BBC - Future - Science & Environment - Space Deflector Shields Inspired by the Moon
Scientists are trying to create a sci-fi spacecraft staple to protect astronauts from exposure to our Sun’s radiation on long missions. Can a solution be found on the Moon?
As any starship captain knows, should Klingons or Romulans ever attack your craft, the first thing you do is to raise the deflector shields. On Earth, scientists are busy trying to recreate this fictional concept, not to protect astronauts from aliens, but from a much more immediate and dangerous threat - streams of charged particles shooting out from our very own Sun.
Dealing with harmful radiation is becoming an ever-more relevant consideration. The renewed interest in human space exploration - with an application process already underway to select two astronauts for an ambitious Mars mission - demands efforts to ensure the safety of astronauts venturing far from Earth’s natural deflector shield, its magnetic field.
Here, below the protective magnetosphere, we are only exposed to UV radiation, which helps us tan, but also can cause skin cancer. On average, humans are hit by around 360 millirems of environmental radiation per year - the equivalent of five chest X-rays. Orbiting 350 kilometres (220 miles) above Earth’s surface the International Space Station (ISS) is still within the magnetosphere, but the planet’s magnetic cocoon is already threadbare, and astronauts are exposed to radiation that amounts to the equivalent of about eight chest X-rays a day. To protect them, crew quarters are lined with high-density polyethylene, several centimetres thick. This material is rich in hydrogen, and hydrogen atoms are great at absorbing and dispersing radiation.
Once you leave the magnetosphere, though, you’ll be in trouble, says Dr Ruth Bamford from the Rutherford Appleton Laboratory (RAL) Space in Oxfordshire, UK. On a several months-long mission to the Red Planet, for instance, the unpredictability of “space weather” poses a problem. If the Sun has a sudden solar flare, or a “coronal mass ejection”, space fills with streams of high-energy protons. For astronauts caught in these streams, it could mean instant death.