Based on my research, which include image composites of two flyby views of Mercury from the MESSENGER spacecraft, I conclude that Mercury has not cooled and shrunken as much as previously thought.
On February 20, 1962, John Glenn, one of the original seven Mercury astronauts, became the first American to orbit the Earth. His service to his country did not begin or end there, however. A U.S. Marine Corps fighter pilot, Glenn was decorated veteran of two wars, a U.S. Senator for Ohio, and an astronaut again when he traveled into space for the second time in 1998. He was also a great friend of the National Air and Space Museum.
At their core, planetary missions are about exploration, pure and simple. It’s hard to beat the excitement of discovering a new feature on the surface of a planet that’s being imaged by spacecraft for the first time. I had this experience many times during the MESSENGER mission.
Being a member of a science team of a planetary mission is like being a starter on a major league baseball team—you’re in the game. That’s how I felt as a member of the MESSENGER mission to Mercury. During the final months of MESSENGER’s time in orbit, before the fuel on the spacecraft was expended and crashed on Mercury’s surface, a decision had to be made—keep the spacecraft in its nominal mapping orbit as long as possible or let the spacecraft altitude drift lower to get as close to the planet as possible.
Today at 8:45 pm EDT (March 18, 2011, 12:45 am UTC), MESSENGER will become the first spacecraft ever to enter Mercury's orbit. With MESSENGER on the last leg of its journey, I’m reminded how long it has taken to get there. I watched the spacecraft launch in the early morning hours of August 3, 2004, almost six and a half years ago. Now after one flyby of Earth, two flybys of Venus, and three flybys of Mercury, the spacecraft will catch up with Mercury again, but this time it will be captured by the planet. You might think as one of our closest neighbors in the Solar System it would take a lot less time to get into Mercury orbit – but because Mercury is the closest planet to the Sun, at a distance where the influence of the Sun’s gravity is much greater, it is a challenge to reach and orbit.
In addition to the “Apollo 11 Codices”, the National Air and Space Museum holds approximately 150 works by the artist Mitchell Jamieson (1915 – 1976). The “Apollo 11 Codices” exemplify Jamieson’s journalistic style of painting, which was one reason NASA brought him into its Fine Art Program. Aboard the U.S.S. Hornet, Jamieson sketched the seamen working to recover the capsule and crew from the successful Apollo 11 mission. Jamieson was known for his depictions of the onlookers at major events rather than the events themselves. This style allows the viewer to believe that they are there as part of the crowd, feeling the energy and excitement. Three of Jamieson’s works are traveling as part of the exhibition “NASA Art: Fifty Years of Exploration” organized by the Smithsonian Institution Traveling Exhibition Service (SITES) in cooperation with NASA and the National Air and Space Museum.