Permanent Human Settlement of the Earth, Space and Ocean Frontiers

Wednesday, January 04, 2006

Very Fast - Very Light - Very Far

In less than two weeks, the launch window will open for the United States Pluto Probe, called New Horizons. The relatively small, piano sized space craft, weighing only about half a ton will streak away from the earth at an amazing 8 miles per second (about 28,800 miles per hour). When the Apollo astronauts left earth, it took them four days to reach the orbit of the moon. New Horizons will reach the limit of the moon’s orbit in only eight hours, traveling an average of 100 times faster than a commercial airliner.

How does it achieve this speed? By strapping a small mass to a large and powerful set of rocket engines: The spacecraft is bolted to a STAR 48B solid propellant third stage and that is bolted to a powerful Centaur second stage and all that is lifted into orbit by the new Atlas V. In other words, it is the lowest payload mass to the largest thrust power ever launched.

The reason for all that power is simple: the Pluto system is a very long way away: about 4 light hours, to be exact. That adds up to somewhere about 3 billion miles at the time of rendezvous. That is a well over three times the distance from earth than the orbit of Saturn. If we want to hear the results of the mission in our lifetimes, it has to be fast.

The nuclear powered spacecraft should arrive at the Pluto system on or about 2015 after picking up a gravitational boost from relatively nearby Jupiter in 2007.

The Pluto system has become more interesting in just the past year. Astronomers have discovered two more small moons(yet unnamed) in orbit around the cold and distant body in addition to the larger companion Charon. And there is also some indication that the icy world - whose surface temperatures may hover 10-20 or so degrees above absolute zero - may also have a set of rings.


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