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Mars Rover Spirit Reaches Winter Tilt
An anonymous reader writes "The Mars rover Spirit has been inching carefully down the north slope of the feature 'Home Plate' to tilt its solar panels into the sun to survive the long Martian winter. On Friday, it reached a tilt of 29.9 degrees, probably the final tilt it will reach for the winter. Although it's used the tilt strategy to increase power over the Martian winter twice before, this year it's especially critical, since a global dust storm last summer has left the solar-powered rover covered with dust and starved for power. Geoffrey Landis, one of the MER scientists, commemorated Spirit's trek to the winter haven with a sonnet on his blog. (The second of the two rovers, Opportunity, is at a landing site that's not as far into the southern hemisphere, and hence has less need to find a tilted surface.) OSU has a website explaining some of the software used to visualize the terrain to optimize the tilt, and for the latest news, the ongoing log of the rover status is updated weekly."
I have some karma to burn, and I feel there is not a better piece to do it on.
Great job rover team.
The two rovers are a constant motivator for all engineers on how a project can still be done right in this world, and how much affect that can have. Nowadays it's depressing when you hear about all the flaws in products people actually sell, and how returning broken shit out of the box is the norm. In business we get delayed projects and stupid alterations at whims sometimes.
But the rovers were done right, and were done for science. And they're still chugging well past their expiration date. I regret I wasn't alive for the moon landings, but in my humble opinion, i sometimes feel as if this was the greater achievement of the two. Especially that they're still going.
Good job. And keep it up.
You never realize how much manually made unmanaged "linked" lists suck, till you have src.link.link.link.link...
Bag-less rover with duel cyclone technology.
Sponsored by Dyson.
A quick Google isn't turning up anything authoritative, but from memory:
For the original 90 day mission length, running out of juice due to dusty panels would not have been a concern. It would have just been another thing to break and would have added to the mass of the rover, quite possibly costing valuable capacity for other scientific tools.
[insert rant about how some of that war budget could do wonders for NASA]
- More Moving Parts
- Weight
- Dust too fine to be brushed off easilly
- Chance to actually reduce power generation on failure by blocking the solar panels
- Needs power itself
And all this aside from the fact that asking someone to make a solar panel wiper for Mars is going to be an enormously expensive and involved operation. Windspeeds, airpressure, particle count, gravity, temperature all play a part in this. And anyone using windshield wipers on their car knows how unreliable they are to begin with.
Coz eternity my friend, is a long *ing time.
I doubt it. RTGs don't normally need devices to clean the dust off of them.
Suddenly, the hairy finger of a familiar monkey tapped me on the shoulder. It was time.--G. T.
Dear mods - Please learn the difference between "I do not agree, you have offended my delicate sensitivities", from "Troll" and "Flamebait".
Though confusingly similar to the untrained eye, people can legitimately disagree with your personal worldview without trolling.
Although metamoderation almost always vindicates me, and I couldn't care less about my karma ("excellent", BTW) I do find it somewhat discouraging that zealots (whether religious, political, or Apple) manage to silence any discussion on topics they don't like by modding to below the default visible threshold.
If you disagree with me, say so. You might even convince me of the error of my ways. Modding me down just reinforces the view that those who silently disagree with me really have no rational arguments worth hearing.
With that said, let me note that dust removal is probably a bit harder than you realize. The optical data showed that suspended dust is extremely fine-- the cross-section weighted average particle radius is about 2.5 microns, so these particles are about the size of the particles in tobacco smoke. Particles this fine are predicted to adhere extremely well, by van der Waals and electrostatic forces. Picture trying to use your windshield wipers to clean the dust off your windshield, without using the wiper fluid. (and wiper fluid is tricky on Mars, too; you need it to stay liquid for long enough to run the wiper, and neither evaporate or freeze before it hits the panel). And blowing dust off is very tricky-- the atmospheric pressure is less than 1% that of Earth's. We could carry fluid, or compressed gas, but those would be consumables-- and if we had designed the mission and budgeted consumables for a 90 sol lifetime, we'd have run out of them years ago anyway, so we'd be in the same position we're in now anyway.
A feather duster might work, but feathers almost certainly violate the planetary protection policy :)
http://www.geoffreylandis.com
What are the triboelectric properties of ostrich feathers? If rubbing an ostrich feather across a solar panel charges up the panel electrostatically (and think of rubbing something on Mars like petting your cat in the middle of a very cold winter, except Mars is really really dry) you are in deep trouble. (obSF: "Dust Rag," Hal Clement).
How do you sterilize an ostrich feather to get it past the planetary protection protocol?
What is your failure-mitigation mechanism for the case the mechanism jams when the feather is halfway across the solar panel? (keep in mind that shadowing just one solar cell in a string will take the entire string off line.)
driven by a magnetic actuatorThe dust on Mars is preferentially attracted to magnets.
Mars is very cold, and very dry, and very dusty. What are you proposing to use to lubricate this mechanism? How are you keeping it from jamming? What's your plan to ensure that the acoustic environment inside the launch shroud doesn't vibrate it until the shaft bends? (That long ostrich feather looks like a cantelever that's going to resonate like heck. Tie downs? OK, another few moving parts; more failure modes, more wires connecting to D/A lines connecting to the computer.)
that is automatically pulled clear of the panels by gravity. That's one moving part, gravity doing half your work for you,I don't even know what you mean here. There's no free lunch, even on Mars; if you have weights and pulleys moving it one way, you need exactly that much more energy to move it the other way.
and since it doesn't rain on Mars there would be a chance of breaking within the first ten years of continuous use of close to zero.Failure analysis is a difficult task, and it's the failure modes that you don't think of that kill you. I'm hard-pressed to think of mechanical devices that work reliably for ten years with no servicing in severe environments on Earth, and you're proposing close to zero chance of breaking on Mars. My car's windshield wipers get a little unreliable at merely 0F; I don't think I'd like to claim "no chance of failure" at, say, -50.
....although it may seem like it, my point here is not merely to poke holes at superficial solutions (to be fair, you did say "off the top of my head."). The point is that space is not like Earth, and there really are reasons that it is harder to do things in space than it is on Earth. Something like you propose probably could be made to work, but your offhand thought that oh, it would be simple and cheap and reliable is just offbase.
http://www.geoffreylandis.com