Eye light flashes on the Mir space station

The phenomenon of light flashes (LF) in eyes for people in space has been investigated onboard Mir. Data on particles hitting the eye have been collected with the SilEye detectors, and correlated with human observations. It is found that a nucleus in the radiation environment of Mir has roughly a 1% probability to cause an LF, whereas the proton probability is almost three orders of magnitude less. As a function of LET, the LF probability increases above 10 keV/micrometer, reaching about 5% at around 50 keV/micrometer.     

Study of cosmic rays and light flashes on board Space Station MIR: the SilEye experiment.

The SilEye experiment aims to study the cause and processes related to the anomalous Light Flashes (LF) perceived by astronauts in orbit and their relation with Cosmic Rays. These observations will be also useful in the study of the long duration manned space flight environment. Two PC-driven silicon detector telescopes have been built and placed aboard Space Station MIR. SilEye-1 was launched in 1995 and provided particles track and LF information; the data gathered indicate a linear dependence of FLF(Hz) ( 4 2) 10(3) 5.3 1.7 10(4) Fpart(Hz) if South Atlantic Anomaly fluxes are not included. Even though higher statistic is required, this is an indication that heavy ion interactions with the eye are the main LF cause. To improve quality and quantity of measurements, a second apparatus, SilEye-2, was placed on MIR in 1997, and started work from August 1998. This instrument provides energetic information, which allows nuclear identification in selected energy ranges; we present preliminary measurements of the radiation field inside MIR performed with SilEye-2 detector in June 1998.     

Study of the radiation environment on MIR space station with SILEYE-2 experiment.

In this work we present preliminary results of nuclear composition measurements on board space station MIR obtained with SILEYE-2 particle telescope. SILEYE-2 was placed on MIR in 1997 and has been working since then. It consists of an array of 6 active silicon strip detectors which allow nuclear and energetic identification of cosmic rays in the energy range between approximately 30 and 200 MeV/n. The device is attached to an helmet and connected to an eye mask which shields the cosmonaut eyes from light and allow studies of the Light Flashes (LF) phenomenon. In addition to the study of the causes of LF, the device is used to perform real time long term radiation environment monitoring inside the MIR, performing measurements in solar quiet and active days.     

Toroidal magnetic fields for protecting astronauts from ionizing radiation in long duration deep space missions

Among the configurations of superconducting magnet structures proposed for protecting manned spaceships or manned deep space bases from ionizing radiation, toroidal ones are the most appealing for the efficient use of the magnetic field, being most of the incoming particle directions perpendicular to the induction lines of the field. The parameters of the toroid configuration essentially depend from the shape and volume of the habitat to be protected and the level of protection to be guaranteed. Two options are considered: (1) the magnetic system forming with the habitat a unique complex (compact toroid) to be launched as one piece; (2) the magnetic system to be launched separately from the habitat and assembled around it in space (large toroid).     

Superconducting magnets and mission strategies for protection from ionizing radiation in interplanetary manned missions and interplanetary habitats

First order evaluations for active shielding based on superconducting magnetic lenses were made in the past in ESA supported studies. The present increasing interest of permanent space complexes, to be considered in the far future as ‘bases’ rather than ‘stations’, located in ‘deep’ space (as it has been proposed for the L1 libration’s point between Earth and Moon, or for Stations in orbit around Mars), requires that this preliminary activity continues, envisaging the problem of the protection from cosmic ray (CR) action at a scale allowing long permanence in ‘deep’ space, not only for a relatively small number of dedicated astronauts but also to citizens conducting there ‘normal’ activities.Part of the personnel of such a ‘deep space base’ should stay and work there for a long period of time. It is proposed that the activities and life of these personnel will be concentrated in a sector protected from Galactic CR (GCR) during the whole duration of their mission. In the exceptional case of an intense flux of Solar Energetic Protons (SEP), this sector could be of use as a shelter for all the other personnel normally located in other sectors of the Space Base.The realization of the magnetic protection of the long permanence sector by well-established current materials and techniques is in principle possible, but not workable in practice for the huge required mass of the superconductor, the too low operating temperature (10–15 K) and the corresponding required cooling power and thermal shielding.However the fast progress in the production of reliable High Temperature Superconducting (HTS) or MgB₂ cables and of cryocoolers suitable for space operation opens the perspective of practicable solutions. In fact these cables, when used at relatively low temperature, but in any case higher than for NbTi and Nb₃Sn, show a thermodynamically much better behavior. Quantitative evaluations for the protection of the sector of the ‘Space Base’ to be protected from GCRs (and therefore from SEPs also) are presented.For possible large outer radius solutions it must in the meantime solve the problem of the assembling or deploying in space the conductors for returning the electric current.     

ALTEA: anomalous long term effects in astronauts. A probe on the influence of cosmic radiation and microgravity on the central nervous system during long flights.

The ALTEA project participates to the quest for increasing the safety of manned space flights. It addresses the problems related to possible functional damage to neural cells and circuits due to particle radiation in space environment. Specifically it aims at studying the functionality of the astronauts' Central Nervous Systems (CNS) during long space flights and relating it to the peculiar environments in space, with a particular focus on the particle flux impinging in the head. The project is a large international and multidisciplinary collaboration. Competences in particle physics, neurophysiology, psychophysiology, electronics, space environment, data analyses will work together to construct the fully integrated vision electrophysiology and particle analyser system which is the core device of the project: an helmet-shaped multi-sensor device that will measure concurrently the dynamics of the functional status of the visual system and passage of each particle through the brain within a pre-determined energy window. ALTEA is scheduled to fly in the International Space Station in late 2002. One part of the multi-sensor device, one of the advanced silicon telescopes, will be launched in the ISS in early 2002 and serve as test for the final device and as discriminating dosimeter for the particle fluences within the ISS.     

Active shielding for long duration interplanetary manned missions

For long duration interplanetary manned missions the protection of astronauts from cosmic radiation is an unavoidable problem that has been considered by many space agencies. In Europe, during 2002–2004, the European Space Agency supported two research programs on this thematic: one was the constitution of a dedicated study group (on the thematic ‘Shielding from cosmic radiation for interplanetary missions: active and passive methods’) in the framework of the ‘life and physical sciences’ report, and the other an industrial study concerning the ‘radiation exposure and mission strategies for interplanetary manned missions to Moon and Mars’. Both programs concluded that, outside the protection of the magnetosphere and in the presence of the most intense and energetic solar events, the protection cannot rely solely on the mechanical structures of the spacecraft, but a temporary shelter must be provided. Because of the limited mass budget, the shelter should be based on the use of superconducting magnetic systems. For long duration missions the astronauts must be protected from the much more energetic galactic cosmic rays during the whole mission period. This requires the protection of a large habitat where they could live and work, and not the temporary protection of a small volume shelter. With passive absorbers unable to play any significant role, the use of active shielding is mandatory. The possibilities offered by superconducting magnets are discussed, and recommendations are made about the needed R&D. The technical developments that have occurred in the meanwhile and the evolving panorama of possible near future interplanetary missions, require revising the pioneering studies of the last decades and the adoption of a strategy that considers long lasting human permanence in ‘deep’ space, moreover not only for a relatively small number of dedicated astronauts but also for citizens conducting there ‘normal’ activities.     

Manned exploration and exploitation of solar system: Passive and active shielding for protecting astronauts from ionizing radiation—A short overview

In deep space manned missions for the exploration and exploitation of celestial bodies of Solar System astronauts are not shielded by the terrestrial magnetic field and must be protected against the action of Solar Cosmic Rays (SCRs) and Galactic Cosmic Rays (GCRs). SCRs are sporadically emitted, and in very rare but possible events, their fluence can be so high to be lethal to a unprotected crew. Their relatively low energy allows us to conceive fully passive shields, also if active systems can somewhat reduce the needed mass penalty. GCRs continuously flow without intensity peaks, and are dangerous to the health and operability of the crew in long duration (>1year) missions. Their very high energy excludes the possible use of passive systems, so that recourse must be made to electromagnetic fields for preventing ionizing particles to reach the habitat where astronauts spend most of their living and working time. A short overview is presented of the many ideas developed in last decades of last century; ideas are mainly based on very intense electrostatic shields, flowing plasma bubbles, or enormous superconducting coil systems for producing high magnetic fields. In the first decade of this century the problem began to be afforded in more realistic scenarios, taking into account the present and foreseeable possibilities of launchers (payload mass, diameter and length of the shroud of the rocket, etc.) and of assembling and/or inflating structures in space. Driving parameters are the volume of the habitat to be protected and the level of mitigation of the radiation dose to be guaranteed to the crew. Superconducting magnet systems based on multi-solenoid complexes or on one huge magnetic torus surrounding the habitat are being evaluated for defining the needed parameters: masses, mechanical structures for supporting the huge magnetic forces, needed equipments and safety systems. Technological tests are in preparation or planned for improving density of the current, lightness and stability, to increase working temperature of superconducting cables, and for finding light supporting structures and suitable safety architectures, delineating a possible development program for affording this difficult problem.     

Status of the GAMMA-400 project

The preliminary design of the new space gamma-ray telescope GAMMA-400 for the energy range 100 MeV–3 TeV is presented. The angular resolution of the instrument, 1–2° at E_γ ∼ 100 MeV and ∼0.01° at E_γ > 100 GeV, its energy resolution ∼1% at E_γ > 100 GeV, and the proton rejection factor ∼10⁶ are optimized to address a broad range of science topics, such as search for signatures of dark matter, studies of Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission, gamma-ray bursts, as well as high-precision measurements of spectra of cosmic-ray electrons, positrons, and nuclei.     

Passive cooling of superconducting magnetic systems in space

The equilibrium temperature of a system in space can be lowered by a suitable choice of its geometry and its attitude. This remark is important for devices based on medium temperature and high temperature superconducting materials, and offers the possibility of their fully passive cooling without or with a marginal recourse to active systems. General parameterizations are given and simple schemes discussed. The adopted geometrical configuration and the attitude can enhance the role of passive cooling of the large superconducting magnetic systems required for protecting from ionizing radiation manned habitats in deep space. A specific example based on MgB₂ cable for protecting large volume habitats (500 and 1000 m³) is treated. The systems can be run in deep space at equilibrium temperatures around 20 K mainly by passive cooling, provided that their geometry and attitude would be suitably chosen.