Curiosity Power Source and Requirements

Greetings,
Question for you guys. How does a 200 watt RTG power all the equipment on the curiosity rover?

I am right in saying this thing weighs in at 1 ton?

With all the efficiency losses I'm struggling to understand where all the power comes from ?

Continuous production of 200W is plenty, combine that with the solar cells and it is even more sufficient.

With proper gearing 200W will move a ton sized machine (albeit slowly).

What you have to keep in mind is that the 200W is continuous power. The rover will not be manouvering continuously. The excess power produced can go into batteries or super capacitor banks for later use to provide peak powers of kilowatts if needed.

I think you underestimate 200W.

Second, there is less gravity on mars, don´t compare mass on different planets...
A ton on earth equals about 376kg on mars.

Originally posted by verschickter
I think you underestimate 200W.

Second, there is less gravity on mars, don´t compare mass on different planets...
A ton on earth equals about 376kg on mars.

edit on 12-8-2012 by verschickter because: (no reason given)

My computer draws 120 watts idle and over 300 watts load. 200 watts is not that much energy when you factor in losses with the amount of equipment and motors on the rover.

reply to post by The Asgard


RTG's are wonderful and quite safe.
We could all have clean "nuclear powered" cars that run for well over a decade without need for fuel were it not for big oil, as well as close-minded concerns over anything that even sounds like "radioactive".
RTGs have been used inside the human body as nuclear batteries for artificial hearts due their long life and reliability.
Yes, a 'radioactive' nuclear battery, such as an RTG can indeed be used inside the human body to no ill effect.
If we had these to power our homes and cars ... well, you get the picture.

200W is more than sufficient for such a vehicle, and, as stated above, excess can go into batteries and cap arrays.

Originally posted by verschickter
I think you underestimate 200W.

Second, there is less gravity on mars, don´t compare mass on different planets...
A ton on earth equals about 376kg on mars.

edit on 12-8-2012 by verschickter because: (no reason given)

The mass is the same, the weight is different. So to get it move to a certain speed needs as much energy on mars as on earth (not counting friction caused by/gravitational pull while climbing hills.)

Also, the fact your computer draws hundreds of watts just means that it is inefficient. I would guess the rovers main computer draws no more than a few W under normal operation.

Originally posted by The Asgard

Originally posted by verschickter
I think you underestimate 200W.

Second, there is less gravity on mars, don´t compare mass on different planets...
A ton on earth equals about 376kg on mars.

edit on 12-8-2012 by verschickter because: (no reason given)

My computer draws 120 watts idle and over 300 watts load. 200 watts is not that much energy when you factor in losses with the amount of equipment and motors on the rover.

edit on 12/8/12 by The Asgard because: (no reason given)

The RTG isn't powering ALL the equipment and drive motors at the same time. It only needs to be powering a few systems at any given time.

I would think the drive motors use the most electricity, but the wheels motors are torqued in a way that provides for efficient use of the electricity -- albeit not a lot of speed. What it lacks in speed, it makes up for in torque and power consumption.

But still, when the wheel motors are turning, there are not a lot of other systems drawing electricity.

reply to post by varikonniemi

In the International System of Units (SI), mass is measured in kilograms (kg).
...
Weight, by definition, is a measure of the force which must be applied to support an object (i.e. hold it at rest) in a gravitational field.

Less gravitational field, less force that pulls it down. Means less energy spend on moving.
You are right, mass keeps the same of course, but weight is reduced. What I wrote was not accurate enough. The problem is, mass is measured in kilograms and most people do not differ between mass and weight. My example 1ton 376kg just wanted to show that you need less force.

reply to post by varikonniemi

So to get it move to a certain speed needs as much energy on mars as on earth (not counting friction caused by/gravitational pull while climbing hills.)

Thats not right. How can you say the same energy is needed on mars and on earth when gravitational field is different. If you do not count friction caused by gravity, you belong into space and not on a planet with this example.

Gravitional pull is everywhere. It doesn´t matter if you are climbing hills or not. If you move around the surface, gravity drags you down, causing friction every time.

Either way, my statement was right:

Don´t compare masses on different planets.

reply to post by Druscilla


There is one Problem with the RTGs for every one its that it runs on Pu238 its man made and not found nature. It can only be made in small quantities and is very tedious to make, unlike its isotopic brother Pu239. For this reason there is no country on earth that still produces it and actually I believe the rest of the usable supply was sent to Mars on Curiosity. Nasa's asking congress for $70M a year to start producing Pu238 and they only plan on making a 4-5 pounds a year. That's $17,000,000 a lb and we think gas is expensive

These are the specs of the MMRTG:

Curiosity's power generator is the latest RTG generation built by Boeing and Idaho National Laboratory, called the "Multi-Mission Radioisotope Thermoelectric Generator" or MMRTG.[18][19] Based on classical RTG technology, it represents a more flexible and compact development step,[18] and is designed to produce 125 watts of electrical power from about 2000 watts of thermal power at the start of the mission.[15][16] The MMRTG produces less power over time as its plutonium fuel decays: at its minimum lifetime of 14 years, electrical power output is down to 100 watts.[20][21] The power source will generate 9 MJ (2.5 kilowatt hours) per day, much more than the Mars Exploration Rovers' solar panels, which can generate about 2.1 MJ (0.6 kilowatt hours) per day. The electrical output from the MMRTG charges two rechargeable lithium-ion batteries. This enables the power subsystem to meet peak power demands of rover activities when the demand temporarily exceeds the generator’s steady output level. Each battery has a capacity of about 42 amp-hours.

Source

It does have Li-Ion batteries which help in peak use phases.

Due to the unreliability of solar power, Curiosity’s 1,982-pound frame is energized by an advanced nuclear power system called the Multi-Mission Radioisotope Thermoelectric Generator. The on-board nuclear power plant is capable of generating electricity from plutonium-238 dioxide for up to 14 years, which should be plenty of time

Read more: www.digitaltrends.com...

I think drakus hit it on the head better.

The RTGs only charge the 2 batteries.
Both batteries are 10 Amp hrs.

So in truth Curiosity runs on batteries.

Originally posted by samkent
I think drakus hit it on the head better.

The RTGs only charge the 2 batteries.
Both batteries are 10 Amp hrs.

So in truth Curiosity runs on batteries.

Yeah that's why its been called - curiosity's nuclear battery