Main results and experience obtained on Mir space station and experiment program for Russian segment of ISS

This article presents main scientific and practical results obtained in course of scientific and applied research and experiments on Mir space station. Based on Mir experience, processes of research program formation for the Russian Segment of the ISS are briefly described. The major trends of activities planned in the frames of these programs as well as preliminary results of increment research programs implementation in the ISS' first missions are also presented.     

Women and couples in isolated extreme environments: applications for long-duration missions

Expedition teams provide a number of analogs relevant to crew selection for long-duration space missions. Three groups were studied that varied in team composition. Group 1 was a two woman international dyad that traversed the Antarctic continent in 97 days. Similarities in problem solving approach, respect for each other's opinions, and a collaborative process of decision making were evident. Group 2 was composed of four women, all from different countries, engaged in a six week trek across Greenland. The most important factors in overcoming interpersonal difficulties and contributing to the successful completion of the expedition were mutual respect and motivation to maintain positive and supportive relationships. Group 3 consisted of three married couples from different countries icelocked on a boat in the High Arctic for a 9 month period. The emotional support of and ability to confide in their partner were extremely important in alleviating interpersonal tensions, and contributed to the generally effective functioning of the group. Women add an element of emotional support and help to other team members that is not as evident in all-male groups. Selection of couples with strong bonds to each other is another paradigm for crew selection for extended missions.     

Lifetime total radiation risk of cosmonauts for orbital and interplanetary flights.

This paper presents results of calculations of total radiation risk for cosmonauts over their lifetimes and assessments of possible shortening of life expectancy on the basis of generalized doses calculated for cosmonauts after a long term interplanetary and orbital space missions on "MIR" station and International Space Station with the use of mathematical expressions coming from a model of change mortality rate of mammals after irradiation. Tumor risk assessments for cosmonauts over lifetime after flights are also given. Dependences of the delayed radiation consequences mentioned above on flight duration, spacecraft shielding thicknesses, solar activity and cosmonauts' age are analyzed.     

A new perspective of carcinogenesis from protracted high-LET radiation arises from the two-stage clonal expansion model.

When applied to the Colorado Plateau miner population, the two-stage clonal expansion (TSCE) model of radiation carcinogenesis predicts that radiation-induced promotion dominates radiation-induced initiation. Thus, according to the model, at least for alpha-particle radiation from inhaled radon daughters, lung cancer induction over long periods of protracted irradiation appears to be dominated by radiation-induced modification of the proliferation kinetics of already-initiated cells rather than by direct radiation-induced initiation (i.e., mutation) of normal cells. We explore the possible consequences of this result for radiation exposures to space travelers on long missions. Still unknown is the LET dependence of this effect. Speculations of the cause of this phenomenon include the suggestion that modification of cell kinetics is caused by a "bystander" effect, i.e., the traversal of normal cells by alpha particles, followed by the signaling of these cells to nearby initiated cells which then modify their proliferation kinetics.     

A search for optical beacons: implications of null results

Over the past few years a series of searches for interstellar radio beacons have taken place using the Parkes radio telescope. Here we report hitherto unpublished results from a search for optical beacons from 60 solar-type stars using the Perth-Lowell telescope. We discuss the significance of the null results from these searches, all of which were based on the interstellar contact channel hypothesis. While the null results of all searches to date can be explained simply by the nonexistence of electromagnetically communicating life elsewhere in the Milky Way, four other possible explanations that do not preclude its existence are proposed: (1) Extraterrestrial civilizations desiring to make contact through the use of electromagnetic beacons have a very low density in the Milky Way. (2) The interstellar contact channel hypothesis is incorrect, and beacons exist at frequencies that have not yet been searched. (3) The search has been incomplete in terms of sensitivity and/or target directions: Beacons exist, but more sensitive equipment and/or more searching is needed to achieve success. (4) The search has occurred before beacon signals can be expected to have arrived at the Earth, and beacon signals may be expected in the future. Based on consideration of the technology required for extraterrestrial civilizations to identify target planets, we argue that the fourth possibility is likely to be valid and that powerful, easily detectable beacons could be received in coming centuries.     

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.     

Long-term operation of "Orlan" space suits in the "Mir" orbiting station: experience obtained and its application

The started assembly of the International Space Station (ISS) and its further operation will call for a great number of extravehicular activity sorties (EVA) to be performed by ISS crews. Therefore, of great importance is to make use of the EVA experience gained by cosmonauts in the process of 15-year operation of the Mir orbiting station (OS). Over the 15-year period, Mir crewmembers wearing Orlan type semi-rigid space suits have accumulated 158 man/sorties from the orbiting station. Crewmembers used 15 suits in orbit and some of the suits were in operation for more than 3 years. The paper presents principal design features, which provide effective and safe operation of orbit-based suits, and briefly describes procedures for preparation and maintenance of suit systems, which ensure long-term operation of space suit in orbit. The paper gives results of the space suit modifications, presents suit performance characteristics and lists novel or upgraded components of the space suit and its systems. The paper also summarizes improvements in the Orlan type suits described in some earlier publications. They refer, in the first run, to the improvement of space suit operations characteristics and reliability, and the utilization of the Orlan type space suit in the ISS program. The paper analyses the experience gained and drawbacks detected and observations made, and gives statistical data on long-term space suit operations aboard the Mir station. The paper reviews certain problems in the process of EVAs performed from the station, and describes the ways of their solution as applied to the further utilization of the suit within the ISS program.     

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.     

Halo White Dwarfs and Baryonic Dark Matter

We describe the formation of hot intergalactic gas along with baryonic remnants in galaxy halos. In this scenario, the mass and metallicity of the hot intracluster and intragroup gas relates directly to the production of baryonic remnants during the collapse of galactic halos. We construct a schematic but self-consistent model in which early bursts of star formation lead to a large remnant population in the halo, and to the outflow of stellar ejecta into the halo and ultimately the Local Group. We consider local as well as high redshift constraints on this scenario. This study suggests that the microlensing objects in the Galactic halo may predominantly be 0.5M white dwarfs, assuming that the initial mass function for early star formation favored the formation of intermediate mass stars with m 1M. However, the bulk of the baryonic dark matter in this scenario is associated with the ejecta of the white dwarf progenitors, and resides in the hot intergalactic medium.