NASA Mars Rover Spirit May Move Forward By Spinning Its Wheels

coondoggie writes "As NASA celebrates its Mars rover Spirit's sixth anniversary exploring the red planet, it is hunting for a way to keep the machine, which is mired in a sand trap, alive to see a seventh year. On its Web site, the space agency this week noted there may indeed be such an option. That option would be spinning the wheels on the north side of Spirit, letting it dig in deeper in the Martian sand but at the same time improving the tilt of the rover's solar panels toward the Sun."

Comments

Incredibly silly headline

[Vyse of Arcadia]

That ranks up there with "People kept alive by breathing."

Re:Incredibly silly headline

[Anonymous Coward]

"Spinning its wheels" is technically what wheeled vehicles do while in motion, but idiomatically, it refers to wheelspin on sand/snow/etc. that doesn't result in forward/backward motion. It's commonly used as a metaphor for futile action, and so when the literal case turns out to be beneficial, the result is a mildly amusing headline. To use your example, it's more like "people kept alive by breathing water", in that it's the opposite of what you'd expect.

Re:Incredibly silly headline

[mea37]

I agree, except you also have to realize that they're using "move forward" idiomatically, in that this idea may keep the rover functioning longer but will increase the chance that it is stationary for the remainder of its functional lifetime.

HillBilly Engineering at its Finest

[Anonymous Coward]

Floor it!

Re:Let's start digging then...

[Geoffrey.landis]

The difference is that winter is coming, and the sun gets low on the horizon. We can, if we chose, dig in on one side so that we tilt toward the sun, which means that we will get more solar energy, and so the solar powered rover will survive the winter.

(We've tilted the rover into the sun every winter so far-- if we don't, this will be the first winter we've tried to survive without tilting into the sun)

And one should add

[Sycraft-fu]

The rover was designed for a 90 day mission. If it made it to Mars operational, and was capable of operating for 90 (martian) days, the mission was a success. Here we are, years later and it is still working. It isn't as though this is a panic "Oh no we have to save the mission!" kind of thing. Rather, this is another step to see how long they can extend a tremendously successful mission. Even if the rover dies tomorrow, it will have far surpassed any expectations set for it.

Also of note is that Opportunity, the other of the two rovers launched, is currently trucking along towards a crater they want to look at.

Re:And one should add

[Osmosis_Garett]

Actually, Opportunity is examining the damaged heat shield from re-entry, which it just arrived at the other day.

Re:And one should add

[Kjella]

Was it really designed for 90 days? It could be that the only way they could sell it to Congress was if they told them that they only had to pay for technicians for 3 months.

Well, yes and no. The models suggested that the solar panels would be clogged up with dust so it'd be like a car with an empty gas tank, after 90 sols it'd be still in great condition but out of juice so that was the mission. In practice dust devils clear most of the dust, but noone knew that before they arrived. Perhaps some speculated and hoped, but certainly not knew or assumed. Nothing about the rover was intentionally limited to three months, though if they knew they'd be out there for many years I'm sure some design choices would have been different. But that's why we can send a second generation if and when these rovers finally kick the bucket.

Re:Heh

[CarlDenny]

Except then you're putting all your eggs in one basket if there's a landslide that drags them both down, a sandstorm that prevents solar charging, or a problem on landing.

Maybe if we sent up two identical rovers, but dropped them off independently at different points on the planet?

Proof of the tenacity and ingenuity of humanity

[preaction]

7 years ago we put together a robot designed to survive a journey off of our own planet (secured to a fireball), through the vacuum of space (oxygen-breathing life need not apply), land on another planet (falling from miles above the surface) about which little is known (and nothing about the proper tire to use in a martian dust-pit). This tiny robot was hoped to survive for 90 days. It has survived for more than 2,500 days. This tiny moment of reflection brought to you by the You Really Are Alive In A Great Period of History Foundation.

Re:Heh

[Muad'Dave]

One of the key issues is having power enough to heat them in the winter.

If the supposedly 'enlightened' greenies wouldn't raise a huge ruckus, the answer is to either alloy Gadolinium 148 into the frame or just have a block of it hanging around. It gives off a huge amount of heat, and essentially no radiation that would harm the rover (it's one of the few strong pure alpha-emitting isotopes).

A fascinating paper on powering medical implants with radionuclides states:

A ~0.2 kg block of pure Gd148 (~1 in^3) initially yields ~120 watts, sufficient in theory to meet the complete basal power needs of an entire human body for ~1 century (given suitable nucleochemical energy conversion and load buffering mechanisms, and a sufficiently well-divided structure).

Also from that paper, an amazingly small sphere of Gd 148 can power small implants:

Among all gamma-free alpha-only emitters with t1/2 > 10^6 sec, the highest volumetric power density is available using Gd148 (gadolinium) which a-decays directly to Sm144 (samarium), a stable rare-earth isotope. A solid sphere of pure Gd148 (~7900 kg/m3) of radius r = 95 microns surrounded by a 5-micron thick platinum shield (total device radius R = 100 microns) and a thin polished silver coating of emissivity er = 0.02 suspended in vacuo would initially maintain a constant temperature T2 (far from a surface held at T1 = 310 K) of [ 600 K ] with a 75-year half-life, initially generating 17 microwatts of thermal power which can be converted to 8 microwatts of mechanical power by a Stirling engine operating at ~50% efficiency.

Re:Design

[MobyDisk]

I really hope you are joking.

If not, you saying that that a rover that survived for 8 years, that was supposed to only survive 90 days - was poorly designed. Oh, and NASA should have known about this problem (based on all the other rovers we've sent over the years) and added a complicated jacking mechanism and bigger wheels. And I guess, if in 20 years it gets attacked by aliens someone will post "oh, and they should have seen this coming and added laser defenses."