Coordinates | 53°12′″N45°01′″N |
---|---|
name | Mars Climate Orbiter |
mission identifier | |
organization | NASA / JPL |
major contractors | Lockheed Martin Astronautics |
mission type | Orbiter |
satellite of | Mars |
launch | 1998-12-11 18:45:51 UTC ( ago) |
launch vehicle | Delta II 7425 / Star 48 |
launch site | Space Launch Complex 17A Cape Canaveral Air Force Station |
mission duration | ''Failure in transit'' (Last contact on day 286) (1999-9-23 09:06:00 UTC) |
nssdc id | 1998-073A |
webpage | Mars Climate Orbiter Website |
mass | |
power | 500 W (Solar array / NiH2 batteries) }} |
The ''Mars Climate Orbiter'' (formerly the Mars Surveyor '98 Orbiter) was a 338 kilogram (750 lb) robotic space probe launched by NASA on December 11, 1998 to study the Martian climate, atmosphere, surface changes and to act as the communications relay in the Mars Surveyor '98 program, for Mars Polar Lander. However, on September 23, 1999, communication with the spacecraft was lost as the spacecraft went into orbital insertion, due to a navigational error. The spacecraft encountered Mars at an improperly low altitude, causing it to incorrectly enter the upper atmosphere and disintegrate.
The primary science objectives of the mission included:
The spacecraft was 3-axis stabilized and included eight, hydrazine monopropellant thrusters ''(four 22N thrusters to perform trajectory corrections; four 0.9N thrusters to control attitude)''. Orientation of the spacecraft was determined with a star tracker, two Sun sensors and two inertial measurement units. Orientation was controlled by firing the thrusters or using three reaction wheels. To perform the Mars orbital insertion maneuver, the spacecraft also included a LEROS 1B main engine rocket, providing 640N of thrust by burning hydrazine fuel with nitrogen tetroxide (NTO) oxidizer.
The spacecraft included a 1.3 meter high-gain antenna to transceive data with the Deep Space Network over the x-band. The radio transponder designed for the Cassini–Huygens mission was used as a cost saving measure. The orbiter also included a two-way UHF radio frequency system to relay communications with Mars Polar Lander upon an expected landing on December 3, 1999.
The space probe was powered with a 3-panel solar array, providing an average of 500 W at Mars. Deployed, the solar array measures 5.5 meters in length. Power is 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 maneuver, to slow the spacecraft until a circular orbit was achieved. The design is 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 processor capable of 5MHz, 10MHz and 20MHz operations. Data storage is maintained on 128MB of random-access memory (RAM) and 18MB of flash memory. The flash memory was intended to be used for highly important data, including triplicate copies of the flight system software.
The cost of the mission was $327.6 million total for both orbiter and lander, $193.1 million for spacecraft development, $91.7 million for launching it, and $42.8 million for mission operations.
}}
Date | Event | ||||||||||||||
Spacecraft launched at 18:45:51 UTC | |||||||||||||||
Mars orbital insertion maneuver. |
Time | Event |
Orbiter stows solar array. | |
Orbiter turns to correct orientation to begin main engine burn. | |
Orbiter fires pyrotechnic devices which open valves to begin pressurizing the fuel and oxidizer tanks. | |
Main engine burn starts; expected to fire for 16 minutes 23 seconds. | |
Orbiter expected to enter Mars occultation, out of radio contact with Earth. • | |
Expected to exit Mars occultation. • |
}}
''Mars Climate Orbiter'' began the planned orbital insertion maneuver on September 23, 1999 at 09:00:46 UTC. However, due to complications arisen from human error, the spacecraft encountered Mars at a lower than anticipated altitude and disintegrated due to atmospheric stresses. Mars Reconnaissance Orbiter has since completed most of the intended objectives for this mission.
}}
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 was computed and 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 226 kilometers on September 23, 1999. However, during the week between TCM-4 and the orbital insertion maneuver, the navigation team indicated the altitude may be much lower than intended at 150 to 170 kilometers. Twenty-four hours prior to orbital insertion, calculations placed the orbiter at an altitude of 110 kilometers; 80 kilometers is the minimum altitude that Mars Climate Orbiter was thought to be capable of surviving during this maneuver. Final calculations placed the spacecraft in a trajectory that would have taken the orbiter within 57 kilometers of the surface where the spacecraft likely disintegrated because of atmospheric stresses. The primary cause of this discrepancy was human error. Specifically, the flight system software on the ''Mars Climate Orbiter'' was written to calculate thruster performance using the metric unit Newtons (N), while the ground crew was entering course correction and thruster data using the Imperial measure Pound-force (lbf). This error has since been known as the ''metric mixup'' and has been carefully avoided in all missions since by NASA.
Category:Mars spacecraft Category:Space accidents and incidents Category:NASA probes Category:Software engineering disasters Category:Lockheed Martin satellites and probes Category:Destroyed extraterrestrial probes Category:Metrication Category:1998 in spaceflight Category:Spacecraft launched by Delta II rockets
bg:Марс Клаймат Орбитър cs:Mars Climate Orbiter de:Mars Climate Orbiter es:Mars Climate Orbiter fr:Mars Climate Orbiter ko:마스 클라이미트 오비터 it:Mars Climate Orbiter lv:Mars Climate Orbiter lt:Mars Climate Orbiter hu:Mars Climate Orbiter ja:マーズ・クライメイト・オービター pl:Mars Climate Orbiter pt:Mars Climate Orbiter ru:Mars Climate Orbiter sk:Mars Climate Orbiter sv:Mars Climate Orbiter zh:火星氣候探測者號This text is licensed under the Creative Commons CC-BY-SA License. This text was originally published on Wikipedia and was developed by the Wikipedia community.
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