Extraterrestrial water
Water outside planet Earth, or at least traces of its existence in the past, are objects
Earth, with 71% of its surface covered by oceans of water, is currently the only planet known in the solar system to contain liquid water.
There is scientific evidence that in someOn the satellites of the giant planets (Jupiter, Saturn, Uranus and Neptune), water can be found under a thick crust of ice covering the celestial body. However, there is currently no clear evidence of the presence of liquid water in the solar system, except on Earth.
Oceans and water may be found in other stellarsystems and / or on their planets and other celestial bodies in their orbit. For example, water vapor was discovered in 2007 in a 1 AU protoplanetary disk. e. from the young star MWC 480.
Previously it was believed that reservoirs and canals with watercan be on the surface of Venus and Mars. With the development of the resolution of telescopes and the advent of other methods of observation, these data were refuted. However, the presence of water on Mars in the distant past remains a topic for scientific discussion.
Thomas Gold, within the framework of the Deep Hot Biosphere hypothesis, stated that many objects in the solar system may contain groundwater.
A microscopic photo of a 1.3 cm hematite nodule, taken by Opportunity on March 2, 2004, shows the presence of past liquid water.
Moon
The lunar seas are as they are nowit is known that huge basalt plains were previously considered reservoirs. For the first time, some doubts about the watery nature of the lunar "seas" were expressed by Galileo in his "Dialogue about two systems of the world". Given that the theory of a giant collision is currently dominant among theories of the origin of the moon, it can be concluded that the moon has never had seas or oceans.
Flash from the collision of the upper stage "Centaurus" of the LCROSS probe with the Moon
In July 2008, a group of American geologists fromThe Carnegie Institution and Brown University found traces of water in the lunar soil samples, in large quantities released from the bowels of the satellite in the early stages of its existence. Most of this water later evaporated into space.
Russian scientists, using what they createdThe LEND instrument installed on the LRO probe revealed the areas of the Moon that are most rich in hydrogen. Based on this data, NASA selected a site for the LCROSS probe to bombard the Moon. After the experiment, on November 13, 2009, NASA announced the discovery of water in the form of ice in the Cabeus crater near the south pole.
According to project manager Anthony Colapret,water on the moon could have appeared from several sources: due to the interaction of the protons of the solar wind with oxygen in the soil of the moon, brought by asteroids or comets or intergalactic clouds.
According to data transmitted by the Mini-SAR radar,installed on the Indian lunar probe Chandrayaan-1, in total at least 600 million tons of water were discovered in the north pole region, most of which is in the form of ice blocks resting at the bottom of lunar craters. Water has been found in more than 40 craters, ranging in diameter from 2 to 15 km. Now scientists no longer have any doubt that the ice found is water ice.
Venus
Before the spacecraft landed onthe surface of Venus, it was hypothesized that there might be oceans on its surface. But, as it turned out, Venus is too hot for that. At the same time, a small amount of water vapor was found in the atmosphere of Venus.
At this point there are good reasonsbelieve that water existed on Venus in the past. The opinions of scientists differ only regarding the state in which it was on Venus. Thus, David Grinspoon from the National Museum of Science and Nature in Colorado and George Hashimoto from Kobe University believe that water on Venus existed in a liquid state in the form of oceans.
They base their conclusions on indirect signs.the existence of granites on Venus, which can form only with a significant presence of water. However, the hypothesis of an outbreak of volcanic activity on the planet about 500 million years ago, which completely changed the planet's surface, makes it difficult to verify data on the existence of an ocean of water on the surface of Venus in the past. The answer could be provided by a sample of Venus soil.
Eric Chassefier from the University of Paris-Sud(Université Paris-Sud) and Colin Wilson from the University of Oxford believe that water on Venus never existed in liquid form, but was contained in much larger quantities in the atmosphere of Venus. In 2009, the Venus Express probe provided evidence that that due to solar radiation, a large volume of water was lost from the atmosphere of Venus into space.
This is how Venus and the biosphere will look like (according to Dane Ballard)
Mars
Telescopic observations since Galileogave scientists the opportunity to assume that there is liquid water and life on Mars. As the amount of data on the planet grew, it turned out that water in the atmosphere of Mars contains an insignificant amount, and an explanation was given to the phenomenon of Martian channels.
It was previously believed that before Mars dried up, itwas more like Earth. The discovery of craters on the planet's surface has shaken this view, but subsequent discoveries have shown that perhaps liquid water was present on the surface of Mars.
There is a hypothesis about the existence in the past of an ice-covered Martian ocean.
There is a number of direct and indirect evidence of the presence of water in the past on the surface of Mars or in its depths.
- About 120 have been identified on the surface of Mars.geographic areas showing signs of erosion, which most likely occurred with the participation of liquid water. Most of these areas are in the middle and high latitudes, with most of them in the southern hemisphere. This is primarily the dry river delta in the Eberswalde crater. In addition, other areas of the surface of Mars, such as the Northern Great Plain and the Hellas and Argyres plains, can be attributed to these areas.
- The Opportunity rover detects hematite, a mineral that cannot form in the absence of water.
- Detection by the rover "Opportunity" of the mountainoutcrop El Capitan. Chemical analysis of the layered stone showed the content of minerals and salts in it, which under terrestrial conditions are formed in a humid warm environment. It is assumed that this stone was once at the bottom of the Martian sea.
- The discovery by the Opportunity rover of the Esperance-6 stone (Esperance 6), as a result of the study of whichthe conclusion that several billion years ago this stone was in a stream of water. Moreover, this water was fresh and suitable for the existence of living organisms in it.
The question remains, where did most of the liquid water from the surface of Mars go.
This is what Mars might look like if it had an ocean
Water outside the solar system
Most of the more than 450 discoveredextrasolar planetary systems are very different from ours, which allows us to consider our solar system to belong to a rare type. The goal of modern research is to discover an Earth-sized planet in the habitable zone of its planetary system (the Goldilocks zone).
In addition, oceans can also be located on large(Earth-sized) satellites of the giant planets. Although the very existence of such large satellites is debatable, the Kepler telescope is sensitive enough to detect them. It is believed that rocky planets containing water are widespread throughout the Milky Way.
Where does the water come from?
- Big explosion
Hydrogen is almost as old as the universe itself:its atoms appeared as soon as the temperature of the newborn Universe dropped so much that protons and electrons could exist. Since then, hydrogen has been the most abundant element in the Universe for 14.5 billion years in both mass and number of atoms. Clouds of gas, mostly hydrogen, fill the entire space.
- The first stars
As a result of the gravitational collapse of the cloudshydrogen and helium, the first stars appeared, inside which thermonuclear fusion began and new elements were formed, including oxygen. Oxygen and hydrogen gave water; its first molecules could have formed immediately after the appearance of the first stars - 12.7 billion years ago. In the form of a highly dispersed gas, it fills interstellar space, cooling it and thus bringing the birth of new stars closer.
- Around the stars
Water present in the cloud that gave birth to the stargas, passes into the substance of the protoplanetary disk and objects that are formed from it - planets and asteroids. At the end of their lives, the most massive stars explode into supernovae, leaving behind nebulae in which new stars explode.
How does water move between celestial bodies?
The new hypothesis links the presence of water on the Moon with the action of the "earth's wind" - a stream of particles thrown out here by the magnetosphere of our planet.
Water can appear directly on the moon.According to one of the new promising hypotheses, the solar wind protons reach its surface, which is not protected by either the atmosphere or the magnetosphere, like our Earth. Here they interact with oxides in the composition of minerals, forming new water molecules and constantly replenishing the supply of moisture escaping into space.
Then, during periods when the moon is brieflysheltered from the solar wind, the amount of water on its surface should decrease. Computer simulations predict that over the course of a few days around the full moon, as a satellite passes through the long, elongated "tail" of the Earth's magnetosphere, water content should drop very noticeably at high latitudes.
This process was reviewed by the authors of the new article.Using data collected by the Japanese lunar probe Kaguya, they recorded changes in the flow of the solar wind, "washing" the satellite. And observations of the Indian apparatus Chandrayaan-1 helped to assess the distribution of water in the circumpolar regions. However, the results turned out to be rather unexpected: no significant changes in the amount of ice occur on the prescribed days.
Therefore, scientists put forward another hypothesisthe origin of water on the Moon, not related to the effects of the solar wind. The fact is that the Earth's magnetosphere is also capable of directing protons and watering the lunar surface with no less number of particles than the solar wind: although not so strongly accelerated. The stream contains both protons and oxygen ions from the upper layers of the earth's atmosphere. This "earthly wind" may be enough for the formation of new water molecules on the moon.
Scientists plan to continue their exploration of the moon with more powerful technology to find better regions for future satellite exploration, as well as mining.
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