Studies of planets are an important integral part of fundamental space research. Their objectives also include understanding the laws of the formation and evolution of the Earth. Scientists also want to gain an insight into the conditions of the origin and propagation of life in the Solar system. They study the Moon as the source of resources, a forward base for studies of remote space, a base for monitoring the asteroids threat and for keeping check on the development of critical situations on our planet. Work on these problems calls for pooling the efforts of different countries (while being mindful of the interests and priorities of national science) and for a more effective organization of our own national program of planetary studies. This problem was discussed at a session of the RAS Presidium by Acad. E. Galimov, Director of the RAS Institute of Geochemistry and Analytical Chemistry in December 2003.
What were the conditions on the Earth during the first hundreds of millions of years of its history? What was the temperature, how the gas and water "shells" of the planet were formed, its primary crust and the oceans; and what was their composition? For answers to these questions scientists have to rely on data of what is known as comparative planetology. We have no data on terrestrial rock of more than 3.9 bn years of age, with the exception of some grains of zircon, although the age of the planet itself is more than 4.5 bn years. In the final analysis our understanding of the evolution and prognostication of the development of the biosphere can be promoted only on the basis of understanding the laws of the origin and peculiarities of the existence of the heavenly bodies of the Solar system.
One of the foremost areas of space studies is associated with the crucial problem of the origin of life. This involves using the achievements of molecular biology, of mathematical modelling with the help of supercomputers; the use of fine geochemical and isotope methods which make it possible to reconstruct early events in our Galaxy whose material "witnesses" have already disappeared once and for all, leaving behind only some indirect traces of their existence. Of great importance in the process of studies of other planets would be the discovery of some extra-terrestrial forms of organisms.
The mystery of the origin of life transcends the boundaries of science, involving deep strata of world outlook. And one has to bear in mind that solving that mystery would lead to a decisive breakthrough in the field of what are known as biotechnologies. Documents on US strategic planning of space studies include the question of whether there exists, or ever existed, life beyond the confines of the Earth and how life originated in the Solar system? And it is not accidental that this question ranks first in the list of other priorities.
Another promising area of research are studies of natural resources. Experts are working on projects of energetics on the Moon since it is believed that our terrestrial sources, including organic and nuclear fuels, will not be enough to meet our industrial requirements by the middle of the next century. One of the ways of dealing with the looming crisis consists in using helium in thermonuclear synthesis. Its isotope can be obtained and delivered from the Moon. According to some calculations this method would be more economically attractive than using the traditional sources, if we possess the technology of such synthesis and an appropriate infrastructure.
At the same time this natural satellite of the Earth can be a convenient and inexpensive cosmodrome for launchings of heavy probes into remote space since there it would be more convenient to obtain the oxidizing agent and titanium. Having no atmosphere, seismic stability and being screened from radio noises, the other side of the Moon is an ideal site for locating astro-physical stations and other objects of this kind. Located there can be bases for permanent observations of asteroids and their likely threats to mankind*, and also technical devices for dealing with possible global catastrophes.
At the 5th conference on lunar studies (Hawaii, USA) held in November, 2003 an important place was given to the problem of building tracking stations (including those required in case of critical situations here on Earth). Already discussed today are problems of international legal provisions in connection with the studies of our closest neighbor in space and the uses of its resources, including commercial ones.
Different tasks have been formulated in the US program of studies of Mars and satellites of Jupiter, above all studies of the conditions for the origin of life and the search for its material "traces". An outstanding achievement of the past few years in this respect have been proofs of the existence of water on Mars. Tens of thousands of high-resolution photos taken from board the US orbiter "Mars Global Surveyor" launched in 1998 show details of winding runlets, beach terraces, and hundreds of valleys which are regarded with a great degree of probability as traces left by water streams.
Neutron and gamma-spectrometers on board the US orbiter "Mars Odyssey" launched in 2001 discovered instrumentally on the Red Planet the presence of water in the polar regions in the near-surface soil layers at the depth of 1 - 2 m and also on the plain of Terra Arabia in the equatorial region**.
Thus we have every reason to believe that Martian soil, at least to the depth of 2 m and probably even deeper, con-
* See: A. Finkelstein, V. Shor, "World of Minor Planets", Science in Russia, No. 2, 2004. - Ed .
** See: I. Mitrofanov, "Unlocking Martian Enigmas", Science in Russia, No. 6, 2002. - Ed.
tains water in the form of dry ice in the amounts of 20 to 70 percent. During seasonal warming water seems to thaw away and then it partially evaporates, leaving behind dust sediments. That is why the "ice-saturated" soil on the slopes must be sliding down, like a glacier, with streams of thawed water producing grooves*.
The angle of inclination of the axis of rotation of Mars to the plane of the ecliptic undergoes considerable oscillations due to the gravitational pull of Jupiter. It now amounts to 25.2°, although on the scale of millions of years it varied from 15 to 35°. This caused appreciable changes of the climate on the planet's surface and in the areal of ice propagation and its impact upon the relief. This can explain the presence of subsoil water not only in the polar, but also in the equatorial regions.
Indications are that the Martian climate changes sharply from warm and humid to cold and dry. And that means that there were water reservoirs in which sedimentary layers formed which are now revealed in some places by erosion. Of course we do not know yet how long there existed conditions for the origin of living organisms. How far advanced was what we call the pre-biological evolution? And did it reach the stage of a living cell?
In all probability life always develops in an avalanche-like manner, having passed the border of the establishment of genetic code-this critical threshold of the evolution. And it is not by chance that the problem of its duration remains open for the Earth: the amazing plasticity, the adaptive possibilities of organisms-known and unknown to us-ensured their preservation and development over billions of years even under adverse conditions (at least in relatively primitive microscopic forms). At the same time the existence on our planet of water basins, combined with its carbon dioxide atmosphere, provided for the sedimentation of carbonates (carbonate salts) which accounts for a significant share of sedimentary rock. And there are practically none of these on Mars. Why is this so? One can assume that the early atmosphere of the Red Planet was reducible and contained methane and carbon oxide. In that case the carbonates formed there, which remained as mineralogical relicts, must have been enriched by the heavy isotope of carbon (13 C) which we do observe today. On the Earth, the atmosphere was preserved, gradually being transformed as a result of oxidation evolution and being enriched with carbon dioxide.
This reducing atmosphere is conducive for the origin of life and is of principle importance for the synthesis of ATP (adenosine triphosphate - a universal accumulator and carrier of energy of all living organisms) - the key molecule of prebiological chemical evolution**.
The satellites of Jupiter - Europa and Callisto - can shed light on the origin and preservation, or survival, of organisms. The US space probe GALILEO took high-resolution pictures of the surface of the former. It is believed to be covered with a "shell" of ice. Plates and slabs are fissured with cracks and there are signs of hummocky structures. These structures seem to be floating in an ocean of liquid water. And big meteorites must pierce from time to time the ice crust, estimated to be some 20 km thick, letting water find its way to the "day-time" surface. Life which could have formed there at earlier stages of the planet's evolution could have become adapted to such difficult conditions in the gloom of the deep ocean (it has been proved that microorganisms are found in similar conditions on the Earth***).
Finally, the problem of the origin of life will be clarified by studies of extraterrestrial volcanic phenomena. They can also provide some most interesting material for studies of the evolution of the Earth's lithosphere, formation of crust of the oceanic and continental types and tectonic processes.
And it should however be stressed that studies of Mars are of the greatest importance for dealing with a set of fundamental scientific problems. This is the objective of a multi-purpose and long-term US program. In keeping with it the Mars Reconnaissance Orbiter Mission should begin in August, 2005, which must, above all, clarify the role of water in the formation of Martian structures down to the depths of some 100 m.
The next such probe-Mars Smart Lander - will make a soft landing, obtain by drilling rock samples, and probably some water, organic matter and will help investigate the geochemical and mineralogical composition of the soil. The goal of the Mars Long-Lived Lander Network is to set up in 2007 or 2009 a network of stations with the central objective of studying the inner structure of the planet, including its core. Geophysical instruments will gather data on the mechanical properties of the soil, heat flux, etc.
Finally in 2011 or somewhat later samples of Martian soil will be brought to the Earth.
Under the program of New Frontiers the probe Kuiper Belt Pluto Explorer will be launched before 2013. It will provide data on the yet completely unexplored part of the Solar system: will fly near Pluto and the more remote Kharon and other objects of the Kuiper belt. They could contain the primary matter from which the planets were formed.
In 2009 there should be an expedition to the Moon for picking up and bringing to the Earth samples of these biggest, deepest and most ancient structures of the South Pole-Eitken Basin. This could lead to the discovery of mantle rock on our nearest celestial neighbor and of accumulations of ice.
Another very interesting project is Jupiter Polar Orbiter with Probe. The orbital station, entering the upper atmosphere of Jupiter, will measure its magnetic field, polar ionosphere, composition of the gas shell and determine the presence of its central core. Launched towards Europa will be a probe called Europa Geophysical
* See: M. Litvak, I. Mitrofanov, "Seasons on Mars", Science in Russia, No. 4, 2004. -Ed.
** See: E. Galimov, "Phenomenon of Life", Science in Russia, No. 5, 2003. - Ed.
*** See: A. Lisitsyn, A. Sagalevich, "Main Discovery in the Ocean", Science in Russia, No. 1, 2001, - Ed .
Noble gases distribution for carbonaceous chondrites, Sun and three planets.
Explorer which will study the ice shell and the underlying matter that could contain some living organisms. But before entering the orbit of Europa, the probe will investigate in the astro-biological aspect two other satellites of Jupiter-Ganymede and Callisto.
After 2011 it is planned to study the isotopic and chemical composition of the atmosphere of Venus and carry out geochemical and mineralogical analyses of its surface. Sample collection techniques will have to be developed for bringing back to the Earth samples of Cytherean (from Venus) soil.
After that work will start on the project Comet Surface Sample Return for getting data on the structure and adhesion of comet matter and its composition with the probe finally returning to Earth.
During the aforesaid space studies US scientists will be perfecting a number of important technologies, including the use of radioisotope sources of energy and nuclear-electric motors (before, the Americans condemned the use of such generators in our country because of some ecological considerations).
Apart from the United States planetary studies are pursued by the European Space Agency (ESA) and Japan which launched the Muses-C probe for taking samples from asteroid 1998SF36 which is located relatively close to the Earth (ionic engine will be used). The results will become known in 2007. Scheduled for the same year is the launch of an Indian lunar satellite equipped with radar, spectrometers and high-resolution camera. Beginning from 2005 the ESA will be launching its large-scale Aurora Program which will function for a quarter of a century (studies of the Moon and Mars with expeditions to both of these planets).
Seen against the background of such international activities, our own stud-
PHOBOS-GRUNT Russian space probe.
ies of the Solar system do not look very impressive. After the failure of putting into orbit our Mars-96 in November of 1996 due to financial considerations the Spektr astrophysical program did not take place in 1998 - 2002 which provided for launching three satellites with telescopes for analyzing extra-terrestrial emissions in different bands of the spectrum.
Under a plan adopted in 1997 our country was to launch a probe to the Moon by the year 2000, and 4 years later another one to Phobos. But after discussions which followed it was decided to launch only the Phobos-Grunt project (until 2005). This provides for obtaining a sample from this satellite of Mars which has an irregular shape (dimensions of 27x22x19 km) and low density (1.9 - 2.0 g/cm3 ). Its surface is covered with craters (the biggest of them - Stickny - with the diameter of 11 km), and also furrows of up to 20 m deep and 200 m wide.
Comprehensive studies of Phobos soil is expected to provide valuable data about it and also about the origin of the Solar system, planets and their satellites. This even more so since scientists could already be in possession of Martian matter. This role belongs to the meteorites Schergotty, Nakhla and Chassigny belonging to the SNC group (by the initial letters of their titles). This includes 12 respective objects out of the several thousands found on the Earth in which the ratio of the three oxygen isotopes differs from any other class of space objects (these could be "struck out" from the surface of Mars by asteroids). Thus studies of the Phobos sample will clarify the origin of SNC-meteorites and establish the degree of "affinity" of the Red Planet and its satellite.
It should be pointed out that by its reflecting parameters the latter is similar to asphaltized material. It probably contains some organic compounds.
Establishing their nature, and the presence of aminoacids and nucleic bases, would be of great importance for solving the general problem of the origin of living organisms.
Incidentally, Russian specialists have developed devices which make it possible obtain core samples which can be 100 cm long and with the weight of some 100 g, and also pick up rock fragments with the help of a micro-video device. The probe is equipped with navigational instruments, a seismometer, a mass-spectrometer, gas chromatograph, thermosensor, etc. Using "economical" technologies in them made it possible cut down nearly by half the original cost of the project-down to 25 mn dollars (plus a carrier rocket of the medium class). And let me recall at this point that "inexpensive" US Discovery projects cost around 320 mn dollars.
The Phobos-Grunt expedition will give our scientists a chance to be in the
forefront in planetology and take an active part in the international program of studies of Mars. And it would be necessary to prepare adequate instruments for laboratory analysis of the collected samples. Otherwise we shall simply be in the role of transporters, and the scientific results will belong primarily to our Western colleagues.
Another big project of ours - Luna-Glob - will be using 10 seismographs for studying the inner structure of the natural satellite of our planet, including the size of its core. This is important for understanding the origin and the early history of the Earth-Moon system. And the chemical and isotopic analysis of matter from the overshadowed polar crater-in which the presence of ice is prognosticated and where cosmic dust piles up-should make it possible identify the possibility of transport of pores-these germs of life-in the interstellar and interplanetary space.
Lunar "projects", apart from their scientific importance, have a number of advantages: they are more economic thanks to the use of medium-class carrier rockets (MOLNIYA, SOYUZ)*; they can be easily prepared thanks to the years of lunar studies by unmanned probes in the 1970s; they are not bound with rigid launching dates and they can be used for careful preparations of expensive expeditions to remote heavenly bodies.
...Space studies actually involve us all and call for close international cooperation. And the budget of ROSAVIA-KOSMOS must provide for the participation of Russian scientists and agencies in projects of this kind including those carried out by other countries and space agencies. And we already have examples of fruitful partnership of this kind, such as in the US program Mars Odyssey. At the same time we have to develop major national projects of our own, including those related to planetology. Speaking about its prospects one should bear in mind that what we are dealing with are scientific and technological projects which are of major importance for dealing with many of our "terrestrial" problems.
Illustrations provided by the author
* See: Yu. Markov, "Destination-Red Planet", Science in Russia, No. 5, 2003. - Ed.
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