Considering that astronauts on a mission to Mars will face more than 250 days of confinement, stress and boredom, an extra bag of peanuts isn't likely to cut it. So Mayo Clinic has been asked to study whether medically induced hypothermia might help them endure the medical and logistical rigors of a journey that NASA hopes to launch less than two decades from now.

Anxiety, depression and personal conflict are just a few of the risks that would face astronauts who remained fully conscious in a cramped craft for a journey of that duration.

But cooling them into a hibernation-like state could make the trip passable, said Dr. Matthew Kumar, an anesthesiologist with Mayo's Aeromedical Unit. And it would simplify and shrink the design of their spacecraft.

"You don't have to have too many TVs," Kumar said in a recent interview. "You don't have to have too many stoves or microwaves."

Popular culture — from the 2016 movie "Passengers" to the video game "Halo" — has long drawn on the idea of cocooning astronauts for prolonged space voyages. But its emergence from science fiction to reality could solve some of the greatest challenges of manned deep space flights now contemplated by NASA, including the health of the crew and the weight of the craft, according to John Bradford, chief operating officer of SpaceWorks, the private flight company working with NASA and Mayo.

For instance, lowering astronauts' body temperatures from 98.6 degrees to 92 degrees would slow their metabolisms, so the spacecraft wouldn't have to carry as much food or oxygen.

"When we add an extra pound of mass to support the crew, the habitat grows in mass, which grows the amount of propellant needed for the mission, which then grows the size and thrust level of the engines required, etc.," Bradford said. "Thus, there is a lot of interest and focus on approaches that can reduce system mass and power."

Solving that challenge through induced hypothermia would be the next leap for a Mayo program that has a 75-year history of aerospace medicine. It was Mayo scientists, for example, that designed once top-secret innovations such as the G-suit, which helped jet pilots endure gravitational forces in flight.

The technological capability remains far off, though.

Worldwide, doctors are using induced hypothermia to stall the brain-cell death that occurs in patients amid heart attacks and strokes.

But such patients are kept in those states for a only few hours, and the crude methods of inducing hypothermia for emergency surgery don't fully block other reactions by the body, such as shivering, to fight off drops in temperature.

And those reflex mechanisms could be counterproductive at best, and dangerous at worst, for healthy astronauts heading to Mars.

"Shivering is a major issue," said Dr. Alejandro Rabinstein, a Mayo neurologist and an expert in hypothermic medicine who is leading the research. "If you start shivering, you spend a lot of energy. So what's the point of doing it?"

'Torpor technology'

Researchers at Mayo and the University of Alaska Fairbanks are examining whether drugs could induce the same hibernation mechanisms that allow animals such as bears and golden squirrels to survive a long winter.

"Right now, we are fighting the body," he said. "The body wants to maintain heat no matter what you try to do. The body tries to bring itself back to [98.6 degrees]. But with these new stimulants, we are discovering we should be able to have the cooperation of the body."

This "torpor technology," as it's known, is at such an early stage that NASA isn't considering it for its official plan to launch the first manned spaceflight to Mars by 2033. According to a recently released NASA timeline, the first mission would involve construction of a "gateway" station orbiting the moon, which astronauts would reach in a smaller craft; they would then depart to Mars in a larger "deep space transport" craft.

Torpor is just one of the concepts under research at NASA's Innovative Advanced Concepts (NIAC) program to accelerate space exploration beyond the initial Mars mission. Other research targets include landing systems for large spacecraft and drugs to reduce bone mineral loss in space.

Hibernation in shifts

"Its research projects have the potential to create breakthrough technologies for possible future space missions," said Jason Derleth, program executive. "However, early stage technology development may not become a part of actual NASA missions."

No one envisions start-to-finish hibernation for astronauts during a Mars journey. More likely, the astronauts would be placed in hypothermic torpor in shifts of a couple weeks or more, while those awake carry out basic functions on the spacecraft.

Nor would astronauts achieve the level of hibernation of slumbering wintertime bears, which don't eat or drink. Rather, they would be medically induced into low energy modes, in which they would still receive nourishment via a catheter or other means.

That, of course, would create another problem that seldom turns up in science fiction movies, Rabinstein said. "You know, you don't think at first about, 'How are they going to poop?' But when you start planning for this, that's what you have to think about."

Mayo researchers are meeting next month with NASA and SpaceWorks officials to develop a road map for developing the hypothermic technology for space travel.

Since induced hypothermia has been rapidly integrated into medical care, Kumar said, he's optimistic that it could be a useful tool in spaceflight. And discoveries regarding prolonged hypothermia in space, he added, should result in improved use of the technology in medical care.

"Human beings, even though we don't have the genetic compositions or mechanisms yet [for hibernation], they probably are hidden in our genes," he said. "We have the advantage of leapfrogging all those millions of years of evolution with the help of pharmaceutical agents."

Jeremy Olson • 612-673-7744