Reliable nuclear device to heat, power Mars Science Lab

Nov 21, 2011
The Mars Science Laboratory's radioisotope power system was fueled and tested at Idaho National Laboratory. Here, magnetic testing ensures that the electric field generated by the system is small enough that it won't interfere with the rover's scientific instruments. Credit: Idaho National Laboratory

NASA's Mars Science Laboratory mission, which is scheduled to launch this week, has the potential to be the most productive Mars surface mission in history. That's due in part to its nuclear heat and power source.

When the rover Curiosity heads to space as early as Saturday, it will carry the most advanced payload of scientific gear ever used on Mars' surface. Those instruments will get their lifeblood from a radioisotope power system assembled and tested at Idaho National Laboratory. The Multi-Mission Radioisotope is the latest "space battery" that can reliably power a deep for many years.

The device provides a continuous source of heat and power for the rover's instruments. NASA has used nuclear generators to safely and reliably power 26 missions over the past 50 years. New generators like the one destined for Mars are painstakingly assembled and extensively tested at INL before heading to space.

"This power system will enable Curiosity to complete its ambitious expedition in Mars' and seasons," said Stephen Johnson, director of INL's Space and Technology Division. "When the unit leaves here, we've verified every aspect of its performance and made sure it's in good shape when it gets to ."

The power system provides about 110 watts of electricity and can run continuously for many years. The is protected by multiple layers of safety features that have each undergone rigorous testing under varied accident scenarios.

The INL team began assembling the mission's power source in summer 2008. By December of that year, the power system was fully fueled, assembled and ready for testing. INL performs a series of tests to verify that such systems will perform as designed during their missions. These tests include:

  • Vibrational testing to simulate conditions.
  • Magnetic testing to ensure the system's won't affect the rover's sensitive scientific equipment.
  • Mass properties tests to determine the center of gravity, which impacts thruster calculations for moving the rover.
  • Thermal vacuum testing to verify operation on a planet's surface or in the cold vacuum of space.
INL completed its tests in May 2009, but by then the planned September 2009 launch had been delayed until this month because of hurdles with other parts of the mission. So INL stored the power system until earlier this summer, when it was shipped to Kennedy Space Center and mated up with the rover to ensure everything fit and worked as designed.

The system will supply warmth and electricity to Curiosity and its scientific instruments using heat from nuclear decay. The generator is fueled with a ceramic form of plutonium dioxide encased in multiple layers of protective materials including iridium capsules and high-strength graphite blocks. As the plutonium naturally decays, it gives off heat, which is circulated through the rover by heat transfer fluid plumbed throughout the system. Electric voltage is produced by using thermocouples, which exploit the temperature difference between the heat source and the cold exterior. More details about the system are in a fact sheet here: http://www.inl.gov/marsrover/.

Curiosity is expected to land on Mars in August 2012 and carry out its mission over 23 months. It will investigate Mars' Gale Crater for clues about whether environmental conditions there have favored the development of microbial life, and to preserve any evidence it finds.

NASA chose to use a nuclear power source because solar power alternatives did not meet the full range of the mission's requirements. Only the radioisotope allows full-time communication with the rover during its atmospheric entry, descent and landing regardless of the landing site. And the nuclear powered rover can go farther, travel to more places, last longer, and power and heat a larger and more capable scientific payload compared to the solar power alternative NASA studied.

"You can operate with solar panels on Mars, you just can't operate everywhere," said Johnson. "This gives you an opportunity to go anywhere you want on the planet, not be limited to the areas that have sunlight and not have to put the rover to sleep at night."

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User comments : 16

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jsa09
5 / 5 (5) Nov 22, 2011
1) Just how big is the nuclear power plant including the water storage and thermocouples?

2) How big a power plant would I need to run my car?
antialias_physorg
5 / 5 (7) Nov 22, 2011

Don't know about the size, but the thing weighs 43kg and produces 120 watts (according to wikipedia)

I'll take my car as an example (80kW - which roughly corresponds to 108hp)

In order to run such a car you'd be lugging around about 285 tons of reactor (and producing about 2.5MW of heat at the same time which you'd need to get rid of somehow). Needless to say that a 80kW car isn't going anywhere with 285 tons in tow.

Oh yeah...you'd also have over three tons of plutonium on board.

On the upside: You'd never need to refuel again.

Well, not until the half life of the plutonium drops it to unsuable levels (80 years later your car would only have 40kW)
Jimbaloid
5 / 5 (4) Nov 22, 2011
285 tons


Please can you break down you math for me. I might be wrong, but it looks like you did 43/120 to get some kind of kg per watt figure and multiplied up by 80,000. Which is 28.6 tonnes (or 31.6 ton), i.e. a whole order of magnitude smaller than you get. It doesn't invalidate your point entirely, though I'm not so sure things would scale linearly like that.
Vendicar_Decarian
3 / 5 (2) Nov 22, 2011
On the other hand I could easily power my house with 4 of those Mars lab generators.
antialias_physorg
5 / 5 (3) Nov 22, 2011
Jimbaloid you're right...just rechecked the math and I'm off by an order of magnitude. Good catch.

On the other hand I could easily power my house with 4 of those Mars lab generators.

You draw 480 Watts max?
Here's typical wattages for some home appliances:
Coffee maker: 9001200
Clothes washer: 350500
Clothes dryer: 18005000
Dishwasher: 12002400
Toaster: 8001400
Vacuum cleaner: 10001440
Water heater (40 gallon): 45005500
Refrigerator (frost-free, 16 cubic feet): 725

Source:
http://www.energy...ic=10040

Unless you're Amish I think that won't work.

antialias_physorg
5 / 5 (2) Nov 22, 2011
though I'm not so sure things would scale linearly like that.

I'm sure it wouldn't scale linearly. But with the small contraption already weighing 43kg even the most optimistic scaling can't reach a level where this would be sensible for a car (or a home)..Totally ignoring that plutonium isn't exactly one of the safest things to be around radiation and toxicity wise.

Plus: You'd need a containment vessel that is maintenance free (under considerable thermal stress) for hundreds/thousands of years. Not sure we CAN even manufacture something like this.
JaySeattle
5 / 5 (1) Nov 22, 2011
If you want to power your car with one of these babies, a hybrid approach is best. Use several of them to charge the battery bank of an electric car. 10 units would deliver 28 kwhr of the course of a day, enough for about 100 miles of driving per day.
Skepticus
not rated yet Nov 22, 2011
All those figure are for thermocouple energy conversion technology. If a better way can be used safely, we don' need tons and tons of hardware.
Nerdyguy
3 / 5 (2) Nov 22, 2011
Jimbaloid you're right...just rechecked the math and I'm off by an order of magnitude. Good catch.

On the other hand I could easily power my house with 4 of those Mars lab generators.

You draw 480 Watts max?
Here's typical wattages for some home appliances:
Coffee maker: 9001200
Clothes washer: 350500
Clothes dryer: 18005000
Dishwasher: 12002400
Toaster: 8001400
Vacuum cleaner: 10001440
Water heater (40 gallon): 45005500
Refrigerator (frost-free, 16 cubic feet): 725

Source:
http://www.energy...ic=10040

Unless you're Amish I think that won't work.



Took me a minute to figure out your table. It's the "dash" that PhysOrg's editor wiped out. I thought those numbers looked way high. :)
antialias_physorg
not rated yet Nov 22, 2011
yep...got a database error because of them and couldn't fix it. Sometimes physorg really is weird about what it accepts and what it doesn't.

If you want to power your car with one of these babies, a hybrid approach is best. Use several of them to charge the battery bank of an electric car. 10 units would deliver 28 kwhr of the course of a day, enough for about 100 miles of driving per day.


Soooo...I need 40kg of plutonium in my garage just to drive 100km per day. Sounds legit.
Vendicar_Decarian
1 / 5 (1) Nov 22, 2011
"You draw 480 Watts max?" - AP

just over 300 watts average.

Currently 80 for this PC, and 50 for lighting, 25 for the fan that just started on my furnace. Oh, and another 12 for the ceiling fan, 9 watts for my clock radio, and for the moment - just a moment, another 60 for several other wall warts.

Vendicar_Decarian
3 / 5 (2) Nov 22, 2011
"You draw 480 Watts max?" - AP

just over 300 watts average.

Currently 80 for this PC, and 50 for lighting, 25 for the fan that just started on my furnace. Oh, and another 12 for the ceiling fan, 9 watts for my clock radio, and for the moment - just a moment, another 60 for several other wall warts.

Water heating today (electric) will come in at 0.5 KWh, Refrigeration less than 0.2 I don't use a clothes dryer as it is wasteful of energy, and as to the coffee maker, washer, vacuum, etc, they run only for minutes a day. 0 minutes for the coffee maker since I don't have one.

I usually have 4 cups of tea on my days off, and use a 900 watt microwave for heating each cup. For heating I have it on full for 4 minutes a cup. So that adds 0.28 KWh per day on weekends. Weekdays averages 1 cup at 0.07 KWh per day.

Callippo
not rated yet Nov 22, 2011
The power source contains about 3,6 kg of Pu-238 in form of dioxide. It wouldn't be good, if the Curiosity would end in the same way, like the Phobos-Grunt mission, because one pound of Pu is able to kill about million of people. The cost of this plutonium is about 90 millions of dollars and it comes from Russia.

http://www.npr.or...ace-fuel
Nerdyguy
1 / 5 (1) Nov 22, 2011
The power source contains about 3,6 kg of Pu-238 in form of dioxide. It wouldn't be good, if the Curiosity would end in the same way, like the Phobos-Grunt mission, because one pound of Pu is able to kill about million of people. The cost of this plutonium is about 90 millions of dollars and it comes from Russia.

http://www.npr.or...ace-fuel


As has been mentioned here before (in response to your post I believe), power sources can -- and are -- designed to survive reentry. One such effort is a new design by an Air Force cadet, of all things.

http://www.space-...999.html

Another good read:

http://www.thespa...e/1777/1
antialias_physorg
not rated yet Nov 22, 2011
just over 300 watts average.

Unfortunately your peak uses (dishwasher, toaster, vacuum cleaner, washing machine, oven, microwave, ... ) use more than the thing can supply. You need to have enough supply for peak use - not average use. Could buffer some with batteries, I guess.
Shootist
1 / 5 (1) Nov 26, 2011
Some kind of urban tard living in a cold water flat.

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