In a move that could see a new generation of deep space CubeSats, NASA has greenlit a project by the Rochester Institute of Technology to develop a nuclear power source that is one-tenth the size of those currently used for planetary missions.
Most satellites in operation today are powered by solar panels that convert sunlight into electricity. A solar panel absorbs photons, creating a potential imbalance in the materials of the panel cells and generating an electric current. These panels work very well, but in deep space beyond the orbit of Mars, or in harsh conditions such as dust storms on Mars or long nights on the Moon, sunlight cannot produce the necessary energy.
Instead, many deep space probes are equipped with multi-mission radioisotope thermal generators (MMRTGs) that harness thermal gradients to generate electricity. That is, radioactive isotopes generate heat, and thermocouples convert heat directly into electricity. This is a principle familiar to engineers, and is widely used on Earth in things like kerosene-powered radios and camping stoves that can also charge portable devices.
The problem with MMRTG is that it’s relatively bulky. For example, the pair used on NASA’s Perseverance Mars rover are each 25 inches (64 cm) in diameter, 26 inches (66 cm) long, and weigh 99 pounds (45 kg). They each contain a 10.6 lb (4.8 kg) plutonium dioxide plug for fuel that supplies heat to solid thermocouples as radioactive elements decay.
As a result, these MMRTGs are reserved for very large spacecraft, and Perseverance is as big as an SUV. This is because the system used has very little mass-to-mass power. This is a measure of how many watts of power can be generated per unit of the machine. Family cars have a mass-specific power output of 50-100 W/kg, while fighters are around 10,000 W/kg.
In contrast, the MMRTG ratio is around 30 W/kg.
By examining the size, weight, and power (SWaP) thermodynamics of potential RTGs, the NASA project hopes to reduce this ratio by an order of magnitude to just 3 W/kg, with similarly large reductions in volume. I’m in. .
This is done by using a new principle that is essentially a solar panel that works in reverse. When a solar panel absorbs light, some of it turns into electricity and most of it turns into heat. The new radioisotope power supply thermal radiation cellHeat in the form of infrared rays impinges on panels containing elements made from indium, arsenic, antinomy and phosphorous in various combinations. This creates a potential difference with opposite polarity to the solar cell.
Simply put, thermal radiation cells generate electricity from heat and release waste energy in the form of infrared photons. Not only does this work in reverse to solar panels, it is also much more efficient. The result is the new thermal radiation generator (TRG).
If this new technology proves practical, future missions to Jupiter and beyond, or to the permanently shadowed craters of the Moon’s poles, could use CubeSats equipped with small generators to provide all the power they need. Means you can use spaceships of that size. This could mean, for example, that the concept’s flagship Uranus mission could be accompanied by a small fleet of CubeSats that could aid exploration by providing more perspectives or acting as communication relays with atmospheric probes. means that there is
Source: NASA
