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On Mars, NASA's Perseverance rover is settling in after landing last week. The space agency also hopes one day to send people to the red planet. But getting there will be tough. NPR's Geoff Brumfiel reports that some experts say the best way to do it might be with a nuclear-powered rocket.
GEOFF BRUMFIEL, BYLINE: Sending people to Mars and back again is a huge undertaking.
ROGER MYERS: There are many factors that need to be considered, including such things as, how fast can you get there? How long do you have to stay on Mars? How quickly and how reliably can you get back?
BRUMFIEL: Roger Myers is a private consultant who used to work for NASA. Those questions, he says, are all really about one thing - minimizing the time from when astronauts leave Earth to when they return. The trip must be as fast as possible, but going fast takes fuel. For even the most basic trip to Mars...
MYERS: I have to launch hundreds, if not a thousand, tons of fuel.
BRUMFIEL: Fuel that would come from Earth on many dozens of little rockets used to gas up a larger Mars-bound spacecraft. It would be expensive and dangerous, and it would still leave astronauts with a 500-day stay on the Martian surface while they waited for Earth and Mars to align for a trip back home. But there is an alternative - nuclear-powered rockets.
VISHAL PATEL: If you want to go to Mars, nuclear is a smart choice.
BRUMFIEL: Vishal Patel is a nuclear rocket scientist with a company called Ultra Safe Nuclear Corporation. They're working on a version of a rocket that would use a nuclear reactor. The reactor would heat hydrogen gas and shoot it out a nozzle. It's way more efficient than a chemical engine. A nuclear rocket could make a round-trip mission possible in as little as half the time needed using conventional rockets. It would also allow astronauts to turn back towards home if they encountered an emergency at the start of their trip. Patel recognizes that launching a nuclear reactor from Earth might make people nervous. But, he says, Ultra Safe Nuclear Corporation is working hard to make it ultrasafe.
PATEL: We'll be using conventional rockets to get it up into space, and we'll have safety measures in place, like, just in case the chemical rocket does malfunction.
BRUMFIEL: Even if the chemical rocket exploded on the way up, the reactor would be safe, and the nuclear rocket wouldn't fire until astronauts were far from the Earth. Patel says so far, the design looks promising.
PATEL: The chemistry looks good. The nuclear physics looks good. The manufacturing seems to be going in the right direction.
BRUMFIEL: The reactor Patel and his colleagues have worked on exists mainly as a computer model right now, but America has already built nuclear rockets.
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UNIDENTIFIED PERSON: Here, in the mid-1950s, scientists set about to determine if nuclear energy really could be used to provide rocket propulsion.
BRUMFIEL: In the Nevada desert, scientists repeatedly fired nuclear rocket engines.
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UNIDENTIFIED PERSON: Each test brought the scientists a little closer to the performance they were seeking.
BRUMFIEL: But the program was cancelled over costs. Since then, nuclear rocket technology has developed in fits and starts. And meanwhile, Roger Myers says other technologies have ended up dominating space travel.
MYERS: We can do a tremendous amount of fantastic science with robots, as we're discovering today, right?
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SWATI MOHAN: Touchdown confirmed. Perseverance safely on the surface of Mars, ready to begin seeking the signs of past life.
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BRUMFIEL: To get to that next step of landing people, Myers says it may be time for nuclear rockets.
MYERS: If we decide to send humans to Mars, nuclear propulsion is very likely going to be central to that journey.
BRUMFIEL: Myer (ph) co-chaired a committee of the U.S. National Academies, which recommended NASA ramp up spending on nuclear research now for a trip towards the end of the 2030s. NASA says it's reviewing the group's findings.
Geoff Brumfiel, NPR News, Washington.
(SOUNDBITE OF MUSIC) Transcript provided by NPR, Copyright NPR.
