During a trip to the Moon or Mars, a crew can receive a radiation dose far higher than that encountered on the ground. NASA has just presented MissionDPT, a tool designed to estimate this exposure and the associated acute risks, before or during a mission.
The principle is to bring together in a single interface several models already used to describe the space radiation environment, the shielding of a vehicle and the transport of particles through matter. The result sought is a dose, that is, a measure of the energy deposited by radiation in tissues or in a dosimeter.
The Orion vehicle flying over the Moon during Artemis I on November 21, 2022.
NASA image
Concretely, MissionDPT can be configured for low Earth orbit, but also for trajectories going beyond this zone protected by Earth's magnetic field. The user can take into account the planned trajectory and shielding in order to obtain an estimate adapted to the mission studied.
The authors compared their calculations with measurements taken by dosimeters during Artemis I and aboard the International Space Station. With known trajectories and shielding files, the simulations give results considered reasonably close to the measurements.
The risk becomes more difficult to manage during solar events that release large amounts of energetic particles. MissionDPT therefore integrates UMASEP, a set of forecasting models developed at the University of Málaga. These can provide information on the dose before such an event.
In other words, the tool is not only useful for preparing a trip months in advance. It can also help a control team when dangerous solar activity appears during the flight.
This combination also makes it possible to replay severe historical solar episodes. Teams can thus test a vehicle, a trajectory or a protection strategy against conditions already observed, then compare the calculated doses and estimated risks. For a crewed mission, this information can in particular help decide when to move to a better-protected area of the vehicle.
MissionDPT nevertheless remains a simulation and forecasting tool: its results depend on the models, available data and the description of the shielding. The next announced step is its use as an operational support tool for upcoming lunar and Martian missions, particularly in situations where solar activity requires a quick decision.