Active tracking of astronaut rad-exposures targeted

The space beyond Earth is awash with radiation. Charged particles emitted from the Sun, confined within Earth’s magnetosphere or originating from the wider Universe are a major cause of satellite anomalies and malfunctions. Credit: SSA

Radiation is an invisible hazard of spaceflight, but a new monitoring system for ESA astronauts gives a realtime snapshot of their exposure. The results will guide researchers preparing for deep-space missions to come.

A key element of the new system launched to orbit with Monday’s Falcon 9 launch to the International Space Station, ensuring it is in place for ESA astronaut Thomas Pesquet’s November mission to the Station.

As a general rule, radiation exposure increases with altitude – people living on mountains receive more than those at sea level, while airline crews receive a small but noticeable additional dose.

Astronauts in orbit receive still more radiation – they are officially classed as radiation workers. The individual dose for the whole flight is carefully measured by keeping a dosimeter on their body, to keep their career exposure within safe limits.

“While sophisticated, these dosimeters are passive,” explains Ulrich Straube, radiologist and flight surgeon at the European Astronaut Centre in Cologne, Germany.

“To gain a clearer picture of astronauts’ , we have developed an electronic dosimeter that can provide almost instantaneous information to its wearer, on their current radiation exposure and dynamics of their immediate environment.”

“This new system is also sensitive enough to differentiate between different radiation types, including the high energies of coming from far out in our Galaxy.”

While some originates from the Sun – in the form of intense but short-lived ‘solar particle events’ – the real risk for future deep-space missions beyond the protection of Earth’s magnetic shield comes from ‘galactic cosmic radiation’ that originates from beyond our Solar System, made up of high-energy, high-speed atomic nuclei spewed out by dying stars.

The very high energy of galactic cosmic radiation means they cannot be entirely shielded against. Anyway, thick shields might – counterintuitively – increase exposure, by producing showers of secondary particles.

“More data are definitely needed to help develop useful ways of reducing this risk,” adds Dr Straube. “Traditional passive dosimeter measurements can only be read after the fact, back on Earth in a lab environment.”

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