Now that mankind has stepped into the third millennium, the task of mapping out the general trend of its future progress and identifying its research and development priorities is no longer a theoretical, but rather a down-to-earth practical priority. These problems are now on the mind of many scientists in this and other countries, including researchers of the Institute of Biophysics (RAS Siberian branch). They include Academician Josef Gitelson, Sergei Bartsev and Viktor Okhonin (both with degrees of Cand. Sc. (Phys.&Math.), and also Vladislav Mezhevikin, Cand. Sc. (Biol.); the project they are working on bears the intriguing name of "Space Wanderer" and concerns future studies of outer (deep) space. And although the subject goes beyond the scope of their direct responsibilities at the Institute, it should merit attention considering the high level of their competence.
To begin at the beginning: while the population of our planet continues to grow, we are facing an ever worse shortage of ores, mineral fuels, fertile soils, clean water and air... This being so, urgent decisions should be taken on setting R&D priorities to cope with the problem.
The authors say that aerospace technologies, especially those used on long manned missions in space, can be successfully applied to some really large-scale projects here on earth and give new impetus to many areas of our conventional science and technology. What we need, in their view, is a new strategy of space exploration in line with the realities of the 21st century plus an appropriate national program.
One of the problems for the near future: is it really necessary and practical to try and reach out into outer space beyond the confines of the earth's orbit? Or should we limit ourselves to near-earth space? The authors feel that a key to a rapid future progress of new technologies is in the explorations of the solar system. Proceeding from this assumption, they have made an analysis of the available technology.
Near-earth space is being investigated with the help of unmanned autonomous probes controlled from the ground or else by crews at orbital stations. The main advantage of the former mode is zero risk to human life, to say nothing of its considerably lower costs. Modern technologies make it possible 'to produce some really light-weight and small-size unmanned probes which do not have to be retrieved at the end of a mission. But even if we do need them back (say, probes with some planetary material), we can save lots of money on expensive life-support systems. Furthermore, unmanned probes are indispensable in studies of space objects or bodies whose environment rules out the presence of man.
On the other hand, there is a range of limiting factors for this mode of space research. Unmanned probes can carry out only some pre-set program, or a set of programs, but they cannot be expected to cope with some unforeseen situations or emergencies. Ground-controlled automatic probes are subject to what we call functional limitations. For example, depending on their position, delays in signals exchange between our planet and Mars can be
from 8 to 40 minutes. And for really effective mission control on a real-time scale such delays should be of not more than a tenth fraction of a second. And one more thing. Mission control from the ground can work on the assumption that there will be no split- second emergencies in orbital flight or at landing. Now recall the first manned landing on the moon. When the crew took a closer look they realized that the prescribed landing spot was unfit for landing, and it was only the lightning decision of Niel Armstrong which saved the mission. At the last moment he was able to switch the lander into horizontal flight and brought it down upon a fitting platform. In a similar situation with an unmanned probe approaching some distant planet, all the Mission Control will be able to see is the scene of crush-landing which will appear on their monitors with a delay of tens of minutes. The survey potential of a space robot will also be limited by its low rate of data transmission, to say nothing of the obvious fact that unmanned probes can hardly be used in a truly effective search for some traces of life on other planets. And that clearly applies to the traditional life forms we know, and if something absolutely "non-traditional" is encountered, unmanned probes will be of no use at all.
The possibilities of unmanned probes are also limited in conducting experiments for the verification of some basic physical theories or hypotheses. And the experience gained from the US Hubble mission and the operation of some complex research units on the Russian Mirstation proves beyond all reasonable doubt that it is only a spaceman-operator who can ensure their functioning for a long time. And last, but not least, human presence on board a space probe makes it possible to simplify to a considerable extent the design of the research instruments and equipment, and carry out experiments in which objects of studies can be manipulated with.
Summing it up, unmanned probes can be effective in space studies if and when the volume of the required data processing is not very large and the nature of such data is known in advance. This includes, for example, the chemical composition and physical parameters of soil samples and other geological parameters which are not subject to rapid changes. On the other hand, manned missions into deep space are very problematic at the present level of aerospace technology, and the expenses and the risks involved can hardly be justified. If, for example, a manned mission lands on the surface of Mars and finds no traces of life there, the vast efforts involved in any such mission will simply be wasted because the only tangible reward will be some additional details on data gathered previously by unmanned probes.
The authors of the project also point out that the shrinking allocations for space research in various countries, Russia including, are a fair measure of the slackening public attention to this area as a whole. In the first place, it is only a narrow circle of specialists who can benefit by studies of this kind. Besides, the high cost of space missions puts added strain on the national budget for reasons obscure for the man in the street. And that means that the future strategy of space studies should match the situation as it exists today. In the first place, steps should be taken to rekindle public interest in these studies, keeping the general public well informed in some simple and captivating ways. And, needless to say, the costs of space missions should be brought down, while their safety standards should be upgraded. In the view of the authors of the project, one of the main conditions for translating their concept into reality consists in the constant presence of man in space and in the growing scale of this presence even as far as the giant planets (Jupiter, Saturn).
The technical foundation for a full-scale implementation of this strategy can be a manned spaceship
of an essentially new type - what the authors have dubbed a "Space Wanderer". Its design should make use of three key innovations: a low-thrust electric engine powered either by solar panels or a nuclear reactor; a closed life-support system for the crew and manipulator-robots with effective remote controls.
The concept of the "Space Wanderer" has logically originated from the desire to increase crew safety on orbital missions, including the most critical stages of takeoff and landing. And the proposed spaceship, which is to be assembled directly in orbit, will be free of these risks in general. Research crews on board this craft will be studying heavenly bodies with the help of a remote-controlled and mobile manipulator-robot, copying the movements of the operator and operating on a real-time scale. To make all this possible, the cosmonauts should come not farther than 10 thousand kilometers from the object of their studies. Say, on board a spaceship orbiting Mars they will be able to steer directly (without time delays for communications) a robot-manipulator on the surface of the Red Planet. Such high-tech probes operating in what is called a "real presence" mode, or "transferred reality", will make it possible to lift the contradictions between the need of human presence at the point of contact with the unknown and safety requirements.
Robots-manipulators, fitted with a high-resolution stereo TV relay system as well as with sonic and tectile data channels, will be controlled by a system similar to computer "virtual reality", which will produce an effect of the operator's presence on the surface of the object of his studies. Direct sensor data obtained by the robot (stereo image, sound and certain sensations) will be recorded and then used by any researcher in the form imitating real, natural perception. The latter will generate the effect of the viewer's personal in-volvement in the studies of space, and not just of a narrow circle of scientists as before.
And there are several other aspects to be born in mind. Using robots in the "transferred reality" mode will make it possible for a layman to "visit" such planets as Jupiter, Venus or Saturn where the actual human presence is absolutely ruled out. What is more, even in the most critical situations in which the robots can be destroyed the operator watching the scene from a safe distance will remain "in the picture" down to the last second of this or that event.
As was said before, the "Space Wanderer" will be propelled by a low-thrust electric, or rather an electrojet engine powered by solar panels or a nuclear reactor. Over the past 25 years units of this kind have been used for satellite orbit correction and orientation. Other units have been developed and tested which can be used as sustainers of spacecraft. As different from the currently used chemical or thermal nuclear rockets with the engine operating for a short time, the new power units will be able to operate within a much broader range of modes. This will do away with the stringent observance of the fixed schedules and stage trajectories so that a space crew, if need be, could remain near the object longer than planned and make some desirable route corrections.
The authors of the project have calculated the optimal versions of the "Space Wanderer" with respect to the payload/spaceship mass ratio for solar-panel and nuclear-reactor versions. These assessments, however, are all of tentative nature since real flight trajectories had to be replaced with some approximate values of summary velocity increases for the conditions of different missions. And even so the calculated data for an unmanned probe powered by an electrojet engine revealed a difference of not more than 10 percent from the actual parameters. The calculations took the mass/power system ratio at 24 kg/kW for solar panels and 10 kg/kW for a nuclear-powered unit. The data
were taken from either the already achieved or shortly expected characteristics. Meanwhile there are also real assessments of nuclear jets using magnetohydrodynamic (MHD) generators of up to 10 MW and specific mass of about 1 kg/kW. Experts have also designed an electric MHD jet engine with a thrust of 1,000 Н and the rate of How of the propellant of up to 20 km/sec. And that means that the parameters of the "Space Wanderer" can be upgraded in practice.
The use in calculations of only the summary velocity increase means that the time of placing the spaceship into orbit around the planets under investigation has not been taken into account. The obtained assessments approach the actual values if we assume that the launch from and return into a near-earth orbit is done with the help of accelerating and decelerating, or braking, stages equipped with chemical motors. These takeoff and landing stages are not parts of the spaceship and are delivered on a near-earth orbit separately
The authors of the project also discuss the life-support systems for space crews. For the "Space Wanderer" they should meet the two main criteria: have a minimal mass and an optimal configuration depending on their service life. So far the so-called hybrid biophysicochemical systems only meet these requirements. The possibility of building such systems in practice has been confirmed by prolonged full-scale trials at the BIOS-3 test site of the Institute of Biophysics (RAS Siberian branch). A research team stayed within an experimental complex for nearly two years with the full regeneration of the air, water and the vegetable part of their diet. It was established that for sustaining one person on a vegetarian diet cultivation area of only some 30 m 2 is required, and for a full regeneration of air (also for one person) it is necessary to have some 14 m 2 of cabin space. These dimensions are quite acceptable for the "Space Wanderer" if one bears in mind that in a compact version of phytotrons * a biocenosis of 14 m 2 can be accommodated within a space of only 6 m 3 .
Having thus considered their three basic assumptions demonstrating the realistic nature of their project, the authors then focus on other aspects of long space missions. This includes, above all, the danger associated with prolonged exposure of man to cosmic rays. One method of protection involves the use of some alkaline metal, like cesium, which is currently used as the working agent in a low-thrust electric engine. A 20 cm layer of this material reduces the level of solar radiation (including flares) down to nearly the earth level, and the intensity of galactic rays is almost halved. Radiation shielding can also be provided by liquified inert gases which are currently used in electric motors.
As said above, the "Space Wanderer" will be assembled in a circumterrestrial orbit. And it is very important that components of the system (engine, robots-manipulators and life-support system) be tested in a space environment. A testing site of this kind can be located at the International Space Station ** . Then the strategy of the "Space Wanderer" will come as a natural follow-up on its R&D program.
* Phytotron - laboratory for plant growing under controlled conditions. - Ed .
** See: V. Senkevich, "Russian Cosmonautics at the Turn of Two Centuries", Science in Russia, No. 1, 2001. - Ed .
J. Gitelson, S. Bartsev, V. Mezhevikin, V. Okhonin, "Deep Space: People or Robots?" - Vestnik RAN, Vol. 70, No. 7, 2000
Prepared by Arkady MALTSEV
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