NASA Wants You to Play Its Satellite Moon-Crash Guessing Game

When will a satellite go splat on the moon? Guess now and you could be a winner.

National Journal
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Alex Brown
April 4, 2014, 1 a.m.

A NASA satel­lite is about to smash in­to little bits and pieces all over the moon.

The space agency wants you to use math — or just a gut in­stinct — to fig­ure out when the crash will hap­pen. The LADEE space­craft could wreck to­mor­row or two weeks from now; guess the closest and NASA will ac­know­ledge your smarts with a per­son­al­ized cer­ti­fic­ate.

The crash-land­ing is part of NASA’s plan; the short-lived satel­lite has already served its pur­pose. “The mis­sion was al­ways de­signed for a re­l­at­ively short life,” said NASA’s Joan Sa­lute. “The prime mis­sion is already in the bag.”

LADEE — the Lun­ar At­mo­sphere and Dust En­vir­on­ment Ex­plorer — has been circ­ling the moon, mak­ing ob­ser­va­tions about the dust particles sur­round­ing it. “We didn’t know very much about the lun­ar at­mo­sphere and dust en­vir­on­ment be­fore we went there,” NASA sci­ent­ist Rick Elphic said. By the time LADEE’s data is ana­lyzed, “we will have at least quad­rupled the amount of [ele­ments] known in the lun­ar at­mo­sphere.”

In ad­di­tion to its dust ana­lys­is, LADEE helped pi­on­eer a su­per­fast, laser-based In­ter­net con­nec­tion — the longest of its kind ever es­tab­lished.

The satel­lite has been or­bit­ing at about 30 miles above the moon since Oc­to­ber. Now comes the fun part. On Sat­urday, LADEE “will rap­idly drop to very low alti­tudes,” said NASA’s But­ler Hine. Skim­ming over the ground, it will start send­ing back up-close read­ings of dust close to the lun­ar sur­face.

“We really dis­cov­er new things every time we drop lower,” Hine said. The plan isn’t fool­proof. Al­though NASA hopes the satel­lite will con­tin­ue its moon study for a couple more weeks, the moon’s “lumpy grav­ity field” makes for a roller-coast­er-like ride. “It’s pretty risky,” Hine said. “We’ve de­signed it so that we get as close as we can without clip­ping the [sur­face], but there’s nat­ur­al un­cer­tainty.”

Even if LADEE avoids an early wipeout, it will have an­oth­er chal­lenge to con­tend with. On April 15, a four-hour ec­lipse will leave it without the sol­ar power it needs to keep go­ing. Ac­cord­ing to a NASA re­lease, this will cre­ate “con­di­tions just on the edge of what it was de­signed to sur­vive.”

If the satel­lite can re­tain enough juice, there’s still a chance the propul­sion sys­tem will freeze in the cold dur­ing the black­out. Should it sur­vive, NASA ex­pects it will hang around un­til about April 21 be­fore fi­nally smash­ing down.

The im­pact — which is sup­posed to hap­pen on the far side of the moon in or­der to avoid his­tor­ic­al lun­ar land­ing sites — could be a single ex­plo­sion on the edge of a crater wall or a series of skips, like a stone across a pond. Either way, it will leave plenty of carnage.

“If you hit any­thing at 1,600 meters per second, this is not something you walk away from,” Elphic said. “This is by no means gentle.”

So how does NASA feel about see­ing LADEE ob­lit­er­ated? “You’re very proud of the suc­cess, but you’re also a little mel­an­choly that you won’t be talk­ing to your space­craft again,” Hine said.

Want to guess when the crash will take place? Here’s NASA’s “Take the Plunge” chal­lenge.

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