For the first time, NASA is set to allow nuclear power sources in upcoming missions. This is a reversal from their earlier policy, which prohibited any type of radioisotope power for use with any space vehicle. While smaller heater units could be powered by radioisotope, the agency had previously disallowed additional use of those sources, citing production and supply concerns.
At a meeting in February of this year, agency representatives discussed the need to consider the demands of future missions while also being mindful of pre-existing plutonium levels. Current goals are to have about 1.5 kilograms a year produced by 2022. A shortage of plutonium could mean that missions the agency books cannot go through. While the agency did say they were considering a review of the plutonium restrictions concerning an upcoming Discovery flight, they did not disclose a timeline or what type of conditions needed to be met.
This decision was in response to a proposed use of the element in a few future missions, including the Mars 2020 rover that is set to be launched aboard Discovery. Dragonfly also wanted to use plutonium-238 to power future missions to the moon. They hope the element can sustain the craft through the lunar night, which typically lasts approximately two weeks.
Director of planetary science at NASA, Jim Green, announced the reversal late last week. One of the main reasons for the change of heart is the rapid progress that has been made in producing plutonium-238. After the meeting in February, NASA officials spoke with the Department of Energy about the production of plutonium-238, asking about current and projected levels. The responses provided lead NASA officials to believe there is a sufficient supply to permit its use on an upcoming Discovery mission.
The plutonium is to be used as part of multi-mission radioisotope thermoelectric generators to provide heat and power to the craft. Plans for this upcoming mission are still in development. A draft announcement regarding the opportunity is scheduled for release in September of this year, with the final announcement to be made the following February. The launch is set to occur no later than December of 2026.
Some have concerns about the use of this isotope in planetary study, given concerns expressed by the Government Accountability Office about its increased production. They may worry that these isotopes are coming to the planetary exploration field at the expense of other scientific development programs. Green responded to those fears by noting the long-standing budgetary shortfalls that traditionally plagued this area of research and development. Thanks to greater interest in the field and budget increases, he believes it is planetary science’s time to shine.