While space agencies are planning a human mission to Mars in the not too distant future, the exposure to ionising radiation during deep space missions is considered to be one of the major barriers for deep space exploration. EU funded FP7 project SR2S is addressing the need for radiation mitigation tools. The project partners are designing and developing a magnetic shield to protect astronauts during these types of future missions.
There are a number of key ways to reduce exposure to ionising radiation, which can be up to 100 times higher in space than that on Earth. Increasing the distance from the radiation source, decreasing the exposure time and shielding. Distance is irrelevant in space, cosmic rays being isotropic. Time should be increased rather than decreased according to plans for exploration and colonisation.
Shielding is the simplest countermeasure, but the current materials provide relatively poor reduction of the dose deposited by high-energy cosmic rays. Within the EU-funded project 'Space radiation superconductive shield' (
SR2S), scientists are experimenting with superconductors for a magnetic shield to deflect cosmic rays, like the Earth's magnetic field protects our planet.
A looping electrically charged wire will produce an intense magnetic field, 3 000 times stronger than the Earth's magnetic field, to wrap around the spacecraft. The magnetic field will extend to about 10m in diameter. Project partners suggest that shielding manned spacecraft from ionising radiation in this way is a prerequisite for exploration missions to the red planet and settling on its surface.
Such a magnetic field could drain power that needs to be conserved for other uses on the spacecraft. The SR2S scientists turned to superconductors that allow electrical currents to run unimpeded, meaning these currents can be maintained without access to a power source. The magnetic shield can be charged by the Sun and remain charged for years.
In addition, superconductors work at very low temperatures making space the ideal setting to use them. The SR2S scientists have chosen to use magnesium diboride. This newly discovered material superconducts at a temperature of 10 Kelvins that is comparable with that in deep space, eliminating the need for liquid helium cooling.
However, the superconducting coil tends to get slightly warm on the side exposed to the Sun so would lose its superconductivity. The SR2S project results, therefore, include lightweight, low-energy cryosystems to keep the coil cool. The envisioned manned mission to Mars has so far proven to be an extraordinary technology driver, which first and foremost will benefit applications on Earth.
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