L3Harris is developing a next-generation radioisotope thermoelectric generator for deep space missions

Solar panels work well in space and are employed for various missions to generate the energy needed for onboard instrumentation and to provide thrust in the case of electric propulsion. However, solar panels cannot be used for all missions, especially when venturing beyond Jupiter in the outer Solar System. Here, sunlight is much weaker, and large surfaces are needed to generate enough energy. This is where radioisotope thermoelectric generators (RTGs) can be used. Missions like the two Voyager probes and New Horizons make use of them, along with Mars rovers like Curiosity and Perseverance.

L3Harris has announced the development of a next-generation radioisotope thermoelectric generator (Next Gen RTG) that passed the critical design review in April. This unit could be used in future NASA missions in deep space, ensuring greater flexibility and superior features compared to the current generation.

According to L3Harris, this new generation of RTG could see its official debut in the early 2030s. Its use would be intended, for example, for an orbiter designed to study Uranus, generating both the electricity necessary for operation and maintaining a suitable temperature for the instrumentation.

As with other RTGs, this model converts heat from the radioactive decay of plutonium-238 into electricity. The technical bases are similar to those of the radioisotope thermoelectric generator used for the Cassini mission (dedicated to Saturn) or for New Horizons. As explained by L3Harris, the Next Gen RTG is developed for space missions and not for those on the surface of planets or moons (thus it will not be used on rovers like Perseverance and Curiosity). Thanks to an optimized design, the mass will be the same as that of other RTGs for "mixed" uses, while the power will be higher. The indicated performance will be about 250 watts at the beginning of its operational life.

Bill Sack (General Manager, RocketWorks and Power Systems at L3Harris) stated, "Exceeding the CDR is an important milestone because it validates that our design meets all technical requirements and can be produced. It also demonstrates that we have successfully restored this critical capability after years of limited production. The Next Gen RTG represents a significant leap forward in terms of efficiency. We are providing more power for the same mass, which is crucial when every kilogram counts for deep space missions."