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Seriously, you can pick up a pair at your local Pep-Boys

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I'm not a scientist, nor do I play one on the Interweb Tubes, but I still can't believe it would be that big of a deal to put a pair of wipers on the solar panels of the rovers we send to Mars.

It seems like this story happens a bit

Controllers Cheer as Data Arrive from NASA's Spirit Rover

The deck of NASA's Mars Exploration Rover Spirit is so dusty that the rover almost blends into the dusty background.

Image credit: NASA/JPL-Caltech/Cornel

Full Image and Caption

Any of you mad rocket scientists out there care to explain why a small set of wipers wouldn't work here?

posted @ 12/8/2008 1:02:45 PM

Comments

Gregory Morris says:

on 12/8/2008 1:11:46 PM

IANARS, but I believe that would have been far too simple for NASA engineers. For future missions, they might come up with some static dust repulsion mechanism, or a fancy gyroscopically stabilized robotic airjet system. But wipers? That'd be too easy. They prefer to be challenged.

Michael Hawkins says:

on 12/8/2008 1:44:24 PM

Wipers would ... err ... put scratches on the panels?

MadRocketScientist says:

on 12/8/2008 1:47:31 PM

As with all things that operate without the support of Terra Firma, weight is king. A wiper blade with motor adds weight that must be tossed into space, shot across millions of miles, and then dropped.

And if you don't use the good rubber on the blades to withstand the cold (Mars is chilly), you'll get those annoying streaks.

Robb Allen says:

on 12/8/2008 1:52:44 PM

I could understand weight to a point, and I realize that "it's only a pound" only works when you're just adding a single part and that you have to take into consideration all the other "only one pound" things you have to cut as well. It just seems like you'd want to prolong the life of the mission and could do so by a simple brush system that could remove the dust.

(and I KNEW MRS would take the bait ;)

OrangeNeckInNY says:

on 12/8/2008 2:00:05 PM

They're already working on a Star Trek type energy shield system using a magnetic field generator around the "ship."

MadRocketScientist says:

on 12/8/2008 2:21:31 PM

I do believe the electrostatic repulsion system actually does work now, but it wasn't ready for the Mars rovers.

Robb: DUH! Of course I'm gonna take that bait!

And it would be more than a pound most likely, since you'd need at least three units. Actually, the best idea would have been a little airjet that sits in the center and rotates. Screens get dusty, the jet does a sweep.

joe says:

on 12/8/2008 2:32:00 PM

Because Mars is so different from earth, they weren't sure what would work. Also the rovers were only spec-ed for 90 days and in that time frame it wasn't like to be a issue. The dust on the panels have in fact behaved in ways they haven't understood, being blown clean of dust by winds wwhen it wasn't expected.

Myles says:

on 12/8/2008 2:44:05 PM

"Actually, the best idea would have been a little airjet that sits in the center and rotates. Screens get dusty, the jet does a sweep."

Wouldn't the lower air pressure of Mars negate the pressure out of the airjet?

MadRocketScientist says:

on 12/8/2008 3:07:19 PM

"Wouldn't the lower air pressure of Mars negate the pressure out of the airjet? "

That's just a case of nozzle design. Mars has air, and winds strong enough to kick up a sandstorm, so a jet of air stands a fair chance of working, and because of the lower air pressure, you would not even need as powerful of a compressor as you do here on earth (the pressure difference is key). The only thing you'd have to do is design the nozzle right, which isn't a huge deal, we've been making nozzles that work at sea level all the way up to orbit (granted not the same nozzle).

Joe has the real answer, the critter was only meant to last 90 days, anything after that was a bonus.

Anthony says:

on 12/8/2008 3:19:21 PM

Can't put wipers on because they would have to send another rover up in 6 months to change the wipers lol

Gregory Morris says:

on 12/8/2008 3:20:03 PM

The next question is, why would they be spending millions of dollars for only a 90 day mission? Actually, the two rovers' longevity is likely to be a curse, because now NASA will be expected to over-achieve like that. I'm all for it :)

Gregory Morris says:

on 12/8/2008 3:22:52 PM

Case in point: marsprogram.jpl.nasa.gov/missions/future/msl.html
It launches in less than a year and doesn't use solar panels.

OrangeNeckInNY says:

on 12/8/2008 3:43:25 PM

Speaking of wiper blades, I bought ONE Rain-X wiper blade with the new design and they vibrate against the windshield when you're traveling at 80mph. They're a lot fatter than the regular wiper blades. Plus they still streak. They're not much better than regular wiper blades. Actually, they're worse. Three months with it and it already needs changing. Rain-X wiper blades - EPIC FAIL!

Robb Allen says:

on 12/8/2008 3:44:29 PM

I don't think 80MPH travel + Rain is something they have to worry 'bout on Mars.

MadRocketScientist says:

on 12/8/2008 4:42:45 PM

"It launches in less than a year and doesn't use solar panels."

That is how all such probes should be powered. Screw solar, it is a great backup power, but bad for primary power is the dark of space.

Stupid Greenpeace (or whoever it was that pitched a fit about sending radioactive material into orbit)

OrangeNeckInNY says:

on 12/8/2008 5:36:49 PM

No no no, they were vibrating against the windshield in the 'Off' position. It wasn't raining. It's a design flaw. It acts like an air dam and vibrates up and down resonating with the air flow oscillating over it at 80 mph.

Standard Mischief says:

on 12/8/2008 9:31:10 PM

well, yea it would cut into the weight and power budget. And the 90 days? That's NASA keeping their expectations low.

I enjoyed the time I worked for NASA as a contractor, but damn, don't forget that they're a government agency.

Scott says:

on 12/9/2008 2:18:52 AM

As stated above:

1) Extremely gritty dust, and would scratch the blazes out of the solar panels, leading to the same end result.
2) They were only to last 90 days, and they're well into FOUR YEARS.
3) Weight, weight, weight. Pounds? The engineers work on shaving grams!
4) Air jets? The dust/grit adheres due in large part to static electricity. Blowing does little - even builds up more static electricity.

Can I go to bed now?

Joe Mama says:

on 12/9/2008 8:22:32 AM

Get one of those New York window washer bums and strap him down off to the side. Add a dispenser that will shoot out a dollar bill every now and then. Problem solved!

George says:

on 12/9/2008 1:42:46 PM

I saw a lecture by a project executive. It seems that periodically, the rover gets hit by dust devils the wind blows all the dust off. It is so pronounced that they can watch the uptick in the power generated by the panels and they know they have been hit.

One more reason wipers won't work...power budget. They are exceptionally restricted in terms of how many watts they can use.

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