Rosetta’s Comet Target is a Rotating Two-body Comet

What do You Do When Your Target Looks like a Rubber Ducky in Space?

Imagine designing a mission to land a probe on a comet. You have to make some assumptions about the comet nucleus, such as its shape, rotation rate, velocity, and what kind of ice it’s made of.  That’s what the planners for the European Space Agency’s Rosetta mission had to do, and this week, they’re getting the first up-close images of the target, Comet 67P/Churyumov-Gerasimenko. When the first views came from the spacecraft, I’m sure the scientists were probably incredibly excited to find out that this comet is not just your run-of-the-mill dented-in icy nucleus with a few jets. No way.  Instead, they’ve drawn the cosmic equivalent of a winning lottery ticket: a sort of double-lobed shaped nucleus that someone described as a rotating “rubber ducky” in space.

Check it out for yourself.

Yes, this is not like any other comet astronomers have seen.  And, it’s spurring a LOT of speculation. For starters, how did it get to be this shape? Was this nucleus once two chunks of ice that somehow slammed together in the past and are now orbiting wildly in orbit?  Or, was it one huge chunk of ice that somehow got eroded or broken apart, leaving behind this rotating ducky-shaped object?

To answer the question the mission scientists will use the Rosetta spacecraft’s instruments and cameras to study the surface characteristics of the comet. The data they gather will tell them the ice and mineral makeup. If the nucleus came from one body, then the whole thing should show the same mineralogical makeup. If it came from two different bodies, then the studies will show slight (or perhaps not-so-slight) differences in the ices and dust grains on the surface.

When Rosetta gets to the comet (and the scientists decide to deploy it), it will send a small lander called Philae to settle down to the surface to give us some views from the comet, and also give some first-hand information about the surface materials it will be sitting on. Of course, with a two-body comet, now the big question is, WHERE do you land it?  In particular, if this comet turns out to be made of two different chunks of ice and dust, which side do you pick to study?

Stay tuned because Rosetta is supposed to be at its closest approach to the comet on the morning of August 6th, 2014. It will be an exciting morning for another solar system “first”!