Incubator escapee wiki

Viking 1

Article Discussion

Template:Short description Template:Italic title Template:About Template:Use American English Template:Use mdy dates Template:Infobox spaceflight

Viking 1 was the first of two spacecraft, along with Viking 2, each consisting of an orbiter and a lander, sent to Mars as part of NASA's Viking program.<ref name="NASA-20061218"/> The lander touched down on Mars on July 20, 1976, the first successful Mars lander in history. Viking 1 operated on Mars for Template:Age in days days (over 6Template:Frac years) or Template:Age in sols Martian solar days, the longest extraterrestrial surface mission until the record was broken by the Opportunity rover on May 19, 2010.<ref name="d504">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

MissionEdit

Following launch using a Titan/Centaur launch vehicle on August 20, 1975, and an 11-month cruise to Mars,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> the orbiter began returning global images of Mars about five days before orbit insertion. The Viking 1 Orbiter was inserted into Mars orbit on June 19, 1976,<ref name=":0">Template:Cite book</ref> and trimmed to a 1,513 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.<ref name=":1">Template:Cite book</ref> The landing was delayed until a safer site was found,<ref name=":1" /> and took place instead on July 20,<ref name=":0" /> the seventh anniversary of the Apollo 11 Moon landing.<ref>Template:Cite book</ref> The lander separated from the orbiter at 08:51 UTC and landed at Chryse Planitia at 11:53:06 UTC.<ref name="NSSDCA">Template:NSSDC</ref> It was the first attempt by the United States at landing on Mars.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

OrbiterEdit

The instruments of the orbiter consisted of two vidicon cameras for imaging, an infrared spectrometer for water vapor mapping, and infrared radiometers for thermal mapping.<ref name="Soffen & Snyder">Template:Cite journal </ref> 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.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Operations included close approaches to Phobos in February 1977.<ref>Template:Cite journal</ref> The periapsis was reduced to 300 km on March 11, 1977.<ref>Template:Cite book</ref> 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 × 33,943 km to 320 × 56,000 km to prevent impact with Mars and possible contamination until the year 2019. Operations were terminated on August 17, 1980, after 1,485 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.<ref name=Jefferson>Template:Cite conference</ref> More than 57,000 images were sent back to Earth.

LanderEdit

File:Viking Aeroshell - GPN-2000-001903.jpg
Viking aeroshell

The lander and its aeroshell separated from the orbiter on July 20 at 08:51 UTC. At the time of separation, the lander was orbiting at about Template:Convert. The aeroshell's retrorockets fired to begin the lander de-orbit maneuver. After a few hours at about Template:Convert altitude, the lander was reoriented for atmospheric entry. The aeroshell with its ablative heat shield slowed the craft as it plunged through the atmosphere. During this time, entry science experiments were performed by using a retarding potential analyzer, a mass spectrometer, as well as pressure, temperature, and density sensors.<ref name="Soffen & Snyder" /> At Template:Convert altitude, traveling at about Template:Convert, the 16 m diameter lander parachutes deployed. Seven seconds later the aeroshell was jettisoned, and eight seconds after that the three lander legs were extended. In 45 seconds, the parachute had slowed the lander to Template:Convert. At Template:Convert altitude, retrorockets on the lander itself were ignited and, 40 seconds later at about Template:Convert, the lander arrived on Mars with a relatively light jolt. The legs had honeycomb aluminum shock absorbers to soften the landing.<ref name="Soffen & Snyder"/>

File:Documentary clip of Viking 1 landing (JPL-19760720-VIKINGf-0002-AVC2002151).webm
Documentary clip recounting the Viking 1 landing with animation and video footage of the control centre

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 Template:Convert of surface material.<ref name="NSSDCA" /> Since most of Viking's experiments focused on the surface material a more straightforward design would not have served.<ref name=v1land>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

The Viking 1 lander touched down in western Chryse Planitia ("Golden Plain") at Template:Coord<ref name="NASA-20061218"/><ref name="NSSDCA" /> at a reference altitude of Template:Convert relative to a reference ellipsoid with an equatorial radius of Template:Convert and a flatness of 0.0105 (22.480° N, 47.967° W planetographic) at 11:53:06 UTC (16:13 local Mars time).<ref name=v1land/> Approximately Template:Convert of propellants were left at landing.<ref name="NSSDCA" />

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.<ref>Template:Cite journal</ref> On the day after the landing the first colour 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 orbiter could transmit to Earth (S-band) at 2,000 to 16,000 bit/s (depending on distance between Mars and Earth), and the lander could transmit to the orbiter at 16,000 bit/s.<ref name=JPL-facts-VMM>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The data capacity of the relay link was about 10 times higher than the direct link.<ref name="Soffen & Snyder"/> Template:Wide image The lander had two facsimile cameras; three analyses for metabolism, growth or photosynthesis; a gas chromatograph-mass spectrometer; 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.<ref name="Soffen & Snyder"/>

File:PSP 001521 2025 RED VL-1 lander.png
Photo of the Viking 1 Mars lander taken by the Mars Reconnaissance Orbiter in 2006

The Viking 1 lander was named the Thomas Mutch Memorial Station in January 1981 in honour of Thomas A. Mutch, the leader of the Viking imaging team.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The lander operated for 2,245 sols (about 2,306 Earth days or 6 years) until November 11, 1982 (sol Template:Age in sols), 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.<ref>Template:Cite report</ref> In 2006, the Viking 1 lander was imaged on the Martian surface by the Mars Reconnaissance Orbiter.<ref>Template:Cite report</ref>

Mission resultsEdit

Viking 1 operated on the surface of Mars for approximately six Earth years and 114 days – until November 11, 1982, when the lander was inadvertently sent a faulty command. The robotic sampler arm successfully scooped up soil samples and tested them with instruments such as the Gas chromatography–mass spectrometer. Atmospheric temperature recordings were as high as -14 C (7 F) at midday, and the predawn summer temperature was -77 C (-107 F). The landers had issues obtaining results from its seismometer.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Search for lifeEdit

Viking 1 carried a biology experiment whose purpose was to look for evidence of life. The Viking lander 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 that could measure the composition and abundance of organic compounds in the Martian soil.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The results were surprising and interesting: the spectrometer gave a negative result; the PR gave a negative result, the GEX gave a negative result, and the LR gave a positive result.<ref>Viking Data May Hide New Evidence For Life. Barry E. DiGregorio, July 16, 2000.</ref> 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."<ref>Viking 2 Likely Came Close to Finding H2O. Template:Webarchive Irene Klotz, Discovery News, September 28, 2009.</ref> 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.<ref>Template:Cite journal</ref> 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.<ref>Friedmann, E. 1982. Endolithic Microorganisms in the Antarctic Cold Desert. Science: 215. 1045–1052.</ref> 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.<ref>Hartmann, W. 2003. A Traveler's Guide to Mars. Workman Publishing. NY NY.</ref> 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.<ref>Alien Rumors Quelled as NASA Announces Phoenix Perchlorate Discovery. Template:Webarchive A.J.S. Rayl, August 6, 2008.</ref> If it is widespread on Mars, carbon-based life would be difficult at the soil surface.

First panorama by Viking 1 landerEdit

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Viking 1 image galleryEdit

  • Titan 3E-Centaur launches with Viking 1.jpg

    Launch of the Viking 1 probe (20 August 1975)

  • NASM-A19790215000-NASM2016-02690.jpg

    Proof test article of the Viking Mars Lander

  • Mars Viking 12a001.png

    First image by the Viking 1 lander from the surface of Mars, showing lander's footpad

  • Mars Viking 12a240.png

    Viking 1 lander image of a Martian sunset over Chryse Planitia

  • Mars Viking 11d128.png

    Trenches dug by soil sampler device

  • PIA00563-Viking1-FirstColorImage-19760721.jpg

    First colour image taken by the Viking 1 lander (21 July 1976)

  • Mars Viking 11h016.png

    Viking 1 lander site (11 February 1978)

  • Mars Viking 11a097.png

    Dunes and large boulder. Pole in the centre is an instrument boom.

  • 12e189(Sol379-7.84).jpg

    Viking 1 Lander Camera 2 Sky at sunrise (Low Resolution Colour) Sol 379 07:50

Test of general relativityEdit

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File:Cassini-science-br.jpg
High-precision test of general relativity by the Cassini space probe (artist's impression)

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.<ref>Template:Cite journal</ref>

Orbiter shotsEdit

See alsoEdit

NotesEdit

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ReferencesEdit

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External linksEdit

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