After the Soviet Union and the United States completed their 1960-1970 lunar programs, few flights have been made to the Earth's satellite: these were U.S. craft Clementine (1994) and Lunar Prospector (1998-1999), with Europe's SMART 1 in the new millennium.
The last probe did not fare well: it crashed into the Moon's surface without gathering any data to speak of.
Japan's Kaguya probe and China's Chang'e I are currently orbiting the Moon.
Russia and India have recently signed an agreement on jointly developing and delivering a research craft to the Moon. India will contribute a GSLV launch vehicle and a spacecraft for interplanetary travel and studies of the Moon from orbit. Russia will build a landing module, a lunar rover, and a set of scientific instruments.
Practically all leading space powers are planning lunar programs of one sort or another, citing the need to develop lunar resources and establish extra-terrestrial bases for manned interplanetary missions.
The Moon is also attractive to fundamental science. It is still not known whether it was formed from a proto-planetary cloud together with our planet, or was shaped from fragments of a large asteroid as it collided with a young Earth.
Encrypted in the age and dimensions of the Moon's surface craters is a record of the history of the solar system.
One of the most intriguing riddles of contemporary Moon exploration is the presence or absence in the polar regions of so-called "cold traps" - craters whose bottoms are always shaded from the Sun.
The Moon is known to have experienced many collisions with comets. Their evaporation would produce a short-lived atmosphere of water vapor, which would then condense and settle at the bottom of such "cold traps."
If there were many such collisions (the history of the solar system is known to have had periods of high cometary activity), then large amounts of water ice could have accumulated over millions of years.
It is the search for water on the Moon that will be central to all the world's next space missions.
One will be in October 2008 when America will launch the Lunar Reconnaissance Orbiter. Its scientific payload includes the Russian-made neutron telescope LEND (Lunar Exploration Neutron Detector).
The new device is a modified version of the Russian detector that is installed on the American Odyssey orbiter and has been looking for water on Mars for the past five years. LEND will look for water on the Moon.
But in order to explore small traps a few kilometers in diameter from the orbit of an artificial lunar satellite, it was necessary to combine the neutron detector with telescopic devices accurate enough to match measurements with crater dimensions.
These measurements will yield a map of hydrogen occurrence on the Moon's surface.
From school textbooks we know that a water molecule consists of two hydrogen atoms and one oxygen atom.
The Russian instrument is sensitive enough to register a hydrogen presence when water content in the Moon's surface is as low as one-tenth of a percentage point by weight.
Water ice in near-polar craters, if it exists, will be highlighted as bright specks showing high hydrogen content.
Also scheduled to be launched in 2008 are the first Indian earth satellite Chandrayaan-1 and the Japanese automated probe Selene, both of which will help to solve the issue of lunar glaciers.
The Russian Luna Globe spacecraft will carry out global studies of the Moon in 2010.
After an interval of more than 30 years Russia is resuming its studies of the Moon's internal structure. It will look for water at the Moon's poles, identify the presence of the core, if any, and determine its size.
The Russian program also provides for landing a fleet of smaller craft in the Moon's equatorial area to set up a network of seismic stations and soil penetrators.
Penetrators are devices that enter lunar soil at high speed to a depth of several meters and make measurements with the help of their instrumentation. Information from these mini-laboratories will be relayed back to the Earth via an orbiter.
The next stage of exploration will be sampling lunar soil and transporting the samples back to the Earth. It will be followed by the Lunny Poligon program, which will set up some infrastructure near the Moon's poles for a future habitable base to carry out a wide range of scientific and technological studies.
The most suitable areas for such a base will be sites with discovered water. Because they are also areas always exposed to the Sun, they could use solar generators to produce electricity to obtain hydrogen fuel from ice for interplanetary ships and the needs of the base.
Scientists also plan a radio astronomical observatory on the Moon. Space radio emissions below certain frequencies are screened off by the earth's ionosphere and cannot be observed from the Earth.
The Moon, which has no ionosphere, is a more convenient place for such investigations, search of planetary systems, study of magnetic and plasma disturbances of solar origin, and solution of many other problems.
A moon telescope would be an antenna field consisting of radio emission receivers spaced over an area of dozens of square kilometers. Information from every element of the system will be fed to its central node and then relayed to the Earth for further processing. If the antenna field is located on the Moon's far side, it will be free of any interfering influence from the Earth and the Sun's radio emissions.
China, too, plans to join the new moon race. In the wake of its orbiter, it is going to send landing modules and remote-controlled lunar vehicles to the Moon.
In the course of these missions, samples of lunar soil will be delivered to the Earth. Considering the push and drive of China's space program, it may well be that the first colonists of the Moon will speak Chinese.
Yury Zaitsev is an expert at the Russian Academy of Sciences' Institute of Space Research.
The opinions expressed in this article are the author's and do not necessarily represent those of RIA Novosti.
