A blog about the space program...

Hi everyone,

With the Space Shuttle Discovery orbiting the earth, attached to the ISS and this being the last flight of the Discovery, I thought I would say a few words about the space program - a favorite subject of mine.

I will come to Discovery and the manned program anon but first let me tell you about the robot spacecraft that I maintain a sharp interest in and why.

1. Messenger - the MErcury Surface, Space Environment, GEochemistry and Ranging spacecraft. After several flybys of Earth and Venus, the John Hopkins University Advanced Physics Laboratory Messenger Spacecraft has completed three flybys of Mercury and is now poised to go into orbit around he planet on March 18th. This is a very difficult thing to do and no spacecraft has ever orbited Mercury before. It is a matter of being slow enough when you get there to get into orbit - falling in toward the sun causes you to speed up so you shed that orbital momentum using the flybys to slow you down. Now Messenger is aligned to do just that. Mercury, while relatively close to us is less known that the other terrestrial planets and there are a number of very interesting aspects to Messengers mission. I will dedicate a blog to Messenger when it enters orbit. The Messenger website is http://messenger.jhuapl.edu/
2. The Dawn Spacecraft, run by NASA's Jet Propulsion Laboratory, is an Ion Propulsion robot which will, should its mission be successful, will be the first to orbit two other objects in the solar system. Well, not quite true, the Apollo spacecraft orbited both the earth and the moon but this is orbiting two Asteroids. Vesta and Ceres - two very different objects, the former very rocky, the second very icy and among the largest of the asteroids. In fact, Ceres, is the largest and is considered to be a dwarf planet like Pluto. Ion Propulsion is really cool. The way most spacecraft work is that they use a bunch of fuel to get into just the right orbit, then coast to their destination and the use a little bit of fuel to slow down and orbit. Alternatively they just fly by and take a lot of pictures in a short time. Dawn is different. It is always using its fuel which is electrically converted to Ions (Atoms with an unequal electrical balance), these are expelled from the engines but because they are so light, the opposite reaction of the spacecraft away from them is very small. The actual thrust is equivalent to that of the weight of a piece of paper on your hand but it is constant and adds up. Ion engines are very efficient and get more out of their propellant than conventional rockets. I will write about Dawn when it arrives at Vesta in July, the site is: http://dawn.jpl.nasa.gov/
3. Next up is New Horizons, also run by John Hopkins. This one is not going to arrive at its destination until July 2015- it is on its way to Pluto and will fly by the planet in just a couple of days. I will also write about this one later but try to imagine a 12 year cruise just to get to where you are going. This is such a long journey that the spacecraft is actually shut off for most of the journey and only really operates 3 months a year. The site is: http://pluto.jhuapl.edu/

As I said, expect followup blogs on each of these but, you know, with the shuttle mission winding down it is easy to believe there is not a lot going on in space - the truth is quite different. Robots work well up there and we learn huge volumes from them.

Back at you on the Shuttle and Manned programs in a couple of days.

Paul