MESSENGER's cameras are working

...but I can't show you any pictures yet.

The MESSENGER mission announced today that the first eight optical navigation images of Mercury have been received on the ground. However, the release didn't actually include the images themselves; I checked with the mission to see if I was just being obtuse in not finding them on the website and was told that no, they aren't actually going to be released until tomorrow's press conference. Now that's just teasing.

So the best I can do is to show you what they should look like, using the handy-dandy Solar System Simulator at JPL; I'm told that the Solar System Simulator now has the most up-to-date information on MESSENGER's trajectory, so the simulations should be accurate. MESSENGER has two cameras, a wide-angle one with a field of view of 10.5 degrees and a narrow-angle one with a field of view of 1.5 degrees, so if you want to see exactly how much Mercury fills the field of view, use the "I want a field of view of __ degrees" option on the Simulator. (10.5 and 1.5 aren't choices you can select from the dropdown, but it's pretty easy to hack the URL to make it show those fields of view.) Here's the wide-angle view as of this moment, and here's the narrow-angle view as of this moment. I should mention that there is a very cool visualization tool for MESSENGER's instruments at the mission website, but the visualization part only covers the closest part of the flyby.

Actually, the Solar System Simulator views are very helpful because it's very clear what part of Mercury was seen by Mariner 10 -- the part that shows craters and stuff in the Simulator views -- and what part has never been seen up close -- the part that is smooth as a billiard ball on Simulator views. As MESSENGER approaches, slightly more than half of the visible hemisphere is what Mariner 10 saw, but if you pay close attention to how much of Mercury is sunlit (just a crescent), you'll see that everything that MESSENGER can see as it comes in for its flyby has already been seen by Mariner 10. It's not until after closest approach that MESSENGER will see terrain not imaged by Mariner 10. And because of the way MESSENGER's communications schedule works out, those images won't start hitting the ground until (probably) January 16, two days after the flyby; and I have no knowledge of how long it will take for the mission to release them to the Internet. Unlike other missions like Cassini, the rovers, and New Horizons, there do not seem to be plans to make a "raw images website" for MESSENGER where images will be made available quickly after their arrival on Earth. So we may have to satisfy ourselves with the visualizations for a while.

I've gathered a bunch of information on the upcoming flyby, including a timeline of science activities. I'll post a longer news story tomorrow after a planned press conference from the mission -- hopefully with some actual images from the spacecraft! -- but in the meantime here is the science activity timeline, for those of you who are on tenterhooks waiting for the first Mercury flyby in 33 years. For a little help in decoding what all the instruments are supposed to do, here's a backgrounder on MESSENGER's instruments.