How will NASA’s Curiosity Land on Mars?

Washington Post —

Seven minutes of terror.

It sounds like a Hollywood thriller, but the phrase describes the anxiety NASA is expecting as its car-sized robotic rover tries a tricky landing on Mars late Sunday.

Skimming the top of the Martian atmosphere at 13,000 mph, the Curiosity rover needs to brake to a stop — in seven minutes.

The rover is headed for a two-year mission to study whether Mars ever had the elements needed for microbial life. Because of its heft, the 2,000-pound robot can’t land the way previous spacecraft did. They relied on air bags to cushion a bouncy touchdown. This time NASA is testing a brand new landing that involves gingerly setting down the rover similar to the way heavy-lift helicopters lower huge loads at the end of a cable. How hard is it? “The degree of difficulty is above a 10,” says Adam Steltzner, an engineer at NASA’s Jet Propulsion Laboratory, which manages the mission.

And American University space policy analyst Howard McCurdy says: “It would be a major technological step forward if it works. It’s a big gamble.”

A communication time delay between Mars and Earth means Curiosity will have to nail the landing by itself, following the half million lines of computer code that engineers uploaded to direct its every move.

After an 8 1/2-month, 352-million-mile journey, here’s a step-by-step look at how Curiosity will land: