Why did the Mars Climate Orbiter fail? Science

A mistake that cost millions

An artist impression of the Mars Climate Orbiter  

What happens every time you make a mistake? Be it at school, home or anywhere else, you are asked not to repeat the mistake again, and you might even be scolded depending on the extent of the mistake. Suppose a group of people collectively make a mistake. A mistake that cost millions. What then? We’ll be looking at one such scenario this week…

Decisions with respect to space missions are fraught with frailties. Laika’s one way trip to space was dubbed a success, but not before the decision to leave her to death was scrutinised and criticised in every manner possible. So when NASA made a mistake in one of its missions, it obviously didn’t go unnoticed.

The last decade of the last century saw NASA press full on towards Mars exploration. Managed by NASA’s Jet Propulsion Laboratory (JPL), the Mars Climate Orbiter was one among a series of missions in a long-term programme. Built at an estimated $125 million, its success would have made it the first weather observer on another world.

Launched on December 11, 1998 to study the Martian climate and atmosphere, communication with the orbiter came to an abrupt end on September 23, 1999, even before it had taken to a stable orbit around Mars. There were warning signs even while it was en route to Mars. There were 10 to 14 times more minor adjustments that had to be made for the spacecraft than the engineers expected. And even the last signals that were transmitted indicated that it was dipping lower than it was supposed to go.

Calculation error

The orbiter eventually came within 37 miles of the Martian surface. And as simulations showed that atmospheric friction would tear the craft apart at any altitude lower than 53 miles, the orbiter stood no chance.

Review committees were immediately formed to identify what had gone wrong and reasons were brought out in a report on this day 15 years ago. And the primary reason: conversion of units from imperial to metric!

There were two teams involved, the Mars Climate Orbiter spacecraft team in Colorado and the mission navigation team in California. While one team measured force in pounds, the other used it in newtons (one pound force is about 4.45 newtons). NASA’s JPL didn’t check, assuming the conversions had been made, and fed the numbers as such for their calculations, leading to the errors.

The Mars Polar Lander, which next followed, also failed to make it to the surface of Mars, thereby forcing a serious rethink of the Mars programme, including scrapping several planned missions. They started to rebuild from the basics, and the result was the Mars Exploration rovers Spirit and Opportunity. Launched in 2003, Spirit was active till 2010, while Opportunity is still working and even beamed images of the comet that passed Mars in October.

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Printable version | Sep 9, 2021 11:47:55 PM | https://www.thehindu.com/in-school/sh-science/a-mistake-that-cost-millions/article6583481.ece

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