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62-646: 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. Viking 2 was operational on Mars for 1281 sols (1,316 days ; 3 years, 221 days ). The Viking 2 lander operated on the surface for 1,316 days, or 1281 sols, and was turned off on April 12, 1980, when its batteries eventually failed. The orbiter worked until July 25, 1978, returning almost 16,000 images in 706 orbits around Mars. The craft

124-414: 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

186-523: 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

248-493: A few hours, at about 300 km attitude, the lander was reoriented for entry. The aeroshell with its ablative heat shield slowed the craft as it plunged through the atmosphere. The Viking 2 lander touched down about 200 km west of the crater Mie in Utopia Planitia at 48°16′08″N 225°59′24″W  /  48.269°N 225.990°W  / 48.269; -225.990 at an altitude of -4.23 km relative to

310-460: A leak in its propulsion system that vented its attitude control gas. It was placed in a 302 × 33,176 km orbit and turned off on July 25, 1978, after returning almost 16,000 images in about 700–706 orbits around Mars. The lander and its aeroshell separated from the orbiter on September 3, 1976, at 19:39:59 UT. At the time of separation, the lander was orbiting at about 4 km/s. After separation, rockets fired to begin lander deorbit . After

372-450: 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

434-448: A reference ellipsoid with an equatorial radius of 3,397.2 km and a flattening of 0.0105 ( 47°58′01″N 225°44′13″W  /  47.967°N 225.737°W  / 47.967; -225.737  ( Viking 2 landing site planetographic ) planetographic longitude ) at 22:58:20 UT (9:49:05 a.m. local Mars time). Approximately 22 kg (49 lb) of propellants were left at landing. Due to radar misidentification of

496-420: A rock or highly reflective surface, the thrusters fired an extra time 0.4 seconds before landing, cracking the surface and raising dust. The lander settled down with one leg on a rock, tilted at 8.2 degrees. The cameras began taking images immediately after landing. The Viking 2 lander was powered by radioisotope generators and operated on the surface until its batteries failed on April 12, 1980. In July 2001,

558-441: 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. At landing (after using rocket propellant)

620-573: Is possible from 2019 onwards. The Viking 1 lander was found to be about 6 kilometers from its planned landing site by the Mars Reconnaissance Orbiter in December 2006. Each Viking lander carried a tiny dot of microfilm containing the names of several thousand people who had worked on the mission. Several earlier space probes had carried message artifacts, such as the Pioneer plaque and

682-452: The Opportunity rover both found sulfates on Mars. Minerals typical weathering products of mafic igneous rocks were found. All samples heated in the gas chromatograph-mass spectrometer (GCMS) gave off water. However, the way the samples were handled prohibited an exact measurement of the amount of water. But, it was around 1%. Studies with magnets aboard the landers indicated that

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744-450: 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 ,

806-573: 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 $ 27.3 million to develop, or about $ 200 million in 2023 dollars. When

868-622: The Viking 2 lander was renamed the Gerald Soffen Memorial Station after Gerald Soffen (1926–2000), the project scientist of the Viking program. The regolith, referred to often as "soil," resembled those produced from the weathering of basaltic lavas . The tested soil contained abundant silicon and iron , along with significant amounts of magnesium , aluminum , sulfur , calcium , and titanium . Trace elements, strontium and yttrium , were detected. The amount of potassium

930-750: The Voyager Golden Record . Later probes also carried memorials or lists of names, such as the Perseverance rover which recognizes the almost 11 million people who signed up to include their names on the mission. Gerald Soffen He earned his A.B.S. from the University of California, Los Angeles , his M.S. from University of Southern California , and his Ph.D. in Biology from Princeton University . He pursued his postdoctoral work at New York University . Working from NASA's Langley Research Center in

992-428: The "Mission to Planet Earth" program; Soffen also served as the project scientist for NASA's Earth Observing System as that program was starting. Soffen's focus shifted to education starting in 1990, when he led the formation of GSFC's University Programs office and became its manager. Three years into that role, Soffen created NASA Academy , NASA's premiere leadership training internship. During 1990–1992, he served on

1054-459: 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 (32 ft). 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

1116-504: The Imaging system design was completed, it was difficult to find anyone who could manufacture its advanced design. 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 however save some money by cutting out a third lander and reducing the number of experiments on the lander. Overall NASA says that $ 1 billion in 1970s dollars

1178-564: 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

1240-538: The Martian soil. The results were Unusual and conflicting: the GCMS and GEX gave negative results, while the PR and LR gave positive results. 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." Many scientists believe that the data results were attributed to inorganic chemical reactions in

1302-486: 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

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1364-478: 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

1426-652: The Science Advisory Committee for Biosphere 2 . Soffen has been memorialized in several ways by his peers and former students. The "Dr. Gerald A. Soffen Memorial Fund for the Advancement of Space Science Education" was established by the NASA Academy Alumni Association "to continue Jerry's commitment to the future of space by supporting motivated students in the fields of space science and engineering". The "Gerald Soffen Memorial Panel/Lecture"

1488-693: The Viking's findings up to that time. "We have started what will become an adventure of mankind in searching for not only the lower forms of life but also the search for intelligent life. This is one of the milestones in the course of human destiny to find cousins". Soffen also predicted that mankind would eventually colonize Mars by using Planetary Engineering . He moved to become NASA Langley's Chief Environmental Scientist in 1968, leading work on remote sensing by satellite as well as laboratory experiments, ground-based measurements, and theoretical models. In 1978, after concluding his work with Viking, Soffen became

1550-472: 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. Astronomer Carl Sagan helped to choose landing sites for both Viking probes. Each lander arrived at Mars attached to

1612-466: The beginning of solar conjunction . The extended mission commenced on December 14, 1976, after the solar conjunction. On December 20, 1976, the periapsis was lowered to 778 km, and the inclination raised to 80 degrees. Operations included close approaches to Deimos in October 1977, and the periapsis was lowered to 300 km and the period changed to 24 hours on October 23, 1977. The orbiter developed

1674-472: 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

1736-596: 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 Viking RTG 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 of continuous power at 4.4 volts. Four wet cell sealed nickel-cadmium 8 Ah (28,800  coulombs ), 28 volt rechargeable batteries were also on board to handle peak power loads. Communications were accomplished through

1798-732: The detection of "extant microbial life on Mars." In addition, new findings from re-examination of the Gas Chromatograph Mass Spectrometer (GCMS) results were published in 2018. The leader of the imaging team was Thomas A. Mutch , a geologist at Brown University in Providence, Rhode Island . The camera uses a movable mirror to illuminate 12 photodiodes . Each of the 12 silicon diodes are designed to be sensitive to different frequencies of light. Several broad band diodes (designated BB1, BB2, BB3, and BB4) are placed to focus accurately at distances between six and 43 feet away from

1860-994: The director of Life Sciences at NASA Headquarters. In this position, Soffen was responsible for the agency-wide program to monitor and maintain the physical well being of NASA astronauts in space, as well as the Biomedical Program, the Space Biology Program, and the Exobiology (also sometimes called the Astrobiology) program. If you ever heard him speak, you know that he was the oratorical equal of luminaries like Carl Sagan. Like Sagan, Soffen spoke cogently, succinctly, and poetically about our search for life beyond earth. In 1983, Soffen transferred from NASA Headquarters to NASA Goddard Space Flight Center (GSFC) in Greenbelt, Maryland. Initially, his role at GSFC focused on establishing

1922-496: The final landing site. The lander separated from the orbiter on September 3, 1976, at 22:37:50 UT and landed at Utopia Planitia . The normal procedure called for the structure connecting the orbiter and lander (the bioshield) to be ejected after separation. However, due to problems with the separation process, the bioshield remained attached to the orbiter. The orbit inclination was raised to 75 degrees on September 30, 1976. The orbiter's primary mission ended on October 5, 1976, at

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1984-543: 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, during launch, while performing correction maneuvers and also during Mars occultation. By discovering many geological forms that are typically formed from large amounts of water,

2046-461: 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

2108-535: 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

2170-452: 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

2232-426: The lander. Terminal descent (after use of a parachute ) and landing used 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 lb f ). The hydrazine was purified in order to prevent contamination of

2294-432: The lander.  A low resolution broad band diode was named SURVEY.   There are also three narrow band low resolution diodes (named BLUE, GREEN and RED) for obtaining color images , and another three (IR1, IR2, and IR3) for infrared imagery. 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

2356-417: The landers had a mass of about 600 kg. Propulsion for deorbit was provided by the monopropellant hydrazine (N 2 H 4 ), through a rocket with 12 nozzles arranged in four clusters of three that provided 32 newtons (7.2 lb f ) 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

2418-428: 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, more than two weeks before Viking 2 ' s arrival in orbit. Viking 2 then successfully soft-landed on September 3. The orbiters continued imaging and performing other scientific operations from orbit while the landers deployed instruments on

2480-427: 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 (8.2 ft) across. The fully fueled orbiter-lander pair had a mass of 3,527 kg (7,776 lb). After separation and landing, the lander had a mass of about 600 kg (1,300 lb) and the orbiter 900 kg (2,000 lb). The total launch mass

2542-415: 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 on August 7. After orbiting Mars for more than a month and returning images used for landing site selection, the orbiters and landers detached;

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2604-522: The mid- to late-1970s, Soffen was project scientist for the NASA's Viking program of Mars landers, the first successful missions to perform unmanned experiments on the surface of the planet. In that role, he oversaw all scientific investigations conducted by the landers, coordinating the work of more than seventy scientists around the nation. In 1977, he appeared on an episode of the popular television series In Search Of entitled "Martians" and he spoke about

2666-438: The mission was that the discovery of organic chemicals was inconclusive. 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 powerful oxidizing agent, which could have eradicated any organic material on

2728-434: 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

2790-493: The presence of branched stream areas suggests that there was once rainfall. The images below are mosaics of many small, high-resolution images. Viking program The Viking program consisted of a pair of identical American space probes , Viking 1 and Viking 2 , which landed on Mars in 1976. The mission effort began in 1968 and was managed by the NASA Langley Research Center. Each spacecraft

2852-459: The soil is between 3 and 7 percent magnetic materials by weight. The magnetic chemicals could be magnetite and maghemite , which could come from the weathering of basalt rock. Subsequent experiments carried out by the Mars Spirit rover (landed in 2004) suggest that magnetite could explain the magnetic nature of the dust and soil on Mars. Viking 2 carried a biology experiment whose purpose

2914-408: The soil. However, this view may be changing due to a variety of discoveries and studies since Viking. These include the discovery of near-surface ice near the Viking landing zone, the possibility of perchlorate destruction of organic matter, and the reanalysis of GCMS data by scientists in 2018. Some scientists still believe the results were due to living reactions. The formal declaration at the time of

2976-482: The surface. The project cost was roughly US$ 1 billion at the time of launch, equivalent to about $ 6 billion in 2023 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. 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

3038-415: The surface. Perchlorate is now considered widespread on Mars, making it hard to detect any organic compounds on the Martian surface. The Viking Orbiters led to significant discoveries about the presence of water on Mars. Huge river valleys were found in many areas. They showed that water floods carved deep valleys, eroded grooves into bedrock, and traveled thousands of kilometers. In the southern hemisphere,

3100-443: The time, which is about $ 1 billion in 2023 dollars. The most expensive single part of the program was the lander's life-detection unit, which cost about $ 60 million then or $ 400 million in 2023 dollars. Development of the Viking lander design cost $ 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

3162-474: 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 m × 1.23 m (62 in × 48 in) 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

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3224-514: The vertices of an equilateral triangle with 2.21 m (7.3 ft) 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

3286-461: Was 2,328 kg (5,132 lb), of which 1,445 kg (3,186 lb) were propellant and attitude control gas. The eight faces of the ring-like structure were 0.457 m (18 in) high and were alternately 1.397 and 0.508 m (55 and 20 in) wide. The overall height was 3.29 m (10.8 ft) 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

3348-399: Was a pronouncement by NASA during the mission saying that the Viking lander results did not demonstrate conclusive 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

3410-452: Was capable of 1,323  N (297  lbf ) thrust, providing a change in velocity of 1,480 m/s (3,300 mph). 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

3472-417: 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

3534-467: 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 (43 and 22 in) long sides, supported on three extended legs attached to the shorter sides. The leg footpads formed

3596-535: Was launched on September 9, 1975. Following launch using a Titan / Centaur launch vehicle and a 333-day cruise to Mars, the Viking 2 Orbiter began returning global images of Mars prior to orbit insertion. The orbiter was inserted into a 1,500 x 33,000 km, 24.6 h Mars orbit on August 7, 1976, and trimmed to a 27.3 h site certification orbit with a periapsis of 1,499 km and an inclination of 55.2 degrees on August 9. The orbiter then began taking photographs of candidate landing sites, which were used to select

3658-415: Was one-fifth of the average for the Earth's crust. Some chemicals in the soil contained sulfur and chlorine that were like those remaining after the evaporation of seawater. Sulfur was more concentrated in the crust on top of the soil than in the bulk soil beneath. The sulfur may be present as sulfates of sodium , magnesium, calcium, or iron. A sulfide of iron is also possible. The Spirit rover and

3720-521: Was slow enough that in a crew shot taken during development of the imaging system 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

3782-404: Was spent on the program, which when inflation-adjusted to 2023 dollars is about $ 6 billion. The craft all eventually failed, one by one, as follows: 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

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3844-605: Was to look for life. The Viking 2 biology experiment weighed 15.5 kg (34 lb) 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 2 carried a Gas Chromatograph/Mass Spectrometer (GCMS) that could measure the composition and abundance of organic compounds in

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