Space Probe to End Moon Mission with a Bang

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An artist's rendering of the Smart-1 spacecraft on its mission to the moon.

An artist's rendering of the Smart-1 spacecraft on its mission to the moon. ESA hide caption

itoggle caption ESA

The Moon's 'Bodies of Water'

Ever heard of the Sea of Serenity? How about the Lake of Luxury or Bay of Love? No, these aren't romantic getaway spots for couples. They're actually the names of lunar plains.

 

The moon's "seas" — or maria, in Latin — are large, dark plains formed by ancient basaltic floods. Early astronomers mistook these features to be actual bodies of water; hence, the names. Lunar "lakes" — lacus in Latin — are smaller basaltic plains of similar origin, while the "bays" — or sinus — are a related set of topographical features.

A European spacecraft will end its mission Saturday night with a crash landing on the moon. Or, as the French press put it, "un rendez-vous explosive avec la Lune." The explosion could be visible with a backyard telescope.

The little spacecraft, called SMART-1, was launched in 2003. And it made it all the way to the moon on solar power. Bernard Foing is lead scientist on the mission with the European Space Agency.

"We have a new revolutionary engine," Foing says. "We broke the Guinness book of record for the lowest amount of fuel, [and] also, of the slowest mission to the moon. It took us 13-and-a-half months."

The engine is called an ion drive. NASA tried it out once. Basically, the craft has solar panels and a bottle of xenon gas. The electricity from the solar panels is used to propel the xenon atoms out the back of the spacecraft, nudging the spacecraft up to speed. It’s a little pokey, but five times more fuel-efficient than a rocket. And sometimes, the slow but steady turtle wins the race.

"This could be a way to bring a lot of cargo to the moon, in parallel to the infrastructure to send a fast taxi for the crew," Foing says.

But where would you go on the moon — the Sea of Tranquility? The Bay of Harmony? The Lake of Luxury? (Yes, those are all real names.) How about a mountaintop upon which the sun never sets? The mission found one of those near the north pole. It's called a "peak of eternal light," and it's the first to be discovered on the moon.

"If you stand on top of the mountain, the sun would always just graze around the horizon," says Detlef Koschney, who worked on the spacecraft's cameras.

"And that, of course, if you talk about colonizing the moon, that would be a place you could go," he adds. "You put solar arrays on the mountain and you have permanent electricity."

There is no such place on Earth. Because Earth's axis is tilted, all parts eventually get some darkness.

Bernard Foing says the temperatures at the peak of eternal light wouldn't be too bad.

"On the top, it's quite comfortable — just a few tens of degrees below freezing," Foing says. "It's possible to install equipment that could last a while."

That's the moon for you. One day a possible human outpost. For the moment, though, it's a dusty graveyard.

SMART-1, which has been orbiting lower and lower around the moon, will soon crash onto the surface of the heavenly body. Koschney puts the time of impact at around about 10:40 p.m. Saturday, Pacific time. He's excited by the prospect.

"It's a little like Christmas," he says. "Of course, we will lose the spacecraft. It's gone afterward. But this is what we knew all the time. At some point, the mission will end. At least it ends with something spectacular."

SMART-1's final resting place? The Lake of Excellence.

The flash of the collision may be visible from some parts of the United States, Koschney says. So if you have a telescope, set it up. The bigger, the better.

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