Deflecting the issue

Electrostatic shield generators to protect astronauts and lunar bases from space radiation are being developed in the US with funding from NASA.

Electrostatic shield generators to protect astronauts and lunar base from space radiation are being developed in the US with funding from NASA.

An electrostatic shield could deflect damaging particles away from lunar bases without the need for heavy shielding, according to ASRC Aerospace, which is investigating the technology.

The researchers envisage metallic spheres, each about 2m across, on the end of poles situated around the base, which would project a 3D field and create a radiation-free shadow beneath.

Dr. John Lane, senior scientist at ASRC Aerospace, said the shield could provide a permanent shelter, and unlike other protection systems would be easy to build on the moon. ‘Magnetic fields would require pretty sophisticated large magnets, with mass and size problems’ he said. ‘A lot of people believe you can just dig in the dirt. But it’s unclear how deep you’d have to go. If it’s tens of metres you are unlikely to have suitable digging equipment on a lunar expedition.’

There are two main sources of radiation raining down on astronauts, one from deep space and the other from solar storms, said Lane. ‘Once the sun erupts in storms there’s a big burst of radiation. It can be predicted and you could get into a shelter but you have to stay there for a few days. The other, galactic radiation, is continuous; there is less of it, but it can be more harmful and energetic. It’s like the difference between getting hit by a high-power rifle bullet or a buckshot. You don’t know which will get you first, but you really want to shield from both.’

Sun storm radiation particles have a low mass and so are easily deflected. Galactic particles are heavier but have a higher charge, said Lane, so are also diverted. ‘In our simulations you begin to see the particle start to change direction from 10-30m out,’ he said.

The main challenges in the first stage are working out how to power the field, and how to get rid of dust that may cause the charge to arc across the vacuum.

ASRC is examining dust-mitigation technologies such as reversing the polarity of the field or superimposing another field to ‘shake’ the dust away. The team is also investigating different positions of the spheres to optimise coverage, and alternative field generators including wires, nets or tent-shaped sheets.

NASA’s Institute for Advanced Concepts has awarded the company $69,000 (£38,000) to assess the feasibility of the technology, and the team aims to bid for a further grant of up to $400,000 (£221,500) to lab-test the devices.

The team said there may also be applications for the technology in medicine, for example in radiology.