Monday, August 22, 2005

Escape rockets for unmanned satellites

Re: Is an EELV safe enough to launch people without "man-rating" it first?

In a May 2003 hearing (before he was head of NASA), Griffin commented “What, precisely, are the precautions that we would take to safeguard a human crew that we would deliberately omit when launching, say, a billion-dollar Mars Exploration Rover (MER) mission? The answer is, of course, ‘none’. While we appropriately value human life very highly, the investment we make in most unmanned missions is quite sufficient to capture our full attention.”

Since then, he's had a change of heart. NASA's line right now is that man-rating an EELV booster is more expensive than designing a new shuttle-derived vehicle.

I agree with the change of heart, at least. Unmanned satellites generally don't have reentry and landing systems packaged with them, as manned vehicles must. If a satellite did have a reentry and landing system, for the expensive portion of the satellite, seperately engineered to be fail-safe for other reasons, I suspect the insurance companies would be quite interested in adding escape rockets to the launcher, to recover the billion-dollar-satellite in the case that the $100-million-dollar launcher blows up or simply fails to get it into a reasonable orbit.

So escape rockets are a good example of something we would deliberately omit from the Mars Exploration Rover. Ironically, the MER does have a reentry and landing system, but one designed to work in the thin atmosphere of Mars. It would have been much different, e.g. heavier and more expensive, if it were also required to get the rover down, safely, into the mid-Atlantic after a failed booster shot.