The First Spacecraft Has Landed On A Comet

And naturally, it’s already tweeting:

Gautam Naik details the exciting news:

Rocket scientists at the European Space Agency’s mission control here erupted in cheers as they received the first signal that the Rosetta mission’s probe, called Philae, had touched down more than 300 million miles away on the forbidding landscape of a small comet known as 67P/Churyumov-Gerasimenko. There were even more cheers, hugs and handshakes when it became clear that it had done so safely.

The landing follows a decade long trek through the solar system to get the up-close-and-personal visit with a comet for a lengthy period of time as it hurtles closer to the sun. “We made history today,” said Matt Taylor, project scientist for the Rosetta mission, who sported a pair of shorts revealing a tattoo on his thigh depicting a successful Philae landing. “I can’t see anyone doing this again anytime soon.”

But Victoria Bryan and Maria Sheahan have some sobering details:

[A]n anchoring system problem may hamper planned investigations into the origins of Earth and the solar system. The 100-kilogram (220-pound) lander – virtually weightless on the comet’s surface – touched down on schedule at about 11 a.m. ET after a seven-hour descent from its orbiting mothership Rosetta, now located a half-billion kilometers (300 million miles) from Earth. But during the free-fall to the comet’s surface, harpoons designed to anchor the probe, named Philae, failed to deploy. Flight directors are considering options to ensure the lander does not drift back into space.

Meanwhile, Dave Gilbert describes the probe:

Built by a European consortium, led by the German Aerospace Research Institute (DLR), the landing probe has nine experiments. According to details on ESA’s Rosetta website, sensors on the lander will measure the density and thermal properties of the surface, gas analyzers will help to detect and identify any complex organic chemicals that might be present, while other tests will measure the magnetic field and interaction between the comet and solar wind. Philae also carries a drill that can drive 20 centimeters (8 inches) into the comet and deliver material to its on-board ovens for testing.

Joseph Stromberg voxsplains the landing’s potential significance:

[T]he comet is believed to have formed 4.6 billion years ago, from material leftover as Earth and the solar system’s other planets were coalescing. As a result, understanding the composition of comets could help us better model the formation of the solar system. Moreover, many scientists believe that in the period afterward, when the solar system was still a chaotic, collision-filled system, comets and asteroids were responsible for bringing water and perhaps even organic molecules to Earth. If water ice is present on this comet, as scientists hope, Philae will calculate the ratio of different sorts of hydrogen isotopes present in it — information that could provide an important clue as to whether the hypothesis is correct.

In other words, data collected by a tiny robot on this lopsided, spinning comet, millions of miles away, could provide a window into the history of all life on earth.

Rachel Feltman and Terrence McCoy discuss the mission’s circuitous journey to the comet:

It’s no easy thing to land on a comet’s surface: These chunks of rock and ice are constantly spinning, and Comet  67P/Churyumov-Gerasimenko, which was discovered in 1969, orbits the sun at a speed of about 85,000 mph. It’s irregularly shaped — like a toddler’s play-dough impression of a duck, or something — and its surface is uneven and pitted. And in a universe of unimaginable proportion, Rosetta’s target is just 2.5 miles in diameter — smaller than Northwest Washington’s Columbia Heights neighborhood.

So Rosetta has taken an onerous journey to get in sync with the comet’s orbit, which would allow it to drop down a lander. In 2004, the spacecraft began what would be three looping orbits around the sun, altering its trajectory as it skimmed Mars, just 150 miles from the surface, and enduring 24 minutes in the planet’s shadow to align with Churyumov-Gerasimenko. The cumulative distance traveled by the craft – with all its looping and gravity assists – is a stunning 4 billion miles. “When the Rosetta signal reappeared after the passage behind Mars, shortly after the end of the ‘shadow’ period, there was a collective sigh of relief,” ESA said. At one point in 2011, the spacecraft even had to hibernate for nearly three years. It flew so far from the sun — nearly 500 million miles — that its solar panels couldn’t leech enough energy to keep the spacecraft operational. But in January of this year, Rosetta woke up, and quickly approached its target.

Meanwhile, Victoria Turk perks up her ears:

We recently found out what [the comet] smells like: space farts. And now we know that it’s “singing” this percussive little ditty as it goes. As one commenter put it, it kind of sounds like a dolphin. ESA announced the observation on its Rosetta blog, and explained that the “music” is produced “in the form of oscillations in the magnetic field in the comet’s environment” picked up by the mission’s magnetometer experiment from a distance of around 100 kilometers.

Scientists were delighted by the discovery:

“This is exciting because it is completely new to us. We did not expect this and we are still working to understand the physics of what is happening,” Karl-Heinz Glaßmeier, head of Space Physics and Space Sensorics at the Technische Universität Braunschweig, Germany, explained on the RESA Rosetta blog. The “song” – as the scientists themselves refer to it – was in fact outside the normal range of human hearing range and has to be boosted in volume by a factor of 10,000. According to scientific theory, the comet releases neutral particles into space where they collide with high-energy particles and that’s what makes the sound. However, “the precise physical mechanism behind the oscillations remains a mystery,” according to the blog.