It’s safer inside the ISS than out

Chinese and German scientists have used data from China’s 2019 Chang’E 4 lander mission to predict the amount of radiation humans would be exposed to on the lunar surface in future crewed missions to the Moon.

It equates, they say, to an average daily radiation dose equivalent to 1369 microsieverts – about 2.6 times higher than the International Space Station crew’s daily dose.

The findings, by a team led by Shenyi Zhang from the Chinese Academy of Sciences, are published in the journal Science Advances.

“The radiation levels we measured on the Moon are about 200 times higher than on the surface of the Earth and five to 10 times higher than on a flight from New York to Frankfurt,” says corresponding author Robert Wimmer-Schweingruber.

“Because astronauts would be exposed to these radiation levels longer than passengers or pilots on transatlantic flights, this is a considerable exposure.”

Long-term exposure to galactic cosmic rays is known to cause health problems including cataracts, cancer, and degenerative central nervous system diseases, while exposure to solar particle events may cause more immediate damage, the researchers say.

The researchers made their calculations using data collected by a stack of 10 silicon solid-state detectors mounted in a compartment of the Chang’E 4 lander, dividing the absorbed dose by accumulated time to arrive at the daily dose rate.

They suggest that the contribution of galactic cosmic rays to this dose rate was likely at its peak, since the Sun was (and it still is) at a solar minimum, in which its magnetic field provides the least protection from these rays at any time during the 11-year solar cycle.

In a related if unrelated initiative, researchers from Australia will this week send a packet of pills into space to study how exposure to microgravity and space radiation affects the stability of pharmaceutical tablet formulations.

It is, in fact, one of two such experiments planned by the University of Adelaide. This first one will see how they cope inside the International Space Station. The second, scheduled for early 2021, will test them in the vacuum of space outside the ISS.

The tablets are in the same kind of blister packs as when sold commercially. They will be onboard NASA NG-14 mission, which is scheduled to take off from Wallops, Virginia, on 30 September.

“Radiation protection was incorporated into the design of the pills by using ingredients with heavy elements,” says Volker Hessel, research director of the University’s Centre for Sustainable Planetary and Space Resources.

“By altering the ingredient-drug complexation – the interaction between the ingredients and the drug – we will be able to examine how these variations affect their stability.”