Flying to Mars right now would give astronauts cancer

Readings taken on the mission to drop Curiosity on Mars have shown that humans making the same trip would be bombarded by dangerous levels of radiation.


Long-term population studies have shown exposure to radiation increases a person’s lifetime cancer risk. Exposure to a dose of 1 Sv, accumulated over time, is associated with a 5 percent increase in risk for developing fatal cancer.

NASA has established a 3 percent increased risk of fatal cancer as an acceptable career limit for its astronauts currently operating in low-Earth orbit. The RAD data showed the Curiosity rover was exposed to an average of 1.8 milliSieverts of GCR per day on its journey to Mars. Only about 5 percent of the radiation dose was associated with solar particles because of a relatively quiet solar cycle and the shielding provided by the spacecraft.

It isn’t just a simple matter of building a bigger shield, though. Cosmic rays are difficult to guard against because the more robust the shield is, the more dangerous it might actually become:

Ars Technica (comments):

Shielding just doesn’t work well for those kinds of particles, at least in the kinds of quantities that we could put on a space vehicle. Part of why shielding against them is so hard is that GCRs carry so much energy that when they hit the shielding, they produce a huge cascade of secondary radiation, which in turn produces additional radiation, etc, producing a large cone of spreading radiation that can work its way right through the shield. In fact, the shield can make a GCR more dangerous, since there are many more particles in the secondary cascade, so the probability of getting hit by a particle (although of somewhat lower energy) is much larger.

It’s mind-boggling when you think about the vast number of technological advances we need to make to achieve safe space-flight and, say, colonization of Mars. Lets hope that the size of the task ahead isn’t enough to deter us.