Fingers crossed for Mars launch at Goddard

Florence Tan says she'll have fingers and toes crossed when NASA's latest Mars mission blasts off as early as Saturday morning from Cape Canaveral in Florida.

The 47-year-old electrical engineer from Montgomery County oversaw all the wiring of an instrument package on board that was designed by NASA's Goddard Space Flight Center here. In the years leading up to the launch, Tan has painstakingly checked and rechecked all 2,000 pieces of wire inside the microwave oven-sized box — enough to stretch more than a third of a mile if strung together.


"I was testing everything and basically sweating bullets," she said Friday after a public presentation on the Mars mission at Goddard's visitors center.

More than seven years in the making and costing $2.5 billion, the unmanned probe carries the largest, most sophisticated mobile laboratory ever assembled by NASA to prospect the cold, dusty red planet for clues that it may have supported microbial life long ago. Roughly the size of a small SUV and weighing almost a ton, the six-wheeled rover Curiosity is about twice as long and five times as heavy as NASA's previous pair of rovers, Spirit and Opportunity, which were launched in 2003.

Goddard's apparatus is the biggest of 10 instrument arrays aboard Curiosity from an international group of laboratories. And to the hundreds of engineers, scientists and technicians here who've labored on it, Sample Analysis at Mars — or SAM, as it's known — is also the most important. Its equipment will analyze gases in the Martian atmosphere and rock and soil samples collected from the surface by the rover's robotic arm.

Previous probes have found evidence that there was water on Mars at one time. Now the most pressing questions that scientists have are about whether the planet's environment could have supported life then, even at the most basic microbial level. To find that out, they need to know what kind of elements and molecules are present in the planet's rocks.

"Our instrument is the one that's going to answer those questions," said Melissa Trainer, a 33-year-old research space scientist from Silver Spring whose job it is to help interpret the data that the rover is to beam back to Earth. Goddard's package is literally "in the driver's seat," Trainer jokes, tucked into the left front of the rover. It was built and tested here, with equipment and help from others, including French researchers and NASA's Jet Propulsion Laboratory in Pasadena, Calif.

SAM is actually a trio of instruments — a mass spectrometer, a tunable laser spectrometer and a gas chromatograph — that should enable scientific sleuths to "follow the carbon" on Mars. Together, the devices will check the samples picked up by the rover for carbon-based compounds that form the molecular building blocks of life on Earth.


Before Curiosity can begin its work, it has to get to Mars. The trip will last 81/2 months, looping 354 million miles out from Earth as the two planets orbit the sun. Landing the rover safely calls for a previously untried feat of engineering, using first a heat shield, then a parachute and finally a "sky crane" that fires retro-rockets to slow its meteoric descent through the thin Martian atmosphere.

The probe is programmed to land Curiosity in the Gale crater, a round dimple in the planet's surface near the equator. The indentation is 96 miles across, with a gently sloping mountain in the center that rises three miles from the crater's floor. Earlier orbiting probes spotted what look like layers of water-deposited sediment there, Trainer said, and there's a range of rock strata exposed that may help researchers decipher the planet's past.

If all goes well, shortly after Curiosity lands early next August, it will begin creeping about at a tenth of a mile per hour, as scientists guide its progress and analyze the images and data sent back. For scientists like Trainer, that's the real high point of the mission.

"A launch is cool, but I'm more excited about the landing," she said. She expects to watch the liftoff, scheduled for 10 a.m., from home.

Meanwhile, Tan notes, she's already working on another instrument package for the next Mars mission, an orbiter dubbed MAVEN slated to launch in 2013 that's to be managed by Goddard.

"They really believe in the idea," she said of her colleagues. "We're audacious enough to go out to Mars."

The launch will be televised on NASA TV, accessible online at http://www.ustream.tv/user/NASAtelevision/shows. To follow on Twitter, @MARSCuriosity.