Mercury from MESSENGER at LPSC 2013
This week I’m at the 44th Lunar and Planetary Science Conference in Houston, Texas, soaking up the new knowledge and offering up my own findings on Mercury. I gave my presentation yesterday – without a hitch, happily!
So what’s new on Mercury? The morning session focussed on new findings from the MESSENGER spacecraft currently orbiting the planet, with most of the talks from people involved in MESSENGER in one way or another. Several speakers looked at the large-scale ‘waves’ in the volcanic plains of Caloris and the Northern plains, as I mentioned here. Jeff Balcerski has worked out the timing of the deformation on the basis of craters which were tilted by it – seems it was more recent in Caloris than in the north. Peter James is trying to work out what caused the deformation by doing modelling of how the planet would respond to different stresses. He reckons relaxation of the surface after the Caloris impact may explain what we see in that basin at least. What’s the relevance of all this? If we can understand the large-scale stresses as play in the crust of the planet, we can make sense of how the planet works now and what affected its volcanic activity over time. It’s good to see we’re getting closer to such an understanding.
The most well-attended talk was ironically by someone who know little about Mercury and about something that might not even be from Mercury: a meteorite. Tony Irving has found one that comes from a differentiated body that was large enough to have a magma ocean during formation, that has a composition unlike any planet we have samples from and which formed under reducing conditions like those you’d find close to the Sun. Could it be from Mercury? If so, that would be fantastic – finally a sample from the innermost planet! There are problems, though: this rock doesn’t match any composition we’ve sensed from orbit – not necessarily a problem as it’s a rock which formed at depth, but not exactly promising. And as for forming on a planet with a magma ocean – in the q&a someone pointed out there are other ways to form it. To which I reply as a heckler did from the crowd: ‘spoilsport!’
Finishing off the session was Louise Prockter, who told us what the MESSENGER team would like to do if they get an extension to their mission. The period they were funded to ran out a few days ago and they haven’t yet heard if they’re getting a further extension to the mission – tense times. If they do get the funding, there’s a lot of great stuff they can do because the spacecraft will get closer and closer to the planet as its orbit decays. That means they can get very high-resolution images of small-scale features like the recent bright hollows, they can look for changes of composition in Mercury’s volcanism over time using targeted x-ray, infrared and colour mapping, they can look in more detail at the ice at the north pole, and much more. Here’s hoping the get the go-ahead – MESSENGER has proved itself an enormous success so far, so it would be a horrible shame to shut it down when it has enough fuel to keep on trucking for another 2 years!