Comet Landing A Success: European Craft Makes 'Fairly Gentle Touchdown'

Hide caption The Philae lander took this photo of its descent onto comet 67P Wednesday, when it was about 3 kilometers from the surface. The landing site is seen with a resolution of about 3 meters per pixel. Previous Next ESA/Rosetta/Philae/ROLIS

Hide caption The Philae lander is seen from the view of its parent spacecraft as it heads toward a first-of-its-kind rendezvous with a comet. Previous Next ESA

Hide caption The first image the ESA released from the Philae lander shows the craft breaking away from the Rosetta orbiter and heading toward 67P. Previous Next ESA

Hide caption A photo illustration from the European Space Agency shows what a landing by the Philae robotic craft might look like on the 67P/Churyumov-Gerasimenko comet. The lander headed toward the comet Wednesday. Previous Next ESA

Hide caption A photo illustration provided by the European Space Agency (ESA) shows the 67P/Churyumov-Gerasimenko comet in a scale comparison to the city of Paris. ESA landed the Philae lander, launched from the Rosetta probe, on the comet Wednesday. Previous Next ESA

Hide caption An image of the surface of comet 67P shows the difficulty of landing a spacecraft on it. Previous Next ESA 1 of 6 i View slideshow

Hundreds of millions of miles from Earth, a man-made object was flung at a comet Wednesday — and now it's sticking to the rock as it hurtles through space.

"We are on the comet," Stephan Ulamec, Philae Lander Manager, announced Wednesday, marking a historic achievement.

The news came after the European Space Agency endured tense hours of uncertainty following the lander's separation from the Rosetta spacecraft, as scientists awaited a message from the lander that would tell them whether it landed safely — or suffered a calamity.

As Ulamec said the lander was secured to the comet's surface by ice screws and the craft had fired its tethering harpoons — and it was now doing its job and communicating with Earth — he sparked an uproar of applause from workers and spectators at the European Space Operations Center in Darmstadt, Germany.

But while the European agency says the lander is in "great shape," it also says that additional analysis suggests that Philae's harpoons did not fire, and that the agency is looking at trying again (see update below).

It took 10 years for the Philae lander to reach a point where it could be sent toward Comet 67P/Churyumov-Gerasimenko. The ESA said this morning that it had received a signal from the lander as it headed toward its rendezvous with the comet, indicating that if all went well, the lander would be able to communicate and send photos from the comet's surface.

We'll update this post with developments from space. You can also follow the news at the ESA's Rosetta page, and at NASA TV, starting at 9 a.m. ET.

Update at 11:50 a.m. ET: 'Harpoons Did Not Fire'

After analyzing telemetry data from the Philae lander, ESA says it seems that the craft's harpoons didn't fire as first thought.

Adding that the lander is in "great shape," the agency says its engineers are looking into options for retrying the harpoon operation, which is meant to secure the craft to the comet's surface.

In a tweet, the agency says the lander "made a fairly gentle touch down on #67P based on amount of landing gear damping."

Update at 11:05 a.m. ET: Philae Has Landed

In a first, the Philae lander is on the comet's surface. We've updated the top of this post to reflect the news.

Update at 10:15 a.m. ET: New Images, And 'A Boot'

"Everything looks really, really good," says Stephan Ulamec, Philae program manager at DLR, in a progress report.

The ESA has released new images from the area around the comet, including one shot of Philae breaking away from the Rosetta craft and heading toward 67P.

Another image shows the lander from the view of its parent spacecraft.

The two scientists who discovered the comet 45 years ago — Klim Ivanovych Churyumov and Svetlana Ivanovna Gerasimenko — are in the unique position today of watching humanity's attempt to land on it.

Churyumov and Svetlana Ivanovna Gerasimenko took part in an event hosted by the ESA that was equal parts news conference and viewing party.

When Gerasimenko was asked the tongue-in-cheek question of how she likes the comet that she and her colleague spotted decades ago, she responded by saying, "I like the form very much — it reminds me of a boot."

Today's comet operation was also being monitored by other space veterans.

Our original post continues:

Comet 67P has several surprising qualities. First of all, it smells really bad.

"It stinks," researcher Kathrin Altwegg told NPR's Geoff Brumfiel last month.

That's because of a mixture of ammonia, hydrogen sulphide, formaldehyde and methanol.

The comet also emits "a mysterious song," according to the ESA blog.

"The comet seems to be emitting a 'song' in the form of oscillations in the magnetic field in the comet's environment," the ESA says. "It is being sung at 40-50 millihertz, far below human hearing, which typically picks up sound between 20 Hz and 20 kHz. To make the music audible to the human ear, the frequencies have been increased by a factor of about 10,000."

Here's what that sounds like — close your eyes and you might be able to pick out "Flight of the Bumblebee":

As Geoff reports, scientists here on Earth see Philae, which is about the size of a refrigerator, as "our remote hands." The lander will take many readings from the comet's surface, in addition to drilling into it.

But before any tests can occur, Geoff notes, the comet's rocky and uneven surface could make the landing very tricky — and that's why the lander has harpoons.

"Moments after its feet touch down, the harpoons will fire," Geoff says, "along with some thrusters to keep the lander grounded. Then screws in the feet will try to get a grip."

Here's how the ESA says things should work if all goes well, with music by Vangelis (we'll warn you: the music is dramatic).