Saturday, May 24, 2008

Looking for water on Mars

Tomorrow, if all goes well, NASA's Phoenix Mars Lander will touch down on Mars, after a 422 million mile voyage that began last August 4,

Here are a few paragraphs from the New York Times:
Barry Goldstein, Phoenix project manager from NASA's Jet Propulsion Laboratory in Pasadena, Calif., said that for him the most hair-raising part of the journey will begin about 14 minutes before touchdown, when the spacecraft reaches the beginnings of the thin Mars atmosphere, jettisons the cruise stage that has nurtured it since leaving Earth and experiences three minutes of radio silence as it turns its heat shield toward Mars.

Then, with seven minutes remaining, Phoenix is to plunge into the atmosphere at 12,750 miles an hour, where friction will slow it, heating the shield to 2,600 degrees Fahrenheit. At 8 miles in altitude and 1,000 miles an hour, the spacecraft will deploy its parachute for the next three minutes of descent, when it is to jettison the heat shield, extend its three landing legs and begin using its radar to gather readings on its speed and distance from the surface.

At six-tenths of a mile above the surface and 125 miles an hour, Phoenix is to separate from its parachute and the back shell that holds it and begin the sequential firing of 12 rocket thrusters that slow it to landing at 5 1/2 miles an hour 40 seconds later.
That the landing can be anticipated with such detail, at such a remove, is simply breathtaking.

Make no mistake, the flight of the Phoenix rests on several bedrock philosophical principles of science:

1. The universe is ruled by natural laws that can be at least partially comprehended by the human mind.

2. The laws are best discovered by the application of Ockham's razor: Do not needlessly multiply hypotheses.

3. Miracles do not occur

4. Teleological causality is a bust.

There is no a priori proof of these principles. But if Phoenix touches down as scheduled, it will be one more stunning reason to have confidence in the naturalist paradigm.