Michael Meyer, about Phoenix and MSL Options

[Cugel]

http://www.marsdaily.com/reports/Managing_...ssions_999.html

Michael Meyer, lead scientist for NASA's Mars Exploration Program, spoke at the recent Viking anniversary celebration. One remarkable quote:

"Considering how long the Spirit and Opportunity rovers have lasted beyond their design lifetimes, it almost boggles the mind to think how long MSL could last. It may be there to greet the astronauts when they arrive on Mars."

That's what I call optimism.
I always thought that the lifespan of an RTG was pretty predictable and that in case of MSL it lasted for about 2 earth years. Maybe he's talking about the solar array powered version?

[Guest_Analyst_*]

I always thought that the lifespan of an RTG was pretty predictable and that in case of MSL it lasted for about 2 earth years. Maybe he's talking about the solar array powered version?

The funny thing about RTGs is there predictable power reduction. They don't die instantly like an empty battery (after i.e. two years). The output decreases very gracefully. The Voyager RTGs are generating today more than half of their output at launch in 1977.

So if MSL uses a RTG (I can't imagine it using solar panels and I can't imagine this decision hasn't been taken already.) and if it behaves like the Voyager RTGs and if all the other rover subsystems keep working and if the rover can work with 50 percent power (like MER) it can still be arround after 30 years.

A lot of if's. But also a beancounters nightmare. Imagine the 15th mission extension.

Analyst

[helvick]

... if it behaves like the Voyager RTGs and if all the other rover subsystems keep working and if the rover can work with 50 percent power (like MER) it can still be arround after 30 years.

That might be the case for the RTG's itself but I'm certain that the RTG will be used to charge up a battery sub-system that will act as a buffer for power demands of the rover's main sub systems. It's less likely that the battery\power mangement sub system will be good for 30 years.

On the issue of solar vs RTG - I assume that this is being kept vague simply to avoid attracting the ire of the anti nuke crowd. I can't see how a solar panel solution would be sufficient given the power requirements and mission duration. The MER's survival for 2+ years through good luck does not change the fact that MSL's power requirements would require _huge_ panels (>8m^2) in order to ensure that it could survive the full blown Martian dust storms that it's mission duration absolutely requires that it needs to be able to survive.