A study estimated that the well-known hazards of space freezing temperatures, crushing pressures, isolation astronauts also face risks from radiation, which can cause illness or injure organs. Though not believed to be an imminent threat to current missions, astronauts may one day face radiation from solar winds and galactic cosmic rays. The study was published in Aerospace Medicine and Human Performance.

They found that the relatively minimal shielding of the MOL program's space vehicle and its high inclination polar orbit would have left the crew susceptible to high exposures to cosmic radiation and solar particle events. Had the mission continued through 1972, astronauts would have faced toxic doses of radiation during a massive solar event.

The researchers focused on radiation from two sources: solar winds and galactic cosmic rays. Some space radiation is believed to pass through the walls of shuttles, while some barrages the shielding and causes a cascade of loose metal ions. A portion passes through the body; the rest deposits its energy on the skin or even inside the body, affecting the organs.

Determining the radiation levels that MOL pilots would have experienced behind the vehicle's light-weight shielding entailed a good deal of data mining, extrapolation, and simulation. Chancellor and his collaborators modeled the MOL's orbit profile, the space weather and geomagnetic forces from those years, and the particle and heavy ion transport that such a trajectory would have encountered.

Based on animal studies, Chancellor and his colleagues anticipate that such exposure would have caused nausea, vomiting, fatigue, and possibly skin burns to the crew. Without prompt instigation of medical countermeasures, the risks could have been even more severe.

OVERCOMING THE LIMITATIONS OF SPACE RADIATION PREDICTION

Efforts to simulate space radiation risk are not new. In fact, historical records show they were a part of NASA and Department of Defense space research from the beginning. But decades of study have achieved few concrete answers or practical measures to mitigate radiation, according to the scientists.

"Despite years of research, understanding of the space radiation environment, and the risk it poses to long-duration astronauts remains limited," Chancellor and his team wrote in a paper that appeared in Nature Microgravity in April 2018. "Given the intended future of human spaceflight, with efforts now to rapidly expand capabilities for human missions to the moon and Mars.

This rapid turn around could enable NASA to run much more accurate models than they currently do to determine, in real-time, how a solar storm or another cosmic event might impact astronauts, a capability that may one day save lives.

There is a pressing need to improve the understanding of the space radiation risk, predict likely clinical outcomes of interplanetary radiation exposure, and develop appropriate and effective mitigation strategies for future missions.