1/7/2015 Two months later, scientists still can't locate the Philae lander ­ Vox

http://www.vox.com/2015/1/6/7500857/philae­missing 1/11

Two months later, scientistsstill can't locate thePhilae landerUpdated by Joseph Stromberg on January 6, 2015, 11:10 a.m. ET @josephstromberg

joseph@vox.com

1/7/2015 Two months later, scientists still can't locate the Philae lander ­ Vox

http://www.vox.com/2015/1/6/7500857/philae­missing 2/11

A rendering of Philae's touchdown. (DLR German Aerospace Center)

In November, after the Philae probe's historic landing on a comet (http://www.vox.com/2014/11/12/7203081/philae-comet-rosetta), it bouncedand likely landed in a shadowy crater — quickly draining its battery due to a lack of sunlight.

As of yesterday, European Space Agency scientists still don't know exactly where it is,according to the BBC ( http://www.bbc.com/news/science-environment-

1/7/2015 Two months later, scientists still can't locate the Philae lander ­ Vox

http://www.vox.com/2015/1/6/7500857/philae­missing 3/11

SCIENTISTS HOPEPHILAE WILL WAKEUP IN LATE SPRING

30683860).

Over the last two months, scientists have usedthe Rosetta orbiter — which originally carriedPhilae to the comet 67P/G-C and is stillorbiting the body — to take high-resolutionphotographs of the comet, manually poringover them for signs of the lander. But eventhough they have a rough idea of where Philaeshould be, they've been unable to find it.

Now, they're hoping that as the comet nears the sun in late spring, more sunlight will reachPhilae's solar panels, allowing it to wake up and resume sending signals back to Rosetta.

How Philae got lost

1/7/2015 Two months later, scientists still can't locate the Philae lander ­ Vox

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A composite shows Philae's view of the comet, from a dark crater. (ESA)

When Philae landed on the comet — the first-ever controlled landing of a spacecraft on one— there were some technical difficulties. The most major one was that the probe'sharpoons, which were designed to fasten it to the comet's surface, failed to fire.

As a result, Philae bounced several times (http://www.vox.com/2014/11/17/7235087/philae-photos-comet). Due to the

1/7/2015 Two months later, scientists still can't locate the Philae lander ­ Vox

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extremely low level of gravity, its first bounce took about two hours, and carried it as highas a kilometer above the surface. After another smaller bounce, it finally settled in ashadowy crater.

1/7/2015 Two months later, scientists still can't locate the Philae lander ­ Vox

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A composite image shows Philae's location right after its initial touchdown. (ESA/Rosetta/MPS for Osiris Team)

As a result, its solar panels were only able to collect about 90 minutes of sunlight every 12hours, which meant the craft had to rely largely on its battery. Though ESA scientists usedmechanical instruments on the craft to turn it slightly in hopes of getting more sunlight, theeffort failed, and Philae powered down (http://www.vox.com/2014/11/15/7225427/philae-comet-rosetta) after 57 hourson the comet.

During this short interval, Philae sent back photos and data, making the mission as a wholea success. Among other things, that data has told us that the water present on the comet isdifferent from that on earth (http://www.vox.com/2014/12/10/7371949/rosetta-comet), making it seem lesslikely that comets like 67P/G-C delivered water to earth billions of years ago.

But even though scientists were able to calculate the region of the 2.5-mile wide cometwhere Philae likely landed, photos taken by Rosetta have failed to reveal exactly where it is.

1/7/2015 Two months later, scientists still can't locate the Philae lander ­ Vox

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1/7/2015 Two months later, scientists still can't locate the Philae lander ­ Vox

http://www.vox.com/2015/1/6/7500857/philae­missing 8/11

A simulation of the comet's surface shows where scientists believe Philae is located. (ESA/Rosetta/Philae/CNES/FD/CIVA (http://www.nasa.gov/jpl/rosetta/pia19097/#.VKwDH2TF9dI))

What's next for Philae

Rosetta has now ascended to a slightly higher orbit, and ESA scientists are no longer tryingto use it to locate Philae. Instead, they're hoping that increased sunlight — the result of thecomet's orbit bringing it closer to the sun — will provide enough solar power for the landerto wake up.

1/7/2015 Two months later, scientists still can't locate the Philae lander ­ Vox

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The comet's current position, and its orbit through December. (Livecometdata.com (http://www.livecometdata.com/comets/67p-churyumov-gerasimenko/))

Yesterday, they said that this could happen sometime in May or June. By September, Philaecould have enough power to begin using its scientific instruments once again, and continuecollecting data.

The bad news, however, is that when the comet reaches its closest point to the sun — inAugust — excessive heat could make Philae inoperable (http://www.esa.int/Our_Activities/Space_Science/Rosetta/Frequently_asked_questions)So even if the lander is indeed able to wake back up, there might be a fairly narrow windowfor it to conduct more science before shutting down for good.

1/7/2015 Two months later, scientists still can't locate the Philae lander ­ Vox

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In thisStoryStream

Philae's historic comet landing

Two months later, scientists still can't locate the Philae lander

The Rosetta probe’s first finding suggests asteroids, not comets,brought water to Earth

11:10A

DEC 10

13 updates

1/7/2015 Two months later, scientists still can't locate the Philae lander ­ Vox

http://www.vox.com/2015/1/6/7500857/philae­missing 11/11

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