The USA is preparing to send a nuclear reactor into space for the first time since 1965

The USA is preparing to send a nuclear reactor into space for the first time since the SNAP-10A mission in 1965.

The USA has brought the use of nuclear energy in space back to the agenda.

The US Space Force awarded a $161 million Strategic Breakthrough contract to Antares Nuclear, a nuclear microreactor developer, to work on space-based nuclear power systems. According to the program announced by the company, in the first stage, the R1-S reactor will be demonstrated on Earth. The system will then be integrated with a spacecraft and tested for flight certification.

The importance of this initiative is that the last time the USA sent a nuclear reactor into space was in 1965.

SNAP-10A, launched on that date, became the United States' first and, to date, only nuclear reactor in space. Thus, if the Antares project is successful, the USA will use nuclear fission technology in space again after a break of more than 60 years.

The first stage will be tested on Earth

The first phase ahead of Antares will be the ground-based nuclear demonstration of R1-S.

R1-S is defined as the space mission-adapted version of the R1 microreactor design developed by the company for terrestrial use. Antares' R1 family uses TRISO fuel and heat pipes to remove heat from the reactor.

The important aspect of this approach is that the company aims to adapt existing microreactor technology to space conditions rather than designing a space reactor completely from scratch.

In the program information previously published by the US Department of Defense, it was stated that Antares R1 was intended to provide a faster transition to high-power space nuclear systems by taking advantage of the existing production infrastructure.

Next step spacecraft integration

After ground tests, R1-S is planned to be integrated with a spacecraft.

At this stage, the system's launch and space environment durability, operation and certification for flight will be evaluated. However, the company has not yet announced which spacecraft will be used or when R1-S will be launched.

Therefore, the $161 million contract does not directly mean "the reactor will be launched on this date." The program currently includes the development, ground demonstration and flight preparation process.

Why do military satellites require nuclear energy?

The main advantage of using nuclear energy in space is that it can provide continuous and high amounts of electricity.

Conventional satellites rely heavily on solar panels and batteries. However, it is expected that high power-consuming technologies such as computers that require higher processing power, advanced sensors, electronic warfare systems and directed energy weapons will be used in future military space systems.

The nuclear reactor, on the other hand, can provide continuous power without relying on sunlight.

The US Space Force also uses high-power nuclear systems; He evaluates that it can pave the way for capabilities that may be limited to solar panels, such as high processing power, continuous electric propulsion, directed energy and electronic warfare.

This could also increase the satellites' maneuverability. Sustained power could allow a spacecraft to perform more frequent and longer maneuvers with less concern for energy reserves.

Another important success came from Antares

The company's space reactor program follows a significant success in its nuclear efforts on Earth.

Antares' Mark-0 microreactor successfully achieved zero-power criticality at Idaho National Laboratory on June 4, 2026. With this development, the company became the first company to achieve fuel criticality under the US Department of Energy's Reactor Pilot Program.

The company also plans to conduct a test for more than six months in 2027 with the Mark-1 reactor it developed for electricity production. This system is intended to be used with a power conversion system for electricity production, unlike R1-S.

USA's nuclear race plan in space

Washington's reorientation towards nuclear energy in space is not limited to the Antares project.

The US administration considers the use of nuclear reactors in space as a broader strategic goal. Within the scope of current plans, it is aimed to send a nuclear reactor into space as early as 2028 and to use nuclear power systems on the Moon surface by 2030.

This approach could directly affect the US's military space capabilities, as well as the growing need for energy in space.

A new energy era may begin in space

If Antares' R1-S project is successful, the USA will become the country that carries nuclear fission reactors into space again after SNAP-10A in 1965.

However, the real goal is not just to send a reactor into orbit. To create a new generation space energy infrastructure in which military satellites that require higher power, advanced sensors, powerful computer systems, electronic warfare and directed energy technologies can be operated.

The process, which started with a $161 million contract, is therefore considered an important technological step in the future military space architecture of the United States.