Error Nearly Wrecked Curiosity's Landing

The landing of the Curiosity rover in August 2012 could well have turned out to be disastrous owing to a blooper by Nasa engineers in calculating Mars's gravity. This startling truth about the final hair-raising moments of the rover's historic touchdown comes from its chief engineer, Rob Manning, who played a key role in the operation.

Manning states: "We were to discover after Curiosity had landed on Mars that we had missed a crucial item. The long list of variable parameters had not included one that should be obvious: gravity. In the simulations, the EDL (entry descent and landing) team used a fixed value for gravity that was rather generic for that part of Mars. We failed to take into account that the shape of the surrounding terrain and hills might affect the actual gravity, and because we didn't try other values, we didn't notice just how sensitive the landing was to being slightly off with the value the team had chosen."

Manning has frankly acknowledged the lapse in his book, 'Mars Rover Curiosity - An Inside Account From Curiosity's Chief Engineer Rob Manning', to be released on October 21.

"The value for Mars gravity used in the simulation turned out to be slightly too high - very slightly, only 0.1% - but significant enough that Curiosity's slowest-ever landing was even slower than we expected. If EDL had taken much longer, the lander could have run out of fuel, the rockets would have been unable to slow the craft sufficiently, and the landing would have turned into a disaster... Just as with the Climate Orbiter navigation mistake, this was a mistake no JPL team will ever make again,'' he writes.

These details were divulged by space activist Emily Lakdawalla in a recent blog. She is senior editor of the US-based Planetary Society, a non-profit space-related organization, founded, by, among others, Carl Sagan in 1980.