodrigue, 2014 Geography, CSULB Mars: History of Mars Exploration • History of Earth-based Mars exploration • The Spectral Analysis era: Martian air pressures • In 1862, Sir William Higgins tried out the new technology to get at Martian atmospheric pressures: All he got was that sunlight reflected off Mars and the planet didn’t glow • In 1867, he and Pierre Jules Jenssen took spectra of Mars to look for water vapor and oxygen and found none • In 1908, Percival Lowell also tried spectroscopy: • Mars’ air pressure looked like 87% of Earth’s • His method was sound, but he didn’t correct for dust • Erroneous as his results were, the method was a significant contribution to launching the use of spectral analysis on Mars and other planets

7. C.M. Rodrigue, 2014 Geography, CSULB Mars: History of Mars Exploration • History of Earth-based Mars exploration • The Spectral Analysis era: Martian temperatures • Any object that absorbs radiation re-emits it at a longer wavelength, because it is necessarily cooler than the original radiant body • Wien’s Displacement Law (L = 2,897 / TK) allows you to calculate temperatures (TK = 2,897 / L ) • In the 1920s, Lowell Observatory established that Mars was very cold, -40 C on average (Earth averages 15  C) • The poles got down around -70  C, and the equatorial areas got as warm as 10  C • In 1954, equatorial highs got as high as 25  C

8. C.M. Rodrigue, 2014 Geography, CSULB Mars: History of Mars Exploration • History of Earth-based Mars exploration • The Spectral Analysis era: Life on Mars? • Mars shows seasonally shifting patterns of spring darkening • Some folks inferred that this could be a wave of vegetation greening up for spring • In 1938, Peter Millman compared the spectra from the dark areas with spectra that had been collected for various kinds of vegetation here on Earth and said they did not resemble one another at all • In 1954, W.M. Sinton said these spectra did resemble organic compounds, later retracting this • Audoin Dofus and Thomas McCord showed that the dark areas were not greenish: That was an optical illusion

9. C.M. Rodrigue, 2014 Geography, CSULB Mars: History of Mars Exploration • History of Earth-based Mars exploration • Telescope observation from near-Earth • Hubble Telescope was designed in 1973, since the Shuttle had been recently approved as a way of schlepping it out • Congress funded it in 1977 and it launched in 1990 • It’s a reflecting mirror type of telescope • The main (2.4 m) mirror turned out to have an optical flaw, enough to give it astigmatism • Corrective optics applied in 1993 • Hubble is no longer being serviced and its equipment is breaking down: Its orbit will eventually decay (~2019-2032) • Angular resolution is 0.05 arcsecond • "If you could see as well as Hubble, you could stand in New York City and distinguish two fireflies, 1 m (3.3 feet) apart, in San Francisco."

10. Mars: History of Mars Exploration • History of Earth-based Mars exploration • Telescope observation from near-Earth: Hubble • Both infrared and visible light imaging of Mars • Best resolution: 19 km • Got best images in August 2003, the best opposition in 59,619 years C.M. Rodrigue, 2014 Geography, CSULB

11. C.M. Rodrigue, 2014 Geography, CSULB Mars: History of Mars Exploration • History of Earth-based Mars exploration • Telescope observation from near-Earth -- Hubble has: • Monitored weather (very useful when Mars Global Surveyor was ærobraking into Martian orbit in 1997!) • Caught a 1996 spring dust storm • Documented cloudiness in 1997 • Caught a polar cyclone in 1999 • Identified water-bearing minerals on Mars

12. Mars: History of Mars Exploration C.M. Rodrigue, 2014 Geography, CSULB

13. C.M. Rodrigue, 2014 Geography, CSULB Mars: History of Mars Exploration • History of the Robotic Missions to Mars • Hugely dangerous: Most missions have failed (about 57%) • "Great Galactic Ghoul," Mars as the "Bermuda Triangle," the "Mars Curse" • There have been launch failures • USSR Mars 1960A failed at liftoff • Russian Space Agency Mars 96 orbiter/lander/penetrator • NASA Mariner 8 1971 • RFSA Phobos-Grunt 2011 • Communications failures • USSR Mars 1 (aka Sputnik 23) 1963 • NASA Mars Observer lost contact at arrival in 1993 • Orbit insertion failures • Japan ISAS Nozomi 1999 *and* 2003 • Crashes on the Martian surface • NASA Mars Climate Observer 1999 • NASA Mars Polar Lander/Deep Space 2 1999 • ESA Beagle lander 2003

14. Mars: History of Mars Exploration • History of the Robotic Missions to Mars • Dangerous! C.M. Rodrigue, 2014 Geography, CSULB

15. C.M. Rodrigue, 2014 Geography, CSULB Mars: History of Mars Exploration • History of the Robotic Missions to Mars • Spacecraft types • Flyby missions (Cassini-Huygens gravity-assists by Earth and Venus) • Orbiters (Earth’s Landsat, IKONOS, SPOT) • Probes (Huygens probe at Titan, NEAR at asteroid EROS) • Landers (USSR Venera, NASA Surveyor on Moon) • Rovers (Spirit and Opportunity, Earth portable spectrometers) • Penetrators (USSR Mars 96 had two) • Balloon probes (USSR Vega 1 at Venus) • Sample return missions (MSRL, Genesis from L1, Stardust from Comet Wild 2)

16. C.M. Rodrigue, 2014 Geography, CSULB Mars: Remote Sensing Basics • Resolution • Spatial • Varying, as in a descending probe (e.g, Huygens descending to Titan) • Fine resolution, 0.5 – 5.0 m (e.g., IKONOS, OrbView-3) • Coarse resolution, 1 km (e.g., MODIS) to 8 m (e.g., GEOS) • Vertical • Generally worse than horizontal spatial resolution • Generated by laser altimeters, InSAR, stereo pairing

17. C.M. Rodrigue, 2014 Geography, CSULB Mars: Remote Sensing Basics • Resolution • Radiometric • How finely differences in values can be detected • Function of bits in a byte • Directional • Nadir only • Backward/forward or right/left • Reflectance and scattering by wavelength differ by direction • Spectral • Panchromatic (all bands within a large range, often fine resolution) • Multispectral (3-100 or so bands, at discrete intervals along the spectrum) • Hyperspectral (16-220 narrow bands contiguous to one another over a spectral range)