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Changing Perspectives of Solar System Surfaces
Spring 2003
Changing Perspectives, 1960s - 1980s
Moon
- Cold origin, accretionary topography.
- Hot accretion, LHB, +Earth Impact Origin.
- Lunik III, Apollo Sample Returns.
Mercury
- Earth-like density + Atmosphere + synchronous rotation (BCM Search for Atmos)
- 3/2 rotation from ground-based radar .
- Mariner 10 discovery of magnetic field; Moon on outside, Earth on Inside.
Venus
- Atmospheric properties?; Thunderstorms? Rotation?
- 100 atmos, 700 K, volcanic terrain
- Venera 4 and Mariner 5; Pioneer Venus; Veneras; Magellan
Mars
- Earth-like spin, obliquity, polar caps, seasonal changes=likelihood of plant life.
- ?Sinton Bands?=evidence of chlorophyll? No, HDO in Earth Atmosphere!
- US National Academy of Sciences endorses search for life on Mars
- Mariners 4,6 and 7. Very low pressure; no liquid water, CO2 polar caps; no life
- Mariner 9, Aqueous phase early, possibility of ancient life habitats, maybe even extant (if assessment hopeful enough!)
- 2 Billion Dollar Viking search for life finds not only lifeless, but that surface is self sterilizing!! No longer promising target for life search. Loss of priority in US exploration.
Jupiter/Saturn Moons
- Spots on plates; peculiar light curves from telescopic observations.
- Became 'new worlds' after Voyagers discovered active volcanism on Io, suggestion of subsurface ocean on Europa, methane phase change system on Titan. Expanded knowledge and modeling from Galileo, improved ground observations and, hopefully, from Cassini.
Changing Perspectives, 1980s - 1990s
(back to top)Moon
- Possibility of ice/dust mixture in Polar craters suggested by marginal Clementine radio link experiment, and further suggested by Lunar Prospector Neutron experiment.
Mercury
- Evidence for thick, pure Ice in Polar Craters
- Possibly sulfur--rich, not like Moon in elemental distribution
Venus
- Totally volcanic surface
- Magellan indicates global resurfacing within last 0.5 Billion years. No ancient crust like other Terrestrial Planets.
Mars
- Chaotic obliquity and other orbital elements with implications for episodes of greater polar heating
- Evidence for ancient, ice-covered lakes during ?middle years? plus even more earth-like environment associated with early bombardment phase.
- Negative evidence for hydrated minerals on surface.
- Evidence for 'recent' water emanations in isolated localities
- Increased plausibility of ancient microbial life in early ground water habitat, but still no evidence of life there.
Outer Planet Moons
- Internal endogenic processes common
- Oceans in subsurface of Europa (at least) considered likely
- Bruce Murray -
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