And a rebuttal to the previous statement (now posted on the same page):

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Everything I need to know I learned through Googling.

You hideously underestimate the complexity of the vehicles. MER is a massively complicated vehicle. Fault protection, attitude control, flash memory management, power management, running and managing the realtime OS, calculating and sequencing communications sessions. writing and checking algorithms for antenna pointing. The list goes on and on.

A mission like MRO or Cassini - they can plan ahead. They know where they will be in 2 months time and can plan, create, test and uplink spacecraft sequencing over a period of several weeks ( for Cassini, sequences were done literally years in advance)

For the rovers - they have to do that entire process almost every day. Get the downlink, check the health of the vehicle. How much power have we got, how much flash memoery is in use, how many files did we get down, what got corrupt, what has to be reset, what can we now delete. Then, what can we do tomorrow, where to we want to point the cameras, put the arm, drive the vehicle, establish autonomous driving rules and waypoints and targets. What communications are we going to have. Something has broken - how to we program a work around, what is it safe to ask the rover to do. Then you have to plan medium term. How much power have we got now - how much will we have in a week, in 3 months. Where do we need to be. How do we get from here to there. When should we stop for a full panorama. How do we manage the flash budget for it. How long do we need the heaters on. If we do this, this, and this over the weekend, what do the thermal models predict the electronics will get down to. If we cut back we'll put less heat in the system, but we'll have more battery power at the end. Test, trade, calculate, simulate, code, check, test, recode, uplink, downlink, review, check, evaluate, test, trade, calculate simulate..... it just. doesn't. stop.


MER is complex to the point where I (and I'd like to think I know more about spacecraft than Joe Public) put my hands up and say "I just don't know how they do it" - both technically, and on a day to day management basis. Personally, that they can do all that for $20m a year - it's a miracle.

Doug

I don't know if $20 million per year for these two rovers is too much or not, but on the whole it's not a lot of money. Of course at some point they will have to shut them off, because even though they have survived for much longer than originally expected, they will not last forever. Also, NASA will send another rover to Mars in a few years (as will ESA). But it's not a lot of money for every tax payer, to do peaceful science and enhance our understanding of the fascinating planet Mars. A lot more money has been spent on much more dubious projects.