Messenger Makes another Pass at Mercury

I noted in July that NASA's Messenger spacecraft had swung by Mercury for the first time. This morning, Messenger began its second pass by Mercury. The neat thing here is that the first pass mostly covered areas that were previously photographed by the Mariner 10 spacecraft in the 1970s. This second pass, on the other hand, is going to cover much of the other side of the planet - areas that have never previously been photographed by any spacecraft. That comes to almost a third of Mercury's surface! We will have a nearly complete map of Mercury after this.

Follow up:

Messenger's closest pass will be a mere 125 miles above Mercury's surface. It's going to be able to do a wide array of observations - surface images, laser topography, atmospheric studies, and more. You can even see an interactive timeline of all the observations. The images will be received by NASA and passed on to the public over the next few days and weeks.

How it got there (and the next step afterward) is also a bit novel. The spacecraft used "solar sailing" to change its orbit to this Mercury approach: rather than using up rocket fuel, it used the pressure of particles and radiation streaming from the Sun - the solar wind - to change course. On the way out, it'll use Mercury's own gravity to direct itself into the proper orbit for its eventual goal: a stable orbit around Mercury in early 2011.

Read more at NASA's Messenger Website.