Nuclear thermal propulsion will get astronauts to Mars in better shape

A team of scientists and engineers at the U.S. Energy Department's Idaho National Laboratory (INL) holds the outcome of a new space race in its hands. The team is spearheading a nationwide effort to develop a nuclear thermal propulsion spacecraft that could cut the travel time to Mars in half. It's a project that could dramatically alter the course of humanity, making us an interplanetary species capable of sustainably sending humans to the Red Planet.

But the U.S. isn't the only country aiming for Mars. The China National Space Administration (CNSA) has exceeded expectations in recent years and has announced plans to send its own crewed mission to explore the Martian surface. In a bid to develop the fastest and most efficient method for interplanetary space travel, the INL engineers chose to focus on nuclear thermal propulsion.

It is capable of powering larger spacecraft, which is essential given the amount of cargo a human mission would have to take along for the ride. "The primary benefit of nuclear rockets compared to chemical rockets is the amount of mass that can be carried at high velocity," Sebastian Corbisiero, senior technical advisor for advanced concepts at INL, told in an interview.

"With the physics we know today, we believe nuclear propulsion can provide the most capable means of delivering large mass payloads to Mars in the shortest amount of time." Developing a nuclear thermal spacecraft Using existing technologies, NASA estimates it would take a human rated spacecraft roughly seven months to reach the Red Planet.

That is a long time for humans to fly through deep space, where long term cosmic radiation exposure can lead to a host of health issues. In fact, one of the great challenges faced by future crewed Mars missions is that astronauts could arrive at the Red Planet with roughly half their muscle mass and with several health problems, making them inefficient or even incapable of completing their mission.

"The space environment is a harsh place for humans," Corbisiero told . "The low gravity impacts on the human body, as well as the effects of solar and cosmic radiation, make it challenging for extended space travel." "With the reduction in transit time that nuclear thermal propulsion can provide, that makes life safer for the humans on board." Not only that, a seven month travel time means that launch opportunities to Mars will only come about once every 26 months, meaning a failed launch could potentially delay a mission by years.

Astronauts would then have to stay on Mars for a year or even two while waiting for a favorable alignment of the planets that would allow them to travel back to Earth. In a recent interview with the , NASA Administrator Bill Nelson said the U.S. space agency aims to reach the Red Planet by 2040. With all the challenges mentioned above in mind, it is necessary to develop entirely new technologies to make that 2040 target possible.

That's where the INL team comes in. The team of engineers will benefit from the work of DARPA's DRACO project, which aims to lift a to low Earth orbit for a space demonstration by 2027, with the help of NASA. "The DARPA DRACO project would be the first reactor the U.S. has launched into space since the SNAP program in the 1960s," Corbisiero said.

"So, in addition to potential technologies that DRACO would develop, any future nuclear reactor project will have the benefit of DRACO laying a path for policy and licensing approaches, such as getting approval to launch," he continued. "Navigating the logistics and approval to launch is a key step in any nuclear space project." To develop its nuclear thermal technology, INL will also build on studies dating back to the 1960s.

"Nuclear propulsion has been investigated since the 1960s during the ROVER and NERVA projects," Corbisiero explained. "Today, like then, a key technology to optimize is the nuclear fuel system, which has to sustain temperatures far higher than traditional commercial nuclear reactors. Developing and testing nuclear fuel is a key part of the program and one we at INL are well equipped to support." Space race 2.0 Both NASA and China's space administration, the CNSA, will hope to take advantage of a Mars opposition in 2033.

An opposition is when another planet is on the opposite side of the Sun, meaning it is the closest it will get to Earth. In 2021, that China aims to send humans to Mars that year. The CNSA successfully landed its first Mars rover on the Red Planet in 2021, and it has hit a list of impressive milestones in recent years.

The nation will follow the first landing on the planet with more missions, allowing it to establish a permanent colony on Mars and extract resources from its surface. The exact technology that will get the first humans to Mars is not set in stone. U.S. Costa Rican company, the Ad Astra Rocket Company, is developing a nuclear electric engine called VASIMR that could power a spacecraft to Mars in just 45 days.

However, the firm's founder, former NASA astronaut Franklin Chang Díaz, in a recent interview that the company has had trouble raising the required funds. Chang Díaz explained that Ad Astra required roughly $200 million in funding. If that investment were secured, he explained, "we could see this engine flying three years from now." Until that happens, however, "everything else will continue to inch along." SpaceX is currently on course to be the first organization to send humans to Mars aboard its massive Starship launch vehicle.

Unlike the INL team's nuclear thermal system and Ad Astra's nuclear electric engine, Starship will use conventional rocket technology, meaning it will take roughly seven months to reach Mars. However, that also means the rocket will take a fraction of the time to develop. SpaceX CEO Elon Musk recently stated that an could fly to Mars as soon as 2024.

Though Musk is confident Starship will be the first to send humans to Mars, there are no guarantees for such an ambitious interplanetary endeavor, and Corbisiero won't rule out a scenario in which the first humans arrive at the Red Planet aboard a nuclear thermal propulsion spacecraft. "Time will tell; it's certainly possible," he said, adding that "we at INL are excited to support NASA to help develop nuclear thermal propulsion and bring this incredible capability to reality." If the INL team succeeds, they will have developed a technology to make humanity an interplanetary species finally.

With many targeting the Mars Opposition in 2033, the next decade may go down as the one in which humans finally establish a presence on Mars..