PERSEO – PErsonal Radiation Shielding for intErplanetary missiOns
Funding Agency: Italian Space Agency – ASI
Principal Investigators: Giorgio Baiocco, Andrea Ottolenghi, University of Pavia, Pavia
Co-Investigator: Cesare Lobascio, Thales Alenia Space – Italy, Torino
Project partners: University of Pavia, Thales Alenia Space – Italy S.p.A., Società Metropolitana Acque Torino (SMAT) S.p.A., AVIOTEC S.r.l., ALTEC S.p.A., University of Rome Tor Vergata
The PERSEO project aims at the construction and test of a demonstrator for a personal radiation protection system, in form of a garment, to be worn by the astronaut in a space habitat to mitigate the harmful effects of cosmic radiation. The jacket will be realized with internal compartments for containers to be filled at need with the water available in the International Space Station: when such containers are full, they provide protective layers for radiation shielding (in particular against protons emitted in interplanetary space by solar events), namely the amount of energy deposited by the radiation in the most sensitive organs is reduced. For example, it is of utmost importance to ensure protection to the bone marrow, responsible for the production of blood cells, whose damage can cause very dangerous and immediate consequences for astronaut health. Through the choice of water on board the ISS as shielding material, the design meets the need of maximum utilization of the resources already present in a space habitats, avoiding additional costs and logistical problems caused by the launch of material intended for the sole purpose of radiation shielding. Together with the jacket, a container filled with water (≈ 1 liter) will be also launched, and then it will be sent back to the ground, in order to perform water contamination analysis. The container will be qualified for launch, and the material it is made of will be tested for its suitability to protect the characteristics of drinking water.
Description of the demonstrator:
The demonstrator PERSEO – Radiation Shield Demo – is a garment, made of NOMEX® (a tissue of common use in space environment), with interior slots for water containers. In the current design, water is distributed in 4 containers, each with a capacity lower than 10 liters, interconnected according to the following scheme:
the container that is housed in the jacket to cover the lower back part of the astronaut interfaces with a specific output port of the water dispenser on board the space station (PWD, Potable water dispenser); other three containers are connected to this container by means of suitable pipes provided with safety valves: one will cover the upper part of the back, while the remaining two symmetrical bags can be folded on the sides and shoulders of the astronaut, to protect the chest.
Operations on board the ISS:
During the experiment on board the space station, the astronaut will be asked to remove the jacket from the transport bag. The astronaut will then have to connect the jacket interface to the water dispenser, thereby starting the filling. The water flow will be interrupted once the desired amount of water – necessary to fill all the garment containers – is reached. The astronaut will wear the garment in the filled configuration, in order to verify the quality of the design of the demonstrator: he will be asked to fill a questionnaire in which he will declare any possible feeling of discomfort, such as movement constriction, as well as to give an opinion on the practicality of the filling and draining procedures. At the end of this wearability test, the content of the jacket bags will be drained into the water recovery system, and everything will be stowed back into the transport bag.
Current strategies for the risk mitigation from cosmic radiation involve the use of thicknesses of shielding materials, distributed outside the space habitat, together with the realization of internal shelters, habitats or areas with a higher level of shielding. This implies that, for example in the event of an intense solar event (SPE, Solar Particle Event), the astronaut could be forced to take refuge in a shelter, risking to be confined in a small volume for long periods of time. In this situation, a personal radiation protection system as the PERSEO garment could ensure the astronaut the possibility to leave the shelter (albeit for a limited period of time), for example to make interventions that may be necessary because of the solar storm itself, as in case of damages to electronics due to radiation. In addition, in the design of inhabited structures on the lunar surface or in future trips to the NEOs (Near Earth Objects) studied by space agencies, the non-availability of large volumes could make radiation protection strategy based on the presence of a shelter not feasible at all. It is therefore necessary to explore complementary or alternative strategies, and optimal solutions are those which, as PERSEO, are based on the use (and not consumption!) of already available resources or waste materials. In this sense, the qualification for the launch of a container, full of water, and the subsequent analysis of the water contained after return to earth holds a role of crucial importance. If it will be shown that the material of the container is able to keep the drinking water without causing alterations, its use could be foreseen in the future for the realization of garments or sleeping bags to be filled with water, serving at the same time as systems for the storage of drinking water and personal radiation protection systems.
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