New nuclear heaters use americium-241 to prevent spacecraft from freezing

Business operations on the Moon will not only be 24 hours a day, but also 24 hours a day, as ispace, inc. and the University of Leicester are teaming up to develop nuclear heaters to enable future landers and rovers to survive the freezing lunar night.

There have been a number of attempts to robotically land on the Moon recently, with varying degrees of success. However, they all have one thing in common: they had a very limited mission lifespan. The problem is that the Moon is subject to extreme temperature variations from day to night. When the sun is up, the thermometer rises to 250°F (121°C) and at night it plunges to -208°F (-133°C).

Daytime isn’t too much of a problem because the Moon’s surface is empty, so it’s relatively easy to control heating with reflective surfaces. Nighttime is another matter. A spacecraft’s heat can quickly dissipate, and by the time the Sun rises again after two weeks of darkness, the lander’s batteries and electronics can be damaged beyond repair.

Envisioning a future with a permanent human presence on the Moon that includes many commercial activities, ispace and Leicester’s Space Nuclear Power group want to develop nuclear heating units for future missions, starting with Series 3 lunar landers and rovers of ispace.

University of Leicester

These units are not nuclear reactors, but so-called radiothermal generators (RTG). They do not work by fission, but by natural radioactive decay of enriched nuclear isotopes such as plutonium. As they disintegrate, they release heat, which can be used to generate electricity or to keep a spacecraft from freezing during lunar night or during deep space missions in the outer solar system and beyond .

Although the idea of ​​using an RTG to keep a lunar lander or rover alive has been around for half a century, the ispace/Leicester project is a little different. Not only is it a private company designed to support private lunar missions, but it also uses a different isotope. Where most other space missions have used plutonium-238, the new heater will use americium-241. It’s not only cheaper and less controversial, but its half-life is over 400 years, keeping a rover warm for many years.

“The radioisotope power generation technology that has been developed at the University of Leicester, in collaboration with the National Nuclear Laboratory, is working extremely well in our ongoing test campaigns,” said Dr Hannah Sargeant, lead of the project, from the School of Physics and Astronomy at the University of Leicester. and Space Park Leicester. “In this project, we will work with ispace to study the feasibility of using radioisotope heating units to provide spacecraft with enough heat to endure the lunar night.

“The first phase of UKSA’s international bilateral funding was used to work with our international partners to understand their energy needs and mission priorities. During Phase 2, we will conduct both laboratory and conceptual studies to demonstrate the feasibility of mission concepts. also provide an opportunity to showcase the technology to the civil and commercial space industry and demonstrate how it could be used to meet the critical energy needs of priority missions.

Source: ispace