By 2035, NASA wants to land humans on Mars. But reaching the red planet, on average around 140 million miles away, will be difficult. Colder than Antarctica and with little to no oxygen, Mars is an unfriendly environment. Besides, the longer it takes astronauts to get there and the longer they stay, the more they are at risk.
That's why scientists are looking at ways to reduce trip time. Seattle-based company Ultra Safe Nuclear Technologies (USNC-TECH) has offered a solution: an NTP engine that could get humans from Earth to Mars in just three months. Such an engine takes advantage of nuclear technology. Currently, the shortest possible trip for an unmanned spacecraft is seven months, but a manned mission is expected to take at least nine months. Shorter missions would limit the astronauts exposure to space radiation, but there is still concern about the radiation sent out from the nuclear reactor inside the spacecraft. This would be mitigated through the rocket's design, which would help ease the scientists' concern.
To protect people on the ground, the NTP spacecraft would not lift off directly from Earth, Jeff Sheehy, a NASA scientist, adds. Instead, a regular chemical rocket would carry it into orbit, and only then would it fire up its nuclear reactor. Once in orbit, it could do little harm, as heat radiation cannot move through a vacuum(真空). If disaster struck and the rocket's reactor broke up, pieces would not land on Earth— or any other planet—for thousands of years. By that time, the radioactive substance would have ''naturally got to the point where it wasn't dangerous anymore”.
Michael Eades, director of engineering at USNC-TECH, says that nuclear-powered rockets would be more powerful and twice as efficient as the chemical engines used today, meaning they could travel further and faster, while burning less fuel. "Nuclear-powered rockets will be key to opening up the solar system but it could be at least two decades before they are used widely,9, he says, adding that numerous demonstrations and tests would need to be carried out before an astronaut is sent to Mars in an NTP rocket.
