The Viking program consisted of a pair of American space probes sent to Mars, Viking 1 and Viking 2. Each spacecraft was composed of two main parts: an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface. The orbiters also served as communication relays for the landers once they touched down.
The Viking program grew from NASA's earlier, even more ambitious, Voyager Mars program, which was not related to the successful Voyager deep space probes of the late 1970s. Viking 1 was launched on August 20, 1975, and the second craft, Viking 2, was launched on September 9, 1975, both riding atop Titan IIIE rockets with Centaur upper stages. Viking 1 entered Mars orbit on June 19, 1976, with Viking 2 following suit on August 7.
After orbiting Mars for more than a month and returning images used for landing site selection, the orbiters and landers detached; the landers then entered the Martian atmosphere and soft-landed at the sites that had been chosen. The Viking 1 lander touched down on the surface of Mars on July 20, 1976, and was joined by the Viking 2 lander on September 3. The orbiters continued imaging and performing other scientific operations from orbit while the landers deployed instruments on the surface.
The project cost roughly US$1 billion in 1970s dollars, equivalent to about 5 billion USD in 2016 dollars. The mission was considered successful and is credited with helping to form most of the body of knowledge about Mars through the late 1990s and early 2000s.
Artist impression of a Viking orbiter releasing a lander descent capsule
|Manufacturer||Jet Propulsion Laboratory / Martin Marietta|
|Country of origin||United States|
|Operator||NASA / JPL|
|Design life||Orbiters: 4 years at Mars|
Landers: 4–6 years at Mars
|Launch mass||3,527 kilograms (7,776 lb)|
|Power||Orbiters: 620 watts (solar array)|
Lander: 70 watts (two RTG units)
|Retired||Viking 1 orbiter|
August 17, 1980
Viking 1 lander
July 20, 1976 (landing) to November 13, 1982
Viking 2 orbiter
July 25, 1978
Viking 2 lander
September 3, 1976 (landing) to April 11, 1980
|First launch||Viking 1|
August 20, 1975
|Last launch||Viking 2|
September 9, 1975
The primary objectives of the two Viking orbiters were to transport the landers to Mars, perform reconnaissance to locate and certify landing sites, act as communications relays for the landers, and to perform their own scientific investigations. Each orbiter, based on the earlier Mariner 9 spacecraft, was an octagon approximately 2.5 m across. The fully fueled orbiter-lander pair had a mass of 3527 kg. After separation and landing, the lander had a mass of about 600 kg and the orbiter 900 kg. The total launch mass was 2328 kg, of which 1445 kg were propellant and attitude control gas. The eight faces of the ring-like structure were 0.4572 m high and were alternately 1.397 and 0.508 m wide. The overall height was 3.29 m from the lander attachment points on the bottom to the launch vehicle attachment points on top. There were 16 modular compartments, 3 on each of the 4 long faces and one on each short face. Four solar panel wings extended from the axis of the orbiter, the distance from tip to tip of two oppositely extended solar panels was 9.75 m.
The main propulsion unit was mounted above the orbiter bus. Propulsion was furnished by a bipropellant (monomethylhydrazine and nitrogen tetroxide) liquid-fueled rocket engine which could be gimballed up to 9 degrees. The engine was capable of 1,323 N (297 lbf) thrust, translating to a change in velocity of 1480 m/s. Attitude control was achieved by 12 small compressed-nitrogen jets.
An acquisition Sun sensor, a cruise Sun sensor, a Canopus star tracker and an inertial reference unit consisting of six gyroscopes allowed three-axis stabilization. Two accelerometers were also on board. Communications were accomplished through a 20 W S-band (2.3 GHz) transmitter and two 20 W TWTAs. An X band (8.4 GHz) downlink was also added specifically for radio science and to conduct communications experiments. Uplink was via S band (2.1 GHz). A two-axis steerable parabolic dish antenna with a diameter of approximately 1.5 m was attached at one edge of the orbiter base, and a fixed low-gain antenna extended from the top of the bus. Two tape recorders were each capable of storing 1280 megabits. A 381-MHz relay radio was also available.
The power to the two orbiter craft was provided by eight 1.57 × 1.23 m solar panels, two on each wing. The solar panels comprised a total of 34,800 solar cells and produced 620 W of power at Mars. Power was also stored in two nickel-cadmium 30-A·h batteries.
The combined area of the four panels was 15 square meters (160 square feet), and they provided both regulated and unregulated direct current power; unregulated power was provided to the radio transmitter and the lander.
Two 30-amp-hour, nickel-cadmium, rechargeable batteries provided power when the spacecraft was not facing the Sun, and during launch, correction maneuvers and Mars occultation.
By discovering many geological forms that are typically formed from large amounts of water, the images from the orbiters caused a revolution in our ideas about water on Mars. Huge river valleys were found in many areas. They showed that floods of water broke through dams, carved deep valleys, eroded grooves into bedrock, and travelled thousands of kilometers. Large areas in the southern hemisphere contained branched stream networks, suggesting that rain once fell. The flanks of some volcanoes are believed to have been exposed to rainfall because they resemble those caused on Hawaiian volcanoes. Many craters look as if the impactor fell into mud. When they were formed, ice in the soil may have melted, turned the ground into mud, then flowed across the surface. Normally, material from an impact goes up, then down. It does not flow across the surface, going around obstacles, as it does on some Martian craters. Regions, called "Chaotic Terrain," seemed to have quickly lost great volumes of water, causing large channels to be formed. The amount of water involved was estimated to ten thousand times the flow of the Mississippi River. Underground volcanism may have melted frozen ice; the water then flowed away and the ground collapsed to leave chaotic terrain.
Each lander comprised a six-sided aluminium base with alternate 1.09 and 0.56 m (3 ft 7 in and 1 ft 10 in) long sides, supported on three extended legs attached to the shorter sides. The leg footpads formed the vertices of an equilateral triangle with 2.21 m (7 ft 3 in) sides when viewed from above, with the long sides of the base forming a straight line with the two adjoining footpads. Instrumentation was attached inside and on top of the base, elevated above the surface by the extended legs.
Each lander was enclosed in an aeroshell heat shield designed to slow the lander down during the entry phase. To prevent contamination of Mars by Earth organisms, each lander, upon assembly and enclosure within the aeroshell, was enclosed in a pressurized "bioshield" and then sterilized at a temperature of 111 °C (232 °F) for 40 hours. For thermal reasons, the cap of the bioshield was jettisoned after the Centaur upper stage powered the Viking orbiter/lander combination out of Earth orbit.
Each lander arrived at Mars attached to the orbiter. The assembly orbited Mars many times before the lander was released and separated from the orbiter for descent to the surface. Descent comprised four distinct phases, starting with a deorbit burn. The lander then experienced atmospheric entry with peak heating occurring a few seconds after the start of frictional heating with the Martian atmosphere. At an altitude of about 6 kilometers (3.7 miles) and traveling at a velocity of 900 kilometers per hour (600 mph), the parachute deployed, the aeroshell released and the lander's legs unfolded. At an altitude of about 1.5 kilometers (5,000 feet), the lander activated its three retro-engines and was released from the parachute. The lander then immediately used retrorockets to slow and control its descent, with a soft landing on the surface of Mars.
Propulsion for deorbit was provided by the monopropellant hydrazine (N2H4), through a rocket with 12 nozzles arranged in four clusters of three that provided 32 newtons (7.2 lbf) thrust, translating to a change in velocity of 180 m/s (590 ft/s). These nozzles also acted as the control thrusters for translation and rotation of the lander.
Terminal descent (after use of a parachute) and landing utilized three (one affixed on each long side of the base, separated by 120 degrees) monopropellant hydrazine engines. The engines had 18 nozzles to disperse the exhaust and minimize effects on the ground, and were throttleable from 276 to 2,667 newtons (62 to 600 lbf). The hydrazine was purified in order to prevent contamination of the Martian surface with Earth microbes. The lander carried 85 kg (187 lb) of propellant at launch, contained in two spherical titanium tanks mounted on opposite sides of the lander beneath the RTG windscreens, giving a total launch mass of 657 kg (1,448 lb). Control was achieved through the use of an inertial reference unit, four gyros, a radar altimeter, a terminal descent and landing radar, and the control thrusters.
Power was provided by two radioisotope thermoelectric generator (RTG) units containing plutonium-238 affixed to opposite sides of the lander base and covered by wind screens. Each generator was 28 cm (11 in) tall, 58 cm (23 in) in diameter, had a mass of 13.6 kg (30 lb) and provided 30 watts continuous power at 4.4 volts. Four wet cell sealed nickel-cadmium 8 ampere-hours (28,800 coulombs), 28 volts rechargeable batteries were also on board to handle peak power loads.
Communications were accomplished through a 20-watt S-band transmitter using two traveling-wave tubes. A two-axis steerable high-gain parabolic antenna was mounted on a boom near one edge of the lander base. An omnidirectional low-gain S-band antenna also extended from the base. Both these antennae allowed for communication directly with the Earth, permitting Viking 1 to continue to work long after both orbiters had failed. A UHF (381 MHz) antenna provided a one-way relay to the orbiter using a 30 watt relay radio. Data storage was on a 40-Mbit tape recorder, and the lander computer had a 6000-word memory for command instructions.
The lander carried instruments to achieve the primary scientific objectives of the lander mission: to study the biology, chemical composition (organic and inorganic), meteorology, seismology, magnetic properties, appearance, and physical properties of the Martian surface and atmosphere. Two 360-degree cylindrical scan cameras were mounted near one long side of the base. From the center of this side extended the sampler arm, with a collector head, temperature sensor, and magnet on the end. A meteorology boom, holding temperature, wind direction, and wind velocity sensors extended out and up from the top of one of the lander legs. A seismometer, magnet and camera test targets, and magnifying mirror are mounted opposite the cameras, near the high-gain antenna. An interior environmentally controlled compartment held the biology experiment and the gas chromatograph mass spectrometer. The X-ray fluorescence spectrometer was also mounted within the structure. A pressure sensor was attached under the lander body. The scientific payload had a total mass of approximately 91 kg (201 lb).
The Viking landers conducted biological experiments designed to detect life in the Martian soil (if it existed) with experiments designed by three separate teams, under the direction of chief scientist Gerald Soffen of NASA. One experiment turned positive for the detection of metabolism (current life), but based on the results of the other two experiments that failed to reveal any organic molecules in the soil, most scientists became convinced that the positive results were likely caused by non-biological chemical reactions from highly oxidizing soil conditions.
Although there is consensus that the Viking lander results demonstrated a lack of biosignatures in soils at the two landing sites, the test results and their limitations are still under assessment. The validity of the positive 'Labeled Release' (LR) results hinged entirely on the absence of an oxidative agent in the Martian soil, but one was later discovered by the Phoenix lander in the form of perchlorate salts. It has been proposed that organic compounds could have been present in the soil analyzed by both Viking 1 and Viking 2, but remained unnoticed due to the presence of perchlorate, as detected by Phoenix in 2008. Researchers found that perchlorate will destroy organics when heated and will produce chloromethane and dichloromethane, the identical chlorine compounds discovered by both Viking landers when they performed the same tests on Mars.
The question of microbial life on Mars remains unresolved. Nonetheless, on April 12, 2012, an international team of scientists reported studies, based on mathematical speculation through complexity analysis of the Labeled Release experiments of the 1976 Viking Mission, that may suggest the detection of "extant microbial life on Mars."
The leader of the imaging team was Thomas Mutch, a geologist at Brown University in Providence, Rhode Island. The camera uses a movable mirror to illumate 12 photo diodes. Each of the 12 silicon diodes are designed to be sensitive to different frequences of light. Several diodes are placed to focus accurately at distances between six and 43 feet away from the lander.
The cameras scanned at a rate of five vertical scan lines per second, each composed of 512 pixels. The 300 degree panorama images were composed of 9150 lines. The cameras scan was slow enough that in a crew shot several members show up several times in the shot as they moved themselves as the camera scanned.
The Viking landers used a Guidance, Control and Sequencing Computer (GCSC) consisting of two Honeywell HDC 402 24-bit computers with 18K of plated-wire memory, while the Viking orbiters used a Command Computer Subsystem (CCS) using two custom-designed 18-bit serial processors.
The two orbiters cost US$217 million (at the time), which is about 1 billion USD in 2016 year-dollars. The most expensive single part of the program was the lander's life-detection unit, which cost about 60 million then or 300 million USD in 2016 year-dollars. Development of the Viking lander design cost US$357 million. This was decades before NASA's "faster, better, cheaper" approach, and Viking needed to pioneer unprecedented technologies under national pressure brought on by the Cold War and the aftermath of the Space Race, all under the prospect of possibly discovering extraterrestrial life for the first time. The experiments had to adhere to a special 1971 directive that mandated that no single failure shall stop the return of more than one experiment—a difficult and expensive task for a device with over 40,000 parts.
The Viking camera system cost US$27.3 million to develop, or about 100 million in 2016 year-dollars. When the Imaging system design was completed, it was difficult to find anyone who could manufacture it so advanced. The program managers were later praised for fending off pressure to go with a simpler, less advanced imaging system, especially when the views rolled in. The program did save some money by cutting out a third lander and reducing the number of experiments on the lander.
The craft eventually failed, one by one, as follows:
|Craft||Arrival date||Shut-off date||Operational lifetime||Cause of failure|
|Viking 2 orbiter||August 7, 1976||July 25, 1978||1 year, 11 months, 18 days||Shut down after fuel leak in propulsion system.|
|Viking 2 lander||September 3, 1976||April 11, 1980||3 years, 7 months, 8 days||Shut down after battery failure.|
|Viking 1 orbiter||June 19, 1976||August 17, 1980||4 years, 1-month, 19 days||Shut down after depletion of attitude control fuel.|
|Viking 1 lander||July 20, 1976||November 13, 1982||6 years, 3 months, 22 days||Shut down after human error during software update caused the lander's antenna to go down, terminating power and communication.|
The Viking program ended on May 21, 1983. To prevent an imminent impact with Mars the orbit of Viking 1 orbiter was raised on August 7, 1980 before it was shut down 10 days later. Impact and potential contamination on the planet's surface is possible from 2019 onwards. It's unknown if the Viking 2 orbiter's orbit was also raised to prevent an impact.
The Viking 1 lander was found to be about 6 kilometers from its planned landing site by the Mars Reconnaissance Orbiter in December 2006. 
The year 1976 in science and technology involved some significant events, listed below.Andrew Chaikin
Andrew L. Chaikin (born June 24, 1956) is an American author, speaker and science journalist. He currently lives in Vermont.
He is the author of A Man on the Moon, a detailed description of the Apollo missions to the Moon. This book formed the basis for From the Earth to the Moon, a 12-part HBO miniseries.
From 1999 to 2001, Chaikin served as executive editor for space and science at Space.com. From 2008 to 2011, he was a faculty member for Montana State University in Bozeman, Montana. In 2013, he wrote and performed the narration on a NASA video re-creating the taking of the famous Earthrise photo during the Apollo 8 mission.His book A Man on the Moon: One Giant Leap states that he grew up in Great Neck, New York, and, while studying geology at Brown University, worked at the NASA/Caltech Jet Propulsion Laboratory on the Viking program.Biological Oxidant and Life Detection
The Biological Oxidant and Life Detection (BOLD) is a concept mission to Mars focused on searching for evidence or biosignatures of microscopic life on Mars. The BOLD mission objective would be to quantify the amount of hydrogen peroxide (H2O2) existing in the Martian soil and to test for processes typically associated with life. Six landing packages are projected to impact 'softly' on Mars that include a limited power supply, a set of oxidant and life detection experiments, and a transmitter, which is able to transmit information via an existing Mars orbiter back to Earth. The mission was first proposed in 2012.Chryse Planitia
Chryse Planitia (Greek, "Golden Plain") is a smooth circular plain in the northern equatorial region of Mars close to the Tharsis region to the west, centered at 28.4°N 319.7°E / 28.4; 319.7. Chryse Planitia lies partially in the Lunae Palus quadrangle, partially in the Oxia Palus quadrangle, partially in the Mare Acidalium quadrangle. It is 1600 km or 994 mi in diameter and with a floor 2.5 km below the average planetary surface altitude, and is thought to be an ancient impact basin; it has several features in common with lunar maria, such as wrinkle ridges. The density of impact craters in the 100 to 2,000 metres (330 to 6,560 ft) range is close to half the average for lunar maria.
Chryse Planitia shows evidence of water erosion in the past, and is the bottom end for many outflow channels from the southern highlands as well as from Valles Marineris and the flanks of the Tharsis bulge. It is one of the lowest regions on Mars (2 to 3 kilometres (1.2 to 1.9 mi) below the mean surface elevation of Mars), so water would tend to flow into it. The elevation generally goes down from the Tharsis Ridge to Chryse. Kasei Valles, Maja Valles, and Nanedi Valles
appear to run from high areas (Tharsis Ridge) to Chryse Planitia. On the other side of Chryse, to the east, the land gets higher. Ares Vallis travels from this high region, then empties into Chryse. Much of Tiu Valles and Simud Valles move toward Chryse as well.
Several ancient river valleys discovered in Chryse Planitia by the Viking Orbiters, as part of the Viking program, provided strong evidence for a great deal of running water on the surface of Mars.
It has been theorized that the Chryse basin may have contained a large lake or an ocean during the Hesperian or early Amazonian periods since all of the large outflow channels entering it end at the same elevation, at which some surface features suggest an ancient shoreline may be present. Chryse basin opens into the North Polar Basin, so if an ocean was present Chryse would have been a large bay.
The Viking 1 landed in Chryse Planitia, but its landing site was not near the outflow channels and no fluvial features were visible; the terrain at that point appeared primarily volcanic in origin. The Mars Pathfinder landed in Ares Vallis, at the end of one of the outflow channels emptying into Chryse.Colorado Center for Astrodynamics Research
The Colorado Center for Astrodynamics Research (CCAR) is a renowned aerospace research centre specializing in orbital mechanics and spacecraft navigation, located at the University of Colorado at Boulder. CCAR was established at the University of Colorado at Boulder in the College of Engineering and Applied science during the fall of 1985 as a part of the University of Colorado's commitment to develop a program of excellence in space science and is hosted by the Department of Aerospace Engineering Sciences. CCAR is a multidisciplinary group involving faculty, staff and students from the Department of Aerospace Engineering Sciences. Its research program emphasizes astrodynamics, satellite meteorology, oceanography, geodesy, and terrestrial vegetation studies.
CCAR was founded by professor George Born who served as Director for 28 years and Director Emeritus until his death in 2016. Born joined University of Colorado at Boulder after working on high-profile missions like TOPEX/Poseidon, Seasat, Mariner 9 and the Viking program at the Jet Propulsion Laboratory during the 1970s.Gilbert Levin
Gilbert V. Levin is an American engineer, the founder of Spherix and the principal investigator of the Viking mission Labeled Release experiment.In 1997, Levin published his conclusion that a 1976 Viking lander had discovered living microorganisms on Mars. He is noted for still claiming that his experiment on board the 1976 Viking Mars landers to detect microscopic life on Mars rendered a true positive result. On 12 April 2012, an international team including Levin reported, based on mathematical speculation through cluster analysis of the Labeled Release experiments of the Viking program, that may suggest the detection of "extant microbial life on Mars."He is one of the science advisers of the International Committee Against Mars Sample Return.He also patented an inexpensive method to make tagatose, an artificial sweetener, in 1988.James S. Martin
James S. Martin may refer to:
James Stewart Martin (congressman) (1826–1907), U.S. Representative from Illinois
James Stewart Martin (author), Germany
James S. Martin (evangelical minister), anti-Mormon preacher
James Slattin Martin Jr. (1920–2002), project manager for the Viking programList of films set on Mars
There is a body of films that are set on the planet Mars. In the late 19th century, people erroneously believed that there were canals on Mars. Into the early 20th century, additional observations of Mars fed people's interest in what was called "Mars fever". One of the earliest films to be set on Mars was the short film A Trip to Mars (1910), which was produced by one of Thomas Edison's film companies. In the 1920s through the 1960s, more films featured Mars or extraterrestrial Martians. In the 1960s and 1970s, the Mariner program and the Viking program revealed new scientific details about Mars that showed little prospect for life. The Guardian said, "These disappointing discoveries changed the place of Mars on humanity's mental map. Films began to reflect this." Films such as Total Recall (1990) and Red Planet (2000) focused more on the colonization of Mars by humans.The Guardian, reporting on the release of John Carter (2012), said, since 1995, six films featuring Mars performed poorly at the box office. Wired, reporting on the release of The Martian (2015), said prior films set on Mars—Red Planet, Mission to Mars (2000), and The Last Days on Mars (2013)—were "notable flops" that were the most recent in a "dismal track record of Mars movies". The Atlantic called The Martian "the subgenre's newest and best entry", citing the positive reviews and strong box office returns on opening weekend. It said, "Many films seek to dramatize the Red Planet’s harsh landscape as a romantic frontier, but The Martian is one that actually succeeds."List of rocks on Mars
This is an alphabetical list of named rocks (and meteorites) found on Mars, by mission. This list does not include Martian meteorites found on Earth.
Names for Mars rocks are largely unofficial designations used for ease of discussion purposes, as the International Astronomical Union's official Martian naming system declares that objects smaller than 100 m (330 ft) are not to be given official names. Because of this, some less significant rocks seen in photos returned by Mars rovers have been named more than once, and others have even had their names changed later due to conflicts or even matters of opinion. Often rocks are named after the children or family members of astronauts or NASA employees. The name Jazzy, for example, was taken from a girl named Jazzy who grew up in Grand Junction, CO, USA. Her father worked for NASA and contributed to the findings and naming of the rocks.List of unmanned NASA missions
Since 1958, NASA has overseen more than 1,000 unmanned missions into Earth orbit or beyond. It has both launched its own missions, and provided funding for private-sector missions. A number of NASA missions, including the Explorers Program, Voyager program, and New Frontiers program, are still ongoing.Lunae Palus quadrangle
The Lunae Palus quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The quadrangle is also referred to as MC-10 (Mars Chart-10). Lunae Planum and parts of Xanthe Terra and Chryse Planitia are found in the Lunae Palus quadrangle. The Lunae Palus quadrangle contains many ancient river valleys.
The quadrangle covers the area from 45° to 90° west longitude and 0° to 30° north latitude on Mars. The Viking I Lander (part of Viking program) landed in the quadrangle on July 20, 1976, at 22.4°N 47.5°W / 22.4; -47.5. It was the first robot spacecraft to successfully land on the Red Planet.Mariner program
The Mariner program was a 10-mission program conducted by the American space agency NASA in conjunction with Jet Propulsion Laboratory (JPL). The program launched a series of robotic interplanetary probes, from 1962 to 1973, designed to investigate Mars, Venus and Mercury. The program included a number of firsts, including the first planetary flyby, the first planetary orbiter, and the first gravity assist maneuver.
Of the ten vehicles in the Mariner series, seven were successful, forming the starting point for many subsequent NASA/JPL space probe programs. The planned Mariner Jupiter-Saturn vehicles were adapted into the Voyager program, while the Viking program orbiters were enlarged versions of the Mariner 9 spacecraft. Later Mariner-based spacecraft include the Magellan probe and the Galileo probe, while the second-generation Mariner Mark II series evolved into the Cassini–Huygens probe.
The total cost of the Mariner program was approximately $554 million.The name of the Mariner program was decided in "May 1960-at the suggestion of Edgar M. Cortright" to have the "planetary mission probes ... patterned after nautical terms, to convey "the impression of travel to great distances and remote lands."" That "decision was the basis for naming Mariner, Ranger, Surveyor, and Viking probes."Mars landing
A Mars landing is a landing of a spacecraft on the surface of Mars. Of multiple attempted Mars landings by robotic, unmanned spacecraft, eight have been successful. There have also been studies for a possible human mission to Mars, including a landing, but none have been attempted.
The most recent landing took place on November 26, 2018 by the NASA probe InSight.Plated wire memory
Plated wire memory is a variation of core memory developed by Bell Laboratories in 1957. Its primary advantage was that it could be machine-assembled, which potentially led to lower prices than the hand-assembled core.
Instead of threading individual ferrite cores on wires, plated wire memory used a grid of wires coated with a thin layer of iron-nickel alloy (called permalloy). The magnetic field normally stored in the ferrite core was instead stored on the wire itself. Operation was generally similar to core, but could also be built with a non-destructive read that did not require refreshing.
Plated wire memory has been used in a number of applications, typically in aerospace. It was used in the UNIVAC 1110 and UNIVAC 9000 series computers, the Viking program that sent landers to Mars, the Voyager space probes, a prototype guidance computer for the Minuteman-III, the Space Shuttle Main Engine Controllers, KH-9 Hexagon reconnaissance satellite and in the Hubble Space Telescope.Viking 1
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 second spacecraft to soft-land on Mars, and the first soft lander to successfully perform its mission. (The first spacecraft to soft-land on Mars was the Soviet Union's Mars 3 on December 2, 1971, which stopped transmitting after 14.5 seconds.) Viking 1 held the record for the longest Mars surface mission of 2307 days (over 6¼ years) or 2245 Martian solar days, until that record was broken by Opportunity on May 19, 2010.Viking 2
The Viking 2 mission was part of the American Viking program to Mars, and consisted of an orbiter and a lander essentially identical to that of the Viking 1 mission. The Viking 2 lander operated on the surface for 1316 days, or 1281 sols, and was turned off on April 11, 1980 when its batteries failed. The orbiter worked until July 25, 1978, returning almost 16,000 images in 706 orbits around Mars.Viking Terra
Viking Terra is a region on the dwarf planet Pluto which lies just west of Sputnik Planum and south of Voyager Terra. It was discovered by the New Horizons probe during the July 2015 flyby of the dwarf planet. It is named after the Viking program.Viking lander biological experiments
The two Viking landers each carried four types of biological experiments to the surface of Mars in 1976. These were the first Mars landers to carry out experiments to look for biosignatures of microbial life on Mars. The landers used a robotic arm to put soil samples into sealed test containers on the craft. The two landers were identical, so the same tests were carried out at two places on Mars' surface, Viking 1 near the equator and Viking 2 further north.Voyager program (Mars)
The Voyager Mars Program was a planned series of unmanned NASA probes to the planet Mars. The missions were planned, as part of the Apollo Applications Program, between 1966 and 1968 and were scheduled for launch in 1974–75. The probes were conceived as precursors for a manned Mars landing in the 1980s.
Originally, NASA had proposed a direct lander using a variant of the Apollo Command Module launched atop of a Saturn IB rocket with a Centaur upper stage. With the discovery by Mariner 4 in 1965 that Mars had only a tenuous atmosphere, the mission was changed to have both an orbiter and lander. This required the use of a Saturn V to launch two probes at once. The orbiter would have been a modified Mariner probe identical to that employed for Mariner 8 and Mariner 9, while the landers would have been Surveyor moon probes modified with the use of aeroshells and a combination parachute/retrorocket landing systems.
Funding for the program, like that of the entire AAP, was cut in 1968 and the mission itself was cancelled entirely in 1971, mainly on the grounds that launching both probes on a single rocket was both risky and expensive. Voyager was the first major space science project to be cancelled by the U.S. Congress.
Despite the cancellation, the planning and development of the Voyager Mars program was eventually carried out by NASA's Viking program in the mid-1970s. Cheaper and simpler than the Voyager Mars program (using the same Mariner 8/9 design for the orbiter, but with an automobile-sized lander with a very expensive microbiology lab), the Viking 1 and Viking 2 probes were launched to Mars on separate Titan IIIE/Centaur rockets in 1975 and reached Mars in 1976.
After the cancellation, the "Voyager" name was recycled for the Mariner 11 and Mariner 12 probes to the outer planets, with the latter probe, Voyager 2 (Mariner 12), completing another ambitious post-Apollo project, the "Grand Tour". The Saturn V had also been planned at one point as the launch vehicle for an upscaled probe for this mission.