Viking Missions to Mars Viking 1 launched August 20, 1975 Viking 2 launched September 9, 1975 Titan 3 Centaur Launch Vehicle Mission Objectives 1) Obtain high resolution photographs of the Martian surface 2) Characterize the structure and composition of the atmosphere and surface 3) Search for evidence of life IKONOS Resolution - A measure of the smallest detectable object Viking: 150 x 300 meters (8 meters at selected locations) IKONOS (Non-military “spy” satellite): 0.6m (best available) Earth to Mars It took nearly 10 months to reach Mars. Like a quarterback on the run, throwing a pass to a moving receiver... You have to know where Mars will be and throw the “ball” to that spot - that’s a 309 MILLION mile trajectory with almost NO room for error. ...OR... In golf, it’s like going for a hole in one from Los Angeles to Houston, Texas! After the landing, depending on the locations of Earth and Mars, it can take up to 22.3 MINUTES to send a radio command to the spacecraft. Earth to Mars Orbit Transit Power Launch Orbits Insertion Days Down Viking 1 8/20/1975 6/19/1976 304 8/17/1980 1400+ Viking 2 9/9/1975 8/7/1976 333 7/25/1978 706 Compare the time that it took the two vehicles to reach Mars orbit... Why did it take 29 additional days for Viking 2 to reach Mars? ... Go to the ORBITS TABLE to see why... The Spacecraft The spacecraft consisted of two parts - the ORBITER (upper section) and the LANDER (lower, ball shaped section). The Spacecraft The spacecraft consisted of two parts - the ORBITER (upper section) and the LANDER (lower, ball shaped section). During the trip to Mars, the ORBITER controlled the trajectory based on commands from earth. The Spacecraft The spacecraft consisted of two parts - the ORBITER (upper section) and the LANDER (lower, ball shaped section). During the trip to Mars, the ORBITER controlled the trajectory based on commands from earth. Once in orbit around Mars, the ORBITER photographed the planet surface to assess the pre-planned landing sites. The landing site was changed based on the images received. See what the Orbiters saw... Viking 1 Orbiter Imagery Central Tithonium Chasma Landslide lobes can be seen on the 6 km deep canyon floor. Some layering is visible on the south wall. The image is ~90 km across. North is at ~11:30. (Viking Orbiter 064A22) Viking 1 Orbiter Imagery Yuty crater in Chryse Planitia The 18 km diameter crater is surrounded by complex ejecta lobes, one of which partly covers an older crater. North is at about ~1:00. (Viking Orbiter 003A07) Viking Orbiter 1 and 2 Mosaic A color mosaic showing Candor Chasma which is part of the Valles Marineris system. This oblique view is looking from the north over the 800 km wide chasm. The walls and floor show evidence of erosion and mass wasting and complex geomorphology. (Viking Orbiter NJ05S070-912A) The Spacecraft The spacecraft consisted of two parts - the ORBITER (upper section) and the LANDER (lower, ball shaped section). During the trip to Mars, the ORBITER controlled the trajectory based on commands from earth. Once in orbit around Mars, the ORBITER photographed the planet surface to assess the pre-planned landing sites. The landing site was changed based on the images received. Once a site was selected, the LANDER was detached from the ORBITER... Retro rockets were fired to begin the descent... A parachute was used to slow the fall. During the descent, the LANDER opened up (deployed) for the final landing. The LANDER then fired its own retro rockets to soften the actual touch-down. The Lander This drawing shows the deployed Lander with the numerous instruments used to photograph, sample, and analyze its surroundings. The Lander was stationary - it could not move to other locations. Landing Sequence Landing Sequence Orbit Transit Power Launch Orbits Insertion Days Down Viking 1 8/20/1975 6/19/1976 304 8/17/1980 1400+ Viking 2 9/9/1975 8/7/1976 333 7/25/1978 706 It took 6 to 13 minutes for the landers to reach the surface of Mars... Why? The answer lies with the Orbit Table... Both vehicles had unique orbits and landing sites The Viking has Landed... Orbit Transit Power Launch Orbits Insertion Days Down Viking 1 8/20/1975 6/19/1976 304 8/17/1980 1400+ Viking 2 9/9/1975 8/7/1976 333 7/25/1978 706 Landing Loss of Life Span Date Signal (Days) Lander 1 7/20/1976 11/13/1982 2307 Lander 2 9/3/1976 4/11/1980 1316 Landing Sites In this distorted view of Mars, you see the Viking and Pathfinder (1997) landing sites - imagine just how LITTLE we have been able to explore of the actual surface! Landing Sites In June and July, 2003, two missions (Spirit and Opportunity) were launched to Mars. In January, 2004... WHERE will the new ROVERs land ? Viking 1 Lander The first panoramic image of Chryse Planitia taken on 23 July 1976, three days after Viking 1 landed. The meteorology boom is at the center of the image and to the left is the support for the high-gain dish antenna. The bright area to the left is the late afternoon Sun in the west. The bright horizontal lines in the sky are not clouds, they are caused by internal reflections in the camera housing. Features on the horizon are about 3 km away. The dark rock at the center of the frame, nicknamed "Big Joe", is about 3 meters across and 8 meters from the lander. The center of the frame shows fine grained material forming a small dune field. The material forms horseshoe shaped scour marks and wind tails around the rocks, which are about 10 cm across. (Viking 1 Lander, P-17428) Viking 1 Lander The sampling arm dug a number of deep trenches in the "Sandy Flats" area of Chryse Planitia as part of the surface composition and biology experiments. The digging tool on the arm (at lower center) could scoop up samples of material and deposit them into the appropriate experiment. Some holes were dug deeper to study soil which was not affected by solar radiation and weathering. The boom holding the meteorology sensors is at left. (Viking 1 Lander, 11D128) Viking 2 Lander This image shows patches of ground frost at the Utopia Planitia. The image was taken at 12:32 local time in late northern winter. The frost layer is extremely thin, only a few hundredths of a mm thick. The frost persisted at temperatures higher than the freezing point of carbon dioxide, and so must be water ice or some combination of water and carbon dioxide ice. The view is looking SWW. The colors have been distorted to enhance the contrast. (Viking 2 Lander, 22E169) Viking 2 Lander Looking back across the Lander, dark boulders are prominent against the reddish soil. The landing site, Utopia Plantia, is a region of fractured plains. The site is about 200 km south of Mie crater, and may be on top of one of the crater's ejecta blankets. The largest rocks are about half a meter in size. The view is approximately to the southwest. (Viking 2 Lander, 22A158) Accomplishments • Photographs from the landers and orbiters surpassed expectations in quanity and quality. The total exceeded 4,500 from the landers and 52,000 from the orbiters. Viking's orbiters mapped 97 percent of the Martian surface. • The infrared thermal mappers and the atmospheric water detectors determined that the residual north polar ice cap (that survives the northern summer) is water ice, rather than frozen carbon dioxide (dry ice) as once believed. • Barometric pressure varied at each landing site on a semiannual basis, because carbon dioxide, the major constituent of the atmosphere, froze to form an immense polar cap, alternately at each pole. The carbon dioxide formed a great cover of snow and then evaporated again with the coming of spring in each hemisphere. When the southern cap was largest, the mean daily pressure observed by Viking Lander 1 was as low as 6.8 millibars; at other times of the year it was as high as 9.0 millibars. The pressures at the Viking Lander 2 site were 7.3 and 10.8 millibars. (For comparison, the surface pressure on Earth at sea level is about 1,000 millibars.) • Martian winds generally blew more slowly than expected. Scientists had expected them to reach speeds of several hundred miles an hour from observing global dust storms, but neither lander recorded gusts over 120 kilometers (74 miles) an hour. Other Significant Discoveries • NO LIFE HAS BEEN DETECTED ON MARS -- The surface contains no organic molecules that were detectable at the parts-per-billion level -- less, in fact, than soil samples returned from the Moon by Apollo astronauts. • The surface is a type of iron-rich clay that contains a highly oxidizing substance that releases oxygen when it is wetted. • Nitrogen, never before detected, is a significant component of the Martian atmosphere, and enrichment of the heavier isotopes of nitrogen and argon relative to the lighter isotopes implies that atmospheric density was much greater than in the distant past. • The greatest concentration of water vapor in the atmosphere is near the edge of the north polar cap in midsummer. From summer to fall, peak concentration moves toward the equator, with a 30 percent decrease in peak abundance. In the southern summer, the planet is dry, probably also an effect of the dust storms. • While the permanent north cap is water ice, the southern cap probably retains some carbon dioxide ice through the summer. Other Significant Discoveries • The density of both of moons is low -- about two grams per cubic centimeter -- implying that they originated as asteroids captured by Mars's gravity. • Measurements of the round-trip time for radio signals between Earth and the Viking spacecraft, made while Mars was beyond the Sun (near the solar conjunctions), have determined delay of the signals caused by the Sun's gravitational field. The result confirms Albert Einstein's prediction to an estimated accuracy of 0.1 percent -- 20 times greater than any other test.
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