Florida-based company L3Harris Technologies has finalised the design of a next-generation nuclear-based power source for future NASA deep space missions, potentially powering an orbital mission to Uranus. Its Next-Generation Radioisotope Thermoelectric Generator (Next Gen RTG) recently cleared its critical design review (CDR), paving the way for a new era of outer solar system exploration.
‘Passing the CDR is an important milestone because it validates that our design meets all the technical requirements and can be manufactured,’ said Bill Sack, general manager, rocketworks and power systems. ‘It also demonstrates we’ve successfully re-established this critical capability after years of limited production.’
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Flight units could power NASA deep space probes starting in the early 2030s, including a proposed Uranus orbiter that would use two Next Gen RTGs for power and for keeping its temperature-sensitive components warm enough to operate in the frigid environment of the outer solar system.
RTGs convert heat from the radioactive decay of plutonium-238 into electricity. Necessary for probes that are too far from the Sun to rely on solar power, they have been in use for 60 years. Early versions continue to supply power to NASA’s twin Voyager probes, which were launched in 1977 and are now travelling in interstellar space.
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The Next Gen RTG is an evolution of the general-purpose heat source RTGs that supplied power to NASA’s Cassini Saturn orbiter and, more recently, New Horizons probe, which carried out a Pluto flyby in 2015 and is now exploring the frozen wonders of the Kuiper Belt. Unlike the L3Harris-built Multi-Mission RTGs currently powering NASA’s Curiosity and Perseverance Mars rovers, the Next Gen RTGs are optimised for spacecraft operating in the vacuum of space rather than on the surface of a planet.
This distinction is critical for future missions. The vacuum-optimised design allows for more efficient heat rejection and power generation in the deep space environment where missions such as the Uranus orbiter will operate. As a result, the Next Gen RTG offers a higher power output ataround the same weight as the Multi-Mission RTG. With the capability to generate about 250 watts of power at the beginning of its life, each Next Gen RTG will provide reliable, long-duration power for spacecraft exploring the outer reaches of our solar system.
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‘The Next Gen RTG represents a significant leap forward in efficiency,’ added Sack. ‘We’re delivering more power in the same mass envelope, which is critical when every kilogram matters for deep space missions.’
According to the company, the availability of Next Gen RTGs opens the door to a range of ambitious missions that have been on NASA’s wish list. Beyond the Uranus orbiter, these power systems could enable: extended missions to Neptune and its moon, Triton; Kuiper Belt-object explorers that can go beyond the range of the New Horizons spacecraft; long-duration missions to the outer planets’ moons or interstellar precursor missions that push even farther than Voyager 1 and Voyager 2.