Mars landing may have some anxious moments

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NASA: Curiosity will be lowered to the Martian surface with cables

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, which has many instruments designed by scientists at the Los Alamos National Laboratory, 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.

Roger Wiens of the Los Alamos National Laboratory, who is the principal investigator for ChemCam, did not seem too worried.

“The size of the Rover makes it trickier,” said Wiens, who will be at the Jet Propulsion Lab in Pasadena, Calif., for the landing tonight. “The previous generation of Rovers used airbags to land and they could hit ground hard and bounce and roll and come out of a cocoon and start their mission.

“With Curiosity weighing over a ton, you just don’t drop it on a planet. … Everybody finally decided to leave rockets off the ground and try to lower the Rover on a tether and then cut the cables.”

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 is a step-by-step look at how Curiosity will land:

• Ten minutes before entering the Martian atmosphere, Curiosity separates from the capsule that carried it to Mars.

• Turning its protective heat shield forward, it streaks through the atmosphere at 13,200 mph, slowing itself with a series of S-curves.

• Seven miles from the ground at 900 mph, Curiosity unfurls its enormous parachute.

• Next it sheds its heat shield and turns on radar to scope out the landing site. Now it’s 5 miles from touchdown and closing in at 280 mph.

• A video camera aboard Curiosity starts to record the descent.

• A mile from landing, the parachute is jettisoned.

• Curiosity is still attached to a rocket-powered backpack, and those rockets are used to slow it to less than 2 mph.

• Twelve seconds before landing, nylon cables release and lower Curiosity. Once it senses six wheels on the ground, it cuts the cords. The hovering rocket-powered backpack flies out of the way, crashing some distance away.

Wiens said assuming the landing goes off without a hitch; ChemCam will be turned on for a “liveness test,” where everything will be checked to make sure it is in working order.

A few days into the mission, Wiens said images will be taken of the back of the Rover and it will get its calibration targets ready.

Eventually, there will be a software update. Right now, the flying software is actually flying the mission, but the ground software will be programmed in.

“That will take several days and everything will have to be verified,” Wiens said. “Toward the end of the second week, we will get to start working with ChemCam.”

Meanwhile, the public is invited to a special opening reception beginning at 10 p.m. Sunday to celebrate Los Alamos National Laboratory technologies aboard the six-wheeled mobile science laboratory.

The Curiosity rover, the centerpiece of NASA’s Mars Science Laboratory mission, is scheduled to touch down on the Red Planet Sunday at 11:31 p.m.  The museum plans to show the landing via NASA TV live that evening.

“This is an exhibit about LANL technology on Mars. We’re really excited to showcase LANL’s scientific and technologic expertise while also providing an educational and fun experience for the public,” said Bradbury Science Museum Director Linda Deck. “We’ve been thinking about this for months and intensely working on it about four weeks,” she said, adding that the exhibit will remain in place indefinitely in the museum’s TechLab.

Visitors will find display models of ChemCam — the rock-zapping laser that will help characterize Martian geology — CheMin, which uses X-ray diffraction to determine the composition of mineral samples collected and dropped into a funnel on the Curiosity rover; and simulated radioisotope thermoelectric generators (RTGs), the tiny plutonium canisters that provide heat and power sources that give Curiosity several times as much electricity as previous-generation rovers — a necessity for the much larger and more-advanced payload on Curiosity.

The museum’s TechLab will have a dozen videos and animations about the Curiosity rover from NASA and the Jet Propulsion Laboratory. A scientist from LANL’s Curiosity team will be on hand to talk to visitors during the opening event.