When NASA’s Orion spacecraft returned to Earth from its trip around the moon, it was moving blazingly fast, nearly 25,000 mph, or 32 times the speed of sound.
On a trip to the moon, a mere 240,000 miles away, that’s a fine speed. For Mars, it’s painfully slow.
Using the technology NASA has, it could take seven months to get to the Red Planet. That’s too long. And it’s dangerous. The radiation on a Mars mission could expose astronauts to levels more than 100 times greater than on Earth.
If NASA’s going to get to Mars, it needs to find a way to get there much faster. Which is one of the reasons it said last week that it is partnering with the Pentagon’s Defense Advanced Research Projects Agency (DARPA) on development of nuclear propulsion technology.
“With the help of this new technology, astronauts could journey to and from deep space faster than ever – a major capability to prepare for crewed missions to Mars,” NASA Administrator Bill Nelson said in a statement.
The goal, he said, is “to develop and demonstrate advanced nuclear thermal propulsion technology as soon as 2027.”
DARPA, the arm of the Defense Department that seeks to develop transformative technologies, has been working on the program since 2021, when it awarded three contracts for the first phase of the program to General Atomics, Lockheed Martin and Blue Origin, the space company founded by Jeff Bezos.
A nuclear-powered rocket would use a nuclear reactor to heat propellant to extreme temperatures before shooting the fuel through a nozzle to produce thrust.
Being able to move fast “is a core tenet of modern Department of Defense operations on land, at sea and in the air,” DARPA said in a statement at the time. “However, rapid maneuver in the space domain has traditionally been challenging because current electric and chemical space propulsion systems have drawbacks in thrust-to-weight and propellant efficiency.”
In other words, traditional systems require too much fuel that burns at relatively inefficient levels.
Under NASA’S agreement with DARPA, the space agency will lead the development of the nuclear thermal engine while DARPA will work to develop the experimental spacecraft that would be propelled by the nuclear engine. The agencies hope they’ll be ready to demonstrate their work with a spaceflight in 2027.
NASA is also working with the Department of Energy on a separate project to develop a nuclear power plant that could be used on the moon and perhaps one day on Mars.
But getting to Mars is exceedingly difficult, and despite claims from NASA for years that it was gearing up to send astronauts there, the agency is nowhere close to achieving that goal.
One of the main obstacles is the distance. Earth and Mars are on the same side of the sun only every 26 months. But even at their closest points, a spacecraft would have to follow an elliptical orbit around the sun will require “a great sweeping arc of around 300 million miles to arrive.
As space becomes a contested environment, developing a system that is far more efficient is something that the Pentagon and the U.S. Space Force have been focused on, especially as threats to satellites have grown.
Satellites usually stay in orbit over a fixed trajectory. Without the power, or propellant to maneuver, that makes them a bit like sitting ducks. But with a more efficient fuel like nuclear propulsion, they could become more agile – and evasive. The need for spacecraft that can maneuver away from the enemy has become clear during the war in Ukraine.
The Pentagon is also searching for better ways to move “larger payloads into farther locations in cislunar space – the volume of space between the Earth and the moon,” DARPA said. But doing that, it said, “will require a leap-ahead in propulsion technology.”
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