Failure of Mars Climate Orbiter

Mars climate orbiter is also called Mars Surveyor ‘98 Orbiter.

Manufactured by Lockheed Martin which is industrial partner of NASA.

It was launched by NASA by Delta II 7425 rocket from Cape Canaveral.

Launched on December 11, 1998.Weight: 338 KilogramsCost of mission $193.25 million.

Introduction of Spacecraft

Delta II

rocket

To determine existence of water on Mars.Monitor weather and atmospheric conditions

on Mars.Determining temperature and surface

changes on Mars.Monitor water vapour and dust contents in

atmosphere.

Objectives of Mission

It contained 8 thrusters. 4 (27 Newton) for controlling altitude and other 4 (0.9 N) for trajectory correction.

Scientific instruments:1. Mars Colour Imager (for taking images)2. Pressure Modulator Infrared Radiometer (for

studying atmosphere)3. Star Tracker (for determining position). Trajectory Correction: means to change path or orbit of spacecraft to get into desired path or orbit. For these Thrusters are fired.

Design of Spacecraft

Path to MarsFour trajectory

corrections done before spacecraft reached Mars.

TCM : Trajectory Correction Maneuver

When spacecraft reached Mars it was 49 seconds early than expected.

Orbit altitude was 60km than the intended orbit altitude of 150Km.

Encounter with Mars

Nov. 10,1999, Mars Climate Orbiter Mishap Investigation Board released a report of failure.

According to report on Sept 15 trajectory correction was done to bring orbiter at 226Km altitude.

But it was found that orbiter was in much lower orbit than 150Km. 80Km was minimum altitude that the orbiter could survive.

On Sept 23,1. 9am: Main engine was started and fired for 16

minutes for entering orbit of Mars.2. After few minutes it lost contact with ground.3. On Sept 25 mission was declared a loss.

Team of engineers of Lockheed developed a software whose results were in English units (Pound, foot, inch).

Mission navigation team of NASA used these results for its system ,expecting it to be in SI units.

During mission, the software of thrusters calculated force in English units.

Results of that software were used in trajectory corrections expecting it to be in SI.

Cause of Failure

1 Pound force = 4.45 Newton force

The main failure was of NASA’s engineering systems and balance and check process to detect the error.

Result of FailureSpacecraft went in

lower altitude (57 Km) than expected (226 Km).

Spacecraft burned due to atmospheric friction and broke into pieces.

Last contact with spacecraft was on September 30, 1999. NASA lost Mars Climate Orbiter on this day.

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