Orbital period 687 days .
24.5 h. rotational period
diameter = 1/2 Earth's
Atmosphere: Thin CO2 (.007 atm).
High winds - seasonal dust storms. Temp. -100 c to 0 c
Vikings 1976 : Approach view: So. Cap
Lander views : rocks, pink sky
Biology experiments: no life
Global Views: S. hemisphere
Cratered, old
Northern hemisphere - geologic activity
Former H2O flows
Canyons: Valles Marinaris
4500 Km 150 - 700 Km wide
Individual canyons 200 Km 7 Km deep
(Earth - Grand Canyon 28.2 Km)
SHIELD VOLCANOES:
Tharsis Ridge: 3 huge Volcanoes
+
largest Olympus Mons, located NW of Tharsis at lower level. 550 Km 25 Km high with 80 Km caldera
Polar Caps: H2O permanent CO2 seasonal
Viking Probes: Two launched 1975. Lander and orbiter.
2 TV cameras each on lander + meteorological
equipment, etc.
(Viking 1 and 2 landed 1976.)
Temps. -85C (-121F) to -30C (-22F), 30 m/h
winds
Soil: Contains silicon & iron, magnetic
SEARCH FOR LIFE:
The two landers conducted four experiments intended to detect the presence of microbiological life on the Martian surface. Soil samples were retrieved by the landers' extendible arms.
The Gas Exchange Experiment (GEX) Added nutrients to soil. Looked (with gas chromatograph) for changes in the makeup of gases in a test chamber, changes that would indicate biological activity. The results from this test were marginally positive, but ultimately taken to counter-indicate biology (probably due to chemical reaction between soil and nutrient).
The Labeled Release Experiment (LR) was set up to detect the uptake of a radioactively-tagged C14 liquid nutrient by microbes. The idea was that gases emitted by these microbes would show the tagging. Initial results were in line with this prediction but in the end, the overall results were inconsistent.
The Pyrolytic Release Experiment (PR) involved "cooking" soil samples that had been exposed to radioactively-tagged carbon dioxide C14 to see if the chemical had been used by organisms to make organic compounds. Seven of nine experimental runs seemed to show small concentration of micro-organisms but the results were later discounted.
The Gas Chromatograph -- Mass Spectrometer Experiment (GCMS) Designed to imitate Martian environment as closely as possible. Heated a soil sample and revealed an unexpected amount of water but failed to detect organic compounds. This absence was so absolute that it seemed there must be some mechanism actually destroying carbon compounds on the surface.
But,
"Teamed
with his son, Ron Levin of MIT Lincoln Laboratory in Lexington,
Massachusetts, the former Viking scientist said their belief is that Earth has
infected Mars. All links in the vital chain connecting Mars and Earth can be clearly
identified.
The bottom
line: Earth and Mars were hospitable over epochs that would have permitted
infection of Mars by Earth microorganisms, and from other sources. 'Biology offers
the only fit to the Label Release data from Mars and is consistent with our new
knowledge about Mars and Earth. It is time to accept the LR results,' he
said."