Posting in Design
The latest Mars rover has ditched the solar panels used in other missions and has opted instead for nuclear. Why this energy source makes sense on Mars and for this mission.
NASA's latest Mars rover, which launched Saturday from Cape Canaveral, will be loaded with some of the most advanced scientific gear ever used on the surface of the red planet. And everything from its ChemCam, which identifies chemical elements using an invisible infrared wavelength, to its rock vaporizing lasers will all be powered by nuclear energy.
This isn't the first space mission that has used nuclear power. In fact, it's the 28th, according to U.S. Energy Department. But it marks a change within the Mars rover program. The previous two rovers Spirit and Opportunity, which launched in 2003, were equipped with gallium-arsenide solar panels, a specialized niche product that requires very high production per square inch, the NYT Green Inc. blog recently noted. The panels worked, although there were challenges, most notably the dust storms that would blot out up to 90 percent of the sun.
Both Spirit and Opportunity carried lithium-ion batteries to store up to 140 watts of produced power. This isn't much on Earth, where 140 watts is enough to power a desktop computer and monitor, NYT reported. On Mars, it was enough to run the radios, cameras and other equipment as well as the vehicle itself.
The nuclear power packs used to operate Curiosity and space missions before it aren't actually reactors. Meaning they don't split atoms. The rover Curiosity is equipped with the Energy Department's Multi-Mission Radioisotope Thermoelectric Generator (MMRTG). The system, which is designed to allow the rover to run where the sunlight is too inadequate that solar panel is impractical, uses heat produced by the natural decay of plutonium-238 to generate 110 watts of electricity. The plutonium 238 is a manufactured isotope that has a radioactive decay that is so fast it glows red hot. The plutonium is toxic. However, the material cannot be used in a bomb.
The electricity that's produced will be used to provide continuous power to the rover and maintain operating temperatures for its 11 scientific instruments, the Energy Department said. Curiosity will investigate whether the Gale Crater on Mars has ever offered environmental conditions that support the development of microbial life. Curiosity is expected to land on Mars in August 2012 and carry out its mission over 23 months, the DOE said.
- Curiosity lands on Mars! (photos)
- NASA's rover, Curiosity, successfully lands on Mars
- The mission of NASA's latest Mars rover, Curiosity
- Looking for the origins of the universe? Head to Chile
- Looking for the origins of the universe in one of Earth’s least habitable places (photos)
- How scientists concluded there is water on Mars
Nov 29, 2011
So now we have to polute Mars with a toxic reactor that will be there for 88 years. Haven't we done enough poluting?
Despite the dust on Mars, the solar cells on Spirit and Opportunity are still going, long after the originally-intended lifetime of the missions. The nuclear power on Curiosity might be even better. Half-life of Pu-238 is 88 years. That sounds promising. And the two Voyagers still have power. But there could be other factors that shorten Curiosity's useful lifetime.
The RTG is just a source of heat with no moving parts. Once the mission is over it will sit there self contained until humans arrive on Mars and pick it up. It's not going to contaminate anything.
dmm99, Good point. The Spirit and Opportunity are still operating despite the challenges of dust on the solar panels. The Curiosity, I should have noted, is much heavier and larger than the other two rovers, indicating a need for more power.
means that its radioactivity decades hence, measured in terms of watts then over watts now, is a much larger fraction than for a reactor.