Meet Philae, the Comet Hitchhiker

19 07 2010

It is an exciting time for space exploration.  The Cassini spacecraft continues to dazzle us from Saturn.  The legendary Mars rovers Spirit and Opportunity continue to prove their Herculean endurance on the desert planet.  The MESSENGER spacecraft is en route to Mercury, and New Horizons is on its way to Pluto.  -And, to my point this evening, the European Space Agency‘s Rosetta space probe has just returned images from a wildly successful flyby of asteroid Lutetia and is on its way to a comet.

To me, the asteroid flyby and future comet interceptions aren’t in and of themselves unique.  NASA’s NEAR Shoemaker spacecraft to asteroid Eros-433 in 2000, and the Deep Impact space mission to comet 9P/Tempel in 2005, have already beaten it to the punch there.  Both even physically rendezvoused with their targets, as NEAR Shoemaker made a daring crash-landing to obtain data at the end of its mission, and Deep Impact famously smashed an impactor into the comet’s nucleus to see what its insides were made of.

What is unique about the Rosetta mission, aside from its eleven original experiments, is what Rosetta is carrying along for the ride: A separate little lander named Philae.

Artist's rendering of the Rosetta spacecraft and Philae lander. Credit: NASA

For starters, Philae is supposed to land on comet 67P/Churyumov-Gerasimenko.  The small lander has piggy-backed on Rosetta’s side, and the scrappy, carbon-fiber-reinforced robotic detective carries with it a formidable array of ten scientific instruments of its own.  Should all go according to plan, it will detach from Rosetta’s body after arrival and fall to toward the comet’s surface.  Three specially-designed legs will absorb the shock of impact and rotate to make sure it sits upright, and Philae will anchor itself in place with a harpoon to make sure it doesn’t drift away from the comet’s weak gravity.

-A regular galactic hitchhiker.

Once Philae’s there, we should be treated with magnificent panoramic views of the comet nucleus as well as microscopic images from an onboard arsenal of cameras.  Then, a spectrometer, two gas analyzers, and a magnetometer should tell us exactly what the comet, (an ancient remnant from the early solar system,) is made of.  A radio sounder should tell us the comet’s internal structure, seismic and acoustic sensors will explore the comet’s outer layers, and sensors on the harpoon will help verify the results from the other instruments.  Finally, a small drill will extract a sample for up-close-and-personal analysis.

Philae is an ambitious little guy, and of all of the space exploration missions, has won my heart.  Get on out there and show us how it’s done, Philae!



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