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Mars Winds Clean Spirit's Solar Panels Again

timothy posted more than 5 years ago | from the like-mom-making-the-bed dept.

Mars 269

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.'"

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Next time . . . (5, Funny)

OhHellWithIt (756826) | more than 5 years ago | (#26906353)

. . . don't forget to pack the broom.

Re:Next time . . . (0, Redundant)

jellomizer (103300) | more than 5 years ago | (#26906385)

Or a windshield washer for the solar panels.

Re:Next time . . . (5, Informative)

Tubal-Cain (1289912) | more than 5 years ago | (#26906525)

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.

Re:Next time . . . (4, Interesting)

SilverJets (131916) | more than 5 years ago | (#26906837)

So what about an air cannon or something? Small pump to take in Martian air, build up pressure, and a small nozzle directed at the panel to blow the dust off.

I know, every ounce of weight and every bit of energy has to be calculated and accounted for. But they had to know that dust would accumulate on the panels and should have accounted for that with some type of design.

Re:Next time . . . (4, Interesting)

solafide (845228) | more than 5 years ago | (#26906869)

90 days.

Re:Next time . . . (4, Interesting)

blueg3 (192743) | more than 5 years ago | (#26906873)

They did know. They also knew that all the possible solutions had significant costs and/or chance of failure. (As far as the air cannon, Mars air is very thin, so you have to have a quite significant wind to move the dust.)

Re:Next time . . . (2, Informative)

Tubal-Cain (1289912) | more than 5 years ago | (#26906953)

Given the thin martian air, it could take a lot of power to build up sufficient pressure to be effective. Also, see this post. [slashdot.org]

Re:Next time . . . (3, Insightful)

sremick (91371) | more than 5 years ago | (#26906937)

I don't see how the benefits are minor, considering how much press and excitement is triggered each time the winds clean the dust off. Also considering the massive longevity to the mission that more runtime creates. More life = more science, and since the whole point of these missions is "science", that's more bang for your buck.

It's not easy to get stuff to Mars, and there are only occasional windows of opportunity. Best to get as much as you can out of the missions you DO send.

I don't see how there can be much "static cling" if just wind can dust them off.

Re:Next time . . . (3, Insightful)

Tubal-Cain (1289912) | more than 5 years ago | (#26907021)

The wind is (somewhat tongue-in-cheek) taking the level of dust from "almost thick enough to grow weeds in" to merely "heavy".

Re:Next time . . . (3, Interesting)

Gerzel (240421) | more than 5 years ago | (#26907041)

They never expected the mission to go this long. Things were calculated at a success level of 90 days.

Indeed because of the success of these two rovers the next missions will be similar. The next mission may or may not benefit as often it is the failures that teach better than the successes.

It may be that the rover happened to have landed in a particularly windy part of the planet, or a part with a particularly un-clingy(love my technical wording!) local dust conditions and the next mission may be different and fail even if the exact same equipment is used.

Re:Next time . . . (4, Interesting)

dpilot (134227) | more than 5 years ago | (#26906973)

Arthur C Clarke wrote a nifty short story that encapsulated some of this. I can't even remember the title, so spoilers are uselss, and I'll just give the gist.

Two astronauts were exploring on the moon, and the wandered into a dust bowl. They got a little dust on their faceplates, and made the mistake of wiping them. The generated static transferred all of the dust to the faceplate, and they were still deep enough in the dust that it attracted more. So even though the dust bowl is shallow enough to simply walk out, they can't see, and so far they haven't found anything they could rub the faceplate with where the static electricity would go the other way, taking the dust off.

Solution:

They rubbed faceplates together. One faceplate takes the charge that takes the dust, the other cleans. Then the astronaut with the clean faceplate can see the way to the buggy, leading the other.

Re:Next time . . . (1, Insightful)

Taibhsear (1286214) | more than 5 years ago | (#26907069)

Just reverse the polarity. In start trek it fixes everything.

Re:Next time . . . (1)

Zantoz (310692) | more than 5 years ago | (#26907157)

What I need is a solar powered lawnmower that runs continuously within my marked off lawn grid.

Power Up
Mow lawn
Run low on power
Write coordinates to a ram chip
Slowly Power Up
Repeat

Re:Next time . . . (0)

Anonymous Coward | more than 5 years ago | (#26907199)

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.

Ok... how abut a cleaning fan or a blower mechanism of some sort? If you can prolong a mission for as long as this one has been perhaps such equipment would be worth the effort? Especially since the Mars winds seem to have proven the concept.

Re:Next time . . . (1)

Mr. Underbridge (666784) | more than 5 years ago | (#26907453)

Ok... how abut a cleaning fan or a blower mechanism of some sort? If you can prolong a mission for as long as this one has been perhaps such equipment would be worth the effort? Especially since the Mars winds seem to have proven the concept.

They may have discovered that an effective fan would require more power than was available. Then there's the complexity and all. Not to mention which, it's a fairly reasonable approach to simply evaluate how frequently such winds occur and decide to rely upon them.

Squeegee kid (3, Funny)

macxcool (1370409) | more than 5 years ago | (#26906357)

That's much better than NASA's alternative plan of sending a Squeegee Kid to do the job.

Re:Squeegee kid (5, Funny)

GargamelSpaceman (992546) | more than 5 years ago | (#26906481)

It was a martian. You see about a billion years ago, the Martian civilization discovered the secret of consiousness. Eventually the robots they created displaced them, and then when the planet's resources were depleted, they left for the stars leaving behind some curators. These curators are not really consious, their robotic creators ensured this so that they would be reliable in their task of preserving their martian heritage, but sometimes they do act in ways that are, almost uncannily lifelike.

This was the case here. The Martian curator bots find the rovers interesting, or rather, they find their controllers interesting. They periodically dust the solar panels so that they will be able to keep roving. They are curious as to what they are doing, maybe even appreciative that someone has visited to appreciate what they have devoted the past eon to preserving. For them, watching us look is most gratifying. They really ache to communicate with us and show us all the Martian history in their underground vaults, but because of their programming to remain inconspicuous, they can't. Still, they are helpful when they can be and not give themselves away.

Re:Squeegee kid (1)

flitty (981864) | more than 5 years ago | (#26906783)

I believe it was actually Dr. Manhattan flying Silk Spectre around. When they passed over, good old Doc blew it off for us.

Re:Squeegee kid (1)

gustolove (1029402) | more than 5 years ago | (#26906791)

It was a martian. You see about a billion years ago, the Martian civilization discovered the secret of consiousness. Eventually the robots they created displaced them, and then when the planet's resources were depleted, they left for the stars leaving behind some curators. These curators are not really consious, their robotic creators ensured this so that they would be reliable in their task of preserving their martian heritage, but sometimes they do act in ways that are, almost uncannily lifelike.

This was the case here. The Martian curator bots find the rovers interesting, or rather, they find their controllers interesting. They periodically dust the solar panels so that they will be able to keep roving. They are curious as to what they are doing, maybe even appreciative that someone has visited to appreciate what they have devoted the past eon to preserving. For them, watching us look is most gratifying. They really ache to communicate with us and show us all the Martian history in their underground vaults, but because of their programming to remain inconspicuous, they can't. Still, they are helpful when they can be and not give themselves away.

+1 Awesome

Re:Squeegee kid (1)

commodore64_love (1445365) | more than 5 years ago | (#26907235)

>>>The Martian curator bots periodically dust the solar panels

I figured the bots performed an upgrade, such that the panels are just as dirty as before, but now they have been upgraded to more-efficient Martian red-dust-based panels.

Another possibility is that the panels have been infected by microbes that scrubbed the surface clean, thereby boosting power levels.

Or it could just be wind.

Re:Squeegee kid (0)

Anonymous Coward | more than 5 years ago | (#26907335)

I prefer to think of it like Mo from Wall-E. Obsessively cleaning any bit of contamination before anything else can happen.

Re:Squeegee kid (2, Funny)

The Great Pretender (975978) | more than 5 years ago | (#26907409)

Actually it was a Mexican. You didn't realize that we had made it that far did ya! To hell with finding water on Mars, we already have a Taco truck with the best horchata in the solar system there waiting for NASA.

Re:Squeegee kid (3, Funny)

JCSoRocks (1142053) | more than 5 years ago | (#26906929)

if only NASA had sent a homeless fellow with some newspaper...

How much longer? (2, Interesting)

i.r.id10t (595143) | more than 5 years ago | (#26906379)

How much longer can this thing go? I mean, it was "designed" to only go a few months, and we are years beyond that. Anyone have a pool on when it will really stop working?

Re:How much longer? (4, Informative)

al0ha (1262684) | more than 5 years ago | (#26906397)

Yep - there are pools at JPL and Caltech. Go Beavers!

Re:How much longer? (1, Funny)

Rob Kaper (5960) | more than 5 years ago | (#26906451)

NASA probably has a good idea. Published estimates were likely wrong on purpose from the start to give them the opportunity for more media coverage and subsequently budget opportunities.

Kirk: âoeHow long to re-fit?â
Scotty: âoeEight weeks. But you donâ(TM)t have eight weeks, so Iâ(TM)ll do it for you in two.â
Kirk: âoeDo you always multiply your repair estimates by a factor of four?â
Scotty: âoeHow else to maintain my reputation as a miracle worker?â

Re:How much longer? (1)

Ethanol-fueled (1125189) | more than 5 years ago | (#26906595)

Published estimates were likely wrong on purpose

I agree with you there.

to give them the opportunity for more media coverage and subsequently budget opportunities

If this [discovermagazine.com] is what you meant by that then I agree with you there ;)

Re:How much longer? (5, Funny)

Chabo (880571) | more than 5 years ago | (#26906657)

And of course, the scene from the TNG episode "Relics":

"Starship captains are like children. They want everything right now and they want it their way. The secret is to give them what they need, not what they want."

"I told the Captain I would have this diagnostic done in an hour."
"And how long will it really take you?"
"An hour!"
"Oh, you didn't tell him how long it would really take, did you?"
"Of course I did."
"Oh, laddie, you have a lot to learn if you want people to think of you as a miracle worker."

Re:How much longer? (1)

MoonBuggy (611105) | more than 5 years ago | (#26906813)

There's also the difference between 'should last 90 days' and 'will absolutely without fail last 90 days'.

The former has a fair chance of breaking down earlier, the latter has a fair chance of breaking down later (much later in this case).

Re:How much longer? (5, Insightful)

dlevitan (132062) | more than 5 years ago | (#26906899)

NASA probably has a good idea. Published estimates were likely wrong on purpose from the start to give them the opportunity for more media coverage and subsequently budget opportunities.

Not exactly. Estimates are based on worst case scenarios. What would have been the public's reaction if NASA had said that the rovers would last 1 year but they only lasted 6 months? NASA guidelines require that when something is supposed to last x months/years, then it's engineered such that it will last that long, no matter what. Specifying mission requirements is actually a tricky problem for the scientists on a mission because you want the most possible science that fits within a budget and that will last for as long as you say it will last. And usually the only way to convince NASA that something will last is if you add in backup systems. With new, expensive technology this becomes even harder.

So yes, the rovers were conservatively estimated to last 3 months. I'm sure the scientists on the mission expected that they would last longer, but 3 months was a good benchmark that provided a good amount of science for a reasonable cost. Everything else has just been icing on the cake (and in this case, a lot of icing). Personally, I think they did a great job and cannot fault them at all.

(I am a grad student working on a NASA mission and have seen a bit of how this process works)

Re:How much longer? (2, Interesting)

osu-neko (2604) | more than 5 years ago | (#26907295)

Published estimates were likely wrong on purpose from the start to give them the opportunity for more media coverage and subsequently budget opportunities.

Bzzt. Wrong. First of all, what you're quoting (90 days) never was an estimated lifespan. If the estimated lifespan of a craft was 90 days, that would mean there's a substantial chance you'll only get 60 days out of it, or 120 for that matter. 90 days was never the expected lifespan. 90 days was the promised minimum lifespan. They were very certain it would last at least 90 days. If you think about that a minute, that means they estimated it would probably last much longer than that, or else they couldn't be that certain it would last at least 90 days. In fact, they expected it to last about three times that -- they expected the rover would keep going until the Martian winter. They just weren't terribly confident it would survive the winter...

Re:How much longer? (3, Insightful)

jellomizer (103300) | more than 5 years ago | (#26906485)

Rule 1 of engineering: Underestimate your estimates.
The thing was designed to run for years. However they gave it a 90 Day limit to save their butts if it breaks in 85 days. as well the mission spec was for 90 days, so they made sure it would last that 90 days as much as possible. It is not like you going to put up a million dollar probe and skimp on parts. You are going to make it as robust as possible as estimating 90 days of operation in the unknown is quite hard.

Re:How much longer? (1)

Tubal-Cain (1289912) | more than 5 years ago | (#26906579)

Anyone have a pool on when it will really stop working?

The way this things are going, that's something best handled here [longbets.org] .

Re:How much longer? (0)

Anonymous Coward | more than 5 years ago | (#26906619)

I understand over-designing systems for 10's of percent, but 100's%?!? That is either wasteful engineering or a bunch of engineers covering their respective gluteus maximus? The project overrun budget estimates and has NASA/JPL have to allocate resources. If the life expectancy was determined more realistically, everybody would have gained.

Re:How much longer? (1)

Kjella (173770) | more than 5 years ago | (#26907083)

How much longer can this thing go? I mean, it was "designed" to only go a few months, and we are years beyond that. Anyone have a pool on when it will really stop working?

They thought the dust would clog the solar panels so that it would be mechanically intact but powerless in three months. Using that to figure out how long it'll last now is like trying to figure out how long a laptop will last on AC power based on how long you thought it'd last on battery power. The short answer is until something breaks, it's mechanical and hasn't been to service for five years but trying to say exactly when is like trying to predict when you'll need a tow truck for your car. Even if it's been built to 10x the spec some things must be wearing out by now...

Re:How much longer? (1)

SpaceLifeForm (228190) | more than 5 years ago | (#26907455)

Windows 7 will be dead before the rovers.

Include cleaners next time? (0, Redundant)

againjj (1132651) | more than 5 years ago | (#26906439)

Maybe next time, NASA should include some type of cleaning devices, so that when the panels get dusty, then a brush or something could wipe the panels. Sure, it's more weight, but it could increase the productivity of the mission.

Re:Include cleaners next time? (4, Informative)

CompMD (522020) | more than 5 years ago | (#26906505)

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.

Re:Include cleaners next time? (1)

morgan_greywolf (835522) | more than 5 years ago | (#26906733)

Hmmmm...couldn't they use electromagnetic effects to minimize weight? Now just hear me out: sit in front of a CRT that's dusty. Now, ground yourself out with a grounding strap or something. Next, pass your grounded hand just barely over the screen without touching it. What happens? The dust on the monitor will now stick to your hand!

Anyway, whatchya think?

Re:Include cleaners next time? (1)

mrchaotica (681592) | more than 5 years ago | (#26906815)

How do you get the dust off your hand afterward (so that it'll be clean for next time)?

Re:Include cleaners next time? (1)

Nikker (749551) | more than 5 years ago | (#26906877)

Well if you want to be like that I would get to point out that if the surface of the rover was able to effect its electrostatic properties the 'dust' would simply fall off wouldn't it?

Re:Include cleaners next time? (1)

morgan_greywolf (835522) | more than 5 years ago | (#26907015)

Yeah, that's what I was getting at.

Re:Include cleaners next time? (1)

Rayban (13436) | more than 5 years ago | (#26907195)

Easy... brush it off on your shirt.

Re:Include cleaners next time? (4, Informative)

smooth wombat (796938) | more than 5 years ago | (#26906601)

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 [newscientist.com] why there are no wipers, or any other cleaning device, on the rovers.

Re:Include cleaners next time? (1)

ITFromHome (1432373) | more than 5 years ago | (#26906607)

I agree. It would be a shame if the mission ended after five years because of dust covering the solar array. TFA says that after the cleaning only 28 percent of the sunlight hitting the array was getting past the dust. Imagine how much more power the rover could have with a cleaner that keeps that number closer to 75 percent.
Lesson learned. Someone write down to send lens cleaner with the first manned mission to mars.

Re:Include cleaners next time? (1)

Colourspace (563895) | more than 5 years ago | (#26906745)

A manned mission to mars would surely come with a human lens cleaner? Maybe they could offer the robotic vehicles roses from a bucket at the same time? (maybe this is a UK phenomenon).

Re:Include cleaners next time? (2, Interesting)

Cheeko (165493) | more than 5 years ago | (#26907245)

The next rover uses an RTG for power, so there won't be a need for wipers or any other such thing:

Mars Science Lab [nasa.gov]

I guess the radiator portion of the RTG could get enough dust on it to cut down on its effectiveness, but Mars in general is still pretty cold, so I doubt there is nearly as big of an issue as dust on solar panels.

Amazing (0, Troll)

MyLongNickName (822545) | more than 5 years ago | (#26906445)

I find it amazing what can be done with so little power. 240 watts? I'm looking around my office and figuring the lights use about twice that. This thing is cruising around mars, keeping itself warm, sending information to Earth. No real point to this post except to express my amazement.

Re:Amazing (3, Funny)

Chabo (880571) | more than 5 years ago | (#26906617)

My computer uses nearly that much power under full load, and it doesn't even have to move!

Re:Amazing (1)

Tubal-Cain (1289912) | more than 5 years ago | (#26906671)

This thing is cruising around mars...

Not as much as you think. [wikipedia.org]

"As of sol 1736 (November 20, 2008), Spirit's total odometry was 7,529 metres (4.68 mi)."

Re:Amazing (5, Informative)

evanbd (210358) | more than 5 years ago | (#26906721)

Not 240 watts; 240 watt-hours. With 24.6 hours per Martian day, that's about 9.75 watts average consumption.

Re:Amazing (1)

tripmine (1160123) | more than 5 years ago | (#26906747)

I think it's even more amazing when you consider that it is 240 watt-hours of energy PER DAY. It's actual power usage I'm guessing is much less. If your lights are incandescent, then they probably use that much energy in less than two hours. Damn, why can't our terrestrial equipment be this efficient?

Re:Amazing (-1, Offtopic)

Anonymous Coward | more than 5 years ago | (#26906845)

Damn, why can't our terrestrial equipment be this efficient?

Don't worry, we'll get there soon. The gov's stimulus package will start working its magic any minute now...

Re:Amazing (-1, Offtopic)

Hordeking (1237940) | more than 5 years ago | (#26907193)

Damn, why can't our terrestrial equipment be this efficient?

Don't worry, we'll get there soon. The gov's stimulus package will start working its magic any minute now...

Will I get my beowulf cluster of ponies, then?

Re:Amazing (2, Funny)

cavtroop (859432) | more than 5 years ago | (#26906955)

because I don't want to pay $456,784 for a lightbulb :)

Re:Amazing (1)

CohibaVancouver (864662) | more than 5 years ago | (#26907149)

why can't our terrestrial equipment be this efficient?

It can be, it's just too expensive or annoying. My PC has all these high tech power saving features. I've disabled most of them because they're annoying.

Re:Amazing (4, Interesting)

Kjella (173770) | more than 5 years ago | (#26906789)

Cruise is something of an exaggeration... they've gone 13 miles in 5 years, put together. The Lunar Rover missions each went longer than both combined in 3-4 hours, at top speed they'd pass the rovers within the first hour. Semi-stationary crawlers is a more accurate description, but of course they've been loaded up with scientific equipment rather than for showing off.

Re:Amazing (1)

Smidge204 (605297) | more than 5 years ago | (#26906819)

240 watt-hours, not 240 watts. (Unless you only want to operate for a single hour!) For comparison, 240WH is roughly the energy in a dozen alkaline "D" cell batteries. If the probe is to operate 24 hours* on that power, that's only ten watts on average.

=Smidge=
(*Earth hours, of course)

Only on Slashdot! (5, Informative)

blind biker (1066130) | more than 5 years ago | (#26906827)

Only on Slashdot can a post that confuses power (watt) and energy (watt-hour) be modded +3 Interesting.

Re:Only on Slashdot! (1)

DMUTPeregrine (612791) | more than 5 years ago | (#26907019)

I don't get watt-hours. What's wrong with Joules? Or kJ? Why have two units for energy?

Re:Only on Slashdot! (3, Informative)

Zenaku (821866) | more than 5 years ago | (#26907325)

For redundancy. If the Joules run out, it can still run off the watt-hours, and vice versa.

Re:Only on Slashdot! (1)

dondelelcaro (81997) | more than 5 years ago | (#26907339)

I don't get watt-hours. What's wrong with Joules? Or kJ? Why have two units for energy?

Because people know about what a watt is, and they know how long an hour is? (It's not like you can't divide by 3600 to get J, or a Watt*Second.)

Re:Only on Slashdot! (0)

Anonymous Coward | more than 5 years ago | (#26907029)

...and generate dozens of responses dealing with semantics and none dealing with the actual intent of the post!

Re:Only on Slashdot! (1)

Bob-taro (996889) | more than 5 years ago | (#26907089)

Only on Slashdot can a post that confuses power (watt) and energy (watt-hour) be modded +3 Interesting.

Actually, "Only on slashdot will some people actually notice that the poster used the wrong units" might be more like it. Whether or not the moderators notice, on slashdot you know *someone* will alert you to your mistakes, whether it's having the wrong units, wrong spelling, or wrong point of view.

More amazing is that it keeps going (2, Funny)

WindBourne (631190) | more than 5 years ago | (#26907053)

What I really want to see is a glider, or a ballon/lander combo survive that long. Something of that nature would be really useful if it could pop all over.

Math? (-1, Troll)

Anonymous Coward | more than 5 years ago | (#26906463)

How is 240Wh "roughly double" 180Wh?

Re:Math? (2, Informative)

Samalie (1016193) | more than 5 years ago | (#26906539)

Jesus, can you fucking read? Not even the article, but the summary...

"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."

180wh for survival. They were generating 210wh. Now they're getting 240wh.

210wh-180wg=30wh discretionary.
240wh-180wh=60wh new discretionary.

No wonder you're not a rocket scientist. Or if you are, you're one of those fucks who confused imperial and metric, aren't you?

Re:Math? (-1, Flamebait)

Anonymous Coward | more than 5 years ago | (#26906597)

180wg

Nice typo, asshole.

MODS: parent is an abusive troll (0)

Anonymous Coward | more than 5 years ago | (#26906621)

the parent is a troll. please mod him as such.

Best,
wbs

MODS: parent is an abusive troll (0)

Anonymous Coward | more than 5 years ago | (#26906669)

the parent is a troll. please mod him as such.

Best,
sbw

Re:MODS: parent is an abusive troll (0)

Anonymous Coward | more than 5 years ago | (#26907371)

the parent is a troll. please mod him as such.

Best,
swb

Re:Math? (0, Troll)

oodaloop (1229816) | more than 5 years ago | (#26906751)

The summary? I don't even read the titles before I start posting.

Re:Math? (1)

JCSoRocks (1142053) | more than 5 years ago | (#26906983)

What're we talking about?

Re:Math? (0)

Anonymous Coward | more than 5 years ago | (#26907417)

If only they'd take the initiative and start banning shitposters who openly gloat about their willful ignorance maybe we could fight the downward spiral /. has been in for some time. Chemotherapy for a cancer patient, if you will.

Calm Down (1)

mosb1000 (710161) | more than 5 years ago | (#26907393)

Dude, calm down. It's just the internet.

Re:Math? (1)

fotoguzzi (230256) | more than 5 years ago | (#26906545)

(Not to be mean), but this might be a case where RTFS would apply.

Re:Math? (1)

Markspark (969445) | more than 5 years ago | (#26906567)

the 180Wh is what it uses regardless. So the increase from 210 Wh in to 240 Wh in makes for a doubling of expendable energy.

Re:Math? (1)

csartanis (863147) | more than 5 years ago | (#26906571)

FTFA:

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. Thirty watt-hours is the amount of energy used to light a 30-watt bulb for one hour.

Re:Math? (1)

meringuoid (568297) | more than 5 years ago | (#26907419)

Thirty watt-hours is the amount of energy used to light a 30-watt bulb for one hour.

A 30W bulb? Wow. The room I'm in now is lit by a single 18W lamp and that's more than adequate. I realise that American homes tend to be more spacious, but seriously - 30W? How large are your rooms?

Re:Math? (1)

v1 (525388) | more than 5 years ago | (#26906589)

They are not counting the overhead to keep the thing alive. They've doubled the amount of power available for science etc.

Re:Math? (0)

Anonymous Coward | more than 5 years ago | (#26906593)

Dimwit, the discretionary power (the power left over after basic needs) is doubled, not the total.

(240-180)/(210-180) = 2.

Clearly the sun on Mars shines brighter than your intellect.

Re:Math? (0)

Anonymous Coward | more than 5 years ago | (#26906687)

Easy, you're counting it wrong. Summary says they have about double discretionary power, aka power that can be chosen to be used. 180 is a minimum and MUST be used for the vehicle to continue functioning.

210Wh(previous daily energy) - 180Wh(required daily energy) = 30Wh(previous discretionary energy)

So another 30Wh doubles it.

Re:Math? (0)

Anonymous Coward | more than 5 years ago | (#26907413)

10/10 trolling. Well done.

Winds of Change... (1)

TheGeniusIsOut (1282110) | more than 5 years ago | (#26906565)

Back in action, let's go for another 4 years...

I love american units (0, Troll)

iris-n (1276146) | more than 5 years ago | (#26906655)

Let's see, we have "180 watt-hours per day". A bit long ins't it? As long as there's 24 hours per day (not so sure of that in mars ;), we can convert it to 7.5 watt-hour per hour. Or 7.5 watts. Humm. So we have a new unit of power!

Lets call it Wh/d, and set the conversion 1 Wh/d = 24 W.

Or we could, you know, use joules.

Re:I love american units (1)

corsec67 (627446) | more than 5 years ago | (#26906775)

You do realize that the sun doesn't shine the entire 24 hours and 39 minutes in each day?

So you don't get a constant power over the day.

Re:I love american units (1)

morgan_greywolf (835522) | more than 5 years ago | (#26906971)

Iris-n is being a bit pedantic here. A watt (W) is 1 joule/second. Using terms like watt-hours per day doesn't make much sense to him or her. What iris-n fails to realize is that, at least in the U.S., we tend to measure electricity usage by the kilowatt-hours (kW/h). Since we're dealing with a much smaller scale with Spirit's solar panels, W/h seems a sensible measurement.

Re:I love american units (1)

iris-n (1276146) | more than 5 years ago | (#26907165)

Yes, I do realize that. It's you who haven't understood the joke. Allow me to explain.

The watt-hour (and it does not matter if it is earth hours or mars hours, if you missed this joke as well) is a common unity, used when you want to talk about joules but they're too small, 1 watt-hour = 3600 J.

But when you say watt-hour per day, you're being a little redundant, and losing the big numbers on the way. Of course in this example they should not use watts to stay consistent with the surrounding text. But you could use joules all the way and make the joules per day point clearly. 648kJ is not such a difficult concept.

It would have been better if I said 7.5 W on average?

PS: Rereading my post, I've scrambled things, its 24 Wh/d = 1 W.

bad data (0)

Anonymous Coward | more than 5 years ago | (#26906679)

I've been going out at night shining a flashlight on it just to throw off their data. Next week I'm going to write my name in the dust on that thing with a green laser pointer.

Okay...why haven't we? (1)

PortHaven (242123) | more than 5 years ago | (#26906731)

We've proved that the budget rover designs have been the most successful designs we've sent to another planet.

They've been resourceful and far roaming...so why haven't we expanded on the design.

I think we should package up some new rovers. Slightly larger with additional equipment. With one additional design feature. A means to self-clean it's own solar panel.

This way the unit could theoretically operate for near perpetuity.

Re:Okay...why haven't we? (1)

Glendale2x (210533) | more than 5 years ago | (#26906921)

Next up is the Mars Science Laboratory. Bigger, better, and nuclear powered with radioisotope thermoelectric generators.

P.S. cleaning a solar panel is hard [newscientist.com] . Did you really think the designers overlooked it?

Re:Okay...why haven't we? (1)

LUH 3418 (1429407) | more than 5 years ago | (#26907049)

I believe the rover accumulates energy in batteries. At some point, these batteries will be dead, so even with completely clean solar panels, it couldn't operate forever. Plus, other components on it could break.

They've shown that martian wind can actually keep the solar panels "clean enough" for long time periods... So if anything, this suggests that not including cleaning equipment is perfectly fine, even for long missions.

That being said, NASA is working on more advanced rovers, including some that can tackle more uneven terrain, if I'm not mistaken. We most likely will see rovers with more equipment on them, or specialized for different purposes.

should've gone with ... (0)

Anonymous Coward | more than 5 years ago | (#26906739)

nuclear rather than new clear energy.

Re:should've gone with ... (2, Informative)

Glendale2x (210533) | more than 5 years ago | (#26906831)

The next one will be; the Mars Science Laboratory will use radioisotope thermoelectric generators.

Re:should've gone with ... (1)

Tubal-Cain (1289912) | more than 5 years ago | (#26906887)

I'm not sure a "Radioisotope thermoelectric generators [wikipedia.org] " provide enough power to run the thing without being too heavy to have a hight likelihood of landing intact. Anyways, it's a 90-day mission. These generators are meant for missions longer than that (Viking and Voyager probes).

Re:should've gone with ... (1)

afidel (530433) | more than 5 years ago | (#26907465)

Sure it would, much of the 180Whrs used to keep the current rovers alive is surely to keep components warm enough which means even the 2.1kg SNAP-3B would be more than sufficient since it puts out almost 1300WHrs of heat per day along with 64.8WHrs of electricity which is the amount they have with the newly cleaned cells. Since just the cells in the 1.2m^2 array have a mass of ~1kg, when the frame and battery are considered I'm sure they have at least as much mass as that RTG.

Boy... (1)

Un pobre guey (593801) | more than 5 years ago | (#26906785)

Boy, those things were built!

What it really is (1)

slackoon (997078) | more than 5 years ago | (#26906905)

OK, so when is this thing going to replace ine Energizer Bunny in the commercials?

Well at least this mission taught us one thing... (1, Funny)

Anita Coney (648748) | more than 5 years ago | (#26906919)

... there are no homeless people on Mars.

I wonder if it would make sense to park the . . . (1)

mmell (832646) | more than 5 years ago | (#26906965)

on local ridges or some other local high points where they would get more exposure to wind. At the density of Mars' atmosphere, even a tornado wouldn't hurt the rovers. Don't need to stay there for long; just long enough to get electrical generation up past 28%.
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