By Academicians Oleg GAZENKO and Anatoly GRIGORYEV; Anatoly YEGOROV, Dr. Sc. (Medicine); RF Research Center -Institute for Medicobiological Problems (IMBP), Russian Academy of Sciences

In our previous article (Science in Russia, No. 3, 2006) we have touched upon problems related to favorable conditions for the health and fitness of space crews out in flights around the earth. Needless to say, orbital stations will keep up as laboratories and test vehicles for research into human endurance in outer space. But the world scientific community has set sights higher than that, on other planets-Mars in particular. Now what medical problems will have to be solved before flying to Mars?

THE RED PLANET

According to some scenarios, the first piloted flight to Mars* is supposed to take 500 terrestrial days and nights, the return journey including. Man has never left the earth for as long as that, though the endurance record of the space medic Valery Polyakov (January 1994 - March 1995) is close to this figure.

Say, if some of the crew is in need of urgent medical aid (and if it is an acute and grave condition), the patient could be brought back to earth from the circumterrestrial orbit within twenty-four hours at the most; but if this trouble happens on Mars or thereabouts, the return journey will take a few months. Besides, we must consider communication snags in a radio dialog with the ground control center in real time (medical tips and all that) because of the lag of 20 and more minutes on account of huge distances. Still worse, a blackout of communication with the earth. Therefore Martian voyagers should be able to fend for themselves; this applies to healthcare, the life-support system, radiation protection and other vital facilities. Every crew member should have a proper medical background, and the presence on board of a skilled surgeon versed in space medicine is a must.

Covering dozens of millions of kilometers between the earth and Mars, an interplanetary spaceship will enter the rarefied atmosphere of the Red Planet.

Continued from Science in Russia, No. 3, 2006.

* See: I. Mitrofanov, "Unlocking Martian Enigmas", Science in Russia. No. 6, 2002; A. Portnov, "The Demise of Life on Mars", Science in Russia. No. 2, 2003; M. Litvak, I. Mitrofanov, "Martian Seasons", Science in Russia. No. 4, 2004; E. Galimov, "Prospects of Planetary Studies", Science in Russia. No. 6, 2004. -Ed.

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A ground-based experimental complex.

According to Michael Duke and Douglas Blanhard of NASA, it is composed largely of carbon dioxide with small admixtures of nitrogen, argon, neon, oxygen and water vapor. This is a hostile environment. Besides, the human organism will have to cope with the lower gravitation (0.38 g), intensive physical loads during extravehicular activities (EVA) on the Martian surface, psychic and emotional stresses, unexpected emergency situations and other happenings. All that-in protective spacesuits, of course.

High fitness and work efficiency-this is one of the key problems. It calls for an essentially new system of medical support drawing upon the most up-to-date achievements of diagnostics, prevention and treatment.

Space flight diagnostics provides for definite health and fitness standards, including those important for EVA, the extravehicular activity. Early detection of organic disorders, if any, is a vital condition. New methods should be developed for visual diagnosis, biochemical, hematological (blood count) and other tests based on computer-aided diagnostic facilities, along with telecommunication technologies for consulting medics at the ground control center. This is the forte of Oleg Orlov (Doctor of Medicine, M. V. Lomonosov Moscow State University).

The prophylactic system for offsetting the negative effect of weightlessness on the organism will be based largely on the available kit upgraded in due course. This is the domain of Dr. Inessa Kozlovskaya, RAS Corresponding Member, and coworkers at the Institute for Medicobiological Problems (IMBP). For instance, coordination locomotor trainers with stress (resistance) loads (such exercises could be done during rest periods) and rehearsing other activities will improve skills in handling the onboard control systems and contribute to psychological comfort on board. For this purpose motor coordination trainers (simulators) will be developed for operating the onboard control systems. Spacesuits equipped with strain gauges (transducers) will be helpful in zero gravity-they will provide g loads on the bones and muscles along the body longitudinal axis. There will also be compensatory footwear in the kit to ease the loads on the lower limbs and make up for deficient stimulation from the feet.

Dr. Adilya Kotovskaya of IMBP is looking into possible uses of a short-radius centrifuge on a journey to Mars for creating an artificial g load equivalent to the terrestrial one. This facility might be good not only as a prophylactic remedy but also for skills training at various levels of gravitation to ease overloadings at touchdown and start on Mars, and on the descent trajectory at the fag end of the return journey to earth.

An interplanetary space voyager is to be equipped with an onboard medical center based on computer-assisted controlling expert systems making it possible to evaluate and prognosticate the crew's health condition, working capacity, level of training and psychological status. These systems should also be able to assess the radiation hazard and the risks involved, and offer adequate recommendations. All this is to be complemented with a computer database on each and every crew member (personality traits and level of physical training, exhaustive health characteristics-medical charts, data on instrumental studies, such as EKGs, roentgenograms, ultrasound scanograms, and the like). The database is also to include diagnostic, prophylactic and treatment algorithms, visual aids and films on first aid. All medical support hardware will be hooked to computer onboard systems and television equipment. During the flight the database should be updated with essential information downloaded from the ground control center on earth to the net: Mars spaceship → aground control center → medical maintenance group.

The proposed onboard health center is to be fitted with multifunctional equipment for clinical diagnostics, first and specialized medical aid, surgery and anesthesia, intensive care and rehabilitation, all that for the in-flight service. Another essential condition: banks of blood and its substitutes, of host bone marrow and preservatives for their long storage.

Certain medical and technical problems will have to be solved to enable invasive surgery on board. This holds for the fixation of instruments under zero gravity, materials and other appliances, and for the postural position of a patient and medical personnel. Surgical chambers will also be needed to minimize the risk of wound infection and ambient air pollution.

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Episodes of the SPHYNX experiment: a - physical exercises on the veloergometer; b - biochemical and immunological studies; c - work efficiency studied by computer testing; d - exercises on the MAKHOVIK ("Flywheel") trainer.

PSYCHOLOGICAL RELIABILITY

Such factors as isolation, confinement to close quarters, humdrum routine, high risk and responsibility, vast distances separating the space crew from the home planet, changed work and rest schedules and troubles in interpersonal contacts-all that plus the impossibility of having direct communication sessions with the earth in real time may cause psychic and emotional problems for crew members. It's a fact that a prolonged stay of man cooped within a spaceship results in asthenia (weakness), strained interindividual relations and conflicts. Accordingly, space medics are searching for new methods of crew selection and health monitoring (working on these problems are Dr. Vyacheslav Myasnikov of IMBP, and physician Rostislav Bogdashevsky of the Yu. A. Gagarin Spacement Training Center).

Here are some of the basic approaches to ensuring the psychophysiological reliability of interplanetary space crews: proper pre-flight selection and manning proceeding from personal characteristics, skills and interindividual compatibility; rational organization of inflight work and rest routines on the basis of the terrestrial circadian rhythm or, if the sojourn on Mars is rather long, adjusting to the Martian circadian time (24 h 39 min.). A psychological backing of spacemen and their families may be of positive significance if it takes account of individual scientific, cultural, religious and other interests. Orbital flights around the earth, comparable in duration to Martian missions, will make the picked crews surer of themselves; also, launchings of automatic probes to Mars, their touch-down on the surface of the Red Planet and their subsequent return to earth will also lend more confidence to prospective voyagers.

Human errors may entail dire consequences. That is why particular attention is attached to rote learning and overlearning with respect to certain essential skills within the limits of permissible psychic and physiological loads (the research field of Dr. Viktor Shcheblanov and his team, Biophysics Institute, Russian Academy of Medicine). This is meant to improve the reliability of crew performance, a capability characterized by an

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The tissue-equivalent spherical phantom (human body model) in a jacket at the Russian section of the International Space Station (ISS). The coordinate system is used for analyzing the radiation doses outside and within the phantom.

overall systemic response of the organism to the conditions of work and habitation medium.

Such studies were carried out in the 1990s by simulating the docking of Soyuz transport vehicles with the orbital station Mir. One tested the onboard psychodiagnostic training complex Neurolab developed jointly by Russia, Bulgaria and Germany. The results were assessed by computing the multidimensional correlation between the quality characteristics of a cosmonaut's performance (accuracy, motion time, fuel consumption) and his condition (EEG and EKG readings, arterial pressure, respiration rate and speech characteristics). Experiments were conducted at different stages of a prolonged simulated flight (with Dr. Vyacheslav Salnitsky of IMBP in charge).

The first simulated docking on the third day of the flight showed diminished performance indicators and the higher "cost" of psychophysiological involvement compared with the ground training sessions. With an increase in the number of fulfilled tasks the performance results went up exponentially and, after 3 or 4 tries, did not actually differ from the pre-flight values. Meanwhile the "cost" of psychophysiological involvement, though on the downtrend, did not reach the level of ground training sessions. This dynamics reflects the process of adaptation to weightlessness and the development of a new motility stereotype; all that is accompanied by enhanced emotional tension.

Such changes were less pronounced on long missions. The skills unlearning caused by an overlong break in training sessions could be overcome after 3 to 6 simulated trial "dockings". These results go to show that prior to the execution of complex dynamic operations in spaceship control, crew members need a series of training sessions at the onboard psychodiagnostic setup. In practical terms, such procedures allow to assess the current level of crew efficiency and, in addition, to predict the reliability of in-flight performance, and enable recovery of skills in imitation training sessions.

DANGER: RADIATION!

Radiation safety is one of the space flight imponderables. The effect of this harmful factor on a space crew and ship depends on the flight trajectory and duration, the time of the start relative to the solar activity cycle and solar flares, too, which may produce radiation above the permissible doses here on earth. As many experts see it, it is advisable to undertake a journey to Mars at the peak of solar activity which corresponds to a minimum of galactic cosmic radiation that attains important biological significance in interplanetary expeditions. This emission consists of hadrons, the atomic nuclei of chemical element (mostly hydrogen and helium) accelerated to high energies and moving at a relativistic velocity. In its penetrating capability this high-energy component of the corpuscular flux exceeds the other forms of ionizing radiation. Biologically the topography of the track of a heavy particle is most important, i.e. the eventuality of its getting into vitally significant organs and tissues.

Before flying to Mars certain problems must be resolved. Such things as radiation conditions along the flight pathway and on the Martian surface, and radiobiological effects arising in the human organism under the action of accelerated heavy charged particles and protons. It is necessary to reliably prognosticate such effects, develop methods of their prevention and cup-

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Cosmonaut Valery Korzun inspecting plants in an orbital greenhouse.

ping off (also within onboard refuges). Other options are also discussed, like generating an electrostatic field around the space vehicle, using radioprotectors and other facilities. To ward off the radiation hazard by the timely engagement of the onboard protective arrays an interplanetary ship should carry an autonomous control and prognosis system based on computer-aided expert evaluation. Developing such a setup is a difficult scientific and technical task, and intensive work is underway toward its solution. EVA will involve constant monitoring and early warning so that in the event of a radiation hazard crew members could have enough time to discontinue work on the Martian surface and retire to a descent module or some other asylum.

In recent years IMBP and other research centers in this country have been looking into the radiation safety of piloted flights (Dr. Vladislav Petrov and coworkers). A control system developed for the International Space Station (ISS) is adjusted to a Mars odyssey. Operating in an automatic mode, this system processes radiation-related data and, if need be, warns the crew beforehand about the menace. It informs the crew about the actual and prognosticated situation and suggests appropriate safeguards.

However, superlong interplanetary voyages need more than just making measurements in different compartments of a ship for radiation levels. It is more important to know the radiation doses received by the vital systems of the organism. Since we cannot implant radiation monitors in every organ and tissue, it is proposed to employ what we call phantoms, or human body models. Thus, ISS is making use of a spherical tissue-equivalent phantom developed by a team of Dr. Vyacheslav Shurshakov of the IMBP. Its sensors measure radiation dose differentials in the human body. This "extra" could be of use on interplanetary voyages as well.

PROMISING LIFE-SUPPORT SYSTEMS

High-reliability autonomous life-support and survival systems (LSS) are a key area of search and development vital to the flight-to-Mars project. At present the focus is on physicochemical systems with closed oxygen/ water cycles (Drs Nikolai Samsonov of the KhimmashResearch Institute and Yuri Sinyakand team of IMBP).

The Mir orbital station employed regenerative LSS for obtaining water from the atmospheric vapor condensate, urine and effluents; also used were apparatuses for oxygen production through electrolysis, for elimination of carbon dioxide and other trace impurities. Such devices bring down the water and oxygen store on board and thus minimize the overall weight and size characteristics.

Physicochemical life-support and survival systems of the morrow will enable more efficient techniques of water regeneration at low energy consumption levels. Their mass will be down, and reliability, up. A gradual transition will take place from physicochemical to integrated physicochemical and biological systems.

A closed ecological LSS will be an optimal solution for interplanetary flights, though not feasible at present. It will make use of autotrophic (unicellular algae, higher plants) and heterotrophic (animals, fishes, domestic fowl) organisms in assisting the biological turnover of substances. The aim is to recreate a living medium similar to the natural biosphere of the earth. But this will involve larger dimensions of a spaceship and higher energy expenditures.

Besides regeneration of the onboard atmosphere, a biological LSS will cleanse it from water-soluble volatile impurities, dust and aerosol particles. It will optimize the aeroionic composition of the medium and stabilize the numerical and species-specific population of the microflora. Model experiments staged on earth at

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That's what Mars will appear like to space travelers (photo from the book SPACE BIOLOGY AND MEDICINE, Vol. 1. M., Nauka Publishers, 1994).

the close of the 20th century demonstrated the theoretical possibility of a system like that (Acad. Iosif Hitelson, Dr. Hannah Meleshko and Dr. Yevgeny Shepelev, IMBP); this is a major accomplishment of Russian science.

The ongoing work at IMBP (Dr. Vladimir Sychev's team) culminated in an achievement, the world's first: four successive generations of seeds of a genetically labeled pea line were harvested on board the Russian section of ISS.* The characteristics of different pea lines grown in a complete cycle of ontogeny in a space greenhouse were not found to be essentially different from the ground control sample. Using a molecular biological method by 10 markers (labels) and analyzing chromosomal aberrations, experimentalists demonstrated: plants that had gone through three full cycles of growth on board did not exhibit any tokens of genetic polymorphism. Consequently, space flight factors did not impact heredity in the first, second and third generations.

Data evaluation in an experiment on four successive generations of pea line 131 show it clearly: the plants can grow for a long time, comparable to that of a Martian expedition, within an orbital station and not lose their reproductive functions in producing viable seed.

Control studies carried out on long-term orbital flights demonstrated a possibility of close ecological LSS on board based on the natural biological turnover. Autotrophic organisms were found to be viable under zero gravity conditions as an element of ecological LSS. All we need is adequate equipment that could redress changes in the ambient environment in weightlessness and provide proper growth conditions. As to heterotrophic organisms (animals), they pose problems, for inborn reflexes and instincts perform in norm only under natural (terrestrial) gravity conditions. Artificial gravity could be a way out.

WHAT THE EXPERIMENT WILL SHOW?

Since interplanetary space crews are bound to be cooped within their spaceship for an overlong time, it is important to make a close study of their psychophysiological reactions in model experiments. One such attempt was made in 1999 and 2000 in the Sphynx experiment launched at IMBP and imitating a 240-day flight of an international crew aboard the space station. Taking part were twenty-one volunteers from 15 countries (fifteen from Russia, three from Japan, and one from Germany, Canada and France each). The results are incorporated in new model studies.

At the present time yet another experiment is being planned at IMBP under Acad. Viktor Baranov of the

* See: Ye. Sidorova, "Hothouses for Orbital Stations", Science in Russia, No. 3, 2006. -Ed.

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Russian Academy of Medicine. A group of volunteers is to be locked up in a hermetically sealed space for as many as 500 days and nights-something without precedent! That's about the same time as the voyage to Mars and back. It is going to be an international crew in the 25 to 50 years age group, people of different professions-engineers, medics, biologists, information experts. A unified selection procedure will have to be applied. The final say will be with the Russians responsible for the volunteers' health and safety.

The modeling of Martian voyage conditions-super-long distances, limited resources, self-sufficiency and modified communication channels-presupposes obtaining data on the state of health and work efficiency of a crew staying for a long time in isolation. The atmosphere in a hermetic space module will be similar to that of an orbital station. We are planning to use ground-based life-support systems that could be controlled by crew members. The food and water stock should last for the entire interplanetary journey. Each crew member will room in a private cubicle doubling as a workplace.

In collaboration with the ground control center in charge of a simulated flight and using telemedicine methods we aim to test autonomous means of diagnostics and health condition prognostication so as to prevent the negative impact of flight factors and give medical and psychological aid. Innovative life-support technologies are going to be tried out, too.

The touch-down of the descent module will be simulated as well. Accordingly, three crew members will have to stay on the imitated Martian surface for as long as 30 days and nights, while the others will remain on a simulated orbit. We shall be studying man's condition and performance after a long stay within the hermetic space of the module. We should provide loads similar to those attending extravehicular activities on the Red Planet.

All that will be part and parcel of our experiment. In addition, in keeping with the principle of self-organization and self-control, each of the volunteers will have to monitor the vital characteristics (physical and psychic condition) of his own self and crew mates. He will be keeping tabs on work efficiency, state of the living medium and will have to be able to make decisions and act on them independently, without outside interference. The volunteer testers will be doing independent research and, if need be, should be able to make repairs, work with telemedical apparatuses and log time on the Martian scale in an episode that will model their stay and work on the planet's surface.

Both unexpected situations (technical glitches) and human factor-related conditions will be studied and evaluated. Say, the possible misuse of consumption quotas may cause psychological tension. Some of the crew members may be incapacitated, partly or in full, by disease or injury. There may also be troubles in interindividual teamwork and even conflicts in a situation when no replacements are possible. Add to this the unscheduled breaks of the work and rest routine, diminished performance, redistribution of team leadership and functional roles on break into groups of conflicting interests.

The results of the upcoming experiment will be condensed in a set of medical, biological and technical standards pertaining to the future manned flight to Mars, including permissible conditions for good health and efficiency.

Apart from the main 500-day experiment, we are thinking of other independent experiments for prospective Mars voyagers. For instance, using the atmosphere of hermospaces for controlling the functional condition of the organism; studying the psychological status of small groups staying in isolation for up to three months. There will be a number of biotechnological tests (waste utilization, water regeneration from vital activity products, and so on). Fresh data obtained at ISS and biological orbiters will be collated with the results of the ground experiment. Test animals will be used for studies involving the level of ionizing radiation on the flight trajectory to Mars, the different isotope composition of the atmosphere and water as well as the toxic aftereffects of chemical agents transformed by radiation.

The job begun by Yuri Gagarin's epic orbital flight in April 1961 is proceeding with much success enriching our knowledge of the surrounding world and man. We are hoping for further strides in the progress of astronautics and in the solution of new ambitious tasks. The arsenal collected by science and engineering in these four decades shows that such high objectives are attainable only by joint efforts of the world scientific community.