#readwise # Mars Climate Orbiter - Wikipedia ![rw-book-cover](https://readwise-assets.s3.amazonaws.com/static/images/article4.6bc1851654a0.png) ## Metadata - Author: [[en.wikipedia.org]] - Full Title: Mars Climate Orbiter - Wikipedia - URL: https://en.wikipedia.org/wiki/Mars_Climate_Orbiter ## Highlights - The Mars Climate Orbiter (formerly the Mars Surveyor '98 Orbiter) was a 638-kilogram (1,407 lb) robotic space probe **launched by NASA on December 11, 1998 to study the Martian climate, Martian atmosphere, and 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 permanently lost as it went into orbital insertion.** - An investigation attributed the failure to a **measurement mismatch between two software systems: metric units by NASA and US Customary (imperial or "English") units by spacecraft builder Lockheed Martin**. - The primary cause of this discrepancy was that **one piece of ground software supplied by Lockheed Martin produced results in a United States customary unit, 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 produced by thruster firings produced results in pound-force seconds. The trajectory calculation software then used these results – expected to be in newton-seconds (incorrect by a factor of 4.45) – to update the predicted position of the spacecraft. - **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.** - According to NASA, **the cost of the mission was $327.6 million ($494.84 million in 2020) total for the orbiter and lander**, comprising $193.1 million ($291.68 million in 2020) for spacecraft development, $91.7 million ($138.51 million in 2020) for launching it, and $42.8 million ($64.65 million in 2020) for mission operations.