[Cid_Yama]

$this->bbcode_second_pass_quote('', 'A')fter making history Wednesday as the first spacecraft to touch down on a comet, Europe’s Philae lander collected data on the rugged alien world’s environment and may have rebounded into space before settling back on the surface, scientists said Wednesday.

The small landing craft deployed from the European Space Agency’s Rosetta spacecraft Wednesday to begin a seven-hour descent to the comet. Tension grew inside ESA’s operations center here as the expected time of touchdown approached, and views inside the Rosetta mission control room showed engineers with strained faces waiting for radio signals confirming the lander had reached the comet.

The dramatic space gymnastics all occurred at comet 67P/Churyumov-Gerasimenko, a bizarre object orbiting the sun more than 300 million miles from Earth. The comet’s tenuous gravity field is one hundred thousand times weaker than Earth’s, and officials worried the lander could bounce off the comet with little pull to hold it on the surface.

Philae flew with a top-mounted cold gas thruster to fire and keep the probe on the surface while it engaged harpoons and ice screws to anchor it to the comet.

But at least two of the landing assist devices did not work.

The thruster system failed to pressurize during lander preparations Tuesday night, and officials said Philae’s two harpoon anchors did not fire when the craft reached the comet Wednesday.

Officials could also not definitively confirm whether the ice screws bored into the comet to keep the lander on the surface.

Ground controllers received the initial notification of Philae’s landing at 1603 GMT (11:03 a.m. EST), triggering an immense emotional release and a wave of cheers and applause.

The status of the lander was put in doubt a few minutes later after a manager from Philae’s control center in Cologne, Germany, reported the craft apparently did not fire the harpoon anchors as planned.

“What we know is that we touched down, so we landed at the comet at the time when you all saw us cheering, when it was announced we had a very clear signal,” said Stephan Ulamec, manager of the Philae mission for DLR, the German Aerospace Center.

Ulamec said Philae transmitted information on its status, and at least some of the lander’s 10 science instruments collected data and delivered the results to Earth.

“The not so good news is that the anchoring harpoons apparently did not fire, so the lander is not anchored to the surface,” Ulamec said. “We started to think about what could be the situation. Did we just land in a soft sand box and everything is fine … or is there something else happening.”

Engineers say they saw fluctuations in the radio signals from Philae being relayed by the Rosetta orbiter, which carries a more powerful communications system.

Cautioning his statement as speculation, Ulamec said information received from Philae is consistent with the lander moving across the surface after its initial contact with the comet.

“Some of these data indicated that the lander may have lifted off again,” Ulamec said.

The lander may have “touched down and we were re-bouncing very slowly because the landing gear worked perfectly well,” Ulamec said. “It was designed to dampen the majority of the impact energy.”

Data signatures from the lander also showed changes in power being generated by solar cells covering the craft’s outer skin, “which could be interpreted that the lander lifted off and started to turn itself because flywheel (stabilization system) was switched off at touchdown,” Ulamec said.

After about two hours, the fluctuations in Philae’s electrical system ceased but the radio signals continued, meaning the lander may have come to a rest.

“Maybe today we didn’t just land once, we even landed twice,” Ulamec said.

Mission control lost contact with Philae soon after — a little earlier than expected, said Paolo Ferri, head of mission operations at ESA.

“We lost the radio link earlier than planned, which is something that we never like, but this is not at the moment concerning,” Ferri said.

Rough terrain may have blocked the line-of-sight radio link between Philae and Rosetta sooner than expected, according to Ferri.

Officials said the next chance to contact Philae will be around 0600 GMT (1 a.m. EST) when Rosetta again flies in range of the lander.

[Newfie]

Here's hoping it sticks.

[Keith_McClary]

Rosetta’s OSIRIS camera captures Philae’s bounce across comet

[Subjectivist]

$this->bbcode_second_pass_quote('', 'T')hough the Philae lander was short-lived on the surface of Comet 67P/Churyumov-Gerasimenko, it was able to return scientific data back to Earth from the first samples ever obtained directly from a comet’s nucleus. During its successful 60-hour-long primary science mission last week, Philae made a very important discovery: the comet contains organic molecules.

Not much has been released about the molecules so far, with the Wall Street Journal breaking the news on Monday. The molecules are carbon-based, but no word has been given on what other elements are present, or how complex they may be. Complex organic compounds, like amino acids, are the building blocks to life.

Philae’s mission was to determine which, if any, organic compounds existed on comets. This knowledge will allow scientists to determine if comets brought the necessary ingredients for life to early Earth. The conditions on the young Earth were not favorable for making those compounds, and it is most likely that they came from an outside source.

The discovery of the molecules was made with Philae’s Cometary Sampling and Composition Experiment (COSAC) instrument. This device analyzes compounds present in the comet’s thin atmosphere, seeking out organic and volatile compounds.

As of right now, it is hard to tell when additional information will be provided about the nature of these molecules, and what implications they may have.

[Keith_McClary]

Rosetta's Comet Revealed: It's Dry on the Outside, Fluffy on the Inside
$this->bbcode_second_pass_quote('', 'T')he comet that's being shadowed by the European Space Agency's Rosetta spacecraft is getting its most detailed once-over yet in a series of scientific papers — revealing a candy-bar structure with a dry, crunchy surface and a soft, fluffy interior.

However, the cosmic candy bar known as Comet 67P/Churyumov-Gerasimenko is being unevenly cooked as it approaches the sun, and the initial reports published in the journal Science suggest it will undergo dramatic changes in the months ahead. That's exactly what the scientists on Rosetta's team are hoping for.

[Keith_McClary]

$this->bbcode_second_pass_quote('', 'T')hat’s a mosaic of four separate images taken using the NAVCAM detector camera, Rosetta’s low-resolution detector, when the spacecraft was just under 29 kilometers from the comet.

The rubber duckie–shaped comet has two lobes connected by a neck; the smaller lobe is at the top, and the larger lobe at the bottom. I increased the brightness of the image a small amount, accenting the streaks of vapor emitted from the comet; those are jets of gas erupting from the surface!
...
On Saturday it will dip down to an astonishing 6 kilometers above the comet’s surface! At that distance, details as small as half a meter should be visible…in the low-res detector. Unfortunately, the OSIRIS high-res camera images aren’t released quickly, so it may be a while before we see them.

[Keith_McClary]

Rosetta space probe takes sharp, close-up images of comet

[Tanada]

Philae comet lander wakes up
$this->bbcode_second_pass_quote('', 'T')he European Space Agency (Esa) says its comet lander, Philae, has woken up and contacted Earth.

Philae, the first spacecraft to land on a comet, was dropped on to the surface of Comet 67P by its mothership, Rosetta, last November.

It worked for 60 hours before its solar-powered battery ran flat.

The comet has since moved nearer to the sun and Philae has enough power to work again, says the BBC's science correspondent Jonathan Amos.