Tuesday, August 26, 2003

Ares, Mars, Tir:

Mars' opposition tomorrow makes a good time to note a few points about Spirit and Opportunity, two NASA rovers speeding towards their January 24 and 25 landings on the red planet.

First, the names. Perhaps in a fit of outsourcing, they chose to use a Chinese contractor to pick the names? We are lucky we did not end up with something like "Golden Butterfly" or "Lucky Wheat Sheaf," but the names they picked are just as bad. IMNSHO.

A recent article in GCN talks about the fact that since memory is limited on the craft, they download different sets of commands at different times in the mission, effectively doing upgrades while en route. In my February 20 2003 blog, I mentioned the fact that each of these probes has their own IP address. NASA will be using these addresses during the November software upgrade, replacing Earth orbit departure and transfer orbit code with Mars orbit insertion code.

The article also talks a bit about the past problems with Mars Polar Lander and the Mars Climate Orbiter. The lander was supposed to land in the polar cap/skirt region and give more insight into the chemistry of water, which has been so puzzling since the Viking experiments caused such excitement. However, software analyzing the movement of the landing gear mistook vibrations for an actual landing, and shut off the retrorockets far too early, dooming the probe to an uncontrolled drop. The orbiter was lost on orbit insertion because a single line of code used English measurements rather than metric.

I posted on January 21 2003 about software development, and how it is becoming increasingly difficult to manage the present commonly used s/w development pattern for quality. It struck me that en route upgrades provide a way for extending deadlines - it's like having FedEx be able to reach Mars and deliver your paper after it was due.

Given the kind of scrutiny NASA has been under, especially today with the release of the Columbia Accident Investigation Board report, this kind of last-ditch recovery option is probably very welcome.