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General Venus Geology Venus Statistics Mariner 2 Venera 4 Venus Statistics • Mass = 80% Earth’s mass General Venus Geology • Uncompressed density = 5250 kg/m3 • Equatorial radius = 6052 km • Orbital period = 225 days GLY 424/524 • Rotational period = 243 (backwards) March 18, 2002 • Gravity = 8.82 m/s2 • Mean surface temp = 482°C • Mean surface pressure = 92 bars Mariner 2 • First successful Venus flyby Venera 4 • December 1962/January 1963 • Objectives • Soviet mission – Atmosphere, magnetic field, charged particle • October, 1967 environment, mass • Atmospheric probe • Results • Penetrated to ~25 km above surface – Retrograde rotation – Atmosphere hot – Hot, high-pressure surface – High pressure – CO2 atmosphere – Permanent clouds – No magnetic field Venera 7 • Venus Lander Venera 8 • August, 1970 • June, 1972 • Returned signals for 23 minutes from • Probe and lander surface before failing • Returned signals for 53 minutes after • First transmission from another planet! landing • Results – Confirmed high surface temps, pressures – High surface temperature – Determined natural light suitable for – High surface pressure photography 1 Venus Mariner 10 Mariner 10 • Slingshot around Venus to reach Mercury • February, 1974 • Confirmed opaque clouds, “chevron” pattern suggesting high-altitude winds Venera 9 Results Venera 9 • Clouds 30-40 km thick with bases at 30-35 km altitude • Orbiter and Lander • Atmospheric constituents including HCl, • October, 1975 HF, Br, and I • Survived for 53 minutes after landing • Surface pressure about 90 (Earth) atmospheres • Surface temperature 485°C • Light levels comparable to those at earth on a cloudy summer day • TV photography showing no apparent dust in the air, and fresh 30-40 cm rocks Venera 9 landing site Venera10 • Lander and orbiter • October, 1975 • Roughly similar results as Venera 9 • Max windspeed of 3.5 m/s Only image returned Horizon in corners Lander pad at center base Rocks 30-40 cm across 2 Venera 11, 12 Pioneer Venus 1 and 2 • September, 1978 • Orbiter and Landers • Low resolution radar mapping of portions of • Instruments Venus – gas chromatograph • Orbiters and multiprobes – scattered solar radiation • Revealed apparently young, tectonically – soil composition complex surface – amospheric electrical discharges • Results – lightning and thunder – highAr36/Ar40 ratio – discovery of carbon monoxide at low altitudes Venera 13 & 14 Venera 13 & 14 Results • March 1982 • Landed near Pheobe Regio • Orbiters and Landers • Images returned • Instruments • XRF suggest weakly differentiated – camera system melanocratic alkaline gabbroids – X-ray fluorescence spectrometer – screw drill and surface sampler – Dynamic penetrometer – seismometer Venera 13 Lander: Venera 13 Lander Opposite views 3 Venera 14 Lander: Opposite Magellan Views • August, 1990 • Near-global coverage in radar ~12.5 cm wavelength • Results – No plate tectonics – 85% covered with volcanics – Anhydrous – Winds slow but effective General Geology Magellan Topography • 2 crustal provinces – Plains • Presumably volcanic • Various degrees of deformation • Low-lying – Tesserae • Russian parquet wooden floors • Formed from plains or older bits of crust poking through? • Topographically above plains Synthetic Aperture Radar Magellan Radar image 4 Alpha Regio Ishtar Terra Strike-slip Fault in Ovda Regio Venera 13 Fractured Plains Landing Site 5 Eastern Aphrodite Terra Coronae Large Coronae Stages in Coronae Evolution 6 7.
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