September 29 at 23.50 Moscow time (20.50 GMT) automatic station “Rosetta” began the rapprochement with the comet 67P / Churyumov — Gerasimenko. In fact, it could be called a fall from a height of 19 km, if not for the speed of convergence is only 0.5 m/s. If all goes according to plan, the spacecraft lands on the comet 13.40 Moscow time (10.40 GMT) on Friday, but you should consider that it will take another 40 minutes before on the Earth will receive confirmation of the landing. After planting all instruments, AMS Rosetta will be switched off, and the mission will end.
the Mission of “Rosetta” lasted 12 years.
Most of that time period the spacecraft was just flying to the comet. The launch took place on March 2, 2004, but the arrival of the comet had to wait until the summer of 2014. The fact that the gravitational force of such small cosmic bodies (diameter about 4 km) is small enough that people could fly into outer space just by jumping on the surface. And speed interplanetary flights, tens of kilometers per second. The only chance to pass is to catch the comet at a relatively low speed.
in fact, the Rosetta became the first spacecraft, which is similar to failed.
the Study of comets is of great interest to the world science. It is believed that the comet is one of the oldest bodies in the Solar system, formed at a time when no one planet was not. Since a large part of his life carried out of the comet away from the Sun, they consist of a very ancient substance and can tell you about the early stages of the existence of the Sun and planets. Another interesting feature of comets is that they represent a huge physical and chemical laboratory, in which one can study different substances in extreme conditions. Many researchers believe that comets are the key to understanding the processes that led to the emergence of life on Earth.
of Course, not everything in the mission “Rosetta” went smoothly. For a start, the comet was not the same simple form as expected. In fact, it had a dual-connected to a thin bridge. For such body shape is quite difficult to calculate the gravitational field, and any unreported detail of relief could be fatal to the mission.
In the second, the descent module Philae failed to gain a foothold on the surface of the comet during landing.
the Probe bounced several times before stuck in a crevice, where it penetrates too little sunlight to power solar panels. It has been speculated that during the flight of a comet near perihelion in its orbit, the amount of light a camera will be enough to continue work. In a sense, what happened. Philae was released on bond June 13, 2015, but the continued full operation failed. The “Rosetta” had to take on a higher orbit around the comet, so maintain contact with spokeman device became impossible. This was done to protect the system from cometary dust and larger debris that inevitably arise with the passage of the perihelion.
Despite the completion of the mission, processing the data obtained by the automatic station will last more than one year. However, we can already say that the “Rosetta” completely changes the perception about the nature of comets. The density of the cometary material was less than that of water ice. This suggests that the substance of the comet 67P/ Churyumov – Gerasimenko is likely porous. At the same time, the surface is covered with a very dark substance. Sometimes the reflectivity compare it with black velvet. The surface structure of the comet should be similar to melted dirty snow formed in the spring by melting snow.
in observations from Earth, astronomers have often noticed that the comet may very dramatically change its brightness, but why it occurs has long remained a mystery. But on the 19th of February 2016 on 67P / Churyumov — Gerasimenko was a real landslide. From under the outer layer exposing the layers of cometary ice, which is exposed to direct sunlight begin to evaporate.
it All happened so fast that he created a powerful ejection of matter from the surface and for a short time, the comet became much brighter.
Also during the mission “Rosetta” was able to find on 67P / Churyumov — Gerasimenko, a large number of various organic substances. Scientists have yet to learn, could such organics to participate in the origin of life on Earth. By the way, the compounds of carbon is due to black color of the outer layers of the comet.
But perhaps one of the most important results of the mission was the discovery of the fact that water on the comet is very different from earth.
the fact that the content of heavy water (water with atoms of deuterium — heavy hydrogen) in the comet three times higher than in the hydrosphere of the Earth.
It negates a pretty common theory that water on Earth has a cosmic origin. At least on our planet it has brought not a comet. Another interesting research result is that 67P / Churyumov — Gerasimenko changes the period of revolution around the axis. If at the time of arrival of the mission period was 12 hours, 24 minutes and 14 seconds, now the comet began to rotate significantly faster, 12 hours, 3 minutes and 18 seconds. This is due to the jet effect of the emission of jets of gas from the surface of 67P / Churyumov — Gerasimenko. Comet unwound owing to intensive evaporation of the substance at the passage of perihelion of the orbit.
When Rosetta was just starting to study the rate of loss of substance of the comet, estimated to be in the space from the surface flew tens of thousands of pounds a day.
But after the perihelion passage, the comet daily lost up to 100 million pounds.
Now the comet Churyumov — Gerasimenko farther away from the Sun, and the solar panels are no longer produce the necessary for the normal functioning of the device the amount of electricity. Also on the health of the probe impact minor damage and failures, which for 12 years the mission has accumulated a lot. But the European space Agency very clever the completion of the mission. It was called “the Grand finale”.
the gist of it is that, began to decline with the height of 19 km above the surface of the comet, “Rosetta” will sit on the surface of the comet. During the descent it will be continually taking pictures of the comet from close range. It will be pictures at the highest resolution for the time of the mission. The landing site will be the region of MA’at (on 67P / Churyumov — Gerasimenko all the details of the relief have Egyptian names). He was selected for two reasons. First, its unusual topography of MA’at has long attracted the attention of researchers. It has a large number of different valleys, whose origin is not yet clear.
There is an assumption that there are frequent emissions of gas and dust. Scientists would like to see this place close. Well, then, MA’at is one of the few areas where Rosetta will be able to carefully down, not crashing. Unfortunately, after landing (about 14.20 Moscow time) the antenna of the spacecraft will no longer point to the Earth, and communication with him will be impossible.