schneiderism

Catching up on the deluge that is my RSS reader lately, I came across this image from APOD of the Caloris basin (also called Caloris Planitia) on Mercury recently snapped by the Mercury Messenger robotic explorer. It’s huge, and one of the largest impact basins from an asteroid-sized object in our solar system. The basin measures over 1,500 km across. The image above is a false color image in order to enhance details not visible in a true color image. The yellowish object dominating the image is obviously the impact crater of the Caloris basin, but the orange spots above denote volcanic activity on Mercury, which is new evidence provided by Messenger that the smooth plains of Mercury are actually lava flows.

I had previously written about Mercury and NASA’s Messenger mission here and here.

I have posted previously about the planet Mercury, so I was excited to learn that the robotic Mercury research spacecraft Messenger had sent back it’s first image of the planet, the first since Mariner 10 visited Mercury 30 years ago. Messenger stands for the MErcury Surface, Space ENvironment, GEochemsitry, and Ranging mission. The image above was was taken on January 11 as Messenger approached Mercury (at just over 1 million miles from the planet). Scheduled for Monday is a pass at about 125 miles over Mercury’s surface. The plan is for Messenger to make two more close passes (in October 2008 and September 2009) before settling into orbit in March of 2011 and initiating its mission of mapping the surface of Mercury in detail. And in color.

Mercury is the fastest planet in our solar system, and the maneuvering that Messenger will have to do (see graphic below from the Messenger website) to comfortably settle into an observational orbit is complex. It involves the three flybys mentioned to help the craft build up enough speed to match Mercury as it settles into orbit, called “Mercury Orbit Insertion,” or MOI. Messenger will also use a series of trajectory corrections and deep space maneuvers achieved by the controlled firing of its thrusters.