Artist's conception of the Mars Climate Orbiter

Mars Climate Orbiter during tests

The Mars Climate Orbiter (formerly the Mars Surveyor '98 Orbiter) was one of two spacecraft in the Mars Surveyor '98 program, the other being the Mars Polar Lander (formerly the Mars Surveyor '98 Lander). The two missions were to study the Martian weather, climate, and water and carbon dioxide budget, in order to understand the reservoirs, behavior, and atmospheric role of volatiles and to search for evidence of long-term and episodic climate changes. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Image File history File links Download high resolution version (2446x3196, 7183 KB) File links The following pages link to this file: Mars Climate Orbiter ... Image File history File links Download high resolution version (2446x3196, 7183 KB) File links The following pages link to this file: Mars Climate Orbiter ... The Mars Surveyor 98 program comprised two spacecraft launched separately, the Mars Climate Orbiter (formerly the Mars Surveyor 98 Orbiter) and the Mars Polar Lander (formerly the Mars Surveyor 98 Lander); on board the Mars Polar Lander spacecraft were two surface-penetrator probes (Deep Space 2). ... Conceptual drawing of the Mars Polar Lander on the surface of Mars. ... 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. ... For the geological process, see Weathering or Erosion. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ...

The Mars Climate Orbiter was intended to enter orbit at an altitude of 140–150 km above Mars. However, a navigation error caused the spacecraft to reach as low as 57 km. The spacecraft was destroyed by atmospheric stresses and friction at this low altitude. The navigation error arose because a NASA subcontractor (Lockheed Martin) used Imperial units (pound-seconds) instead of the metric units (newton-seconds) as specified by NASA. [1]. Two bodies with a slight difference in mass orbiting around a common barycenter. ... Lockheed/BAE/Northrop F-35 Lockheed Trident missile C-130 Hercules; in production since the 1950s, now as the C-130J Lockheed Martin (NYSE: LMT) is an aerospace manufacturer formed in 1995 by the merger of Lockheed Corporation with Martin Marietta. ... The Imperial units or the Imperial system is a collection of English units, first defined in the Weights and Measures Act of 1824, later refined (until 1959) and reduced. ... 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. ... The International System of Units (symbol: SI) (for the French phrase Syst me International dUnit s) is the most widely used system of units. ... The newton (symbol: N) is the SI unit of force. ...

Science objectives

The Orbiter had as its primary science objectives to:

1. monitor the daily weather and atmospheric conditions
2. record changes on the martian surface due to wind and other atmospheric effects
3. determine temperature profiles of the atmosphere
4. monitor the water vapor and dust content of the atmosphere
5. look for evidence of past climate change.

Specifically it was to observe and study dust storms, weather systems, clouds and dust hazes, ozone, distribution and transport of dust and water, the effects of topography on atmospheric circulation, atmospheric response to solar heating, and surface features, wind streaks, erosion, and color changes. The orbiter was to use two instruments to carry out these investigations. The Mars Climate Orbiter Color Imager (MARCI) was to acquire daily atmospheric weather images and high resolution surface images and the Pressure Modulated Infrared Radiometer (PMIRR) was to allow measurement of the atmospheric temperature, water vapor abundance, and dust concentration. The orbiter was also to serve as a data relay satellite for the Mars Polar Lander and other future NASA and international lander missions to Mars. “Sandstorm” redirects here. ... This article is about clouds in meteorology. ... For other uses, see Ozone (disambiguation). ... For morphological image processing operations, see Erosion (morphology). ...

Spacecraft and subsystems

The Mars Climate Orbiter was a box-shaped spacecraft about 2.1 m high, 1.6 m wide, and 2 m deep, consisting of stacked propulsion and equipment modules. The total spacecraft launch mass of 629 kg includes 291 kg of propellant. An 11 square meter solar array wing, measuring 5.5 m tip-to-tip, is attached by 2-axis gimbal to one side and a 1.3 m diameter high-gain dish antenna is attached by 2-axis gimbal to a mast at the top of the propulsion module. The MARCI and PMIRR instruments, as well as a UHF antenna and battery enclosure, are mounted to the bottom of the equipment module.

Propulsion was achieved via a 640 N bipropellant (hydrazine/nitrogen tetroxide) main engine, mounted with the propellant tanks in the propulsion module, and hydrazine thrusters. The orbiter is 3-axis stabilized. Attitude control and maneuvering capability is provided by four 7 N thrusters (pitch/yaw) and four 0.3 N thrusters (roll) in combination with reaction wheels. Attitude was determined using an inertial measurement unit, a star tracker, and analog Sun sensors with knowledge of 25 mrad and stability of 1.5 mrad/(1 s) and 3 mrad/(3 s). F-1 rocket engine (The kind used by the Saturn V.) A bipropellant rocket engine is a rocket engine that uses two fluid propellants stored in separate tanks that are injected into, and undergo a strong exothermic reaction, in a rockets combustion chamber. ... Hydrazine is the chemical compound with formula N2H4. ... Nitrogen tetroxide (or Dinitrogen tetroxide) (N2O4) is a hypergolic propellant often used in combination with a hydrazine-based rocket fuel. ... A momentum wheel is a type of flywheel used primarily by spacecraft to change their angular momentum without using fuel for rockets or other reaction devices. ...

Spacecraft power was provided by 3 panels of GaAs/Ge solar cells on the 5.5 meter long single-wing solar array which provide 1000 W of power at Earth and 500 W at Mars. Power is stored in nickel metal hydride (NiMH) common pressure vessel batteries. Thermal control is achieved through a combination of louvers, MLI, Kapton, paints, radiators and heater circuits. Communications with Earth were in X band using Cassini Deep Space Transponders and 15 W RF solid state power amplifiers through the 1.3 m high gain antenna for both uplink and downlink, a medium gain transmitting antenna, and a low-gain receiving antenna. A 10 W UHF system was to be used for 2-way communications with the Mars Polar Lander. A RAD6000 processor was used for on-board command and data handling. A solar cell, made from a monocrystalline silicon wafer A solar cell or photovoltaic cell is a device that converts light energy into electrical energy. ... Modern, high capacity NiMH rechargeable batteries A nickel metal hydride (or NiMH) battery is a type of rechargeable battery similar to a nickel-cadmium (NiCad) battery but which does not contain expensive (and environmentally risky) cadmium. ... Kapton is a polyimide film developed by DuPont which can remain stable in a wide range of temperatures, from -269 °C to +400 °C. Kapton is used in, among other things, flexible printed circuits (flexible electronics) and Thermal Micrometeoroid Garments, the outside layer of spacesuits. ... The X band (3-cm radar spot-band) of the microwave band of the electromagnetic spectrum roughly ranges from 5. ... The RAD6000 radiation-hardened single board computer, based on the IBM POWER CPU, is manufactured by BAE SYSTEMS and is mainly known as the onboard computer of numerous NASA spacecraft. ...

Mission profile

Mars Climate Orbiter was launched on a Delta 7425 (a Delta II Lite launch vehicle with four strap-on solid rocket boosters and a Star 48 (PAM-D) third stage). Launch was at 18:45:51 UT (1:45:51 p.m. EST) on December 11, 1998 from Pad A of Launch Complex 17 at Cape Canaveral Air Station, Florida. After a brief cruise in Earth orbit, the Delta II 3rd stage put the spacecraft into trans-Mars trajectory and about 15 days after launch the largest trajectory correction maneuver (TCM) was executed using the hydrazine thrusters. During cruise to Mars, three additional TCM's using the hydrazine thrusters were performed on March 4, July 25, and September 15, 1999. The Space Shuttle is initially launched with the help of solid-fuel boosters A Solid rocket or a solid fuel rocket is a rocket with a motor that uses solid propellants (fuel/oxidizer). ... The Star 48 is a type of solid rocket motor used by both the Space Shuttle and the New Horizons probe. ... is the 345th day of the year (346th in leap years) in the Gregorian calendar. ... Year 1998 (MCMXCVIII) was a common year starting on Thursday (link will display full 1998 Gregorian calendar). ... This article is about the area of Florida. ... is the 63rd day of the year (64th in leap years) in the Gregorian calendar. ... is the 206th day of the year (207th in leap years) in the Gregorian calendar. ... is the 258th day of the year (259th in leap years) in the Gregorian calendar. ... This article is about the year. ...

The spacecraft reached Mars and executed a 16 minute 23 second orbit insertion main engine burn on September 23, 1999 at 09:01 UT (5:01 a.m. EDT) Earth received time (ERT, signal travel time from Mars will be 10 minutes 55 seconds). The spacecraft passed behind Mars at 09:06 UT ERT and was to re-emerge and establish radio contact with Earth at 09:27 UT ERT, 10 minutes after the burn was completed. However, contact was never re-established and no signal was ever received from the spacecraft. Findings of the failure review board indicate that a navigation error resulted from some spacecraft data being reported in Imperial units instead of metric. This caused the spacecraft to miss its intended 140–150 km altitude above Mars during orbit insertion, instead entering the martian atmosphere at about 57 km. The spacecraft would have been destroyed by atmospheric stresses and friction at this low altitude. is the 266th day of the year (267th in leap years) in the Gregorian calendar. ... This article is about the year. ...

The burn would have slowed the spacecraft and put it into a 14 hour elliptical (~150 × 21 000 km) capture orbit. The orbiter was to begin aerobraking, using the solar panel to provide resistance and continue until a 90 × 405 km orbit was achieved, nominally on 22 November 1999, with periapsis at 89 N. The hydrazine thrusters would be used to change the orbit to a 2-hour, 421 km near-circular polar science mapping orbit on 1 December 1999. The orbit was to be nearly Sun-synchronous, crossing the daytime equator at about 4:30 p.m. local time. The first phase of the mission was to support the Mars Polar Lander from its landing on Mars on 3 December 1999 to the end of the lander primary mission on 29 February 2000. The orbiter would pass over the lander site 10 times per martian day for 5 to 6 minutes each time, communicating via the UHF 2-way relay link at 128 kbit/s. Mars science operations and mapping, involving operation of the MARCI and PMIRR, would initiate on 3 March 2000 and continue for one martian year (687 days). At the end of the mapping mission on 15 January 2002, the orbiter was to be placed in a stable orbit and function as a UHF relay for the Mars 2001 mission. Two bodies with a slight difference in mass orbiting around a common barycenter. ... is the 326th day of the year (327th in leap years) in the Gregorian calendar. ... This article is about the year. ... is the 335th day of the year (336th in leap years) in the Gregorian calendar. ... This article is about the year. ... is the 337th day of the year (338th in leap years) in the Gregorian calendar. ... This article is about the year. ... February 29 is a day added into a leap year of the Gregorian calendar. ... Year 2000 (MM) was a leap year starting on Saturday (link will display full 2000 Gregorian calendar). ... is the 62nd day of the year (63rd in leap years) in the Gregorian calendar. ... Year 2000 (MM) was a leap year starting on Saturday (link will display full 2000 Gregorian calendar). ... is the 15th day of the year in the Gregorian calendar. ... Also see: 2002 (number). ...

The metric mixup

The metric mixup which destroyed the craft was caused by a software error back on earth. The software was used to control thrusters on the spacecraft which were intended to control its rate of rotation, but by using the wrong units, the ground station underestimated the effect of the thrusters by a factor of 4.45. A thruster is a small propulsive device used by spacecraft and watercraft for station keeping, attitude control, or long duration low thrust acceleration. ...

This is the difference between a pound force - the imperial unit - and a newton, the metric unit. The software was working in pounds force, while the spacecraft expected figures in newtons. A pound or pound-force (abbreviations: lb, lbf, or lbf) is a unit of force. ... The Imperial units or the Imperial system is a collection of English units, first defined in the Weights and Measures Act of 1824, later refined (until 1959) and reduced. ... For other uses, see Newton (disambiguation). ... A metric system is a system of units for measurement developed in late 18th century France with decimal multipliers. ...

The problem arose partly because the software had been adapted from use on the earlier Mars Climate Orbiter, without proper testing before launch, and partly because the navigation data provided by this software was not cross-checked while in flight.

The Mars Climate Orbiter thus drifted off course during its voyage and entered a much lower orbit than planned, and was destroyed by atmospheric friction.

Project cost

Total project cost was $327.6 million for both orbiter and lander (not including Deep Space 2). Out of this, $193.1 million were for spacecraft development, $91.7 million for launch, and $42.8 million for mission operations^[1].

See also

• Exploration of Mars
• Metrication
• Space exploration
• Unmanned space missions

Computer-generated image of one of the two Mars Exploration Rovers which touched down on Mars in 2004. ... Metrication or metrification refers to the introduction of the SI metric system as the international standard for physical measurements—a long-term series of independent and systematic conversions from the various separate local systems of weights and measures. ... Space exploration is the physical exploration of outer space, both by human spaceflights and by robotic spacecraft. ... It has been suggested that Space probe be merged into this article or section. ...

References

• Isbell, D., M. Hardin, and J. Underwood, Mars Climate Orbiter Team Finds Likely Cause of Loss. NASA news release, September, 1999. 30: p. 1999.
• Euler, E.E., Jolly, S.D., and Curtis, H.H. "The Failures of the Mars Climate Orbiter and Mars Polar Lander: A Perspective from the People Involved." Proceedings of Guidance and Control 2001, American Astronautical Society, paper AAS 01-074, 2001.
• Mars Climate Orbiter Mishap Investigation Board Phase I Report. November 10, 1999.
• Mars Surveyor Project Readiness Review, Part I. August 26-27, 1998. JPL D-16057-01B, page 65.

The National Aeronautics and Space Administration (NASA) (IPA [ˈnæsə]) is an agency of the United States government, responsible for the nations public space program. ...

External links

Wikimedia Commons has media related to:

Mars Climate Orbiter

• Mars Climate Orbiter Mission Profile by NASA's Solar System Exploration
• http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1998-073A
• http://www.jamesoberg.com/mars/loss.html Why "metric-mixup" was just the tip of the problem