The Fog Creeps in on Methane Feet

On Titan, That Is

Artist's concept of Titan surface beneath its foggy atmosphere. Courtesy NASA. Click to embiggenate.

Astronomer Mike Brown of CalTech (who tweets under the name PlutoKiller) has a fascinating discussion on his blog about fog banks hovering over Titan’s south pole. Titan, if you haven’t been following outer solar system news, is the largest moon of Saturn. It has this thick atmosphere hanging over a frigid surface which itself boasts pools of hydrocarbons in the form of liquid and ice. The hydrocarbons are in the form of ethane (on the surface) and now it appears that the methane forms fog banks in the atmosphere. Methane breaks down in the presence of sunlight to make ethane, so this whole thing seems to point to some sort of cycle between atmosphere and surface on Titan.

I say “seems” because, as Mike discusses, there’s a lot of atmospheric science work to be done to completely understand what’s happening on this shrouded world to make methane clouds form.  Want to know more and see a cool pic? Run over to Mike’s blog and read what he has to say. He also has a link to his science paper outlining the fogbank on Titan and a nice, insightful discussion on peer review of his paper — and he invites folks knowledgeable in the Titan atmosphere to review his paper before it goes to publication.  How cool is that!

How We Look

To LCROSS

Earth and Moon from LCROSS orbit. August 17, 2009. Click to embiggen. Courtesy NASA/Ames.

Imagine you’re on this spacecraft coming to Earth — this is the scene you’d see from a vantage point of 520,294 kilometers from Earth and 880,850 kilometers from the Moon. You’d know there’s a planet there, and its moon would be tantalizingly far away… but it would be exciting to see.  If I were the alien piloting the ship, I’d be excited to see another world and, given the instruments on my ship showing the components of that planet’s atmosphere, I’d know there was life there.

Well, this isn’t a view from an alien ship — it’s the view that the Lunar Crater Observation and Sensing Satellite (LCROSS) mission, which is on a journey to study the Moon and, on October 9, crash a Centaur rocket stage into the south polar region.  The impact should kick up a plume of dust and other materials — and hopefully some of that stuff will be hydrogen or even water vapor. If there is water there, then we’ll know that there’s a supply of ice at the lunar south pole. How much ice is yet to be determined — but if there’s a lot, it could be a useful supply for future moon explorers.

So far, the LCROSS mission is on schedule for its delivery date, despite a sensor anomaly that caused one of the spacecraft’s thruster to fire excessively. That action consumed quite a lot of fuel, but the team estimates that the spacecraft still has enough to complete its full mission. They’re still assessing the situation and trying to figure out the complete chain of events that led to the over-firing of the thruster.  For a nice background on LCROSS from the Astronomical Society of the Pacific, head to their Astronomy Behind the Headlines web page for a podcast interview I did with LCROSS team member Brian Day. This is going to be an exciting mission come early October, so stay tuned!