Mars Rover Opportunity Sets Longevity Record 61
s31523 writes "The Mars rover Opportunity has beaten the original record of six years and 116 days operating on the surface of Mars, originally set by the Viking 1 Lander. While the Spirit rover has been on the surface longer than the Opportunity by three weeks, it has been out of communication since March 22. If Spirit comes back online, it will attain the new Martian surface longevity record. This feat, right on the heels of another longevity feat (Voyager 2 and twin on the verge of entering interstellar space and still kicking) is healing some of NASA's past black eyes. It is quite remarkable given original spec of 90 days for the mission. With the passing of the solstice, warmer temperatures and more sun will likely mean the rover will continue on."
Re:Mission spec too low? (Score:5, Informative)
No one knew if there would be enough wind to wipe the dust off of the solar panels. That was the limiting factor, it was figured it could go for 90 days before its solar panels would be too dusted to power the rover.
The specs were fine, we just under estimated the wind.
At least that is what I have been told.
Re:Mission spec too low? (Score:3, Informative)
How low are the specs for these missions are set if it's been operating for 25x longer than it was designed to?
IIRC they expected dust to settle on the solar panels rendering them useless fairly quickly. That the wind clears them as effectively as it does came as a surprise at the time.
Designed for worst case [Re:Go technology go!] (Score:4, Informative)
Feats like the Mars Rovers show us that our space-engineering prowess is not only continuing to mature, but indeed getting quite robust.
I don't doubt we are getting better at building equipment that can stand the rigors of space or Mars (better alloys, better lubricants, better electronics, simple design) but this also says something about our ability (or lack thereof) to estimate the durability of the things we build. Lasting twice as long as we expect is a great thing, lasting 25x as long means they were afraid to give a real estimate.
The rovers were engineered to survive 90 sols (Martian solar days) under worst-case conditions.
Turns out that the conditions they actually experience were not as bad as worst case.
Most notably, they were designed to operate in the (solar-energy-positive conditions) of Martian summer. They were definitely not designed to survive Martian winter. The fact that they were able to survive Martian winter is a tribute to, yes, the fact that the engineers overdesigned (partly, the fact that they overdesigned to withstand worst-case summer condidtions that didn't actually occur), partly that components used actually do continue to perform despite being well outside the design envelope (nobody had ever subjected the rechangable lithium batteries to these extreme cycles, until we did it on Mars), and partly by great work on the part of the operations crew. And then, after that, it was due to the fact that Mars cooperated by cleaning our solar arrays.
Kind of like how Scotty says "It will take 8 hours to get it fixed, Captain!", to which Kirk says "You have 2 hours", and yet it still gets fixed. The engineers are likely underestimating the "average" time to cover their own butts.
No, it's not a "cover your butt"-- it's the fact that if you are given a spec of, say 900 Martian days, the review board is going to require that the engineers show test results before launch proving that they will meet that spec-- on most of the components, this means testing to three times the design life. For an environment for which a lot of the conditions are not completely known, and so you'll have to test for worst case conditions. This would balloon the cost up unreasonably.
This actually makes it *harder* to get some science done, as you are scrambling to create new tasks with the extra time you weren't expecting, never knowing when it will give up the ghost.
In some ways this is true-- it would be nice to know how long the mission was going to last, if for no other reason than to know for how long I needed to rent an apartment in Pasadena. For MER, however, the team has had no problems coming up with new things to do with the extra time.