Mars Rovers Update 320
BoldAC writes "CNN is reporting that engineers will upload a software hack to decrease the recent power drain plaguing the rover Opportunity. The hack works by reducing the power supply to a poorly functioning switch." p3tersen writes "Opportunity has photographed a blue martian sunset (it's blue because of the optical scattering properties of dust in the martian atmosphere). In other news, the rovers are beginning to experience power supply problems due to the accumulation of dust on their solar panels."
Solar problems (Score:5, Interesting)
Re:Solar problems (Score:2, Interesting)
I know you are joking, but I'm actually surprised that they haven't thought of a way to keep the solar panels clean.
I mean, they can get the thing to mars, they should be able to do that, no?
Re:Solar problems (Score:3, Informative)
Re:Solar problems (Score:4, Insightful)
Re:Solar problems (Score:4, Interesting)
Stack 10 sheets of this and voila, lifetime of the rover multiplied x10.
Re:Solar problems (Score:4, Insightful)
How is the motor supposed to pull the correct wire (you wouldn't use thread)? Ten different motors?
What do you do with the tear-off once you pull it? Leave it clumped at the bottom or just have hang around trailing behind the rover or right on top of the panels? Cut the wire you say? Kind of difficult to do that if you rolled the wire up on a spool with a motor. Going to need ten pyros for that.
Don't forget that you have to pack all of this onto the rover and fold up the panels. Better hope your wires don't tangle up and prevent the panels from unfolding.
All of this stuff takes up weight and adds complexity. Do you really want to do all of that?
Re:Solar problems (Score:5, Informative)
A simple set of 10 mechanical gears made of plastic and stacked in a row would do this. The driving gear jumps from first to last as needed. My printer does something similar to this everyday to a precission of 720 dpi so...
What do you do with the tear-off once you pull it?
Cut the wire between the plastic sheet and the gears that rolled the wire. No need to have 10 cutting devices, since only one wire will get rolled at a time.
Don't forget that you have to pack all of this onto the rover and fold up the panels.
Implement one of these in each fixed panel, not in the panels as a whole.
All of this stuff takes up weight and adds complexity
Sending 2 probes to Mars and getting scientific data back is waaaaay more complex than this. And the weight... it adds a little more $$ for fuel, but the result is a _much_ longer lifetime.
Re:Solar problems (Score:5, Informative)
Re:Solar problems (Score:3, Insightful)
Implement one of these in each fixed panel, not in the panels as a whole.
Another minor problem: this mechanism must be located the width of the panel away from the edge of the panel, i.e. any closer and it wouldn't be able to peel the layer off completely. Imagine, if you will, such a panel sitting before you with the film on it. Grab a corner of the film and attempt to remove it by pulling in a straight line, without l
Layers on Panels are a Bad Idea (Score:5, Insightful)
A thread attached to a corner of every plastic sheet running diagonally to the opposite corner and an electric motor that activates when the sheet is dirty.
Stack 10 sheets of this and voila, lifetime of the rover multiplied x10.
Conceptually, this is a great idea, except for one problem:
Every layer of $whatever you put on the panels attenuates some of the light striking the panels. The sunlight is also that much dimmer there (at the very least by the inverse square law of distance from the sun, if not also because of atmospheric conditions), so every single watt-hour those things can capture is critical.
Of course, to compensate for the thin film layers, they could have made the solar panels bigger - but that adds launch weight... not to mention the bigger solar panels would make the whole thing more top heavy and likely to tip over due to wind or ground obstructions, meaning you'd want to add size and wheelbase to this thing, meaning you'd need more solar panels... Do we see a vicious circle yet? [grin]
Re:Layers on Panels are a Bad Idea (Score:3, Funny)
And i know what i'm talkin' bout coz i park my car outside and never clean it
Re:Layers on Panels are a Bad Idea (Score:5, Insightful)
Yea, well, but i suppose accumulated dust attenuates way more light than a few thin plastic sheets, no?
Probably after a time, yeah. But the folks at NASA aren't stupid; I'm sure they would have come up with something like that - at least *after* Pathfinder if not before - and decided that cost/benefit analysis didn't make it worthwhile.
(ie. launch weight of the sheets and pulling mechanism, chances of binding and either obscuring a panel or getting caught in the wheels or instruments, chances of it catching the wind like a sail during sheet removal, reduced efficiency of cells over the long run rather than reduced efficiency of cells simply due to dust accumulation toward the end of the mission, etc.)
Re:Layers on Panels are a Bad Idea (Score:4, Funny)
They're so incredibly smart, in fact, that they don't even need to convert metric measurements to the archaic system they insist on using.
Go NASA!
Don't Knock US/Imperial/SAE Measurements! (Score:5, Insightful)
They're so incredibly smart, in fact, that they don't even need to convert metric measurements to the archaic system they insist on using.
Don't knock US/SAE measurements, there's a good reason they've stayed around.
For scientific analysis, without question, Metric rules.
But when you're actually building and working on things, most of the time a 10% tolerance is good enough. As a result, usually you can stick your thumb across something and say, "Yup, that's an inch - close enough". The base units are more intuitive, although admittedly the interconversion between units is a bitch - but conversions are more common in analysis than construction/maintenance.
My perspective here? Canada went Metric in 1976. I grew up in Metric. I went to school in Metric, fuelled up my cars in Metric, got a set of Metric wrenches when I was a kid, etc. Heck, you wanna know Metric inside and out? Try taking an engineering degree in Canada!
And yet, I know I'm 6'4" tall, 185lbs. I don't know in Metric.
Every time I work on a car, I want to know first, Metric or SAE? (And I don't mean the speedometer, they've all been Metric in Canada since 1976.) Not because I care which wrenches, sockets and feeler gauges I bring, but because I like working on SAE much more.
Why?
I've had more cars with Metric fasteners and specs than I have SAE, and yet, somehow, I can still just put my thumb across a bolt and know, "Hey, that's not 1/2", that's 7/16"!" Why can't I do that with Metric? I sure which I could, especially since I've got more experience with Metric.
Re:Layers on Panels are a Bad Idea (Score:4, Insightful)
Re:Layers on Panels are a Bad Idea (Score:3, Funny)
I like the way how you try to appear intelligent and how you capitalize "bad idea" to show what an eleet hax0r you are.
Ah, yes. My AC Fan Club at work again. I've been suspecting for a while that I have a stalker.
The subject line is the title of a diatribe, and in general, as a title, it should be capitalized.
If I wanted to be an "eleet hax0r", I probably would have capitalized the "A", for the full effect of "A Bad Idea". But I didn't.
Furthermore, I'm not gonna be much of a hax0r anyway; I'm an elect
agreed (Score:5, Funny)
Re:Solar problems (Score:3, Interesting)
Say, a step motor and some mechanical jiggery-pokery ending with a stiff wire, a hook on its end, the layers would have tabs with holes in them to pull at.
Or.. a glue between layers that deteriorates on contact with Martian athmosphere and so the layers will peel off after a fixed (based on chemistry) time.
I mean, give me a break, those took less then 10 seconds to come up with and I am sure NASA engineers could have thought up much more effective methods.
Re:Solar problems (Score:3, Interesting)
Re:Solar problems (Score:5, Interesting)
Hmm, after another 15 minutes of mental effort: a thin brush on an arm mounted to the side of the camera mast. You lower the (very thin and light single file brush) with a small step motor to the horizontal position and then you rotate the camera mast to create a sweeping motion on the panels. You could brush the 2 side panels that way, since if you planned for it, there would be no portruding gear to get in the way of the brush (all such gear would be back of the mast).
And so on...
I am really flabbergasted why there is absolutely no provision for any sort of cleaning (even a partial one) on the rovers. Its not like this wasnt expected. I smell some sort of hidden agenda in shortening the life of the rovers.
Re:Solar problems (Score:5, Interesting)
There have been many ideas tested for the solar panels, including removable plastic coverings, wiper blades, etc. None of them have proven practical. The dust on Mars is extremely fine and electrostatically charged. It sticks to the panels , and every other surface, amazingly well. Figuring out a way to remove Martian dust from surfaces is a field that a lot of thought and experiment has gone into, without discovering any feasible solutions, so far.
During the Pathfinder Mission in 1997, it was found that, by driving the rover over 'large' rocks (large for the rover), some of the larger dust can be shaken off. This is, as I've heard from members of the engineering team, something they intend to try with the MER rovers when needed. It doesn't make a huge improvement, on the order of a couple percent, but every little bit helps.
Re:Solar problems (Score:4, Insightful)
Re:Solar problems (Score:4, Insightful)
Not a likely situation.
Re:Solar problems (Score:4, Interesting)
Look harder! (Score:5, Funny)
Re:Solar problems (Score:4, Interesting)
Re:Solar problems (Score:3, Interesting)
look at the tape cleaning systems that have been around for oh, about 100 years... those problems have long been solved.
Re:Solar problems (Score:3, Insightful)
If you think the people t NASA can't figure it out, then nobody can, you are just kidding yourself.
Re:Solar problems (Score:4, Insightful)
I dont buy this for a second. Removal of fine, electro-statically dust, has been practiced on this planet for centuries if not millenia. There are entire industries [windex.com] based on this practice. I am convinced that it was one of those famous NASA managerial pissing contests that ensured no "feasible" or "practical" solution. Read: the companies which proposed the solutions were not part of the "in" crowd.
Re:Solar problems (Score:5, Insightful)
The key difference you're missing is, in your own words, "on this planet". The fact that the rovers are on mars has two important effects. First, the atmospheric composition, weather conditions, and the nature of the martian dust itself render common dust abatement methods here on earth ineffective. The most common, spraying liquid and wiping, is totally out of the question when the temperature is -20 to -80 degrees C. Second, the inaccessability of a rover on mars means that complex mechanical "wiping" solutions are out of the question-- there's no one there to smack the side of the unit when a cam arm gets stuck, or replace a solar panel when a wiper blade gouges it with a sharp pebble.
If you're so sure there's an easy solution, let's hear it. Your bizarre conspiracy theory makes no sense.
Re:Solar problems (Score:3, Interesting)
Why oh why would someone coat the panels with something that can even remotely be prone to chemically binding with soil?! And I am going to repeat the million times mentioned simple solution of a peel-off film! And guess what? ONE coat of peeloff film means twice the lifetime of the rover. Ponder that!
BTW, the RTGs are so politically loaded that noone is going to send any anywhere anytime soon. Besides they are apparently much heavier then they wante
electrostatic dust (Score:5, Interesting)
***SPOILER ALERT*** (and suggestion)
Since rubbing causes static electicity, they rub their faceplates together. One charges one polarity, the other the opposite. So one faceplate comes out even dustier, the other clean. The explorer with the clean faceplate can lead the other back to the vehicle.
Actually I always though static electricity came from rubbing dissimilar materials, so I wouldn't expect rubbing two identical-material faceplates to do squat. But there may be a lesson here. If the primary problem is really electrostatic, might there be some sort of electrostatic solution? (on future rovers) The most extreme would be an ion-wind generator with the 'benign' (dustwise) polarity attached to the panel. Another might be a charged wiper blade. I'm sure there could be other simpler electrostatic-based solutions.
Re:Solar problems (Score:3, Interesting)
Being particularly curious, I dug a couple out of the soil. Being covered in dust, the first thing they would do is make a loud buzzing noise to warm up (and which would shake off the dust) and then open their wing case and take off.
Would this method work with solar panels?
Re:Solar problems (Score:4, Interesting)
(1) Vibration.... the panels are lifted sideways and a motor at the top vibrates them for a few minutes. This will cost(1) the vibration motor (2) the lifting motor (3) lifting arm and hinges.
(2) Clapping two solar panels together.
(3) Compressed air. This is my fav. A small cylinder onboard could blow air across the panels about 10 times... increasing the life of the rovers 10 times. If theres enough gas in the atmosphere, replace the cylinder with a compressor. Its mechanically easy, less risk, and with a tiny compressor will add just a tiny bit of weight.
(4) Wiper blades. The blades will have feathers on them like a feather duster.
(5) Rotating panels. The panels would be disc-shaped and are rotated real fast like a CD to shake off the dust.
(6) Flippin panels. Turn the panels upside down for a little while. Optionally, jerk them.
(7) Roller film. Unlike camera film, one loop of film covers the panel and two axels at the panel ends loops the film around. Small brushes at one end will keep cleaning the film.
(8) Driving into rocks. The rover can tilt its panel forward facing and drive into a large rock with a bumper. That way the martians wouldnt think much of our intelligence and cancel the invasion.
(9) Tiny micro-rovers built by MIT undergrads to wander over the panels cleaning it. The micro-rovers will themselves have connectors to recharge. I'm thinking 2mm^2. Tricycle-shaped with a trailing brush.
(10) Drive over a high dune just before losing power. That way when theres a wind storm, enough dust will be blown away to allow the rover to communicate with the satellite. Hopefully, most of the dust will be blown away.
Some of the above ideas were taken from other posters. I believe they could have been used to build a rover that could in theory work forever.
Re:Solar problems (Score:3, Interesting)
Tilting and vibrating them might, possibly, shake some of the dust off?. Obviously this has to be balanced against the wear caused by the vibration so it may not be possible...
Re:Solar problems (Score:4, Interesting)
Just a guess based on Nasa commentary is the batteries will fail before the solar panels fail to charge them.
Re:Solar problems (Score:3, Funny)
got rid of all their squeegee guys!
Re:Solar problems (Score:5, Funny)
ACPI (Score:4, Funny)
You know, they could just tell the rover to use its ACPI functionality and go into standby and spin down its hard disks....
Fan (Score:4, Interesting)
The weight penalty should be offset by being able to work longer.
Or is the dust sticky? Maybe something akin to a wiper?
Re:Fan (Score:4, Interesting)
Re:Fan (Score:5, Informative)
The ONE robot arm cannot articulate to a position to reach the panels (it is mounted underneath). Also, the brush is made of wire. Not something you would want rubbing against a solar panel.
The RAT is not exactly a brush.. (Score:3, Informative)
In the same way you'd not be keen to use a RAT to brush your teeth, you probably would not wish to use the RAT to clean a transparent surface of a solar panel. In fact I think you may have just given some poor engineer at NASA a heart attack just by suggesting the RAT come near the solar panels!
Re:Fan (Score:2, Insightful)
Re:Fan (Score:3, Informative)
Lack of air mass. A fan on Mars would be only 1% the efficiency of the same fan on Earth, because there's that much less air. Plus then you're using more power and using up the batteries, to not much effect.
I would have suggested an electrostatic charger, like the old Diskwasher Zerostat, for removing the charge from vinyl LPs, making them easier to clean.
Re:Fan (Score:3, Interesting)
Besides, as has been pointed out, any solution adds power requirements, weight, and complexity/points of failure. Does the extra power provided by clean solar panels outweight the added risk of equipment failure?
What no Roomba? (Score:2, Troll)
Difficulties in planning space missions (Score:4, Insightful)
Re:Difficulties in planning space missions (Score:5, Informative)
I've also seen on SpaceFlight Now reports that projections show they will be probably be able to run both rovers well beyond the initially planned 90 days, so they're looking into plans for extended missions now.
However, like others on the thread have wondered, why not devise something to remove the dust? I'm sure there must be a good reason why they didn't do something - I can't imagine the NASA engineers simply didn't think about this.
Re:Difficulties in planning space missions (Score:3, Funny)
This just in from Saturn (Score:5, Interesting)
Re:This just in from Saturn (Score:5, Informative)
Re:This just in from Saturn (Score:3, Insightful)
Re:This just in from Saturn (Score:4, Informative)
Sure, try Jupiter [nasa.gov], or mabye Uranus [nasa.gov]. Of course, they aren't nearly as prominent; Saturn's rings are the only ones that can be easily seen by an amateur observer. However, I'd think that any solar system with gas giants has a decent chance of having ringed planets, as it's really just dust and rocks that have fallen into a stable orbit and haven't globbed together into a moon. We couldn't really directly detect ringed planets around other stars from Earth; the distances are just too great. It would be great, though, to send some sort of interstellar probe to a distant solar system and have our heirs recieve images of a Saturn-like ringed planet.
Also from space: "Humble" telescope (Score:4, Informative)
It's a neat little $10 million 50 kilo unit. The best part is that a software upgrade improved the stability 10x. Hopefully there'll be some pictures soon.
Seasonal changes (Score:5, Interesting)
Dan East
Re:Seasonal changes (Score:5, Insightful)
"CNN is reporting that engineers will upload a software hack to decrease the recent power drain plaguing the rover Opportunity. The hack works by reducing the power supply to a poorly functioning switch." p3tersen writes "Opportunity has photographed a blue martian sunset (it's blue because of the optical scattering properties of dust in the martian atmosphere). In other news, the rovers are beginning to experience power supply problems due to the accumulation of dust on their solar panels."
Dan East
As nice as it would be... (Score:3, Informative)
Re:As nice as it would be... (Score:3, Insightful)
That is a good fact. But from my viewpoint the major cost has been the mission failures. All that money spent when a probe goes up in smoke is just completely gone with absolutely no return. It seems to me that 90% of the problem is getting the probe simply to have a successful landing. Since
Re:As nice as it would be... (Score:4, Interesting)
There are 2 types of cost involved in this daily figure, those that are 'out of pocket' and those that are 'just accounting'. Take for example, the DSN time used to retrieve data from the rovers. Yes, it's very expensive I'm sure, those deep space monitoring stations cannot be cheap to build and operate. Every hour they spend pointed at mars collecting data from the MER vehicles is surely tracked, and cost accounted to the MER program, and rightfully so. BUT, it's not like they wouldn't cost anything if they were not pointed at the mars probes, the actual cost of operating the DSN system is for all practical purposes a known and fixed cost, and it's gonna be paid, no matter where they are pointed. This is why I'd call that portion of the daily cost 'just accounting', because the taxpayer is going to foot the bill for the deep space network, regardless of where it's pointed. But, when it's pointed at mars, the mars programs are being accounted as the 'cost', and rightfully so.
While the rovers are on active surface mission, there are a lot of extra people hanging around jpl, and i'm sure most of them are 'rather expensive' to keep on hand. this type of expense is 'out of pocket', it's an expense that wouldn't be happening if the rovers were not on surface mission. My own guess offhand is that the 3 million a day is probably half and half, one half true 'out of pocket' expenses, and the other half just accounting for equipment/personnel that would be on hand anyways, but are currently involved in the MER program. For the sake of easy math tho, I'm gonna suggest 1 mill is 'accounting' and 2 mill is 'real cost'.
Now take a look at the overall value proposition. the entire program is running in the 850 million range, and it's targetted for 2 rovers on surface, for 90 days each. That's 180 science days for a total cost of 850 million, or 4.72 million per active rover science day, as per mission parameters. this was the value proposition of the original mission, and the mission(s) were launched on this basis.
Now that surface operations are in progress, the daily burn rate is 3 million, for 2 rovers on surface. If a million of that is stuff like accounting for dsn time, then 2 million is the actual 'out of pocket' expense, or approximately 1 million per rover science day. this is 21% of the projected overall cost per day of science returned on the original budget.
The up front cost of placing the equipment on the surface of mars has been absorbed, and is planned to amortize over the first 90 days on surface. After 90 days, it becomes a simple value proposition. The 'real cost' of maintaining full operations earthside is 21% of the original budget. In terms of the 'accounting costs' for things like the dsn time, it's the same type of value proposition. The dsn network WILL be kept busy, it's simply a case of determining where there is more value. The 70 meter dish can point out at voyageur and get engineering data from the deep space probe (which will still be there in another 2 months), or it can point at mars, and take advantage of the 'limited time offer' of recieving martian data at 79% discount off the 'full retail' price that was paid for the first 90 days of surface time.
This is a large project, with lots of accounting involved, and surely there's more than its fair share of 'pork' buried in the 850 million price tag. BUT, it's real right now, and the real cost of retrieving a day of data from a single rover is in the range of $1 million. Considering the 'full retail' price for that runs 4.72 million after you amortize in all the launch costs etc, this is one time when a significant budget overrun due to 'extended surface time' is an absolute bargain.
This is kind of a double edged sword though. A design life of 90 days means there is budget for 90 days of operation. An overrun of 90 days on operational time represents a huge value proposition for
Dust on solar panels issue (Score:5, Insightful)
1. It's going to weight more.
2. It's another potential failure.
3. IF it fails, it can cause other things to fail (say, for example, a switch sticks ON and it drains the battery)
Not installing a wiper or other device to clear the solar panel wasn't an oversight. They made a (probably) well-informed decision not to install such a device. I think the progress so far is remarkable and should be commended. Hopefully they've learned a lot and can make improvements for the next mission.
Hindsight is always 20/20...
The Martian Dust (Score:5, Interesting)
One thought I had was to gradually apply a charge to the solar panels and then suddenly apply an opposite charge, causing the dust to be repelled from the surface, to be carried away by the Martian winds.
I've no idea if it would actually work or not, but it seemed an elegant solution that didn't require any moving parts.
Re:The Martian Dust (Score:4, Interesting)
Probably using a vaccum would not damage the glass. Although this approach also adds more complexity...
>>> One thought I had was to gradually apply a charge to the solar panels and then suddenly apply an opposite charge, causing the dust to be repelled from the surface, to be carried away by the Martian winds.
Unfortunately this will not work since the electrical charge is not uniformy applied in only one direction on the surface glass. The small irregularities of the surface will cause a variation in the electrical distribution over time - for example a small peak in the glass might be more positively charged compared with inner of a nearly-located scratch. The same thing happens on some dust particles - due to their free movement in the air, their electrical distribution will end up non-uniform as well. So they will end up attracting as magnets - the small peak will attract particles on their negative-charged part, and the scratch will do the same on positively-charged surfaces. Now, since all these materials are good electrical insulators, the non-uniform distribution will stick on for a long time.
Probably what would help is to use a blower that would wipe off the dust with martian air. The blown air needs to be ionized to prevent more electrostatic charge to add up by just blowing. The ionized air will have a weak electrical conductivity which will tend to "shortcut" the charged areas. Now, since the martian air is mostly CO2 this pre-ionization process shouldn't require too high voltages - the energy consumption would be pretty low...
Re:The Martian Dust (Score:3, Interesting)
Degauss the solar panels? Brilliant!
~UP
Re:The Martian Dust (Score:3, Interesting)
Blue Sunset is NO Surprise (Score:5, Funny)
It just plain makes sense, when you think about it.
The whole solar thing... (Score:5, Interesting)
Why did NASA stray from 'nuclear' batteries, like they've used with the Pioneer, Galileo, Voyager and Cassini missions? Those could power a rover for years.
And what's stopping them from making a way to keep the panels clear? This is what contributed to the end of the Pathfinder mission...What is it about solutions to this problem that make them so difficult to implement?
Wipers add an extra mechanical system to worry about, but what about static fields? Maybe there could be a way to attract the dust to a specific area while keep the the panels clear?
Re:The whole solar thing... (Score:4, Interesting)
And I'll give the NASA geeks the benefit of the doubt that if there were a reliable and cost-effective wy of cleaning the solar panels, they would have implemented it long ago.
Re:The whole solar thing... (Score:5, Insightful)
Most likely because the batteries would out-last the rover itself. It's a complex machine in a hostile environment- something will fairly soon. The solar panels will probably still be operating well after the rovers themselves have failed.
Re:The whole solar thing... (Score:4, Insightful)
This mission is a landing mission in the inner solar system, where the sun is bright enough to power the landers.
Second, the use of radioelectric power generators is risky, dangerous and expensive. If there's a less risky, less dangerous and less expensive option, NASA will gladly take it.
No_Nukes = Cost * PR^^2 (Score:5, Informative)
So why nukes for Viking, and none for MER A & B?
1) Viking had money. Sure, NASA was getting into a budget hurt locker by the time the missions made it to Mars in '76, but the money was there when it was needed during the planning and construction. The landers got the kitchen sink, and the biggest Titan II launchers then avaiable to get 'em going. By contrast, the MER team had to make sure their package was not much heavier and absolutely no bigger than Pathfinder. The planetary missions are bastard stepchildren to a NASA which is mandated to keep the Space Shuttle and ISS going on an inadequate budget, even if it all went to the manned space program.
2) Three Mile Island, Chernobyl. Hadn't happened yet, so the no nukes crowd was still the wacko fringe during Viking. Compare to the fuss made over Cassini before launch and while making a gravity-assist Earth flyby. "200,000 deaths!" "Dump it in the Sun!" In general, people have mellowed out a bit, but the PR angle makes a good excuse when one doesn't have the money to gold-plate a mission, anyway.
Re:mainly because people are ignorant (Score:3, Insightful)
Challenger. Columbia. Nuclear?
Re:mainly because people are ignorant (Score:5, Informative)
In 1968, a SNAP 19-B2 RTG landed in the Pacific after its launch vehicle failed to reach orbit and was destroyed. They fished it out and re-used it on a later mission. Apollo 13's lunar module also had an RTG which re-entered and landed, intact, in the Pacific. No nuclear material was released.
The Challenger explosion generated pressures well under 2000 psi. The theoretical worst case for a hydrogen-oxygen explosion is 2075 psi, with a reflected peak pressure of 5300 psi. RTGs are designed and tested at 19,600 psi.
Shuttle explosions won't cause a release of nuclear material from an RTG. They're not only designed for such failures, they've been tested to survive them, both in the lab and in real life failures.
Re:mainly because people are ignorant (Score:3, Insightful)
Shrapnel propelled by an overpressure of 5300psi isn't going to hurt a a hardened unit than can take 19,600psi. The physics just aren't there.
Remember using similar statistical data the US military calculated that the M1 tank was invincible against RPG attacks, yet the Iraqis managed to destroy one in last the war.
I seriously doubt you are privy to the statistical data for either case you mention, and besides
Re:mainly because people are ignorant (Score:3, Informative)
In fact, the TD50 of Pu236 is compareable to nicotin.
Its not healthy, yes, but it isnt that bad.
Clean Solar cells, Do what porn stars do! (Score:4, Insightful)
I've been reading all the other posts, Every idea from peelable plastic sheets to fans..
Just attatch a vibrating motor to the underside of the solar panels. When it's time for them to get clean, just raise them to a 90 degree angle, turn on the "orgasmotron vibrating motors" and shake the dust off?
Maybe I watch too much pr0n, but I'm sure that would work for the heavier dust. Especially since there was an earlier comment on how the engineers purposefully drive these things over rocks to shake off the larger dust particles.
One more thing, movable solar panels can track the sun, and give better light collecting efficiency than ones that just sit there stationary.
--toq
Re:Clean Solar cells, Do what porn stars do! (Score:4, Insightful)
Re:Clean Solar cells, Do what porn stars do! (Score:3, Informative)
Because I want one in space (Score:5, Funny)
Sunset (Score:4, Insightful)
I have to say though, despite being an extremely short video clip, it is one of the most awe inspiring things I've seen in a while. Think about it. We just viewed a sunset ON ANOTHER PLANET. I can just imagine an art gallery featuring nothing but pictures of sunsets on other planets. As much as I love our planet Earth, I hope the day comes when I'll be able to stand on Mars and watch this for myself. The beauty of the universe is infinite, but every now and then a little piece of that beauty finds its way back to Earth, and we experience this beauty, and smile a little, not quite realizing the magnitude of what has just occured.
Re:Sunset (Score:3, Interesting)
The sky would be red as normal, but sometimes there would be a halo of blue sky surrounding the sun. Only sometimes because it depends on the amount of dust in the air. The Pathfinder mission saw sunsets with and without the halo. The halo may also happen during the daytime. There have been no colour pictures of the sun when it's high in the Mars s
No power supply problem, just less power (Score:5, Insightful)
This makes things sound worse than they actually are. They are not beginning to experience power supply problems -- they are simply getting less power than they were when it first landed, and they are taking some steps to operate more efficiently.
From SpaceFlightNow, in the report for THURSDAY, FEBRUARY 26, 2004 2215 GMT (5:15 p.m. EST) [spaceflightnow.com]:
From the Reuters [reuters.com] report:
What the NASA official (Richard Cook) actually said was: "The vehicle is continuing to perform fine but we are starting to modify our daily process to respond to the decreasing power."
Both the dust accumulation and the decrease of sunlight were anticipated. The lifetime (designed to be 90 days) of each Rover is determined when the batteries can no longer be charged enough to survive the cold nights. Spirit is already 54 days into its 90-day "death sentence".
Concerning charged particles... (Score:3, Interesting)
Astronomy Picture of the Day (Score:3, Informative)
They don't want long life for rovers (Score:4, Interesting)
Cost aside, there most likely is a way to greatly extend the life of a rover.
From the noises NASA has been making, there will be a series of unmanned missions to Mars before an attempt to send humans will be made (I don't necessarily agree with the premise of sending humans to Mars).
NASA has said the limiting factor is power, because of the dust accumulation on the solar panels.
Let's say that the cost of implementing a way to eliminate the dust doubled the cost of the mission (probably would be less). If dust were eliminated, then the rovers could operate until the batteries could not longer hold a sufficient charge to do science.
What I'm getting at here is politics. A solution could be engineered to greatly extend the life of the rovers. But that would result in a reduced number of missions and *less funding*.
Ok, I've removed my tinfoil hat. Comments?
Blue skys on Mars ... (Score:3, Funny)
the martian atmosphere
That's Scullys Xplanation.
Mulder says different.
Or it's because NASA's mission faking division forgot to photoshop the
images before releasing em.
It's called fines, not dust! (Score:3, Interesting)
That's like calling dust gravel, jeeze.
(with apologies to KSR's Red Mars)
The obvious joke (Score:3, Funny)
Why no solution to remove dust (Score:4, Insightful)
What? (Score:4, Informative)
Rover Science Reports (Score:3, Insightful)
I attended a talk on this today at Texas A&M (Score:5, Informative)
So I just happened to be lucky enough to get front row seats (I work as a sysadmin in the physics department here) to a talk by one of the people on the JPL team that works on the lander, and he mentioned this earlier. It's a bit more than a little hack to the software because it involves changing out the operating system and turning the rover completely off during the night to avoid power drain. What the fellow talking about it mentioned was that there is the possibility that the rover wont actually turn back on after the update, leaving a $400 million piece of junk on the surface of mars.
The reason for the update is needed because there is a heater on the rover that defrosts the probe that allows them to take samples from the rocks and such--which wont turn off anymore. This might not be a problem except that it puts an excess power strain on the rover, meaning that its useful life is greatly diminished. So essentially this hack means turning everything off at night because they can't switch off just the heater.
Latest Image (Score:3, Funny)
Re:Java problems? (Score:5, Informative)
Repeat after me.
There is NO Java on the rovers. Java is used on the ground to process the results.
Idiot. Enough has been posted on this site about where Java is being used.
Re:Java problems? (Score:5, Interesting)
That isn't a slight against Java. It's just that they need real-time software, which can't be had with an interpreted language (even if it is only interpreted from bytecode).
How fast do you think a 20mhz processor could run a Java app?
Re:Java problems? (Score:5, Informative)
i.e. I need a real-time OS & software stack if my rocket control algorithm needs the data from, say, a serial port altimiter within the next 20 milliseconds or else. if you cant get the data within the specified timeframe then the results are useless. the system will not accept requests that it cannot "guarantee" to fulfil from a system resource standpoint. (you have to watch your multitasking, swapping and other kernel-level tasks to achieve this)
so you could have a 20 mhz "real-time" system, as long as it's response was guaranteed by the OS within parameters for what you are doing (and you would program with those guaranteed response times in mind.) Conversely, a 20 Ghz system may not qualify for real time, if the OS pre-empts your rocket control task and decides to swap for a few milliseconds too long, or context switches to another thread just when you needed to adjust a control surface...
when you hear about people hacking linux for real-time work, they are not making it go faster (though that's always nice), they're making it work predictable.
Re:Java problems? (Score:3, Informative)
you can get real-time behavior out of an interpreted system, if both the interpreter and underlying operating system are designed for it. For Java, GC and instruction transla
Re:Planning Ahead (Score:5, Insightful)
Given CNN's lack of technical depth, for all we know it could be a command to the rover to tell it not to turn on the heater anymore. Either way, they designed the rovers so they can fix them while they're in space, which is pretty good.
Given the limited amount of storage on the rover, it's a higher priority to make sure the upgrade process works, and that it is possible to fix stuff with software, than to make the rover fix stuff automagically.
Re:Planning Ahead (Score:5, Informative)
Re:Compressed Gas to blow the dust off? (Score:5, Informative)