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Mars Rover Spirit Reaches Winter Tilt

kdawson posted more than 6 years ago | from the playing-pinball-on-the-fourth-planet dept.

Mars 88

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."

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Stupid but obvious (3, Funny)

Goalie_Ca (584234) | more than 6 years ago | (#22556334)

If dust is a problem why don't they attach a brush to it or something.

Re:Stupid but obvious (3, Funny)

Eddi3 (1046882) | more than 6 years ago | (#22556348)

Yeah, because they can do that from 36-250 million miles away.

Re:Stupid but obvious (3, Funny)

Anonymous Coward | more than 6 years ago | (#22556378)

They could carry it with a swallow.

Re:Stupid but obvious (2, Funny)

RuBLed (995686) | more than 6 years ago | (#22556418)

Wait a minute! Supposing two swallows carried it together?

Re:Stupid but obvious (2, Funny)

Celeritas (33191) | more than 6 years ago | (#22556740)

Are those African or European Swallows?

Re:Stupid but obvious (3, Insightful)

Kinthelt (96845) | more than 6 years ago | (#22557494)

I don't know. AAAAAAAaaaaaaaaaaaa.........

Re:Stupid but obvious (1)

A nonymous Coward (7548) | more than 6 years ago | (#22559982)

He's on third.

Re:Stupid but obvious (3, Funny)

Dance_Dance_Karnov (793804) | more than 6 years ago | (#22556394)

I've always wondered why they didn't build them with a brush or something to clean the panels off with. Seems like a pretty obvious thing that someone should have brought up in the design stages.

Re:Stupid but obvious (5, Insightful)

jasonwea (598696) | more than 6 years ago | (#22556438)

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]

Re:Stupid but obvious (2, Insightful)

Dance_Dance_Karnov (793804) | more than 6 years ago | (#22556444)

I suppose. but I bet the next rover gets a dust clearing device of some kind.

Re:Stupid but obvious (2, Informative)

jasonwea (598696) | more than 6 years ago | (#22556528)

I think that would be a safe bet considering how long these 2 have lasted.

They have already been working on a few ideas [nasa.gov] in the labs.

Re:Stupid but obvious (0)

ForestGrump (644805) | more than 6 years ago | (#22556532)

Yep, the next rover is going to have a dust cleaning device - astronauts.

You see, the problem with astronauts is that spending extended periods of time in space exposes their bodies to high levels of radiation. According to OSHA guidelines, an astronaut is not to remain in space for more than 18 months per 4 year period.

Because a round trip to mars takes 21 months, the next rover will not be deployed with any dust cleaning device.

Question answered?

Re:Stupid but obvious (3, Insightful)

pla (258480) | more than 6 years ago | (#22556682)

According to OSHA guidelines, an astronaut is not to remain in space for more than 18 months per 4 year period. [...] Because a round trip to mars takes 21 months, the next rover will not be deployed with any dust cleaning device.

No, it means no rovers will have an American dust cleaning device.

And as happens more and more, the rest of the world will laugh at us as we legislate ourselves into a third-world mediocrity.


As an aside - OSHA actually has guidelines for one of the rarest of human professions in all history, but they can't keep coal miners safe? Whiskey Tango Foxtrot?

Re:Stupid but obvious (2, Informative)

sumdumass (711423) | more than 6 years ago | (#22556718)

I agree with about everything you said but the part about OSHA and coal miners. OSHA does cover coal miners. That would be MSHA, a separate ordeal all together specifically designated for the mining industry.

"I disagree" != "Troll" (5, Insightful)

pla (258480) | more than 6 years ago | (#22557106)

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.

I disagree... (1)

spun (1352) | more than 6 years ago | (#22558958)

People should just mod down anything they don't agree with, especially if it challenges their world view. Rationality is overblown, my gut tells me I'm right.

If I had any mod points, I'd mod you down right now.

Re:"I disagree" != "Troll" (0)

Anonymous Coward | more than 6 years ago | (#22561392)

Yeah, I disagree with you. You're being melodramatic and sensational when you equate a never-tested 18mo limit on astronaut flight with legislating ourselves into third-world mediocrity. (Or you're a loon, but I'll give you the benefit of the doubt). Certainly no third-world countries can think of putting someone in space for even 18 months, it would take anyone in the world 10+ years to put a man on Mars from a cold start even if they really wanted to, and I sincerely doubt that OSHA regulations would be a serious obstacle. It's not really a troll, but it's also neither insightful nor informative, and it probably fits into the "America-bashing" subset of karma-whoring. It could be flamebait.

Re:Stupid but obvious (0)

Anonymous Coward | more than 6 years ago | (#22561402)

The next US rover will be nuclear powered. It won't need to worry about dust.

OSHA guidelines don't do squat if you don't obey them. And sometimes blind luck bites you too. For further specious criticisms of the same nature see: traffic laws, medical malpractice, and Stryker armored personel carrier. Nothing is perfect. Get used to it.

Re:Stupid but obvious (1)

haakondahl (893488) | more than 6 years ago | (#22562906)

Guess what--OSHA (or *SHA) "actually has guidelines" for mining as well. Guidelines don't keep anybody safe. Enforcement does. "Hold it right there, Buddy, or I'll call 911" is a guideline. "Freeze." (click) is enforcement.

And I probably disagree with you about many things, but I agree whole-heartedly with your point about childish mods. Conversation with people you always agree with is called *smalltalk*.

Re:Stupid but obvious (4, Informative)

Aglassis (10161) | more than 6 years ago | (#22556600)

I doubt it [wikipedia.org] . RTGs don't normally need devices to clean the dust off of them.

Re:Stupid but obvious (1)

Mr2cents (323101) | more than 6 years ago | (#22558280)

Unless, of course, they need to dissipate so much energy that they need radiators. If those radiators get covered with dust, then heat transfer could become more difficult. But I'm guessing that it won't be a problem with MSL.

Re:Stupid but obvious (2, Informative)

Convector (897502) | more than 6 years ago | (#22560696)

As I understand it the Mars Science Laboratory (MSL) is going to have a Radioisotope thermoelectric generator (RTG), so there won't be any solar panels to get dusty. It will need the extra power to move around as the bloody thing is the size of a mini-cooper, and could RUN OVER the MERs. It also has a high-powered laser to vaporize bits rock in order to do spectroscopy on it. Sounds scary to me; I'm glad I'm not a native Martian.

Re:Stupid but obvious (1)

pdboddy (620164) | more than 6 years ago | (#22563068)

Hate to say it, but you're not a non-native Martian either. :D

Re:Stupid but obvious (1)

Cheeko (165493) | more than 6 years ago | (#22563564)

Doesn't the next rover use an RTG?

No need for solar panels.

Re:Stupid but obvious (2, Informative)

warrigal (780670) | more than 6 years ago | (#22556478)

Part of the reason is probably that the rovers weren't supposed to last long enough to need cleaning.

Obviously, they were over-engineered because the environment on Mars was not known very well at design time.

If it had been known very well there would have been no point in sending them.

What I want to know is why the dust can't be shaken loose by rocking either the solar panel or the whole rover.

Re:Stupid but obvious (2, Insightful)

sveard (1076275) | more than 6 years ago | (#22557536)

Have you ever tried shaking dust off of something on earth? I think static electricity keeps it on there or something.

Re:Stupid but obvious (1)

onlau (1164843) | more than 6 years ago | (#22557070)

Travelers should always bring their towel...

Re:Stupid but obvious (1, Funny)

Anonymous Coward | more than 6 years ago | (#22558366)

Towelie says, "Do you wanna get high?"

Dust removal, hard but possible (5, Informative)

Geoffrey.landis (926948) | more than 6 years ago | (#22557848)

We actually had built a dust experiment to test out some methods of removing dust. It had been scheduled to fly on the Mars-2001 Surveyor Lander, but the 2001 lander mission was cancelled after the failure of the 1999 Polar Lander (which used the same basic spacecraft design). In fact, we talked about dust removal technology for the MER, but it simply turned out that the most reliable solution was to increase the size of the panels so that they would still be at nominal power after 90 days worth of calculated dust accumulation. (My Pathfinder data showed about a quarter of a percent loss of power due to dust per (Martian) day, for what it's worth, but the longer term data looked hint that it was leveling out with time). There's just a lot of reliability in the no-moving-parts solution, and as a bonus, it gave the rover quite a bit of power margin at landing (and, in fact, after landing too-- the dust-related power loss in fact does tail off.)

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 :)

Re:Dust removal, hard but possible (1)

greedyturtle (968401) | more than 6 years ago | (#22558152)

Good job with those rovers by the way. :)

Re:Dust removal, hard but possible (1)

VultureMN (116540) | more than 6 years ago | (#22562408)

Very much agreed. :) Many kudos. I still check the rover website everyday; I just wish it was updated more often.

Anyway, one quick question for the GP; is the dust just less 'sticky' than you expected? If the Martian wind can clean off the panels (and, IIRC, it was a huge difference in the level of dust on the panels, literally overnight), do you think it would have been possible for, say, a small fan to have had the same effect ? I'm not saying you should have thought of that to begin with, just asking if it could work.

Re:Dust removal, hard but possible (1)

Dance_Dance_Karnov (793804) | more than 6 years ago | (#22558294)

thanks. that satisfies my curiosity :) what about using a transparent version of those electromagnetic thingies mentioned(to lazy to look up link, sorry)?

Re:Dust removal, hard but possible (2, Interesting)

jbeaupre (752124) | more than 6 years ago | (#22559070)

Out of curiosity, did anyone look at piezo electric or electrostatic methods? How did they fare?

For piezos, I'm thinking of the "dog shake" method. A little buzz from time to time to loosen the dust. If the panels are tilted, some of the dust might flow off. Clean the panels? Unlikely. But maybe keep the dust from exceeding some limit.

For electrostatic, someone might be clever enough to figure out how to do it with no moving parts. But all I can think of is to charge a small ribbon or wire and pass it over the panels without touching them. Hoover up some dust with static electricity. Then move the wire over the side, turn off, and let the dust drop. If the effect is strong enough, maybe the wire could always sit over the side. All assuming the high voltages don't cause more trouble than they are worth.

I wouldn't be surprised if both were looked and dumped, but just curious how they stacked up.

Re:Dust removal, hard but possible (4, Informative)

Geoffrey.landis (926948) | more than 6 years ago | (#22559688)

Out of curiosity, did anyone look at piezo electric or electrostatic methods? How did they fare?

Yeah, both of these were looked at. We thought about miniature piezo vibrators on the cells, but didn't actually get to the point of doing any tests under Mars conditions. We did a bit of work with electrostatics-- in fact, the mitigation technique I like best right now uses a DC glow discharge ("Paschen discharge") which is pretty easy to start at Mars pressure, very near the Paschen curve minimum.

Re:Dust removal, hard but possible (1)

gstoddart (321705) | more than 6 years ago | (#22559692)

I love Slashdot. This is one of the few places where someone who was actually there can chime in and give an actual answer to all of our speculations. =)

And, allow me to reiterate the sentiment -- kudos to the entire rover team. Coolest things in a long time.

Cheers

Re:Dust removal, hard but possible (1)

Rene S. Hollan (1943) | more than 6 years ago | (#22562570)

Er, what about an electrostatic solution: charge the damn panels and use electrostatic repulsion to drive the dust off?

I can see a problem if the charge also attracts charged particles, but I should think that could be mitigated,

Re:Stupid but obvious (5, Insightful)

splutty (43475) | more than 6 years ago | (#22556460)

- 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.

Re:Stupid but obvious (3, Insightful)

EdIII (1114411) | more than 6 years ago | (#22556752)

You could weigh the costs versus the benefits. I agree with other posters, that we just did not know how long they would last and that dust would be a problem at all. So taking resources to design around a problem that did not even factor in to the mission was unlikely, and wasteful at the time.

That being said, I think you are overstating the complexity and cost a little bit. Now that we do know it would be valuable and extend the lifetime of the mission, it would be trivial to add a kind of "dustbuster" if you will.

- More Moving Parts
This will be true no matter what we are talking about doing with the rover, with the exception of its electronics and sensors. It is essentially a robot, and must have moving parts to achieve locomotion and carry out missions with its arms. So what you are saying is obvious. The question is if the value it adds to the mission justifies it costs.

- Weight
Once again, this is a consideration with every aspect of the mission, from getting it there, to the energy expended while on the surface. The question should once again be if the value it adds to the mission justifies the costs.

- Dust to fine to be brushed off easily
Does it need to be brushed in the first place? I know the poster asked specifically about a brush, but they also asked about "something". It need not be a windshield wiper, but could simply blow whatever atmosphere there is against the panels like an air canister. Since the canister and pumping apparatus could provide variable amounts of pressure, it could be configured to blow the air just enough to start getting rid of the dust without doing significant damage to the solar panels, or at least no more significantly than the dust already did when landing on the solar panel itself.

- Chance to actually reduce power generation on failure by blocking the solar panels
Now this applies only if it was really designed like a brush (a large tool), and even less if it was a windshield wiper (very small tool). If it was a robotic arm with a "wand" it could be designed to only block a very small portion of the panels during use. Even windshield wipers block a very small percentage of any windshield if they are stopped in the middle of a sweep.

Heck, you could ditch the wand entirely, and just implant into the surface a bunch of raised nozzles like the ones we have on cars now that spray the windshield wiper fluid. A simple omni-directional nozzle could spray out the air onto the solar panel, and would not block the solar panel under any conditions.

- Needs power itself
Well thats kind of redundant and unnecessary as a comment, no offense. EVERY device on these Rovers is going to require power, either what it brings from Earth, or what it can generate on Mars. Not a reason to dismiss anything out of hand. Once again, if it is justified by the value it adds to mission, its energy costs are then factored in and must be worth it.

As for the power requirements, is it feasible to just reserve a small percentage of the incoming power to keep the air canisters pressurized at all times? I realize that it must use some of the same power it is attempting to protect, but air canisters can remain pressurized for extended periods of time. The amount of power that would be necessary to run pumps to "top off" the air canister should be minimal when spread over such a large duration of time.

There was also a recent post about a type of nanotech windshield that was wiper less and only required a power source. If the power required was low enough, it could be powered directly from the solar panels themselves. There would only be reduction in the amount of power delivered to the main systems. Another possibility, and one that is certainly solid state and required no moving parts, and may only add a small percentage of weight to the panels overall.

The entire endeavor is an "enormously expensive and involved operation". Now that we know this is important we probably should spend the time and money to develop systems to mitigate the problems of dust on the solar panels. I don't mind saying that I am probably a moron compared to some of the engineers that work at NASA and JPL, and even I could come up with a few ideas that mitigate some of your obvious concerns rather quickly.

So just maybe it is not as hard or complex a problem as you state. Just my 2 cents.

P.S - I have yet to receive a bid on eBay for my 2 cents yet, so that value is speculative at best.........

Re:Stupid but obvious (1)

splutty (43475) | more than 6 years ago | (#22556886)

So just maybe it is not as hard or complex a problem as you state. Just my 2 cents.

Thanks for your post :) I pretty much agree on your points, and I wasn't trying to make a statement it would be too hard. I only tried to list a couple of things that could/should be taken into account with these sort of things.

In the original mission briefing the reduced power output of the solar panels due to dust buildup were actually mentioned, but it wasn't actually considered a serious problem, since it would only start to really influence the mission after roughly 8 to 9 months.

There was also a recent post about a type of nanotech windshield that was wiper less and only required a power source.

I read that as well, and I agree that this would, if plausible, be a perfect solution (I love my commas).

As for the power requirements, is it feasible to just reserve a small percentage of the incoming power to keep the air canisters pressurized at all times? I realize that it must use some of the same power it is attempting to protect, but air canisters can remain pressurized for extended periods of time. The amount of power that would be necessary to run pumps to "top off" the air canister should be minimal when spread over such a large duration of time.

This sounds very logical, but I think you're forgetting one rather important thing: The air density on Mars is insanely low in comparison to earth, so actually getting these canisters pressurized is either going to take proportionately more power or time (or both). Taking pressurized air containers (generally quite heavy in comparison to their effective payload) then seems the only solution, which I can imagine to be prohibitively expensive/heavy/etc.

All in all, though, the engineers have learned a ton from building and deploying these 2 bots, and I'm sure a next generation Mars robots will be hugely different, and will incorporate a lot of ideas and realizations that came out of these.

Go Buggies :)

Re:Stupid but obvious (1)

Speare (84249) | more than 6 years ago | (#22560334)

Windshield wiper: may scratch panels, causing catastrophic or severe power-gathering capabilities. It's the $2 option on a Terran car, but only because the constraints are well-known and not mission-critical.

Transparent rolling film: works for NASCAR cameras, but film may tear or get caught in winding mechanism. Still needs squeegie (weight) or electrostatic squeegie (power drain) or mission-length supply of film (weight, estimation error). Material science: transparent film is likely plastics-based, which may not deal with low-temperature/low-pressure environment well.

Electrostatic glass: attracts dust, doesn't eject dust.

Broom: see wiper, except it's even heavier.

Compressed air: the weight of the canister or pressurizing apparatus is a problem; it's a power drain to actuate (low) or compress more air (high); no guarantee that compressed air would actually clear the surface reliably until we had solid science on the behavior of the dust and seasonal weather. Moving air may cause electrostatic effects (see above). Any nozzle must be dust-proof for all possible sizes and shapes of dust particles.

Every single motor on the unit is a potential power drain whether in-use or not. Every single feature of the unit must be able to fold out from its launch-to-landing composition without endangering any other feature. Every actuator circuit takes time to develop and debug beyond a shadow of doubt: sucks when YOUR division by zero breaks a million dollar device. All components must deal with wide temperature swings that include conditions significantly colder and lower air-pressure than Terran ranges, where things get brittle. Anything soft like plastic or rubber will gas-out.

Re:Stupid but obvious (1)

Mr. Jaggers (167308) | more than 6 years ago | (#22561278)

Transparent rolling film: works for NASCAR cameras, but film may tear or get caught in winding mechanism. ...


Not to mention that a failure mode where it's fully deployed over the panel and then sticks. I'm not sure what sort of power generation can be expected with a thin translucent plastic film covering the panels.

Re:Stupid but obvious (1)

sumdumass (711423) | more than 6 years ago | (#22556808)

A simple compressor/Co2 cartridges with tubes blowing onto the panels in different places could remove quite a bit of the dust without fancy arms and brushes. They have compressed air devices that you attach to mirrors that clean them pretty well. They are usually used with large truck which already have a supply of compressed air.

It doesn't need to be complexes. Just something that could effective provide enough wind to blow the dust and dirt off. I don't think they has to worry about moisture. Co2 tanks or a simple compressor attached to one of the wheel motors would work. Maybe an electric clutch so it wouldn't have to turn the compressor all the time.

Re:Stupid but obvious (1)

cnettel (836611) | more than 6 years ago | (#22557298)

Considering that the wheel motors are a power hog (relatively speaking) , the clutch would absolutely be needed. I'm far from convinced that the compressed air method would be any safer, simpler or more efficient than a brush. It's quite possible that the choice not to have a cleaning device was wise, even consdiering the current lifetime.

Re:Stupid but obvious (1)

sumdumass (711423) | more than 6 years ago | (#22557718)

I have been thinking about this since I made that post. I'm sort of wondering, seeing how they extended the solar panels in the first place, why couldn't we just make it reversible where contracting them back basically cleaned them. Might be even simpler then a compressor. Another small change could be instead of them coming back in the same way they went out, we might be able to lift them and clean the top portion too.

Of course this would assume the panels would open up like a fan instead of unfolding like opening an envelope.

I also have thought about the flexible solar cells making their way around. What if they were simple connected like a belt and just pulled from one side to the other like a ribbon in a typewriter. Use a couple pieces of felt or something on the ends and it would get a brushing coming of the panel and going back on it. I don't know. I can think of a few low tech things that might or might not work depending on the specific environment. It is an interesting brain teaser.

Re:Stupid but obvious (1)

afidel (530433) | more than 6 years ago | (#22557812)

The dust is electrostatically charged to the panels so it requires more force then the force of gravity on Mars to remove it.

Re:Stupid but obvious (3, Interesting)

sumdumass (711423) | more than 6 years ago | (#22558046)

Yea, that's why I was thinking of felt or some stationary wiper. And yea, the panels would have slide out beside each other instead of unfolding.

I think the original rovers folded the panels on top of each other. I think if this were changed to stack and slide together like a sliding winder, at the points they meat, it could use the deployment motors to periodically retract the panels which would cause them to be brushed by the felt or velcro strip along the seems of the pannels. Then deploy the panel wings on the opposite side of the craft and you would essentially have swiped both sides the entire panel array.

The only draw back is that you would need to manipulate which panel was on top in order to ensure they could all three (or five or whatever) be cleaned by this maneuver. It appears that it only needs to happen a couple times a year. I'm sure even the simplest design could outlast the crafts.

It might not be as easy as this. Or whats that saying, sound easy until you try to do it. But I think that out of a few simple approaches, something might be able to be worked through relatively easily without costing too much weight or bulk.

Re:Stupid but obvious (1)

timtwobuck (833954) | more than 6 years ago | (#22557336)

There are times (winter-night) on the Martian surface where this CO2 would be a solid, this may pose a problem

(temp -78C)

Re:Stupid but obvious (1)

bytesex (112972) | more than 6 years ago | (#22557724)

Not under the pressure conditions on Mars, right ?

Re:Stupid but obvious (1)

sumdumass (711423) | more than 6 years ago | (#22557854)

Well, I guess that would be a problem. Unless we had some sort of antifreeze or something that could work with it. Or maybe a liquid that could be heated just above freezing. I would guess that if Co2 could freeze without multiplying the atmospheric pressure, it would place unique challenges on a compressor that uses regular air.

I'm wondering of simply lining the Co2 cartridge with nickel or a nickel alloy and injecting a drop or so of hydrogen peroxide would work. The biggest draw back there would be the violent conversion to steam and 300 degree F temps involved. I'm not sure they would want to introduce water into the martial atmosphere and it would likely freeze easier then the Co2 would. But surely a chemical similar might be available. OR maybe something like a Piezoelectric warmer sandwiched between other dissimilar materials that would expand and contract greater then the Piezoelectric materials. But then we are talking added weight and all. And by warmer, I am thinking of attempting to use Piezoelectricity to power heat tape or something else like na electro chemical process to generate heat.

Re:Stupid but obvious (1)

fumblebruschi (831320) | more than 6 years ago | (#22560720)

A simple compressor/Co2 cartridges with tubes blowing onto the panels in different places could remove quite a bit of the dust without fancy arms and brushes.

Leaving aside the weight and moving-parts issues, how much volume of compressed gas could the rover carry? I'd think it would all get used up pretty fast and then the rover would be right where it is now, only with a useless empty gas tank to lug around.

Re:Stupid but obvious (1)

sumdumass (711423) | more than 6 years ago | (#22569488)

Well, you wouldn't need much more pressure and air then what a BB gun Co2 cartridge would supply for a sufficient cleaning. Usually they hold abut 12 grams of Co2 and a couple of ounces for the canister. Grossman makes an 88 gram cartridges which while weighing more with the container, would probably be more then enough for an entire mission.

I would probably suggest multiple 12 gram cylinders that can be dropped when depleted. If you used just one or better yet, a rubberized balloon of sorts, and included a small pump or some chemical process to provide the air, you could trade limits of supply for weight in convenience of unlimited refills. Seeing how this container could be filled over a long period of time, it wouldn't need to be a big or powerful pump. Just something capable of getting 10 or 20 pounds of pressure (or less) and store enough to sweep across all or part of the cells. I'm not sure how much pressure an inflated balloon has. It doesn't seem to be much but it could be used to temporarily store enough pressure to blow quite a bit of dust off.

Re:Stupid but obvious (2, Interesting)

Lifyre (960576) | more than 6 years ago | (#22557140)

One thing that EVERY person in this conversation about dirt clearing devices is forgetting are the recent developments in windshield wipers. Namely the wiperless kind...

It seems to me that something like http://science.slashdot.org/article.pl?sid=08/02/22/2342233 [slashdot.org] would be right up NASA's alley.

Of course I read WAY too much /. and don't forget about it the next day...

Re:Stupid but obvious (1)

Bombula (670389) | more than 6 years ago | (#22557550)

The optimum design would be nothing like a conventional car windshield wiper. Think closer to a free-spinning ostrich-feather duster driven by a magnetic actuator that is automatically pulled clear of the panels by gravity. That's one moving part, gravity doing half your work for you, 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. Total added weight = less than 1 lb per panel. Seems like a fair trade to ensure the rover doesn't drop dead from a bit of dust. And that's just one solution off the top of my head.

There are parts of the rovers that are genuinely rocket science. Solar panel dust-removers are not among them.The only valid objection to having panel wipers on the rovers is that their original expected lifetime was only 90 days.

not obvious, but possibly stupid (4, Informative)

Geoffrey.landis (926948) | more than 6 years ago | (#22558458)

The optimum design would be nothing like a conventional car windshield wiper. Think closer to a free-spinning ostrich-feather duster

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 actuator

The 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.

Re:not obvious, but possibly stupid (0, Troll)

Bombula (670389) | more than 6 years ago | (#22559626)

You're vastly overcomplicating something that is really quite simple. This is because Mars is not space. There are environments on Earth that are very much like Mars, with the exception of higher atmospheric pressure and the possibility of water precipitation. Building a duster that would work in Antarctica or the dusty Siberian tundra is trivial compared to the real challenges of spaceflight. It's a DUSTER. It. Just. Isn't. That. Complicated.

Re:not obvious, but possibly stupid (1)

pdboddy (620164) | more than 6 years ago | (#22563208)

Right, so when is your mars probe going up then? Since it's not all that complicated and Earth is Mars-like in so many ways.

Re:not obvious, but possibly stupid (0)

Anonymous Coward | more than 6 years ago | (#22564344)

I think he has a probe, unfortunately its exploring a damp dark region of the human anatomy.

Re:not obvious, but possibly stupid (1)

Geoffrey.landis (926948) | more than 6 years ago | (#22564004)

In fact, the history of Antarctic exploration is filled with accounts of equipment that failed even though it worked perfectly well in less harsh environments than Antarctica. Designing for Antarctica is non-trivial.

And the environment of Antarctica is benign compared to Mars.

Re:not obvious, but possibly stupid (1)

Bombula (670389) | more than 6 years ago | (#22572268)

Yeah, yeah, mod me troll, whatever. Sorry to tread on everyone's precious pocket-protector sympatico over NASA's egregious oversight not to put fucking dusters on their billion-dollar-probes' solar panels. But I'm afraid I'm just not in the business of making excuses for stupidity. We had a goddamn car driving around on the moon forty years ago when the world's most powerful supercomputer had no more muscle than your cellphone. And fucking dusters are an insurmountable space engineering problem?

And as for Antarctica posing formidable problems for equipment, does anyone here honestly think that Burt Rutan or the engineers at any major oil company couldn't have dusters designed and built within a year that would withstand conditions there just fine? I didn't think so.

Re:not obvious, but possibly stupid (1)

greedyturtle (968401) | more than 6 years ago | (#22592092)

It's too bad that you aren't in the business of making excuses for stupidity, because by the time you finished excusing yourself, you'd have a pretty massive portfolio going.

Anyway, since you don't do it, I'll explain how it's done.

1. Correct your ignorance of the original post.
You might be right in your exhortations, but even if you were correct,(you're not btw) you have no idea why or the reasons for your arguments. So, go ahead and read the original post carefully. Move on to the articles. Interesting, interesting. Maybe even look at a photo. [nasa.gov] Maybe even look at the sonnet [sff.net] by Geoffry Landis, one of the MER scientists. Maybe poetry ain't your thing, but at least recognize the name and what it commemorated.
2. Correct your ignorance of the conversation.
Read the significant posts that have came before you. Read the names of who wrote them and draw conclusions about their ability to be involved in the discussion. (Hint, some [slashdot.org] are more qualified than others, be sure to look out for their [slashdot.org] comments. [slashdot.org] )
3. Correct your ignorance of your own general statements.
You've mentioned egregious oversights, billion-dollar-probes, cars on the moon, insurmountability, Burt Rutan, engineers at any major oil company. and fucking dusters. I'll help you out some here.
  • Egregious Oversights - According to one of the scientists working on the project [slashdot.org] :

    We actually had built a dust experiment to test out some methods of removing dust. It had been scheduled to fly on the Mars-2001 Surveyor Lander, but the 2001 lander mission was cancelled after the failure of the 1999 Polar Lander (which used the same basic spacecraft design). In fact, we talked about dust removal technology for the MER, but it simply turned out that the most reliable solution was to increase the size of the panels so that they would still be at nominal power after 90 days worth of calculated dust accumulation.
  • Billion-Dollar-Probes - Cost: Approximately $820 million total (for both rovers)
    $645 million for design/development + $100 million for the Delta launch vehicle and the launch + $75 million for mission operations
  • Cars on the moon - Didn't have solar panels.
  • insurmountability - No one claims the problem was insurmountable.
  • Burt Rutan - Aerospace Engineer. He could probably make the rovers fly in the Martian Atmosphere, but wouldn't be able to help much with the dust.
  • engineers at any major oil company - These engineers don't tend to work with solar panels, but with the massive profits available to these companies, bending their R&D budgets towards a dust-removal system would probably have some great conclusions as well.
  • fucking dusters - Significantly more complex than just a fucking duster will be able to remove. Don't think 'dust' think 'grime'. [wikipedia.org]
4. Draw Conclusions and recognize stupidity
The hardest part of this process is recognizing stupidity where it lies. I can't do this for you, so I'll leave this as an assigned exercise.
5. Actually make excuse for stupidity to public
The creative task involves coming up with a good excuse. The best aren't pious but sincere and have a dose of self-depreciative humor, which shows your recognition of the mistake, preferably with a solution to not repeating it, the best explanation for the mistake, newfound understanding, and your willingness to try harder in the future to avoid the same mistakes. Some good examples are:

Yeah, I was an asshat; (amusing self-depreciation, correlating to actually wearing your own ass like a hat, which implies that your head is actually inside your ass. This doubles as an explanation, but a more specific one would be preferrable.) I guess I should have read more carefully before posting. (recognition of the problem and with solution) Dust looks like a lot more complicated problem in complex environments than I thought. (newfound understanding) I'll be sure to check my sources better next time. (willingness to try harder, with bonus points awarded for sounding like a journalist)


Try this with some of your other mistakes. You'll soon be making excuses with the best of us!


On another note, I'm horribly sorry to bust into someone publicly, I don't really enjoy doing it, but people who antagonize someone refereed in the OP tend to rub against the shark skin. Probably shouldn't have done it at work either! Hopefully no one who read this was too offended or wasted that much time on it, but I promise to avoid such grandstanding in the future.

Re:not obvious, but possibly stupid (1)

Bombula (670389) | more than 6 years ago | (#22592610)

Your points are moot. Of the seven points of mine you addressed, six sailed right over your head. My original criticism stands because you don't gamble hundreds of millions of dollars on the weather; you show up prepared, rain or shine - or dust.

Here's an assigned exercise for you: make an excuse for the stupidity that allowed NASA to crash a Mars probe by forgetting to convert units between imperial and metric. Good luck. You're going to need it. Maybe when you're done with that you can get back to me about the fucking dusters.

Re:not obvious, but possibly stupid (1)

greedyturtle (968401) | more than 6 years ago | (#22594348)

I don't need to make one, I can rip the press release straight out of ftp.hq.nasa.gov, /pub/pao/pressrel/1999/99-114. You can also see how they followed up on it at http://oig.nasa.gov/old/inspections_assessments/g-00-021.pdf [nasa.gov] . Everyone makes mistakes.

NASA didn't gamble on the weather, they prepared what was necessary for the 90 day mission, showed up and succeeded, even through brutal dust storms. They've continued, dusterless, for 1327 days beyond their original spec, that's more than 14x the time they planned for. You're essentially accusing the crew of Apollo 17 of stupidity and lack of preparation for spending 56 days on the moon, and finally saying they might have to leave soon because they didn't bring the chemicals to clean the CO2 out of their oxygen scrubbers. (They're still game to try and stay a week or two more though.)

Your excuse follows, and yes, it was very stupid of them.

Douglas Isbell
Headquarters, Washington, DC Sept. 30, 1999
(Phone: 202/358-1753)

Mary Hardin
Jet Propulsion Laboratory, Pasadena, CA
(Phone: 818/354-5011)

Joan Underwood
Lockheed Martin Astronautics, Denver, CO
(Phone: 303/971-7398)

RELEASE 99-113

MARS CLIMATE ORBITER TEAM FINDS LIKELY CAUSE OF LOSS

          A failure to recognize and correct an error in a transfer of
information between the Mars Climate Orbiter spacecraft team in
Colorado and the mission navigation team in California led to the
loss of the spacecraft last week, preliminary findings by NASA's
Jet Propulsion Laboratory internal peer review indicate.

          "People sometimes make errors," said Dr. Edward Weiler,
NASA's Associate Administrator for Space Science. "The problem
here was not the error, it was the failure of NASA's systems
engineering, and the checks and balances in our processes to
detect the error. That's why we lost the spacecraft."

          The peer review preliminary findings indicate that one team
used English units (e.g., inches, feet and pounds) while the other
used metric units for a key spacecraft operation. This
information was critical to the maneuvers required to place the
spacecraft in the proper Mars orbit.

            "Our inability to recognize and correct this simple error
has had major implications," said Dr. Edward Stone, director of
the Jet Propulsion Laboratory. "We have underway a thorough
investigation to understand this issue."

        Two separate review committees have already been formed to
investigate the loss of Mars Climate Orbiter: an internal JPL peer
group and a special review board of JPL and outside experts. An
independent NASA failure review board will be formed shortly.

          "Our clear short-term goal is to maximize the likelihood of a
successful landing of the Mars Polar Lander on December 3," said
Weiler. "The lessons from these reviews will be applied across the
board in the future."

          Mars Climate Orbiter was one of a series of missions in a
long-term program of Mars exploration managed by the Jet
Propulsion Laboratory for NASA's Office of Space Science,
Washington, DC. JPL's industrial partner is Lockheed Martin
Astronautics, Denver, CO. JPL is a division of the California
Institute of Technology, Pasadena, CA.

                                              - end-

Re:not obvious, but possibly stupid (1)

Bombula (670389) | more than 6 years ago | (#22572244)

Yeah, yeah, mod me troll, whatever. Sorry to tread on everyone's precious pocket-protector sympatico over NASA's egregious oversight not to put fucking dusters on their billion-dollar-probes' solar panels. But I'm afraid I'm just not in the business of making excuses for stupidity. We had a goddamn car driving around on the moon forty years ago when the world's most powerful supercomputer had no more muscle than your cellphone. And fucking dusters are an insurmountable space engineering problem?

And as for Antarctica posing formidable problems for equipment, does anyone here honestly think that Burt Rutan or the engineers at any major oil company couldn't have dusters designed and built within a year that would withstand conditions there just fine? I didn't think so.

Pathetic.

Re:not obvious, but possibly stupid (1)

Chris Tucker (302549) | more than 6 years ago | (#22578148)

OK, no one, NO ONE has said that a dust removal mechanism is

an insurmountable space engineering problem.

The design criteria for such a device, vs. the financial budget for the mission as a whole vs. the weight budget for the mission as a whole vs. the power budget for the mission as a whole vs. the science investigation budget for the mission as a whole is the deciding factor.

Is the money and the weight and the power there? If not, what gets sacrificed.

It's not a matter of a few pounds extra and few more volts and a few hundred dollars.

The Rovers were designed with a criteria of saving ounces and millivolts so that one more sensor and one more tool and another few square inches of solar cell could be included.

But, as you're a slashdot poster, you, of course, know more about designing for the mixed environments of Earth's gravity and atmosphere, storing the Rovers until they move to Florida, transporting the Rovers to Florida, launch phase, cruise phase, entry phase, descent phase, landing phase, deployment phase, rolloff phase and the Martian surface environment, than the thousands of people who had a hand in designing, building, testing, launching and operating the Rovers.

Please submit your resume to NASA/JPL ASAP, where it will receive the appropriate attention!

<sound of toilet flushing>

Re:not obvious, but possibly stupid (1)

Bombula (670389) | more than 6 years ago | (#22582048)

But, as you're a slashdot poster, you, of course, know more about designing for the mixed environments of Earth's gravity and atmosphere, storing the Rovers until they move to Florida, transporting the Rovers to Florida, launch phase, cruise phase, entry phase, descent phase, landing phase, deployment phase, rolloff phase and the Martian surface environment, than the thousands of people who had a hand in designing, building, testing, launching and operating the Rovers.

Oh that's right, there's never been an egregious oversight or moronic mistake made by NASA scientists - certainly not those working on Mars missions. They would never do something as stupid as, say, crash a $500 million probe by forgetting to convert imperial units to metric...

Spare me your silly tirade. If NASA is dumb enough to bork their missions by failing to convert units, they're plenty stupid enough to allow dust on solar panels to kill their missions because they have no way to clean them off. What good is an extra instrument if none of them work for lack of power? NASA has so far been lucky with these probes. There could have been a dust storm the day after they landed and that would have been it, game over. Then you'd be singing my tune. Here's a quick planning tip that applies not just on Mars but here on Earth too: when there's a billion dollars on the line, you don't gamble on the fucking weather.

Re:not obvious, but possibly stupid (1)

Chris Tucker (302549) | more than 6 years ago | (#22589234)

I note that you neither addressed nor even attempted to refute a single one of the points I mentioned in my previous message.

Good Show! You have mastered the Slashdot Way of Discussion:

Ignore everything even vaguely relating to the issue at hand, maintain an arrogant know it all attitude and toss in a few gratuitous obscenities.

You would make an excellent GOP/Neocon politician.

Re:not obvious, but possibly stupid (1)

Bombula (670389) | more than 6 years ago | (#22590894)

I only comment on what is relevant. You made no relevant points, and therefore got the reply you deserved.

Re:not obvious, but possibly stupid (1)

HeyLaughingBoy (182206) | more than 6 years ago | (#22578762)

but your offhand thought that oh, it would be simple and cheap and reliable is just offbase.


Thank you for saying that. I was trying really, really hard to resist the urge not to flame that stream of poorly thought-out, half-baked posts :-)

I live in Minnesota, and even on a normal winter day here, my 3 year old sports car bitches about starting when it's -10F. Seals don't work right, electrical subsystems switch on and won't switch back off until it warms up (drained an entire tank of windshield washer fluid that way!), etc. I hate to think what the engineering challenges are for Mars, or even Antarctica.
Scratch that! I'd actually love to be able to work on solving said challenges.

But not with ostrich feathers.

Re:Stupid but obvious (1)

MBGMorden (803437) | more than 6 years ago | (#22561700)

And anyone using windshield wipers on their car knows how unreliable they are to begin with.
"anyone using"? Did they become optional equipment all of a sudden?

I swear they really are cutting costs now.

Re:Stupid but obvious (1)

pdboddy (620164) | more than 6 years ago | (#22563350)

Their use is always optional, even if their inclusion on the car is not. :)

Re:Stupid but obvious (1)

ArsonSmith (13997) | more than 6 years ago | (#22566072)

Arizona they might as well be. When it rains you find out they are dried out so you go replace them. Then it doesn't rain again until they are dried out again.

I gave up and rarely use them effectively. Just wipe enough away to get me home.

Re:Stupid but obvious (1)

dl107227 (632747) | more than 6 years ago | (#22557804)

They contemplated a system to clean dust off of the solar panels when they made the rovers. In the end they decided not to go with a complex cleaning system and just make the solar panels larger. They discussed it on some TV show a few years ago.

Thanks for the update (1)

jasonwea (598696) | more than 6 years ago | (#22556340)

I was wondering what was happening with these two guys. Neither spiritrover [livejournal.com] nor opportunitygrrl [livejournal.com] have posted to their LJs for a while now.

Re:Thanks for the update (1)

stevesliva (648202) | more than 6 years ago | (#22557864)

You should keep an eye on unmannedspaceflight.com (forum) and planetary.org (huge monthly updates [planetary.org] with one due soon).

A Job well done. (4, Insightful)

Umuri (897961) | more than 6 years ago | (#22556346)

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.

Rover III (4, Funny)

sakdoctor (1087155) | more than 6 years ago | (#22556400)

Bag-less rover with duel cyclone technology.
Sponsored by Dyson.

Wonderful (3, Interesting)

PrayingWolf (818869) | more than 6 years ago | (#22556496)

I hope the martian winds blow some of that dust off of the panels.
Great to see these amazing robots still at work!
I read "Roving Mars" a couple of years ago and even back then the mission had superseded all of its goals.

Indeed a very inspiring episode in space exploration

29.9 (3, Interesting)

Thanshin (1188877) | more than 6 years ago | (#22556542)

You know they're talking about the apex of human technology when they control tenths of a degree of inclination of a robotic car running over another planet.

I can't even know the angle of the keyboard I'm writing this, with such precision.

Re:29.9 (1)

cnettel (836611) | more than 6 years ago | (#22557312)

Hands up everyone who believe they just chose asin 0.5, but used float and shitty rounding when converting from radians...

Re:29.9 (1)

DerekLyons (302214) | more than 6 years ago | (#22558656)

You know they're talking about the apex of human technology when they control tenths of a degree of inclination of a robotic car running over another planet.

Nah. They don't control the inclination - they measure the inclination and park the rover at the best possible spot within various limits. Even measuring to a tenth of a degree isn't all that spectacular, I was measuring to a hundredth with electronic equipment nearly twenty years ago.
 
 

I can't even know the angle of the keyboard I'm writing this, with such precision.

You could - if you bothered to try.

Re:29.9 (0)

Anonymous Coward | more than 6 years ago | (#22561668)

I can't even know the angle of the keyboard I'm writing this, with such precision.
Maybe if you had an instrument on your keyboard specifically designed to report the angle of tilt to within a tenth of a degree, you would.

Just sayin..

That rover should just take a break (0)

Anonymous Coward | more than 6 years ago | (#22557006)

That dust really put a bad beat on the rover. It should really take a break instead of trying to do science on tilt. That can only lead to losing a lot of money.

Re:That rover should just take a break (0)

Anonymous Coward | more than 6 years ago | (#22564104)

It appears nobody has gotten your joke. Considering that poker is a social activity, and this is slashdot, I'm not really surprised.

inspirational (1)

GordonCopestake (941689) | more than 6 years ago | (#22557082)

I do hope it survives the winter. Even though it's WAY past it's sell by date I think it's inspirational to others as to "how it should be done". Great work and great "products".

Re:inspirational (0)

Anonymous Coward | more than 6 years ago | (#22558538)

Actually, it should be WAY past it's use by date. It was sold a long time ago, and only first used after many months shipment.

Re:inspirational (0)

Anonymous Coward | more than 6 years ago | (#22559352)

It's not the only piece of electronics that has long outlasted its 90-day warranty. (I know I have plenty of those around.) It just happens to be a high profile gov't purchased piece of electronics which has done so.

nah, its no problem. (2, Funny)

apodyopsis (1048476) | more than 6 years ago | (#22558496)

nah, its no problem - a good martian winter downpour will wash the dust off. and, voila, the problem is eliminated.

they'll need to get close to one of the canals if they want to wash of some of the sand clogging the treads as well.

:)
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