NASA Evaluates Explosion Risks of Methane-Fueled Rockets

NASA and the U.S. Space Force are conducting tests to assess the explosion hazards associated with methane-fueled rockets. This initiative aims to refine safety protocols as the aerospace industry increasingly adopts methane as a propellant.

Over the past 15 years, companies like SpaceX and Blue Origin have developed powerful methane-fueled engines, such as the Raptor and BE-4, each generating over half a million pounds of thrust. These engines offer advantages like reduced sooty residue and easier handling compared to traditional fuels.

However, the introduction of methane brings new safety considerations. The U.S. Space Force and NASA, responsible for range safety at federal spaceports, seek to understand how explosion hazards from methane-fueled rockets differ from those using other propellants. This understanding is crucial as launch frequencies increase and launch pads are situated closer together.

Col. Brian Chatman, commander of the Eastern Range at Cape Canaveral Space Force Station, highlighted the need for comprehensive analysis: "We just don't have the analysis on those to be able to say, 'Hey, from a testing perspective, how small can we reduce the BDA and be safe?'"

The testing involves filling rockets with fuel, detonating them in controlled environments, and measuring the resulting explosions. Jason Hopper, deputy manager for the methalox assessment project at NASA's Stennis Space Center, described the process: "We put fuel in a rocket, blow it up in a remote location, and measure how big the boom is."

Initial tests began in January with baseline explosions using C-4. Subsequent tests in February incorporated methane and liquid oxygen, simulating various failure scenarios. Engineers plan to scale up these tests to assess the explosive potential of larger rockets, such as SpaceX's Starship, which carries over 10.8 million pounds of propellant at liftoff.

NASA stated that the findings from these tests are expected to influence launch site planning and safety requirements for years to come. The testing is scheduled to conclude in June.

For now, the Space Force is maintaining conservative safety measures, treating any methane-fueled rocket with "100 percent TNT blast equivalency" and enforcing maximized keep-out zones to ensure public and worker safety. Col. Chatman noted that while initial studies suggest these zones may be reduced, definitive conclusions await the test results.

Industry data suggests that the government should set its TNT blast equivalency to no greater than 25 percent, a change that would greatly reduce the size of keep-out zones around launch pads, according to the Commercial Space Federation, a lobbying group whose members include SpaceX, Blue Origin, and other companies with methane-fueled rockets.

In written testimony to Congress in 2023, the federation urged the government to use "existing industry data" to understand the explosive yield of methane and liquid oxygen rather than spending federal dollars on an independent test campaign. In the end, NASA, the Space Force, and the FAA decided their own tests were worth the money.