Mars Climate Orbiter
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The ''Mars Climate Orbiter'' (formerly the Mars Surveyor '98 Orbiter) was a
robotic Robotics is an interdisciplinarity, interdisciplinary branch of computer science and engineering. Robotics involves design, construction, operation, and use of robots. The goal of robotics is to design machines that can help and assist human ...
space probe A space probe is an artificial satellite that travels through space to collect scientific data. A space probe may orbit Earth; approach the Moon; travel through interplanetary space; flyby, orbit, or land or fly on other planetary bodies; or ent ...
launched by
NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...
on December 11, 1998, to study the Martian climate,
Martian atmosphere The atmosphere of Mars is the layer of gases surrounding Mars. It is primarily composed of carbon dioxide (95%), molecular nitrogen (2.8%), and argon (2%). It also contains trace levels of water vapor, oxygen, carbon monoxide, hydrogen, and no ...
, and surface changes and to act as the communications relay in the Mars Surveyor '98 program for
Mars Polar Lander The Mars Polar Lander, also known as the Mars Surveyor '98 Lander, was a 290-kilogram robotic spacecraft lander launched by NASA on January 3, 1999, to study the soil and climate of Planum Australe, a region near the south pole on Mars. It for ...
. However, on September 23, 1999, communication with the spacecraft was permanently lost as it went into
orbital insertion Orbit insertion is the spaceflight operation of adjusting a spacecraft’s momentum, in particular to allow for entry into a stable orbit around a planet, moon, or other celestial body. This maneuver involves either deceleration from a speed in e ...
. The spacecraft encountered Mars on a trajectory that brought it too close to the planet, and it was either destroyed in the atmosphere or escaped the planet's vicinity and entered an orbit around the Sun. An investigation attributed the failure to a measurement mismatch between two software systems: metric units by NASA and US customary units by spacecraft builder
Lockheed Martin The Lockheed Martin Corporation is an American aerospace, arms, defense, information security, and technology corporation with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It ...
.


Mission background


History

After the loss of ''
Mars Observer The ''Mars Observer'' spacecraft, also known as the ''Mars Geoscience/Climatology Orbiter'', was a robotic space probe launched by NASA on September 25, 1992, to study the Martian surface, atmosphere, climate and magnetic field. During the inte ...
'' and the onset of the rising costs associated with the future
International Space Station The International Space Station (ISS) is the largest modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA ...
,
NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...
began seeking less expensive, smaller probes for scientific interplanetary missions. In 1994, the Panel on Small Spacecraft Technology was established to set guidelines for future miniature spacecraft. The panel determined that the new line of miniature spacecraft should be under with highly focused instrumentation. In 1995, a new Mars Surveyor program began as a set of missions designed with limited objectives, low costs, and frequent launches. The first mission in the new program was
Mars Global Surveyor ''Mars Global Surveyor'' (MGS) was an American robotic space probe developed by NASA's Jet Propulsion Laboratory and launched November 1996. MGS was a global mapping mission that examined the entire planet, from the ionosphere down through the a ...
, launched in 1996 to map Mars and provide geologic data using instruments intended for ''Mars Observer''. Following Mars Global Surveyor, ''Mars Climate Orbiter'' carried two instruments, one originally intended for Mars Observer, to study the climate and weather of Mars. The primary science objectives of the mission included: *determine the distribution of
water on Mars Almost all water on Mars today exists as ice, though it also exists in small quantities as vapor in the atmosphere. What was thought to be low-volume liquid brines in shallow Martian soil, also called recurrent slope lineae, may be grains of f ...
*monitor the daily weather and atmospheric conditions *record changes on the Martian surface due to wind and other atmospheric effects *determine temperature profiles of the atmosphere *monitor the water vapor and dust content of the atmosphere *look for evidence of past climate change.


Spacecraft design

The ''Mars Climate Orbiter'' bus measured tall, wide and deep. The internal structure was largely constructed with graphite composite/aluminum honeycomb supports, a design found in many commercial
airplane An airplane or aeroplane (informally plane) is a fixed-wing aircraft that is propelled forward by thrust from a jet engine, propeller, or rocket engine. Airplanes come in a variety of sizes, shapes, and wing configurations. The broad spe ...
s. With the exception of the scientific instruments, battery and main engine, the spacecraft included dual redundancy on the most important systems. The spacecraft was 3-axis stabilized and included eight
hydrazine Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine ...
monopropellant Monopropellants are propellants consisting of chemicals that release energy through exothermic chemical decomposition. The molecular bond energy of the monopropellant is released usually through use of a catalyst. This can be contrasted with biprop ...
thrusters: four thrusters to perform trajectory corrections and four thrusters to control attitude. Orientation of the spacecraft was determined by a
star tracker A star tracker is an optical device that measures the positions of stars using photocells or a camera. As the positions of many stars have been measured by astronomers to a high degree of accuracy, a star tracker on a satellite or spacecraft may ...
, two
sun sensor A sun sensor is a navigational instrument used by spacecraft to detect the position of the sun. Sun sensors are used for attitude control, solar array pointing, gyro updating, and fail-safe recovery. In addition to spacecraft, sun sensors fin ...
s and two inertial measurement units. Orientation was controlled by firing the thrusters or using three
reaction wheel A reaction wheel (RW) is used primarily by spacecraft for three-axis attitude control, and does not require rockets or external applicators of torque. They provide a high pointing accuracy, and are particularly useful when the spacecraft must be ...
s. To perform the Mars orbital insertion maneuver, the spacecraft also included a
LEROS Leros ( el, Λέρος) is a Greek island and municipality in the Dodecanese in the southern Aegean Sea. It lies (171 nautical miles) from Athens's port of Piraeus, from which it can be reached by an 9-hour ferry ride or by a 45-minute flight fr ...
1B main engine rocket, providing of thrust by burning
hydrazine Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine ...
fuel with
nitrogen tetroxide Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russia rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium ...
(NTO) oxidizer. The spacecraft included a
high-gain antenna A directional antenna or beam antenna is an antenna which radiates or receives greater power in specific directions allowing increased performance and reduced interference from unwanted sources. Directional antennas provide increased performance ...
to transceive data with the
Deep Space Network The NASA Deep Space Network (DSN) is a worldwide Telecommunications network, network of American spacecraft communication ground segment facilities, located in the United States (California), Spain (Madrid), and Australia (Canberra), that suppo ...
over the
x band The X band is the designation for a band of frequencies in the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of the X band is rather indefinitely set at approxim ...
. The radio transponder designed for the ''
Cassini–Huygens ''Cassini–Huygens'' ( ), commonly called ''Cassini'', was a space research, space-research mission by NASA, the European Space Agency (ESA), and the Italian Space Agency (ASI) to send a space probe to study the planet Saturn and its system, i ...
'' mission was used as a cost-saving measure. It also included a two-way UHF radio frequency system to relay communications with
Mars Polar Lander The Mars Polar Lander, also known as the Mars Surveyor '98 Lander, was a 290-kilogram robotic spacecraft lander launched by NASA on January 3, 1999, to study the soil and climate of Planum Australe, a region near the south pole on Mars. It for ...
upon an expected landing on December 3, 1999. The space probe was powered with a 3-panel solar array, providing an average of at Mars. Deployed, the solar array measured in length. Power was stored in 12-cell, 16-amp-hour Nickel hydrogen batteries. The batteries were intended to be recharged when the solar array received sunlight and power the spacecraft as it passed into the shadow of Mars. When entering into orbit around Mars, the solar array was to be utilized in the
aerobraking Aerobraking is a spaceflight maneuver that reduces the high point of an elliptical orbit (apoapsis) by flying the vehicle through the atmosphere at the low point of the orbit (periapsis). The resulting drag slows the spacecraft. Aerobraking is ...
maneuver, to slow the spacecraft until a circular orbit was achieved. The design was largely adapted from guidelines from the Small Spacecraft Technology Initiative outlined in the book, ''Technology for Small Spacecraft''. In an effort to simplify previous implementations of computers on spacecraft, ''Mars Climate Orbiter'' featured a single computer using an IBM
RAD6000 The RAD6000 radiation-hardened single-board computer, based on the IBM RISC Single Chip CPU, was manufactured by IBM Federal Systems. IBM Federal Systems was sold to Loral, and by way of acquisition, ended up with Lockheed Martin and is ...
processor utilizing a POWER1 ISA capable of 5, 10 or 20 MHz operation. Data storage was to be maintained on 128 MB of
random-access memory Random-access memory (RAM; ) is a form of computer memory that can be read and changed in any order, typically used to store working Data (computing), data and machine code. A Random access, random-access memory device allows data items to b ...
(RAM) and 18 MB of
flash memory Flash memory is an electronic non-volatile computer memory storage medium that can be electrically erased and reprogrammed. The two main types of flash memory, NOR flash and NAND flash, are named for the NOR and NAND logic gates. Both us ...
. The flash memory was intended to be used for highly important data, including triplicate copies of the flight system software.


Scientific instruments

The Pressure Modulated Infrared Radiometer (PMIRR) uses narrow-band radiometric channels and two pressure modulation cells to measure atmospheric and surface emissions in the thermal infrared and a visible channel to measure dust particles and condensates in the atmosphere and on the surface at varying longitudes and seasons. Its principal investigator was Daniel McCleese at JPL/CALTECH. Similar objectives were later achieved with ''Mars Climate Sounder'' on board ''
Mars Reconnaissance Orbiter ''Mars Reconnaissance Orbiter'' (MRO) is a spacecraft designed to study the geology and climate of Mars, provide reconnaissance of future landing sites, and relay data from surface missions back to Earth. It was launched on August 12, 2005, an ...
''. Its objectives: * Map the three-dimensional and time-varying thermal structure of the atmosphere from the surface to 80 km altitude. * Map the atmospheric dust loading and its global, vertical and temporal variation. * Map the seasonal and spatial variation of the vertical distribution of atmospheric water vapor to an altitude of at least 35 km. * Distinguish between atmospheric condensates and map their spatial and temporal variation. * Map the seasonal and spatial variability of atmospheric pressure. * Monitor the polar radiation balance. The Mars Color Imager (MARCI) is a two-camera (medium-angle/wide-angle) imaging system designed to obtain pictures of the Martian surface and atmosphere. Under proper conditions, resolutions up to are possible. The principal investigator on this project was Michael Malin at
Malin Space Science Systems Malin Space Science Systems (MSSS) is a San Diego, California-based private technology company that designs, develops, and operates instruments and technical equipment to fly on unmanned spacecraft. MSSS is headed by chief scientist and CEO Mich ...
and the project was reincorporated on ''
Mars Reconnaissance Orbiter ''Mars Reconnaissance Orbiter'' (MRO) is a spacecraft designed to study the geology and climate of Mars, provide reconnaissance of future landing sites, and relay data from surface missions back to Earth. It was launched on August 12, 2005, an ...
''. Its objectives: * Observe Martian atmospheric processes at global scale and synoptically. * Study details of the interaction of the atmosphere with the surface at a variety of scales in both space and time. * Examine surface features characteristic of the evolution of the Martian climate over time.


Mission profile


Launch and trajectory

The ''Mars Climate Orbiter'' probe was launched on December 11, 1998, at 18:45:51 UTC by the
National Aeronautics and Space Administration The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding th ...
from Space Launch Complex 17A at the
Cape Canaveral Space Force Station Cape Canaveral Space Force Station (CCSFS) is an installation of the United States Space Force's Space Launch Delta 45, located on Cape Canaveral in Brevard County, Florida. Headquartered at the nearby Patrick Space Force Base, the station ...
in Florida, aboard a Delta II 7425 launch vehicle. The complete burn sequence lasted 42 minutes bringing the spacecraft into a
Hohmann transfer orbit In astronautics, the Hohmann transfer orbit () is an orbital maneuver used to transfer a spacecraft between two orbits of different altitudes around a central body. Examples would be used for travel between low Earth orbit and the Moon, or ano ...
, sending the probe into a 9.5 months, trajectory. At launch, ''Mars Climate Orbiter'' weighed including propellant. File:Mars Climate Orbiter - launch configuration.png, alt=Wireframe diagram of the rocket and orbiter, Exploded diagram of Delta II launch vehicle with ''Mars Climate Orbiter'' File:Mars Climate Orbiter - launch.jpg, alt=Rocket during launch, Launch of ''Mars Climate Orbiter'' by NASA on a
Delta II Delta II was an expendable launch system, originally designed and built by McDonnell Douglas. Delta II was part of the Delta rocket family and entered service in 1989. Delta II vehicles included the Delta 6000, and the two later Delta 7000 va ...
7425 launch vehicle File:Mars Climate Orbiter - interplanetary trajectory.png, alt=Diagram of the interplanetary trajectory, Interplanetary trajectory of ''Mars Climate Orbiter'' File:Mars Climate Orbiter - aerobraking.png, alt=Diagram of aerobraking approach with periods of 2, 5, 9, and 15 hours, Aerobraking procedure to place ''Mars Climate Orbiter'' into orbit around Mars


Encounter with Mars

File:Mars Climate Orbiter - Mars encounter - PIA02330.jpg, alt="Half moon" image of Mars, This image of Mars on September 7, 1999, is the only image acquired by the ''Orbiter''. File:Mars Climate Orbiter - mishap diagram.png, alt=Comparative diagram of the two trajectories, Diagram comparing the intended and actual trajectories of the ''Orbiter''
''Mars Climate Orbiter'' began the planned orbital insertion maneuver on September 23, 1999, at 09:00:46 UTC. ''Mars Climate Orbiter'' went out of radio contact when the spacecraft passed behind Mars at 09:04:52 UTC, 49 seconds earlier than expected, and communication was never reestablished. Due to complications arising from
human error Human error refers to something having been done that was " not intended by the actor; not desired by a set of rules or an external observer; or that led the task or system outside its acceptable limits".Senders, J.W. and Moray, N.P. (1991) Human ...
, the spacecraft encountered Mars at a lower-than-anticipated altitude and it was either destroyed in the atmosphere or re-entered heliocentric space after leaving Mars' atmosphere. ''
Mars Reconnaissance Orbiter ''Mars Reconnaissance Orbiter'' (MRO) is a spacecraft designed to study the geology and climate of Mars, provide reconnaissance of future landing sites, and relay data from surface missions back to Earth. It was launched on August 12, 2005, an ...
'' has since completed most of the intended objectives for this mission.


Cause of failure

On November 10, 1999, the ''Mars Climate Orbiter'' Mishap Investigation Board released a Phase I report, detailing the suspected issues encountered with the loss of the spacecraft. Previously, on September 8, 1999, Trajectory Correction Maneuver-4 (TCM-4) was computed, and was then executed on September 15, 1999. It was intended to place the spacecraft at an optimal position for an orbital insertion maneuver that would bring the spacecraft around Mars at an altitude of on September 23, 1999. However, during the week between TCM-4 and the orbital insertion maneuver, the navigation team reported that it appeared the insertion altitude could be much lower than planned, at about . Twenty-four hours prior to orbital insertion, calculations placed the orbiter at an altitude of . was the minimum altitude that ''Mars Climate Orbiter'' was thought to be capable of surviving during this maneuver. During insertion, the orbiter was intended to skim through Mars' upper atmosphere, gradually
aerobraking Aerobraking is a spaceflight maneuver that reduces the high point of an elliptical orbit (apoapsis) by flying the vehicle through the atmosphere at the low point of the orbit (periapsis). The resulting drag slows the spacecraft. Aerobraking is ...
for weeks, but post-failure calculations showed that the spacecraft's trajectory would have taken it within of the surface. At this altitude, the spacecraft would likely have skipped violently off the denser-than-expected atmosphere, and it was either destroyed in the atmosphere, or re-entered heliocentric space. The primary cause of this discrepancy was that one piece of ground software supplied by
Lockheed Martin The Lockheed Martin Corporation is an American aerospace, arms, defense, information security, and technology corporation with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It ...
produced results in a
United States customary unit United States customary units form a system of measurement units commonly used in the United States and U.S. territories since being standardized and adopted in 1832. The United States customary system (USCS or USC) developed from English units ...
, contrary to its Software Interface Specification (SIS), while a second system, supplied by NASA, expected those results to be in SI units, in accordance with the SIS. Specifically, software that calculated the total
impulse Impulse or Impulsive may refer to: Science * Impulse (physics), in mechanics, the change of momentum of an object; the integral of a force with respect to time * Impulse noise (disambiguation) * Specific impulse, the change in momentum per uni ...
produced by thruster firings produced results in pound-force seconds. The trajectory calculation software then used these results – expected to be in
newton-second The newton-second (also newton second; symbol: N⋅s or N s) is the unit of impulse in the International System of Units (SI). It is dimensionally equivalent to the momentum unit kilogram-metre per second (kg⋅m/s). One newton-secon ...
s (incorrect by a factor of 4.45) – to update the predicted position of the spacecraft. Still, NASA does not place the responsibility on Lockheed for the mission loss; instead, various officials at NASA have stated that NASA itself was at fault for failing to make the appropriate checks and tests that would have caught the discrepancy. The discrepancy between calculated and measured position, resulting in the discrepancy between desired and actual orbit insertion altitude, had been noticed earlier by at least two navigators, whose concerns were dismissed because they "did not follow the rules about filling out heform to document their concerns". A meeting of trajectory software engineers, trajectory software operators (navigators), propulsion engineers, and managers was convened to consider the possibility of executing Trajectory Correction Maneuver-5, which was in the schedule. Attendees of the meeting recall an agreement to conduct TCM-5, but it was ultimately not done.


Project costs

According to NASA, the cost of the mission was $327.6 million ($ million in ) total for the orbiter and lander, comprising $193.1 million ($ million in ) for spacecraft development, $91.7 million ($ million in ) for launching it, and $42.8 million ($ million in ) for mission operations.


See also

*
List of missions to Mars This is a list of the 50 spacecraft missions (including unsuccessful ones) relating to the planet Mars, such as orbiters and rovers. Missions ;Mission Type Legend: Mars landing locations There are a number of derelict orbiters around ...
*
List of artificial objects on Mars The following table is a partial list of artificial objects on the surface of Mars, consisting of spacecraft which were launched from Earth. Although most are defunct after having served their purpose, the ''Curiosity'' rover, ''Perseverance'' rov ...
*
List of software bugs Many software bugs are merely annoying or inconvenient but some can have extremely serious consequences – either financially or as a threat to human well-being. The following is a list of software bugs with significant consequences. Space * ...
*
Metrication Metrication or metrification is the act or process of converting to the metric system of measurement. All over the world, countries have transitioned from local and traditional units of measurement to the metric system. This process began in F ...


Notes


References


External links


Mars Surveyor '98 launch press kit''Mars Climate Orbiter'' arrival at Mars press kitMars Climate Orbiter Mission Profile
b
NASA's Solar System ExplorationNASA Space Science Data Coordinated ArchiveMars Climate Orbiter Mishap Investigation Board Phase I Report - November 10, 1999
{{Use mdy dates, date=May 2020 Climate of Mars Missions to Mars Space accidents and incidents in the United States NASA space probes Lockheed Martin satellites and probes Destroyed space probes Metrication in the United States Spacecraft launched in 1998 Spacecraft launched by Delta II rockets