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Mars Winds Clean Spirit's Solar Panels Again
Titoxd writes "In a blast from the past, NASA reports that Spirit's solar panels have received a much-needed cleaning courtesy of the Red Planet. The report states, 'The cleaning boosts Spirit's daily energy supply by about 30 watt-hours, to about 240 watt-hours from 210 watt-hours. The rover uses about 180 watt-hours per day for basic survival and communications, so this increase roughly doubles the amount of discretionary power for activities such as driving and using instruments.'"
Yep - there are pools at JPL and Caltech. Go Beavers!
Did you ever wake up in the morning, with a Zombie Woof behind your eyes? -- FZ
Weight = money. At $10,000 per pound, it would have been a waste of money for a vehicle designed to last only three months.
If the vehicle were designed to last five years, it might be a different story.
They decided that a windshield wiper didn't have a good benefit/cost (in both money and weight) ratio. Especially for a 90-day mission. I understand that the best they could get the wipers to do was smear the dust around (something about static cling keeping it from coming off), so it wasn't going to do much good, anyways.
Maybe next time, NASA should include some type of cleaning devices,
This comes up every time the rovers are mentioned. Here is a detailed explanation why there are no wipers, or any other cleaning device, on the rovers.
We will bankrupt ourselves in the vain search for absolute security. -- Dwight D. Eisenhower
Not 240 watts; 240 watt-hours. With 24.6 hours per Martian day, that's about 9.75 watts average consumption.
Only on Slashdot can a post that confuses power (watt) and energy (watt-hour) be modded +3 Interesting.
"The agriculture ministry is not in charge of Gundam" - Japanese ministry official.
90 days.
Which is how long they estimated it would take for the rovers' solar panels to be covered in too much dust for the rover to function. Dust is why the mission was scoped at 90 days. They didn't know that the Martian wind would be of any use whatsoever in cleaning off the panels.
Yet even though dust is what was limiting the scope of the mission, NASA still decided not to put on a brush, wiper, or (sorry but lol) air compressor. Given there's enough obvious tradeoffs in mass/space/power use for anything you add, I'll give NASA the benefit of the doubt and assume they actually calculated the tradeoffs and said "not worth it".
The enemies of Democracy are
The Mars Science Lander is two years late and a billion dollars over budget because it has developed lots of new technology. It was supposed to launch during the 2009 optimal planetary configuration, but will have to wait until the 2011 one. The next lander uses a nuclear source and rocket landing instead of airbags. I'm a little fearful all the new stuff may not work as planned. I am also fearful NASA budgetary troubles may still kill it.