From Encyclopedia of Astrobiology
|Mission type||orbiter and lander|
|Website||Viking Project Information|
orbiter:1846 days (1797 sols) |
lander:2306 days (2245 sol)
Orbiter:883 kg (1,947 lb)|
Lander:572 kg (1,261 lb)
|Start of mission|
|Launch date||21:22, August 20, 1975|
|Launch site||LC-41, Cape Canaveral|
|End of mission|
|Last contact||November 13, 1982|
|Spacecraft component||Viking 1 Orbiter|
|Orbital insertion||June 19, 1976|
|Periareion||320 km (200 mi)|
|Apoareion||56,000 km (35,000 mi)|
|Spacecraft component||Viking 1 Lander|
July 20, 1976 |
11:53:06 (MSD 36455 00:34 AMT)
Viking 1 was the first of two spacecraft (along with Viking 2) sent to Mars as part of NASA's Viking program. On July 20, 1976, it became the first spacecraft to land successfully on Mars and perform its mission. Viking 1 held the record for the longest Mars surface mission of 2307 days (over 6¼ years) or 2245 sols until that record was broken by Opportunity on May 19, 2010.
Mission[edit | hide all | hide | edit source]
Following launch using a Titan/Centaur launch vehicle on August 20, 1975, and a 10-month cruise to Mars, the orbiter began returning global images of Mars about 5 days before orbit insertion. The Viking 1 Orbiter was inserted into Mars orbit on June 19, 1976, and trimmed to a 1513 x 33,000 km, 24.66 h site certification orbit on June 21. Landing on Mars was planned for July 4, 1976, the United States Bicentennial, but imaging of the primary landing site showed it was too rough for a safe landing. The landing was delayed until a safer site was found, and took place instead on July 20, the seventh anniversary of the Apollo 11 Moon landing. The lander separated from the orbiter at 08:51 UTC and landed at 11:53:06 UTC. It was the first attempt by the United States at landing on Mars.
Orbiter[edit | hide | edit source]
The instruments of the orbiter consisted of two vidicon cameras for imaging (VIS), an infrared spectrometer for water vapor mapping (MAWD) and infrared radiometers for thermal mapping (IRTM). The orbiter primary mission ended at the beginning of solar conjunction on November 5, 1976. The extended mission commenced on December 14, 1976, after solar conjunction. Operations included close approaches to Phobos in February 1977. The periapsis was reduced to 300 km on March 11, 1977. Minor orbit adjustments were done occasionally over the course of the mission, primarily to change the walk rate — the rate at which the areocentric longitude changed with each orbit, and the periapsis was raised to 357 km on July 20, 1979. On August 7, 1980, Viking 1 Orbiter was running low on attitude control gas and its orbit was raised from 357 × 33943 km to 320 × 56000 km to prevent impact with Mars and possible contamination until the year 2019. Operations were terminated on August 17, 1980, after 1485 orbits. A 2009 analysis concluded that, while the possibility that Viking 1 had impacted Mars could not be ruled out, it was most likely still in orbit.
Lander[edit | hide | edit source]
The landing rockets used an 18-nozzle design to spread the hydrogen and nitrogen exhaust over a large area. NASA calculated that this approach would mean that the surface would not be heated by more than one 1 °C (1.8 °F), and that it would move no more than 1 millimeter (0.04 inches) of surface material. Since most of Viking's experiments focused on the surface material a more straightforward design would not have served.
The Viking 1 lander touched down in western Chryse Planitia ("Golden Plain") at at a reference altitude of −2.69 kilometers (−1.67 mi) relative to a reference ellipsoid with an equatorial radius of 3,397 kilometers (2,111 mi) and a flatness of 0.0105 (22.480° N, 47.967° W planetographic) at 11:53:06 UT (16:13 local Mars time). Approximately 22 kilograms (49 lb) of propellants were left at landing.
Transmission of the first surface image began 25 seconds after landing and took about four minutes (see below). During these minutes the lander activated itself. It erected a high-gain antenna pointed toward Earth for direct communication and deployed a meteorology boom mounted with sensors. In the next seven minutes the second picture of the 300° panoramic scene (displayed below) was taken. On the day after the landing the first color picture of the surface of Mars (displayed below) was taken. The seismometer failed to uncage, and a sampler arm locking pin was stuck and took five days to shake out. Otherwise, all experiments functioned normally. The lander had two means of returning data to Earth: a relay link up to the orbiter and back, and by using a direct link to Earth. The data capacity of the relay link was about 10 times higher than the direct link.
The lander had two facsimile cameras, three analyses for metabolism, growth or photosyntheses, a gas chromatograph-mass spectrometer (GCMS), an x-ray fluorescence spectrometer, pressure, temperature and wind velocity sensors, a three-axis seismometer, a magnet on a sampler observed by the cameras, and various engineering sensors.
The Viking 1 lander was named the Thomas Mutch Memorial Station in January 1982 in honor of the leader of the Viking imaging team. The lander operated for 2245 sols (about 2306 Earth days or 6 years) until November 11, 1982, (sol 2600), when a faulty command sent by ground control resulted in loss of contact. The command was intended to uplink new battery charging software to improve the lander's deteriorating battery capacity, but it inadvertently overwrote data used by the antenna pointing software. Attempts to contact the lander during the next four months, based on the presumed antenna position, were unsuccessful. In 2006 the Viking 1 lander was imaged on the Martian surface by the Mars Reconnaissance Orbiter.
Search for life[edit | hide | edit source]
Viking 1 carried a biology experiment whose purpose was to look for evidence of life. The Viking spacecraft biological experiments weighed 15.5 kg (34 lbs) and consisted of three subsystems: the pyrolytic release experiment (PR), the labeled release experiment (LR), and the gas exchange experiment (GEX). In addition, independent of the biology experiments, Viking carried a gas chromatograph/mass spectrometer (GCMS) that could measure the composition and abundance of organic compounds in the martian soil. The results were surprising and interesting: the GCMS gave a negative result; the PR gave a negative result, the GEX gave a negative result, and the LR gave a positive result. Viking scientist Patricia Straat stated in 2009, "Our (LR) experiment was a definite positive response for life, but a lot of people have claimed that it was a false positive for a variety of reasons." Most scientists now believe that the data were due to inorganic chemical reactions of the soil; however, this view may be changing after the recent discovery of near-surface ice near the Viking landing zone. Some scientists still believe the results were due to living reactions. No organic chemicals were found in the soil. However, dry areas of Antarctica do not have detectable organic compounds either, but they have organisms living in the rocks. Mars has almost no ozone layer, unlike the Earth, so UV light sterilizes the surface and produces highly reactive chemicals such as peroxides that would oxidize any organic chemicals. The Phoenix Lander discovered the chemical perchlorate in the Martian soil. Perchlorate is a strong oxidant so it may have destroyed any organic matter on the surface. If it is widespread on Mars, carbon-based life would be difficult at the soil surface.
Viking 1 image gallery[edit | hide | edit source]
Test of general relativity[edit | hide | edit source]
Gravitational time dilation is a phenomenon predicted by the theory of General Relativity whereby time passes more slowly in regions of lower gravitational potential. Scientists used the lander to test this hypothesis, by sending radio signals to the lander on Mars, and instructing the lander to send back signals, in cases which sometimes included the signal passing close to the Sun. Scientists found that the observed Shapiro delays of the signals matched the predictions of General Relativity.
Orbiter shots[edit | hide | edit source]
See also[edit | hide | edit source]
References[edit | hide | edit source]
- Williams, David R. Dr. (December 18, 2006). "Viking Mission to Mars". NASA. Retrieved February 2, 2014.
- "Viking 1". NASA.
- Nelson, Jon. "Viking 1". NASA. Retrieved February 2, 2014.
- The Soviet Union's Mars 3 landed successfully on December 2, 1971 but stopped transmitting after 14.5 seconds.
- Soffen, G.A.; Snyder, C.W. (August 1976). "The First Viking Mission to Mars". Science, New Series. 193 (4255): 759–766. Bibcode:1976Sci...193..759S. doi:10.1126/science.193.4255.759. JSTOR 1742875.
- Jefferson, David C; Demcak, Stuart W; Esposito, Pasquale B; Kruizinga, Gerhard L (10–13 August 2009). An Investigation of the Orbital Status of Viking-1 (PDF). AIAA Guidance, Navigation, and Control Conference.
- Mutch, T.A.; et al. (August 1976). "The Surface of Mars: The View from the Viking 1 Lander". Science, New Series. 193 (4255): 791–801. Bibcode:1976Sci...193..791M. doi:10.1126/science.193.4255.791. JSTOR 1742881.
- D. J. Mudgway (1983). "Telecommunications and Data Acquisition Systems Support for the Viking 1975 Mission to Mars" (PDF). NASA Jet Propulsion Laboratory. Retrieved 2009-06-22.
- "NASA Mars Orbiter Photographs Spirit and Vikings on the Ground". NASA. 2006. Retrieved 2011-07-20.
- Malin Space Science Systems Archived October 20, 2014, at the Wayback Machine.
- Viking Data May Hide New Evidence For Life. Barry E. DiGregorio, July 16, 2000.
- Viking 2 Likely Came Close to Finding H2O. Archived September 30, 2009, at the Wayback Machine. Irene Klotz, Discovery News, September 28, 2009.
- Stuurman, C.M.; Osinski, G.R.; Holt, J.W.; Levy, J.S.; Brothers, T.C.; Kerrigan, M.; Campbell, B.A. (September 28, 2016). "SHARAD detection and characterization of subsurface water ice deposits in Utopia Planitia, Mars". Geophysical Research Letters. 43 (18): 9484–9491. Bibcode:2016GeoRL..43.9484S. doi:10.1002/2016gl070138.
- Friedmann, E. 1982. Endolithic Microorganisms in the Antarctic Cold Desert. Science: 215. 1045–1052.
- Hartmann, W. 2003. A Traveler's Guide to Mars. Workman Publishing. NY NY.
- Alien Rumors Quelled as NASA Announces Phoenix Perchlorate Discovery. Archived September 4, 2010, at the Wayback Machine. A.J.S. Rayl, August 6, 2008.
- Reasenberg, R. D.; Shapiro, I. I.; MacNeil, P. E.; Goldstein, R. B.; Breidenthal, J. C.; Brenkle, J. P.; et al. (December 1979). "Viking relativity experiment – Verification of signal retardation by solar gravity". Astrophysical Journal Letters. 234: L219–L221. Bibcode:1979ApJ...234L.219R. doi:10.1086/183144.