By Daniel Merino
BU News Service
Antarctic greenhouses, 3D printed habitats and year-long Mars habitation simulations are preparing us for life on the red planet, but the trip there is something that cannot be simulated on Earth. And with Mars, getting there might be more than half the battle.
In a recent press release the European Space Agency (ESA) announced findings from its ongoing ExoMars mission, which showed that cosmonauts would receive extremely large amounts of radiation when traveling to Mars.
“Radiation doses accumulated by astronauts in interplanetary space would be several hundred times larger than the doses accumulated by humans over the same time period on Earth and several times larger than the doses of astronauts and cosmonauts working on the International Space Station,” said Jordanka Semkova, the lead scientist behind the radiation-measuring dosimeter on ExoMars’s Trace Gas Orbiter.
The majority of this radiation would be Galactic Cosmic Radiation (GCR), a mix of high energy protons and atomic nuclei from far outside the Solar System, travelling at nearly the speed of light.
Earth’s atmosphere does an excellent job protecting us from these rays, but in space they become one of the biggest health dangers cosmonauts face. Exposure to this radiation increases the risk of cancer, cardiovascular and degenerative diseases, disrupts sleep and hand-eye-coordination.
In a recent interview, Alexey Malakhov of the ExoMars mission said: “A round trip to Mars will account for 60 percent of radiation dose allowed to a cosmonaut during his entire career. You can go higher with radiation doses, but above 100 percent you can stay healthy or you may get sick. Lethally sick in some cases.”
Shielding can protect against some of this radiation, but it is incredibly heavy and mind-bogglingly expensive.
Nathan Schwadron is a physicist at the University of New Hampshire and the lead scientist on a number of NASA missions. “Every kilogram costs you about $1 million. We are constantly balancing risk, the cost of bringing things into space and developing new technologies to combat the risks of the space environment.”
But as Schwadron explained, GCR is not the only radiation in space and perhaps not even the most dangerous.
Within the solar system, there is a battle going on between our sun and galactic radiation. The more energy the sun puts out, the less GCR can get to the inner Solar System. The sun cycles between high-energy solar maximums and low-energy solar minimums on an 11-year cycle. During solar maximums, GCR deflects away and is considerably lower than during solar minimums. The high readings from ExoMars are in part due to the fact that we are currently in a solar minimum with increased GCR as a result.
If cosmonauts want to minimize exposure to GCR and limit the associated health risks, the best time to travel to Mars is during a solar maximum.
Schwadron would advise caution traveling during solar maximums though. Solar flares and coronal mass ejections, massive bursts of solar radiation that can destroy electronics and cause acute radiation sickness or even death, are much more likely during solar maximums.
“The nightmare is that they are going to have some giant solar ejection. From an operational perspective, they are always worried about solar flares because they never know when they are going to happen,” says Schwadron.
Shielding technology is improving, but no amount of preparation will completely remove all risk from space travel. Schwadron compared the current era of space exploration to the early days of exploration here on Earth.
“I like to say we have become a spacefaring nation. Just as when you become a seafarer you have to know the seas, when you become a spacefarer you have to know space.”
A combination of better shielding technology and solar “weather models,” a field of research Schwadron is in, will go a long way in improving the survivability of a trip to Mars, but we are still in our infancy as a spacefaring species.
Before we can start colonizing the red planet, we have to be able to get there (and back) safely.