by Natalya KRIVOVA, Dr. Sc. (Biol.), director of the Research Institute of Biology and Biophysics, Tomsk State University, Tomsk, Russia; Kirill TRUKHANOV, Dr. Sc. (Technol.), leading researcher, Institute of Medicobiological Problems, Russian Academy of Sciences, Moscow, Russia

Next year, 2011, will see an epic jubilee-fifty years since man's pioneering space flight. On April 12, 1961, Yuri Gagarin circumnavigated the earth aboard the spaceship VOSTOK. Today man sets his sights higher than that-on Mars, in particular. Plans are afoot to build longtime lunar bases. Piloted interplanetary missions are in order. What makes them different from routine orbital flights?

PROTECTIVE "SHIELD" OF THE EARTH

Tentatively a Martian odyssey is expected to take 1.4 years or so. We might recall that the endurance flight of Valery Polyakov, a medical doctor, on board the MIR orbital station in 1994 and 1995 was almost as long as that-1.2 years.*

Compared with circumterrestrial and even lunar flights, an interplanetary mission will be an endurance flight (no cargo ships to supply oxygen, food, water, equipment and the like; there will be a time lag-as much as 40 minutes for a Martian mission-in two-way radio communication sessions. And there will be no geomagnetic field that we are so much used to. Extending far beyond our planet's boundaries, it deflects the larger part of high-energy charged particles coming from the Milky Way galaxy or from the sun, especially during solar flares, and thus shields our bio-sphere. Fortunately the radiant flux (hard electromag-netic radiation quanta-X-ray and high-energy fluxes) reaching the earth from outer space is very small. The geomagnetic field shields the planet's atmosphere, too-otherwise the solar wind would have "blown" it away.

Fluxes of galactic cosmic rays are far more intensive in deep space whose interplanetary field is from three to five orders as low as the terrestrial geomagnetic field; this poses a greater radiation hazard for would-be astro-

* See: O. Gazenko, A. Grigoryev, V. Yegorov, "Space Medicine: Yesterday, Today, Tomorrow", Science in Russia, Nos. 3, 4, 2006.-Ed.

Geomagnetic field in shorthand.

nauts. Particularly dangerous are multicharge HZE par-ticles (heavy ions). As one American physicist has put it, the Lord did not suppose His beloved children would start flying about His unshielded nuclear reactors...

So, no geomagnetic field out there. What is the threat of its absence? Back in the 1960s and 1970s most scien-tists were of the opinion that weak magnetic fields, stat-ic fields in particular (this is what the earth magnetic field is like) could not cause any significant biological effect. Experimental results running counter to this view were dismissed as dubious.

This view firmed up in the 1960s as US lunar astro-nauts involved in the Apollo mission stayed for some time in a geomagnetic field thousandfold as low; they did not show any significant deviations in their condi-tion. However, only general vital activity indicators were registered in those cases, and the action of the weak field was rather short, about ten days and nights.

But these orthodox notions had to be revised. It comes out that a geomagnetic field reduced 500 to 1,000-fold, has a negative effect on organisms, especially during their growth. This could be seen in the malgrowth of Japanese spotted newt (Triturus vulgaris) larvae, with bicephalous (two-headed) individuals born as a result (as demonstrated by Professor Makato Asashima of Tokyo University); in the paresis (paralysis) of limbs and wings in 20 to 40 percent of newly hatched chickens (Acad. Vlail Kaznacheevofthe Russian Academy of Medicine); in the arrest of the growth of two-cell embryos of mice (studies at the RAS Institute of Cell Biophysics carried out by RAS Corresponding Member Yevgeny Fesenko). Furthermore, hypomagnetic (low-level magnetism) conditions are shown to affect man's cognitive functions (results obtained by a research team of Dr. Vladimir Bingi, Prokhorov Institute of General Physics, RAS).

Conducting medical examinations of people exposed to a geomagnetic field only 3 to 10-fold as low (in screened structures, in ferroconcrete underground premises, and so forth), Drs Yuri Paltsev and Larissa Po-khodzey of the Research Institute of Labor Medicine (Russian Academy of Medicine), have detected disor-ders in the central nervous, cardiovascular and immune systems, and in blood. In particular, they have found imbalances in the principal nerval processes as manifest-ed in pervasive inhibition, slower responses, and so on.

And last, the molecular mechanism implicated in the action of hypomagnetic factors has been interpreted from the standpoint of quantum mechanics.

These findings are there not only in scientific publi-cations alone. In May 2009 the Sanitation and Hygiene Regulations effective in Russia were supplemented with standards limiting a decrease in the geomagnetic field level in residential and public buildings versus outdoor values.

IT ALL BEGAN WITH THE COMPASS

The phenomenon of terrestrial magnetism was dis-covered centuries ago, between the nine and twelve hun-dreds. Little by little more information on its character-istics was coming in, especially throughout the 16th century, the age of the Great Geographical Discoveries (Christopher Columbus*, Vasco da Gama, Ferdinand Magellan, English seafarers). This was done with the help of the ordinary compass and its magnetic needle deflection.

In 1600 the English physicist William Gilbert, Queen Elizabeth's surgeon, published his opus classicum on terrestrial magnetism De magnete, magneticisque cor-poribus et de magno magnete tellure (Physiologia nova, Londini, 1600). Regarding the earth as a "large magnet", he summed up what was known on the matter then as well as the results of his own inquisitions. For one, he demonstrated that the distribution of magnetism on our planet concurred with the magnetism of a magnetized sphere.

It is common knowledge today: the phenomenon of earth magnetism is due to electric currents within its liquid core (geodynamo). On the terrestrial surface the magnetic field of these currents looks like a magnetic dipole field.**

The virtual dipole, which is the closest analog of the main terrestrial magnetic field (taken with no account of magnetic anomalies), is shifted more than 400 km relative to the globe's center lying as deep as 6,378 km from the surface and tilted 11° to the earth's rotation

* See: R. Petrov, "The Way to America", Science in Russia, No. 4, 1992.-Ed.

** Magnetic dipole-two equivalent magnetic charges of the opposite sign at some distance from each other. Although used widely in calcula-tions, they have not yet been detected in real terms.-Auth.

axis. At the magnetic poles, which do not coincide with geographical ones, the field intensity is at a maximum; at the equator, it is half as much. And in the region of the South Atlantic magnetic anomaly, taking in a larger part of Brazil and Argentina, it is only a third of the maxi-mum and persists as such to altitudes of 1,000 km or thereabouts. That is why the field is like a "funnel" here for high-energy cosmic particles.

The dipole's field wanes in the inverse proportion to the cube of the distance from it. On board a space station moving in a circular orbit at altitude 300 to 400 km, the geomagnetic field value is only 15 to 20 percent lower than in a region it overflies. But the onboard field varies all along because of changes in the station's coordinates.

The magnetic poles are keeping adrift, and this process is significantly faster now. Besides, the geomag-netic field undergoes periodic inversions (several times in a million years), that is it goes to zero and changes polarity. Biospheric changes, down to planetary biolog-ical disaster, are often attributed to such events. As one planetary scientist has put it, inversion is like a sieve that sifts the biosphere. The inversion, according to paleo-magnetic evidence, occurred about 730 thousand years ago. The next polarity change is expected to set in sever-al thousand years from now. Judging by paleomagnetic data again, the inversion process may take from 100 to 8 thousand years.

The geomagnetic field of the earth shows small low-frequency pulsations (fluctuations) ranging from a few seconds to hundreds and thousands of seconds. By way of example we could recall an episode aboard the Soviet space station SALYUT-6 in 1978. The crew comman-der, Vladimir Kovalenok, noticed sudden excitability and irritability of his mates, as seen in a conflict with the Flight Control Center during a routine radio communi-cation session. After a while their tension subsided, and they calmed down. In a follow-up flight testimony, Vladimir Kovalenok and Dr. Sergei Avakyan (Vavilov State Optical Institute in St. Petersburg) found that a blackout in all kinds of geomagnetic field pulsations had occurred exactly at that time. They inferred that the absence of such pulsations in an interplanetary flight might have a negative effect on the crew's physical con-dition. Next, experiments carried out on board the orbi-tal complex MIR (1990-1997) demonstrated that fluc-tuations in the onboard geomagnetic field level because of changes in the station's geomagnetic coordinates as well as magnetic storms act upon the heart activity of crew members, and this effect continues during the ground rehabilitation period, too (experiments were conducted by Roman Baevsky, RAS Institute of Medico-biological Problems).

MAGNETORECEPTION MECHANISMS

Mechanisms implicated in the action and, conse-quently, reception of magnetic fields roughly equivalent to the geomagnetic field are among magnetobiology's imponderables. We can infer their presence by postulat-ing that the entire evolutionary process on earth has been going on with the terrestrial magnetic field around. Navigation of birds, sea and other animals, especially in long-distance migrations, is put down to the phenome-non of magnetoreception. Bees make use of it in dances during honey-gathering to indicate the location of mel-liferous plants. Many research scientists object to the action of such mechanisms by pointing out that the energy of interaction of a field with biological substance is far less than the heat motion energy of its molecules. That is to say, heat motion should immobilize, "knock out" any orderly processes induced by a weak field. But nature is smart enough and can circumvent, and ele-gantly at that, the fundamental "don'ts" of its own. The discovery in the 1960s and 1970s of magnetite (lode-stone) particles of biogenic origin in living organisms was a major step forward in explaining the very phe-nomenon of magnetoreception. Still and all, many aspects of this mechanism were still obscure. Vladimir Bingi and Dr. Dmitry Chernavsky (RAS Lebedev Physics Institute) have studied the dynamics of magne-tosomes in the cytoskeleton acted upon by weak mag-netic fields to demonstrate that the cell responds to magnetic field fluctuations.

Back in the 1980s experimental data were obtained on the action of relatively weak static and variable magnet-ic fields on chemical and biochemical reactions involv-ing radicals; a theory was evolved to explain the mecha-nism of this action (Acads Anatoly Buchachenko and Renad Sagdeev; RAS Corresponding Member Kev Salikhov, and Dr. Yevgeny Frankevich). They demon-strated: collisions of molecules caused by heat motion are too short-lived to affect the action of a magnetic field on such reactions. A hypothesis based on the quan-tum mechanics theory was advanced to explain the bio-logical effects of a static magnetic field by the interfer-ence by ion-protein complexes that have a major part to play in vital activity (Vladimir Bingi). It was predicted and then proved experimentally that hypomagnetic con-ditions make for the higher probability of dissociation of these complexes, that is, metabolism is changed thereby. This results in cellular dysfunctions.

All that is conspicuous at the molecular level. Yet it is hard to evaluate the subsequent scenario-the further transformations of the signal of the magnetic field's pri-mary target in the chain of biophysical and biochemical conversions. We are not certain about the interaction of magnetobiological effects in different systems of the organism and finally, about its overall condition induced by geomagnetic field fluctuations.

IN THE EXPERIMENTAL MIRROR

In 2007 and 2008 a research team (Drs Tatyana Zamo-shchina, Ravil Tukhvatulin, Marina Khodanovich, Olga Zaeva and Tatyana Mizina) of the Research Institute

of Biology and Biophysics (Tomsk State University), jointly with the RAS Institute of Medicobiological Problems in Moscow, made a close study of the effect exerted on the organism by hypogeomagnetic conditions approximated to an interplanetary field. Taken as test subjects were white laboratory rats; their behavioral responses were monitored in course of these experiments.

There is an array of standard techniques used in exper-imental physiology for short-term observations. For example, the "open field" test, 5 min long, allows to assess the behavior of a test animal in an ordinary situa-tion, its integral activity and emotional responses. Longer observations, however, are a very laborious pro-cedure. But advanced video observation technologies (with the use of IR instrument illumination at night hours) and computer filing of the photo material enable around-the-clock monitoring of test subjects and their behavioral reactions. A special-purpose program devised for video files management makes it possible to ana-lyze the locomotor activity of rats within twenty-four hours (the author of this program is Dr. Dmitry Sukhanov of the Siberian Physicotechnical Institute, Tomsk State University).

Hypogeomagnetic conditions had to be also simulat-ed. The following procedure was chosen in the end. It amounted to weakening the vertical and horizontal components of the geomagnetic field by means of oppo-sitely directed magnetic fields induced by two systems of Helmhoftz rings* respectively. The axes of the rings were within the plane of the magnetic meridian. A cage with test rats was placed in the region of the homogeneous field induced by the experimental setup. Magnetometers under the cage worked nonstop, measuring the vertical and horizontal components of the earth magnetic field. The data thus obtained were loaded into the computer controlling the currents induced in the rings and making the residual geomagnetic field correlate with the preas-signed value. In this particular experiment it was equal to 50 nanoteslas, a value equivalent to a geomagnetic field as if it were 1,000-fold as low at Tomsk.

Taken as test animals were white male rats. Proceeding from the results of "open field" testing, the animals were broken into three groups. The first one comprised ani-mals with high locomotor activity and low emotionalism; the second-those with middle-level values of the above parameters; and the third group was characterized by low locomotor activity and high emotionalism. Twenty-four rats were selected out of 62-those exhibiting median val-ues, i.e. the balanced excitation and inhibition respons-es. These 24 rats were randomly divided into two equal groups of 12-control and experimental groups.

The experimental group was locked in a cage, and the control group-put three meters away from the setup in a magnetic field, not disturbed in practical terms. Two series of experiments were conducted: one taking 25 days (October 18 to November 12, 2007), the other-10 days (Feb. 23 to march 5, 2008). Why twenty-five days to begin with? One proceeded from the tentative time of man's mission on the Martian surface, with the human life span being extrapolated to the lifetime of laboratory rats. The shorter, ten-day experiment, was necessary for determining the dynamics of changes in the condition of the test animals.

* This magnetic system was suggested in the 19th century by the German physicist, biophysicist and physiologist Hermann Helmholtz. It comprises a pair of circular coils of the same diameter positioned parallel and co-axially to each other at the distance of a radius. The currents induced in the coils are equal and forward. A magnetic field approximate to a homogeneous one is induced in the central region in between.- Auth.

Reduced magnetic field affecting aggressiveness of rats: the number of short (〈5 s) and long (〉5 s) episodes of aggression between 6 and 7 hr in the morning.

Locomotor activity of rats between 0 and 9 hr a.m.

Their behavioral reactions in the video files obtained on the round-the-clock basis were evaluated by the level of overall locomotor activity and with the aid of a visual count of short (〈5 s) and long (〉5 s) bouts of aggression (scuffles). At night (rats being nocturnal animals) the integral locomotor activity of the experimental group was much higher than that of the control group. At day-time and evening hours the control rats were found to be more agile than the experimental ones. Why?

Now, the locomotor activity peak was registered between 6 and 7 hours in the morning. Accordingly, an additional visual study of the video recordings had to be made. The number of long and short episodes of aggres-sion was counted (counting the scuffles is easier than usual movements of the twelve experimental rats in the cage).

During the 10-day experiment the number of both short and long scuffles in the experimental group was higher than in the control. The highest number in the long bouts of aggression within the experimental group (12 times as many as in the control) was observed in the initial three days. On the fourth and fifth days such scuffles subsided (the difference margin was five-fold), while toward the 11th day of the round-the-clock experiment they went up again (11-fold). There were more episodes of short scuffles in the experimental group than in the control one, but this margin was down by the end of the experiment. As we see it, the above dif-ferences in the aggressive behavior of rats under hypo-geomagnetic conditions are the most important result of our experiments.

Aggressive responses of rats are a way of establishing hierarchical relationships within a group. This process takes less than three days, as it was observed in the con-trol group. Things took a different turn in the experi-mental group staying in a reduced geomagnetic field: these rats failed to build hierarchical relations. There may be a variety of causes behind that. Yet we have shown that neurotropic effects of the geomagnetic field on rats result in memory lapses and affect activity learning.

Using markers, we were able to compare the results of "open-field" testing before and after the experiment for each rat. Some of the control group rats explored the "open field" at a first go, but then their interest slack-ened somewhat, as seen in their diminished locomotion. In the experimental group, however, the rats stayed active after the experiment, though their emotional responses waned. This indicates lower locomotor activ-ity motivation in test animals and diminished memo-rization.

We have also studied other functional changes in the organism caused by the cumulative effect of heavy ions and hypogeomagnetism. Some of these indicators reflected unidirectional changes both in the 25-and in

the 10-day experiments (diminished formation of free radicals in blood plasma, the higher index of erythrocyte aggregation-this index shows a correlation of aggrega-tion and disaggregation processes in blood). The pres-ence or absence of other malfunctions (in the antioxi-dant activity level, distribution of electrolytes in blood plasma and in urine, weight coefficient of organs) could be put down to seasonal functional variations in rats.

But the main result-higher aggressiveness of behav-ior-was reliably registered in the 25-day and in the 10-day experiments alike. Presumably this newly discovered effect as well as memory lapses under hypogeomagnetic conditions (with the field reduced 700 to 1,000-fold) should be studied further for the benefit of future inter-planetary crews or those on endurance working missions on the moon.

ARTIFICIAL GEOMAGNETIC FIELD

One way out is to create an artificial analog of the nat-ural magnetic field of the earth aboard a piloted inter-planetary spaceship by using a special magnetic system (the idea put forward by Kirill Trukhanov, one of the authors of the present article, and Dr. Lev Lugansky, of the Kapitza Institute of Physical Problems). This sys-tem should induce an onboard field-homogeneous enough and close in its intensity to the natural geomag-netic field. The setup should be compact in mass and dimensions, it should consume little power, and fit well into the spaceship.

Some biological problems crop up as well. For instance, about the lowest value and homogeneity of an artificially induced geomagnetic field. Should it be sus-tained continuously, or could it be switched on and off? What biologically significant variations of this field should be reproduced? The mode of the field analog's operation has another implication-one has to monitor the interplanetary field's characteristics during the flight, for example. Power-activated systems will be preferable: it will be easier to regulate their parameters. If need be, they could imitate biologically significant variations of the geomagnetic field.

If the crew compartment is cylindrical in form, it would be advisable to use systems in which field homo-geneity is achieved through an optimal arrangement of coil couples in symmetry lengthwise, with the current of the same value in each.

By way of example here are our calculations for a 50 µT geomagnetic field analog (close to one in the Moscow region) for a 32 m-long crew compartment having a 2 m radius. The mass of aluminum conductors will total 150 kg, and energy consumption, around 0.15 kW. These are low values compared with analogous parame-ters of a piloted interplanetary ship. If we choose the same field intensity as in the South Atlantic anomaly,

the mass of conductors and energy consumption will be cut by half. This means that the proposed onboard sys-tem of an artificial magnetic field will have a relatively small mass and power consumption compared with other systems of a piloted interplanetary spaceship.

Further in-depth medical and biological studies are needed, particularly with respect to magnetobiological effects and other hazards in deep space. This is of fun-damental interest from the standpoint of basic science, for we shall gain a better idea of the significance of the earth magnetic field and its evolutionary role.

In 1985 two American scientists, Abraham Liboff and Carl Blackman, discovered the phenomenon of a cumu-lative biological effect of a static magnetic field and a parallel variable field, with a peak response depending on the charge and mass of an ion, and on a static field value. That is, the former (static magnetic field) was like a tuning knob. As we have already said, a theory has been developed here in Russia (Vladimir Bingi) explain-ing this effect within the framework of quantum mechanics.

Incidentally, behavioral experiments carried out for convenience in a static magnetic field ten-fold as intense as the natural magnetic field of the earth demonstrated that the effect exerted at the frequency of Ca ions inhib-ited the cognitive activity of male rats, while the effect produced at the frequency of Mg ions stimulated their locomotor and cognitive activity (Dr. Mikhail Zhadin, RAS Institute of Biophysics of the Cell, 1996). It is like-ly that having an analog of a natural geomagnetic field on board, we could supplement it with a variable field on respective frequencies to contribute to a better psy-chological atmosphere among the crew. But first, we should have it out if this combined effect could entail any negative consequences for man in the future.

Hellenic myths tell of Antaeus, born by Poseidon, the god of the sea, and Gaea (Ge), the earth personified as a goddess. Antaeus, a giant wrestler, was invincible as long as he was touching his mother, the earth.

The same probably holds for man, too. Setting out on an interplanetary odyssey or on a lunar voyage, he would have to take a particle of Mother Earth, her geo-magnetic field.