Larry J said:

>Without the severe time and money constraints of the current project, I
>wonder how difficult it would be to build several copies of an improved Beagle
>lander (getting critical details like the ones you've mentioned right this time)
>and sending them on a simplified bus to Mars. The bus could carry the
>propulsion, guidance, and TT&C systems for several Beagles (4 would be a
>good number) and aim them for different landing zones on Mars. It could
>then enter orbit to serve as a communications relay. Such a mission would
>probably cost no more than the current one (perhaps less since a lot of the
>R&D for the sensors has already been accomplished) and would have a
>greater chance of success. If more than one lander succeeded, it would
>increase the return substancially.

The original idea of MESUR (forgot what it stands for) was exactly what Larry suggested. NASA Ames was managing the MESUR project but lost control of it. There has been a long standing turf war between JPL and NASA Ames over interplanetary projects. After JPL got MESUR, they allowed mass creep to get out of hand until there was only enough launch capability to send one entry vehicle. At that point they renamed the project "Mars Pathfinder" and sold it as an engineering prototype for a future MESUR project. It's a "pathfinder" for future multiprobe missions. As the project proceeded, JPL realized that Pathfinder lacked sex appeal so they threw in a little rover. The rover had almost no science capability except for this little alpha particle spectrometer. Nobody bothered to calibrate the spectrometer so the data that it did return was of limited value. Old NASA engineers fought tooth-and-nail against the little rover (they thought the concept was too Hollywood and would eat into the Pathfinder's budget). However Dan Goldin was dead set to include the rover. The Old engineers were bought off after being told that extra money would be allocated for the rover. As an engineering prototype, Mars Pathfinder was an incredible success. Also by including the little rover, the stage was set for the Mars Exploration Rover (MER) which is based upon a rover derived from the abandoned Mars Sample Return Athena rovers.

The problem with using four Beagle-2 type probes for a multiprobe mission is it would result in four simultaneous failures. The design of Beagle-2 has too many issues. It would be better to start from a clean piece of paper. I've often thought about designing a multiprobe mission. I'd used a 70 deg. sphere-cone aeroshell with a thermal protection system made out of balsa wood. The fore and aft bodies of the aeroshell would separate using a pyrotechnic device. The action of separation would deploy the single parachute. The payload would hang from a very long kevlar thread below the parachute. I'd extend a single cylindrical bag below the payload that was filled with crushable gas filled cells. Just above the payload on the kevlar thread I'd have a small solid rocket motor (basically an Estes rocket motor). The payload would have the equivalent of a policeman's radar gun looking below the vehicle (use it to ballast the crushable cylinder). When the payload was just above the surface, the radar gun would trigger the Estes rocket to kill off the vertical velocity. The gas cell filled cylinder would crush on the first impact (no bouncing and rolling around).

Gary