Viking mission profile.

NASA's Viking program consisted of two unmanned space missions to Mars, Viking 1 and Viking 2. Each mission had a satellite designed to photograph the surface of Mars from orbit, and to act as a communication relay for the Viking lander that each mission carried. It was the most expensive and ambitious mission ever sent to Mars. It formed most of the database of information about Mars until the late 1990's and early 2000's. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... The National Aeronautics and Space Administration (NASA) is an agency of the United States federal government, responsible for the nations public space program. ... It has been suggested that Space probe be merged into this article or section. ... Mars is the fourth planet from the Sun in the solar system, named after the Roman god of war (the counterpart of the Greek Ares), on account of its blood red color as viewed in the night sky. ... The Viking 1 was the first of two spacecraft sent to Mars as part of NASAs Viking program. ... Frost on Mars. ... An Earth observation satellite, ERS 2 For other uses, see Satellite (disambiguation). ... This article or section does not adequately cite its references or sources. ... m. ...

The Viking program grew from NASA's earlier, and 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 III-E rockets with Centaur upper stages. Each spacecraft consisted of an orbiter and a lander. After orbiting Mars and returning images used for landing site selection, the orbiter and lander detached and the lander entered the Martian atmosphere and soft-landed at the selected site. The orbiters continued imaging and other scientific operations from orbit while the landers deployed instruments on the surface. 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 spacecraft was controlled by a RCA 1802 Cosmac microprocessor CPU. The Voyager program was a planned series of unmanned NASA probes to Mars. ... Voyager Project redirects here. ... Uses of the word launch: A launch can be a type of boat: see launch (boat). ... August 20 is the 232nd day of the year (233rd in leap years) in the Gregorian calendar. ... 1975 (MCMLXXV) was a common year starting on Wednesday. ... September 9 is the 252nd day of the year (253rd in leap years). ... 1975 (MCMLXXV) was a common year starting on Wednesday. ... The Titan IIIC is a space booster used by the United States Air Force. ... Model of Centaur with Surveyor as payload. ... The Space Shuttle Discovery as seen from the International Space Station. ... An orbiter is a spacecraft that orbits a planet or moon without landing on it in order to study the objects surface from a safe distance. ... A lander is a type of spacecraft which descends to come to rest on the surface of an astronomical body. ... Atmosphere is the general name for a layer of gases that may surround a material body of sufficient mass. ... Soft landing is a landing in which buoyancy is slightly decreased. ... Part of a scientific laboratory at the University of Cologne. ... Captain Nemo and Professor Aronnax contemplating measuring instruments in Twenty Thousand Leagues Under the Sea In physics and engineering, measurement is the activity of comparing physical quantities of real-world objects and events. ... Unsolved problems in physics: What causes anything to have mass? The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. Mass is the property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. It was assigned to the United States in 1889 and is periodically recertified and traceable to the primary international standard, The Kilogram, held at the Bureau International des Poids et... The RCA (CDP)1802 (aka RCA COSMAC*, COSMAC 1802) is an 8-bit CMOS microprocessor (µP) introduced by RCA in early 1976, and presently being manufactured by Intersil Corporation. ... A microprocessor is a programmable digital electronic component that incorporates the functions of a central processing unit (CPU) on a single semiconducting integrated circuit (IC). ... CPU can stand for: in computing: Central processing unit in journalism: Commonwealth Press Union in law enforcement: Crime prevention unit in software: Critical patch update, a type of software patch distributed by Oracle Corporation in Macleans College is often known as Ash Lim. ...

Spacecraft design

Orbiter

Viking orbiter (NASA)

The primary objectives of the Viking orbiters were to transport the landers to Mars, perform reconnaissance to locate and certify landing sites, act as a communications relays for the landers, and to perform their own scientific investigations. The orbiter, based on the earlier Mariner 9 spacecraft, was an octagon approximately 2.5 m across. 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 power was provided by eight 1.57 × 1.23 m solar panels, two on each wing. The solar panels were made up of a total of 34,800 solar cells and produced 620 W of power at Mars. Power was also stored in 2 nickel-cadmium 30-A h batteries. Viking orbiter (small). ... Viking orbiter (small). ... Mariner 9 launch Mariner 9 was a NASA space probe orbiter that helped in the exploration of Mars and was part of the Mariner program. ... For other uses, see Octagon (disambiguation). ... The or meter (see spelling differences) is a measure of length. ... A coordinate axis is one of a set of vectors that defines a coordinate system. ... A laundromat in California with flat-plate solar water heating collectors on its roof. ... The nickel-cadmium battery (commonly abbreviated NiCd or NiCad) is a popular type of rechargeable battery for portable electronics and toys. ... Four double-A (AA) rechargeable batteries In science and technology, a battery is a device that stores energy and makes it available in an electrical form. ... Four double-A (AA) rechargeable cells A Duracell AA alkaline cell In science and technology, a galvanic cell is an electrochemical cell that stores chemical energy and makes it available in an electrical form, and a battery is a string of two or more cells in series. ...

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 1323 N (297 lbf) thrust, translating to a delta-V 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 high-gain 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 Mbits. A 381-MHz relay radio was also available. A remote camera captures a close-up view of a Space Shuttle Main Engine during a test firing at the John C. Stennis Space Center in Hancock County, Mississippi Spacecraft propulsion is used to change the velocity of spacecraft and artificial satellites, or in short, to provide delta-v. ... An electrical bus (sometimes spelled buss) is a physical electrical interface where many devices share the same electric connection. ... F-1 rocket engine (The kind used by the Saturn V.) A bipropellant rocket is a rocket that uses separate fuel and oxidizer propellants. ... Monomethylhydrazine (MMH) is a volatile hydrazine with the chemical formula CH3N2H3. ... Nitrogen tetroxide (or Dinitrogen tetroxide) (N2O4) is a hypergolic propellant often used in combination with a hydrazine-based rocket fuel. ... A cold (un-ignited) rocket engine test at NASA A rocket engine is a reaction engine that can be used for spacecraft propulsion as well as terrestrial uses, such as missiles. ... A gimbal is a mechanical device that allows the rotation of an object in multiple dimensions. ... A degree (in full, a degree of arc, arc degree, or arcdegree), usually symbolized °, is a measurement of plane angle, representing 1／360 of a full rotation. ... The newton (symbol: N) is the SI unit of force. ... The pound-force is a non-SI unit of force or weight (properly abbreviated lbf or lbf). The pound-force is equal to a mass of one pound multiplied by the standard acceleration due to gravity on Earth (which is defined as exactly 9. ... General In general physics delta-v is simply the change in velocity. ... Metre per second (U.S. spelling: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector), defined by distance in metres divided by time in seconds. ... // In the context of spacecraft, attitude control is control of the angular position and rotation of the spacecraft, either relative to the object that it is orbiting, or relative to the celestial sphere. ... In the context of spacecraft, attitude control is control of the angular position and rotation of the spacecraft, either relative to the object that it is orbiting, or relative to the celestial sphere. ... In the context of spacecraft, attitude control is control of the angular position and rotation of the spacecraft, either relative to the object that it is orbiting, or relative to the celestial sphere. ... A gyroscope For other uses, see Gyroscope (disambiguation). ... An accelerometer or gravimeter is a device for measuring acceleration and the effects of gravity. ... The watt (symbol: W) is the SI derived unit of power, equal to one joule per second. ... The S band ranges from 2. ... A gigahertz is a billion hertz or a thousand megahertz, a measure of frequency. ... Antenna tower of Crystal Palace transmitter, London A transmitter (sometimes abbreviated XMTR) is an electronic device which with the aid of an antenna propagates an electromagnetic signal such as radio, television, or other telecommunications. ... A TWTA or travelling-wave tube amplifier is an electronic device used to produce high-power radiofrequency signals. ... The X band, ranging from 8. ... In radio communications, a downlink is the link from a satellite to a ground station. ... This article deals with Uplink in the telecommunications terminology. ... In electronics, gain is usually taken as the mean ratio of the signal output of a system to the signal input of the system. ... A parabola A graph showing the reflective property, the directrix (light blue), and the lines connecting the focus and directrix to the parabola (blue) In mathematics, the parabola (from the Greek: παραβολή) (IPA pronunciation: ) is a conic section generated by the intersection of a right circular conical surface and a plane... A dish antenna is a type of antenna in which a parabolic dish focuses a signal onto an antenna, located at the parabolas focal point. ... The Megabit is a unit of information storage, abbreviated Mbit or sometimes Mb. ... MegaHertz (MHz) is the name given to one million (106) Hertz, a measure of frequency. ...

The Lander

Carl Sagan with a model of the Viking Lander, for scale (NASA)

The lander consisted of a six-sided aluminum base with alternate 1.09-m and 0.56-m 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 sides when viewed from above, with the long sides of the base forming a straight line with the two adjoining footpads. Instrumentation was attached to the top of the base, elevated above the surface by the extended legs. Power was provided by two radioisotope thermal generator (RTG) units containing plutonium-238 affixed to opposite sides of the lander base and covered by wind screens. Each generator was 28 cm tall, 58 cm in diameter, had a mass of 13.6 kg and provided 30 W continuous power at 4.4 volts. Four wet cell sealed nickel-cadmium 8 A·h, 28-volt rechargeable batteries were also onboard to handle peak power loads. Image File history File links Sagan_Viking. ... Image File history File links Sagan_Viking. ... Insert non-formatted text here Carl Edward Sagan (November 9, 1934 – December 20, 1996) was an American astronomer and astrobiologist and a highly successful popularizer of astronomy, astrophysics, and other natural sciences. ... Aluminum is a soft and lightweight metal with a dull silvery appearance, due to a thin layer of oxidation that forms quickly when it is exposed to air. ... A radioisotope thermoelectric generator (RTG) is a simple electrical generator which obtains its power from radioactive decay. ... General Name, Symbol, Number plutonium, Pu, 94 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery white Standard atomic weight (244) g·mol−1 Electron configuration [Rn] 5f6 7s2 Electrons per shell 2, 8, 18, 32, 24, 8, 2 Physical properties Phase solid Density (near r. ... Josephson junction array chip developed by NIST as a standard volt. ... A wet cell is a kind of electrochemical cell used as a learning tool for electrochemistry. ... It has been suggested that secondary cell be merged into this article or section. ...

Propulsion was provided for deorbit by a monopropellant hydrazine (N₂H₄) rocket with 12 nozzles arranged in four clusters of three that provided 32 N thrust, giving a delta-V of 180 m/s. These nozzles also acted as the control thrusters for translation and rotation of the lander. Terminal descent and landing was achieved by 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 N to 2667 N. The hydrazine was purified to prevent contamination of the Martian surface. The lander carried 85 kg 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. Control was achieved through the use of an inertial reference unit, four gyros, an aerodecelerator, a radar altimeter, a terminal descent and landing radar, and the control thrusters. A (usually liquid) rocket propellant that can be used by itself, without the need for a second component. ... Hydrazine is the chemical compound with formula N2H4. ... A thruster is a small propulsive device used by spacecraft and watercraft for station keeping, attitude control, or long duration low thrust acceleration. ... In Euclidean geometry, translation is a transformation of Euclidean space which moves every point by a fixed distance in the same direction. ... A sphere rotating around its axis. ... A descent during air travel is any portion where an aircraft decreases altitude, and is the opposite of an ascent. ... MyTravel Airways Airbus A320 landing Landing is the last part of a flight, where a flying animal or aircraft returns to the ground. ... Most rocket engines and ramjets can only be turned on (at full power) or completely off. ... General Name, Symbol, Number titanium, Ti, 22 Chemical series transition metals Group, Period, Block 4, 4, d Appearance silvery metallic Standard atomic weight 47. ... A Radar Altimeter measures altitude above the terrain presently beneath the aircraft. ... This long range radar antenna, known as ALTAIR, is used to detect and track space objects in conjunction with ABM testing at the Ronald Reagan Test Site on the Kwajalein atoll. ...

Each lander was covered over from launch until Martian atmospheric entry with an aeroshell heatshield designed to slow the lander down during the entry phase, and also to prevent contamination of the Martian surface with Earthly microbial life that can survive the harsh conditions of deep space (as evident on the Surveyor 3 moon probe). As a further precaution, each lander, upon assembly and enclosure within the aeroshell, were "baked" at a temperature of +250 °F (120 °C) for a total of seven days, after which a "bioshield" was then placed over the aeroshell that was jettisoned after the Centaur upper stage fired the Viking orbiter/lander combination out of Earth orbit. The methods and standards developed for planetary protection for the Viking mission are still used for other missions. Surveyor 3 was the third lunar lander of the Surveyor program that explored the Moon. ... Planetary Protection is the term used to describe a guiding principle in design of an interplanetary mission that aims to prevent biological contamination of both the target planet/celestial body and the Earth. ...

Communications were accomplished through a 20-W S-band transmitter and two 20-W TWTAs. 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. A UHF (381 MHz) antenna provided a one-way relay to the orbiter using a 30 W relay radio. Data storage was on a 40-Mbit tape recorder, and the lander computer had a 6000-word memory for command instructions. A TWTA or travelling-wave tube amplifier is an electronic device used to produce high-power radiofrequency signals. ... An omnidirectional antenna is an antenna system which radiates power uniformly in one plane with a directive pattern shape in a perpendicular plane. ... This article is about the radio frequency. ...

Image from Mars taken by Viking 2

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. Image File history File links Size of this preview: 760 × 600 pixelsFull resolution (939 × 741 pixel, file size: 62 KB, MIME type: image/jpeg) viking 2 lander - NASA - File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Viking program... Image File history File links Size of this preview: 760 × 600 pixelsFull resolution (939 × 741 pixel, file size: 62 KB, MIME type: image/jpeg) viking 2 lander - NASA - File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Viking program... This article or section does not cite any references or sources. ... Benzene is the simplest of the arenes, a family of organic compounds An organic compound is any member of a large class of chemical compounds whose molecules contain carbon and hydrogen; therefore, carbides, carbonates, carbon oxides and elementary carbon are not organic (see below for more on the definition controversy... Inorganic chemistry is the branch of chemistry concerned with the properties and reactions of inorganic compounds. ... Satellite image of Hurricane Hugo with a polar low visible at the top of the image. ... Seismology (from the Greek seismos = earthquake and logos = word) is the scientific study of earthquakes and the propagation of elastic waves through the Earth. ... Magnetic lines of force of a bar magnet shown by iron filings on paper In physics, magnetism is one of the phenomena by which materials exert an attractive or repulsive force on other materials. ... Large format camera lens. ... It has been suggested that this article or section be merged with Magnetism. ... Seismometer (in Greek seismos = earthquake and metero = measure) are used by seismologists to measure and record the size and force of seismic waves. ... A test target is a common feature on interplanetary landing craft such as the Viking Lander and Mars Exploration Rovers. ... A mirror, reflecting a vase. ... This article or section does not cite any references or sources. ... Gas-liquid chromatography (GLC), or simply gas chromatography (GC) is a type of chromatography in which the mobile phase is a carrier gas, usually an inert gas such as helium or nitrogen, and the stationary phase is a microscopic layer of liquid on an inert solid support. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... Fluorescence induced by exposure to ultraviolet light in vials containing various sized Cadmium selenide (CdSe) quantum dots. ... The use of water pressure - the Captain Cook Memorial Jet in Lake Burley Griffin, Canberra. ... In cargo transport, the payload is the valuable contents of the vehicle. ...

The total cost of the Viking project was roughly one billion United States dollars. ISO 4217 Code USD User(s) the United States, the British Indian Ocean Territory,[1] the British Virgin Islands, Cambodia, East Timor, Ecuador, El Salvador, the Marshall Islands, Micronesia, Palau, Panama, Turks and Caicos Islands, and the insular areas of the United States Inflation 2. ...

Mission End

The craft eventually failed, one by one, as follows:

The whole of the Viking program was finally shut down on 21 May 1983. The Viking 1 was the first of two spacecraft sent to Mars as part of NASAs Viking program. ... June 19 is the 170th day of the year (171st in leap years) in the Gregorian calendar, with 195 days remaining. ... 1976 (MCMLXXVI) was a leap year starting on Thursday. ... August 17 is the 229th day of the year (230th in leap years) in the Gregorian calendar. ... 1980 (MCMLXXX) was a leap year starting on Tuesday. ... The Viking 1 was the first of two spacecraft sent to Mars as part of NASAs Viking program. ... July 20 is the 201st day (202nd in leap years) of the year in the Gregorian calendar, with 164 days remaining. ... 1976 (MCMLXXVI) was a leap year starting on Thursday. ... November 13 is the 317th day of the year (318th in leap years) in the Gregorian calendar, with 48 days remaining. ... 1982 (MCMLXXXII) was a common year starting on Friday of the Gregorian calendar. ... Frost on Mars. ... August 7 is the 219th day of the year in the Gregorian Calendar (220th in leap years), with 146 days remaining. ... 1976 (MCMLXXVI) was a leap year starting on Thursday. ... July 25 is the 206th day (207th in leap years) of the year in the Gregorian calendar, with 159 days remaining. ... 1978 (MCMLXXVIII) was a common year starting on Sunday. ... Frost on Mars. ... September 3 is the 246th day of the year (247th in leap years) in the Gregorian calendar. ... 1976 (MCMLXXVI) was a leap year starting on Thursday. ... April 11 is the 101st day of the year in the Gregorian calendar (102nd in leap years). ... 1980 (MCMLXXX) was a leap year starting on Tuesday. ... May 21 is the 141st day of the year in the Gregorian calendar (142nd in leap years). ... 1983 (MCMLXXXIII) was a common year starting on Saturday of the Gregorian calendar. ...

Results of the Biological Experiments

Main article: Viking biological experiments

Images taken from the Viking 1 lander. The bottom image shows trenches dug by the soil sampler.

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. The results were initially positive and one experiment met all NASA's criteria for the detection of life. But, based on the results of another test that failed to reveal any organic molecules in the soil, most scientists became convinced that the results were likely caused by a nonbiological chemical reaction. However, the matter is still under debate and some recent research adds support to the biological interpretation. Each NASA Viking Lander carried three biological experiments to the surface of Mars in the late 1970s. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Each NASA Viking Lander carried three biological experiments to the surface of Mars in the late 1970s. ...

Further reading

• On Mars: Exploration of the Red Planet
• Viking Orbiter Views of Mars

See also

Wikimedia Commons has media related to:

Viking mission

• Viking Biological Experiments
• Exploration of Mars
• Space exploration

Image File history File links Commons-logo. ... The Wikimedia Commons (also called Wikicommons) is a repository of free content images, sound and other multimedia files. ... Each NASA Viking Lander carried three biological experiments to the surface of Mars in the late 1970s. ... Computer generated image of one of the two Mars Exploration Rovers which touched down on Mars in 2004. ... Space exploration is the physical exploration of outer space, both by human spaceflights and by robotic spacecraft. ...

External links

• NASA Mars Viking Mission
• Solar Views Project Viking Fact Sheet
• Viking Mission to Mars Video