Astronauts could travel to Mars and Venus by hitching a ride on asteroids, burying under the surface to protect themselves from radiation.
High levels of harmful radiation from the sun and galactic cosmic rays would be a major concern for humans making long journeys beyond Earth’s protective magnetic field.
“Going to Mars and coming back again is going to double or triple the amount of time people are exposed to radiation [compared with an International Space Station mission],” says at Space Radiation Services in the UK. “We’re not talking Chernobyl levels of radiation sickness, but there is going to be a higher probability of getting cancer in their lifetime.”
Advertisement
One way to protect against this radiation is to build spacecraft with additional shielding. But Arsenii Kasianchuk and at Taras Shevchenko National University of Kyiv in Ukraine have proposed an alternative: travelling inside an asteroid. “It is more cost-effective to use an alternative material that is already floating in space,” says Kasianchuk.
The pair studied 35,000 known asteroids near Earth’s orbit to see if any could be used for interplanetary missions between now and 2120. Specifically, they looked for asteroids that passed close enough to Earth, Mars or Venus that a spacecraft could easily land on and depart, and were also large enough to house a spacecraft.
That gave them a list of 120 asteroids, some of which fly past the planets regularly every two to three years, while others are less frequent, with only one pass in a century.
The idea is that astronauts would ride one asteroid to one destination, such as Earth to Mars, and then wait for another asteroid to pass in the other direction for their return journey. “The asteroids in this case are really like trains,” says Kasianchuk. The journey times were up to 180 days for missions to Mars or Venus.
One asteroid will fly from Earth to Venus to Mars in 230 days in 2079 and another will come back in the other direction in 2080, providing an opportunity to visit both planets in one mission. Although Venus’s orbit is closer to the sun than the two other planets, an asteroid can pass it in the middle when Earth and Mars are on opposite sides of the sun.
at the University of Edinburgh in the UK says there are some practical challenges to the idea. For one thing, matching the speed of a passing asteroid to land on its surface would be very difficult.
“They’re talking about velocities of up to 30 kilometres a second,” he says – about 67,000 miles per hour – requiring a “crazy amount of fuel”, although some of the flyby speeds are as low as 2 kilometres a second, or 4500 mph.
Finding a way to bury into the surface of an asteroid would also be extremely difficult. “There’s a whole world of things that are technologically challenging about digging holes in the middle of asteroids,” says Snodgrass.
Kasianchuk says this could be done by firing an uncrewed device ahead of the rendezvous to excavate a cylindrical tunnel into the asteroid that a spacecraft could then fly into.
He hopes that more asteroids might be found in the coming years that could be used for such voyages between the planets. “More and more near-Earth asteroids are discovered every year,” he says. “The number of candidates for interplanetary transfers will continue to grow.”
arXiv
