[X] My Assistant

[Phil Stooke]

I like asking questions, and where better than a place like this?

So here's one... Mars Climate Orbiter burned up during a too-low pass through the atmosphere. So where would its debris have fallen?

This ought to be a fairly straightforward question to answer. We presumably know, or can find, the details of its trajectory as it approached Mars. We know the orientation of Mars at the time. The location of periapsis in Mars coordinates ought to be easy to find. This might be buried in a technical report somewhere, or it might be possible to figure it out with one of the solar system simulator type programs. Can anybody help answer this?

(if so, we can extend it to Pioneer Venus and Magellan later in a separate thread)

Phil

[edstrick]

One possible at least partial solution to the entry problem would be to include a relatively small limb scanning radiometer/spectrometer on the cruise stage for an entry mission, and to have somewhat more capability than current entry vehicles to adjust lift/drag during entry.

A dedicated single-purpose limb scanning instrument operating up to maybe 5 minutes before entry interface should be able to profile temperature structure, solve for the density profile automatically, and generate commands to vary entry-vehicle orientation (like Apollo) to optimize lift/drag. It's nice to be able to jettison a cruise stage well before entry, but there's no essential reason it can't be done later, nearly at the last minute.

If you KNOW the entry profile before hitting the atmosphere, you can probably go in at a shallower angle as well, giving more entry margin. That increases the along-track landing ellipse length, but if you know the entry profile and can steer the entry, you counter that effect and can probably reduce the landing ellipse length below an unguided entry.

We don't right now, but will eventually want to land packages at higher altitudes than we have on Mars. Certainly we'll want to deploy geophysical payloads (seisometers, magnetometers, meteorology) well up on the Tharsis bulge, and landers limited to a kilometer or two altitude don't hack it.