Landing on a comet. Why did scientists land a probe on the surface of a comet? Planets, satellites, asteroids, comets, solar system, sizes of planets, mercury, venus, earth, mars, jupiter, saturn, uranium, neptune, pluto Relief and internal structure
The “family” of satellites, asteroids and comet nuclei is very diverse in composition. On the one hand, it includes the huge satellite of Saturn Titan with a dense nitrogen atmosphere, and on the other hand, small ice blocks of comet nuclei, spending most of the time on the far periphery Solar system There has never been a serious hope of discovering life on these bodies, although research on them organic compounds as precursors of life is of particular interest.
AT recent times the attention of exobiologists (specialists in extraterrestrial life) is attracted by Jupiter's moon Europa. (See appendix fig. 3) There must be an ocean of liquid water under the ice crust of this satellite. And where there is water, there is life: Lake Vostok, located in Antarctica, enjoys increased attention from researchers, since it is considered the terrestrial analogue of the surface of Europa, the satellite of Jupiter. The conditions of this lake, covered by almost four kilometers of ice, are close to those expected for an ocean found under the icy crust of Jupiter's moon, scientists say. Until recently possible cause the occurrence of both water formations was considered geothermal heating. These reservoirs are covered with such a thick layer of ice that for millions of years no water has entered there. atmospheric air, nor sunlight. Therefore, if in the future scientists can detect life in Lake Vostok (at present, drilling wells have not yet reached the liquid layer), then this will serve as a real argument in favor of the existence of life in the Europa ocean. " Most of Life on the Earth's surface - on land or in the sea - depends on photosynthesis. The first link in the food chain is the conversion of chlorophyll sunlight into chemically stored energy. But imagine the ocean on Europa - a huge reservoir of water covered with kilometers of ice. Photosynthesis doesn't work there. However, no matter what, there are other ways for life to exist there,” Chaiba said.
The data coming from the Galileo spacecraft suggest the existence of an ocean under the surface layers of not only Europa, but also other satellites - Ganymede and Callisto. The presence of liquid water is the most important prerequisite for the development of life, but to maintain it, an energy source is also needed "Oxygen, a product of photosynthesis, is an important oxidizing agent in Earth's oceans, but it is unlikely to play any role in the oceans of Jupiter's moons. It is possible that oxidizing agents, like hydrogen peroxide, can be formed in the ice sheet by high-energy particles from Jupiter's magnetosphere and seeping into the ocean through the ice sheet, such substances can serve as the basis for the necessary reactions.
Scientists are not sure that such a mechanism plays a leading role, and therefore they have been looking for other possibilities for the formation of molecular oxygen in the oceans. One of them turned out to be the potassium-40 isotope, the presence of which is possible both in ice and in water. The decay of potassium-40 atoms leads to the splitting of water molecules and the formation of molecular oxygen. The amount of oxygen thus produced is sufficient to sustain the biosphere in the oceans of the satellites.
In meteorites that have fallen to the ground, complex organic molecules are sometimes found. At first there was a suspicion that they fall into meteorites from the earth's soil, but now their extraterrestrial origin is quite reliably proven. For example, the Murchison meteorite that fell in Australia in 1972 was picked up the very next morning. 16 amino acids were found in its substance - the main building blocks of animal and vegetable proteins, and only 5 of them are present in terrestrial organisms, and the remaining 11 are rare on Earth. In addition, among the amino acids of the Murchison meteorite, left and right molecules (mirror symmetrical to each other) are present in equal proportions, while in terrestrial organisms they are mostly left. In addition, in meteorite molecules, carbon isotopes 12C and 13C are presented in a different proportion than on Earth. This undoubtedly proves that amino acids, as well as guanine and adenine, the constituents of DNA and RNA molecules, can independently form in space.
So, while in the solar system nowhere except the Earth, life has not been discovered. Scientists don't care about this high hopes; Most likely the Earth will be the only living planet. For example, the climate of Mars in the past was milder than it is now. Life could originate there and advance to a certain stage. There is a suspicion that among the meteorites that hit the Earth, some are ancient fragments of Mars; in one of them strange traces were found, possibly belonging to bacteria. These are still preliminary results, but even they attract interest to Mars.
Them in the bowels of the Sun. But this escape does not go unnoticed. When approaching comets to the star, the radiation evaporates part of the icy substance that makes up comets, which results in the sparkling tails we are accustomed to see at comets. Every time you fly by a star comets lose weight. When comets are greatly reduced, they can break into several parts or even ...
https://www.site/journal/114740
A circular orbit that is unique to planets - comets moving along highly elongated parabolas. It became clear that Herschel managed to discover another, seventh planet, and the solar system, the boundaries ... View Uranus from the side of the dark, northern hemisphere Celestial Shakespeare Uranus is surrounded by a system satellites, the orbits of most of which almost coincide with the plane of the equator planets. In this way, satellites Uranus do not move in the plane of its orbit (as happens with satellites all others planets ...
https://www.site/journal/14855
Experts who consider the existence of extraterrestrial life possible believe that the probability of its discovery is high enough for planets and them satellites, where there is liquid water. The thing is that the basis of life forms known to science is ... formed only in the course of complex chemical processes. Most likely, organic matter accumulates on the surface of the subglacial ocean in form thinnest film. Here, in the surface layer, complex chemical reactions. The main components of such chemical ...
https://www.site/journal/147455
In addition, the moons of "hot Jupiters" can form from the remnants of those that crashed on them satellites. Astronomers hope that in the near future they will be able to expand their understanding of extrasolar moons planets thanks to the Kepler telescope - its sensitivity turned out to be so high that it can " see" satellites exoplanets. More recently, scientists analyzing the data collected by Kepler have found themselves at the center of...
https://www.site/journal/128689
Produced by the deforming rocky core in response to gravity from Jupiter and others satellites revolving around planets. This is the existing assumption - the oceans on satellites heat up mainly due to the deformation of their nuclei. In the case of Europe, it's... like the microorganisms found in hydrothermal vents and other places on Earth. It is known that many planets and satellites deviate within their orbital planes. The earth, for example, has an axial tilt of approximately 23...
Spacecraft are moving in orbits of the Sun, Venus, Saturn, and several are preparing to leave the solar system. There are two rovers on Mars, and astronauts on board the ISS are doing experiments and taking amazing photos, writes The Atlantic.
The family photo album of the solar system has been replenished with new pictures: the sunset on Mars, the Churyumov-Gerasimenko comet, dwarf Ceres, Pluto and, of course, photographs of our home, planet Earth.
The dwarf planet Pluto and Charon, one of its five moons, photographed on June 23, 2015 by NASA's New Horizons interplanetary station from a distance of 24.4 million kilometers. New Horizons will make its closest approach to Pluto on July 14, 2015, on which day it will be 12,500 kilometers from the planet.
Saturn's moon Dione, photographed by the Cassini spacecraft on June 16, 2015. The spacecraft was located 516 kilometers from the surface of the satellite. The bright rings of Saturn are visible on the left.
Satuna's satellite Hyperion, photographed by Cassini on May 31, 2015 from a distance of about 60,000 kilometers, is Cassini's closest contact with a satellite for this mission. Hyperion is the largest of Saturn's moons. irregular shape. In the photo, the north of Hyperion is at the top and rotated 37 degrees to the right
At the bottom of the image you can see the ring A, at the top - the limb of Saturn. The rings cast shadows on the part of the planet depicted here, creating a checkerboard pattern of dark and light areas. This pattern can even be seen through ring A, which, unlike the neighboring ring B, is not completely opaque. Ring shadows often intersect on Saturn's surface at bizarre angles. This image was taken by the narrow-angle camera of the Cassini spacecraft on December 5, 2014.
Bright spots on the dwarf planet Ceres, photographed by the Dawn spacecraft on May 6, 2015. This is one of the first images taken by the Dawn spacecraft from a circular orbit at a distance of 4,400 kilometers. The resolution is 410 meters per pixel. Scientists have not yet been able to find an explanation for these spots - they suggest that these are deposits of salt and ice.
The dwarf planet Ceres, photographed by the Dawn spacecraft on May 5-6, 2015 from a distance of 13,600 kilometers
The Opportunity rover has been on Mars for more than a decade - and continues to do so. The center of this false-color image taken by the Pancam rover's camera is an oblong crater called the Spirit of St. Louis and a mountain peak in it. April 26, 2015 was the 4,000th Martian day (sol) of the rover's operation. The rover has been studying Mars since early 2004. The small crater of the Spirit of St. Louis is 34 meters long and about 24 meters wide, its bottom is slightly darker than the surrounding plain. Rock formations in the far part of the crater rise about 2-3 meters above the edges of the crater
In this self-portrait, the Curiosity rover captured itself in Mojave Crater, where it took a second soil sample on Mount Sharp. Collected here are dozens of images taken in January 2015 by the MAHLI camera on the rover's mechanical arm. The rover is surrounded by the pale Pahrump Hills, with the peak of Mount Sharp on the horizon.
In this image of the Martian surface, taken on April 8, 2015 by the Mars Reconnaissance Orbiter, the Curiosity rover passes through Artists Drive Valley on the lower slope of Mount Sharp. The photo was taken HiRISE camera. It shows the position of the rover after it traveled about 23 meters on the 949th Martian day, or sol, of its operation on Mars. The image shows an area approximately 500 meters long.
The surface of comet 67P/Churyumov-Gerasimenko, photographed by the camera of the Rosetta spacecraft from a distance of 15.3 kilometers, February 14, 2015
Comet 67P/Churyumov-Gerasimenko photographed by the Rosetta spacecraft from a distance of 77.8 kilometers on March 22, 2015
South of the Scandinavian Peninsula on the eve of midnight April 3, 2015. Green aurora in the north, Baltic Sea black patch (bottom right), clouds (top right) and snow (in Norway) illuminated by a full moon
Terra's MODIS probe captured this image of cloud swirls over the Canary Islands and Madeira on May 20, 2015
off the coast South Korea algae are grown in nets, which are held on the surface with the help of special floats. This technique allows the algae to stay close enough to the surface to receive the required amount of light at high tide, and keep them from sinking to the bottom at low tide. This image of a shallow water seaweed farm off Sisan Island was taken by the Landsat 8 Earth Remote Sensing Satellite on January 31, 2014.
Sunset on Mars. The Curiosity rover took this picture of the setting sun at the end of the 956th Martian day, or sol (April 15, 2015 Earth time), while in Gale Crater. There are small particles in the dust of the Martian atmosphere, due to which light of blue color propagates in it stronger than light of a color with a longer wavelength. For this reason, blues appear in the brighter part of the sky, and yellows and reds are farther from the Sun.
By all indications, we have entered an era of new discoveries. Many followed the Rosetta mission last year with bated breath. Landing on a comet, the first in history, was the most difficult operation, like the entire program as a whole. However, the difficulties that have arisen do not detract from the significance of both the event itself and the data that the space probe has already obtained and is still supplying. Why was it necessary to land on a comet and what results did astrophysicists get? This will be discussed below.
Main secret
Let's start from afar. One of the main tasks facing the entire scientific world is to understand what contributed. Since the time of Antiquity, a lot of hypotheses have been expressed on this topic. One of the modern versions says that comets played an important role here, falling on the planet in many during the period of its formation. It is believed that they could become suppliers of water and organic molecules.
Evidence of the beginning
Such a hypothesis in itself perfectly justifies the interest of scientists, from astronomers to biologists, in comets. However, there are a few more interesting points. Tailed creatures carry enough detailed information through space about what happened at the earliest stages of the formation of the solar system. This is when most comets formed. Thus, landing on a comet makes it possible to literally study the matter from which our piece of the Universe was formed more than four billion years ago (and no time machine is needed).
In addition, the study of the movement of a comet, its composition and behavior when approaching the Sun gives a lot about such space objects, allows you to check a lot of assumptions and scientific hypotheses.
Background
Naturally, tailed "travelers" have already been studied with the help of spacecraft. Seven flybys were made of comets, during which photographs were taken and certain information was collected. These were precisely the flybys, since the long tracking of a comet is a complicated matter. In the 80s, the US-European apparatus ICE and the Soviet Vega acted as the miners of such data. The last such meeting took place in 2011. Then the data on the tailed space object was collected by the Stardust apparatus.
Previous studies have given scientists a lot of information, but this is not enough to understand the specifics of comets and answer many of the questions mentioned above. Gradually, scientists came to realize the need for a rather bold step - the organization of a spacecraft flight to a comet with the subsequent landing of a probe on its surface.
Mission uniqueness
In order to feel how difficult landing on a comet is, you need to understand what it is like. It rushes through space at a tremendous speed, sometimes reaching several hundred kilometers per second. At the same time, the comet's tail, which is formed when the body approaches the Sun and looks so beautiful from the Earth, is a mixture of gas and dust. All this greatly complicates not only landing, but also moving in a parallel course. It is necessary to equalize the speed of the device with the speed of the object and choose the right moment for approach: the closer the comet is to the Sun, the stronger the emissions from its surface. And only then can landing on a comet be carried out, which will be further complicated by low gravity.
Object selection
All these circumstances necessitated a careful approach to the choice of the purpose of the mission. Landing on the Churyumov-Gerasimenko comet is not the first option. Initially, it was assumed that the Rosetta probe would be sent to comet Virtanen. However, an accident intervened in the plans: shortly before the intended departure, the engine of the Ariane-5 launch vehicle failed. It was she who was supposed to take the Rosetta into space. As a result, the launch was postponed and it became necessary to select a new object. They became the comet Churyumov-Gerasimenko or 67P.
This space object was discovered in 1969 and named after the discoverers. It is one of the short-period comets and makes one revolution around the Sun in about 6.6 years. Nothing particularly remarkable 67P differs, however, it has a well-studied flight path that does not go beyond the orbit of Jupiter. It was to her that Rosetta went on March 2, 2004.
"Stuffing" of the spacecraft
The Rosetta probe took with it into space a large amount of equipment intended for research and fixing their results. Among them are cameras capable of capturing radiation in the ultraviolet part of the spectrum, and devices necessary for studying the structure of a comet and soil analysis, and instruments for studying the atmosphere. In total, Rosetta had 11 scientific instruments at its disposal.
Separately, it is necessary to dwell on the Philae descent module - it was he who had to land on the comet. Part of the high-tech equipment was placed directly on it, as it was necessary to study the space object immediately after landing. In addition, the Fila was equipped with three harpoons for reliable fixation on the surface after it was lowered by the Rosetta. Landing on a comet, as already mentioned, is fraught with certain difficulties. The gravity here is so low that in the absence of additional mounts, the module runs the risk of getting lost in outer space.
Long haul
The 2014 comet landing was preceded by a ten-year flight of the Rosetta probe. During this time, he found himself close to the Earth five times, flew near Mars, and met two asteroids. Gorgeous photographs taken by the probe during this period, in again reminiscent of the beauty of nature and the universe in its various corners.
However, a logical question may arise: why did Rosetta circle the solar system for so long? It is clear that the photographs and other data collected during the flight were not his goal, but rather became a pleasant and interesting bonus for researchers. The purpose of this maneuver is to approach the comet from behind and equalize speed. The result of a ten-year flight was to be the actual transformation of Rosetta into a satellite of the Churyumov-Gerasimenko comet.
Rapprochement
Now, in April 2015, it is safe to say that the landing of the probe on the comet was generally successful. However, in August last year, when the apparatus had just entered the orbit of a cosmic body, this was still a matter of the near future.
The probe landed on the comet on November 12, 2014. Almost the whole world followed the landing. The undocking of Phila was successful. The problems began at the moment of landing: the harpoons did not work and the device could not gain a foothold on the surface. "Fila" bounced off the comet twice and only the third time was able to descend, and it flew off from the place of the proposed landing for about a kilometer.
As a result, the Fila module found itself in a zone where the batteries needed to replenish the energy charge almost do not penetrate. In case the landing on the comet was not entirely successful, the device was equipped with a charged battery, designed for 64 hours. He worked a little less, 57 hours, but even during this time Phila managed to do almost everything for which it was created.
results
Landing on the comet Churyumov-Gerasimenko allowed scientists to obtain extensive data on this cosmic body. Many of them have not yet been processed or require analysis, but the first results have already been presented to the general public.
The studied cosmic body is similar in shape to (landing on the comet was supposed to be in the “head” area): two rounded parts of comparable size are connected by a narrow isthmus. One of the tasks facing astrophysicists was to understand the reason for such an unusual silhouette. Today, two main hypotheses are put forward: either this is the result of a collision of two bodies, or erosion processes led to the formation of an isthmus. So far, no definitive answer has been received. Thanks to the research of "Phila", it became only known that the level of gravity on the comet is not the same. The largest indicator is observed in the upper part of the core, and the smallest - just in the "neck" area.
Relief and internal structure
The Philae module detected various formations on the surface of the comet that looked like mountains and dunes. In their composition, most of them are a mixture of ice and dust. Hills up to 3 meters high, called goosebumps, are quite common on 67P. Scientists suggest that they were formed in the early stages of the formation of the solar system and may cover the surface of other similar celestial bodies.
Since the probe did not land on the comet in the most successful way, scientists were afraid to start the planned drilling of the surface. However, it was nevertheless carried out. It turned out that under the top layer there is another, denser one. Most likely, it consists of ice. This assumption is also supported by the analysis of vibrations recorded by the apparatus during landing. At the same time, spectrograph photographs show an unequal ratio of organic compounds and ice: there are clearly more of the former. This does not agree with the assumptions of scientists and casts doubt on the version of the origin of the comet. It was assumed that it was formed in the region of the solar system, near Jupiter. A study of the images, however, refutes this hypothesis: apparently, 67P formed in the Kuiper belt, located beyond the orbit of Neptune.
Mission continues
The Rosetta spacecraft, which closely followed the activities of the Philae module until it fell asleep, has not left the Churyumov-Gerasimenko comet so far. It continues to monitor the object and send data back to Earth. So, among his duties is fixing emissions of dust and gas, which increase as the comet approaches the Sun.
Previously, it was found that the main source of such emissions is the so-called neck of the comet. The reason for this may be the low gravity of this area and the effect of the accumulation of solar energy reflected from neighboring areas that occurs here. In March of this year, Rosetta also recorded an emission of dust and gas, which is interesting in that it occurred on the unlit side (as a rule, such phenomena occur as a result of surface heating, that is, on the solar part of the comet). All of these processes and features of the 67P have yet to be explained while data collection continues.
The first landing on the surface of a comet in the history of mankind was the result of labor a large number scientists, technicians, engineers and designers for almost forty years. Today, the Rosetta mission is recognized as one of the most ambitious events of the space age. Naturally, astrophysicists do not intend to put an end to this. Ambitious plans for the future include a lander capable of walking on the surface of a comet and a spacecraft capable of rendezvousing with an object, collecting soil samples and returning them to Earth. In general, the successful Rosetta project inspires scientists to more and more daring programs to master the secrets of the universe.
The European Space Agency has announced the successful landing of the Philae probe on comet 67P/Churyumov-Gerasimenko. The probe separated from the Rosetta apparatus on the afternoon of November 12 (Moscow time). Rosetta left the Earth on March 2, 2004 and flew to the comet for more than ten years. The main goal of the mission is to study the evolution of the early solar system. If successful, ESA's most ambitious project could become a kind of Rosetta stone not only for astronomy but also for technology.
long-awaited guest
Comet 67P/Churyumov-Gerasimenko was discovered in 1969 by Soviet astronomer Klim Churyumov while studying photographs taken by Svetlana Gerasimenko. The comet belongs to the group of short-period comets: the period of revolution around the Sun is 6.6 years. The semi-major axis of the orbit is a little over 3.5 astronomical units, the mass is about 10 13 kilograms, the linear dimensions of the nucleus are several kilometers.
The study of such cosmic bodies is necessary, firstly, to study the evolution of cometary matter, and, secondly, to understand the possible influence of gases evaporating in a comet on the motion of surrounding celestial bodies. Data obtained using Rosetta missions, will help explain the processes of evolution of the solar system and the emergence of water on Earth. In addition, scientists hope to find organic traces of the L-forms ("left-handed" forms) of amino acids, which are the basis of life on Earth. If these substances are found, the hypothesis of extraterrestrial sources of terrestrial organic matter will receive new confirmation. However, by now, thanks to the Rosetta project, astronomers have learned a lot of interesting things about the comet itself.
The average surface temperature of the comet's nucleus is minus 70 degrees Celsius. Measurements made as part of the Rosetta mission showed that the temperature of the comet is too high for its core to be completely covered with a layer of ice. According to the researchers, the surface of the core is a dark dusty crust. Nevertheless, scientists do not exclude that there may be ice patches there.
It has also been found that the stream of gases emanating from the coma (clouds around the comet's nucleus) includes hydrogen sulfide, ammonia, formaldehyde, hydrocyanic acid, methanol, sulfur dioxide and carbon disulfide. Previously, it was believed that as the icy surface of a comet approaching the Sun heats up, only the most volatile compounds, carbon dioxide and carbon monoxide, are released.
Also thanks to the Rosetta mission, astronomers drew attention to the dumbbell shape of the nucleus. It is possible that this comet could have formed as a result of a collision of a pair of protocomets. It is likely that the two parts of the 67P/Churyumov-Gerasimenko body will separate over time.
There is another hypothesis that explains the formation of a double structure by intense evaporation of water vapor in the central part of the comet's once spherical nucleus.
With the help of Rosetta, scientists have found that every second comet 67P / Churyumov-Gerasimenko releases water vapor into the surrounding space in the amount of about two glasses (150 milliliters each). At this rate, the comet would fill an Olympic-sized pool in 100 days. As we get closer to the Sun, the steam emission only increases.
The closest approach to the Sun will occur on August 13, 2015, when comet 67P/Churyumov-Gerasimenko will be at the perihelion point. Then the most intense evaporation of its matter will be observed.
Rosetta spacecraft
The Rosetta spacecraft, together with the Philae descent probe, was launched on March 2, 2004 on an Ariane 5 launch vehicle from the Kourou launch site in French Guiana.
Name spacecraft received in honor of the Rosetta stone. The deciphering of the inscriptions on this ancient stone slab, completed by 1822 by the Frenchman Jean-Francois Champollion, allowed linguists to make a giant breakthrough in the study of Egyptian hieroglyphic writing. Scientists expect a similar qualitative leap in the study of the evolution of the solar system from the Rosetta mission.
Rosetta itself is an aluminum box measuring 2.8x2.1x2.0 meters with two solar panels of 14 meters each. The cost of the project is 1.3 billion dollars, and its main organizer is the European Space Agency (ESA). NASA, as well as the national space agencies of other countries, take a smaller part in it. In total, 50 companies from 14 European countries and the USA are involved in the project. Rosetta hosts eleven scientific instruments - special systems of sensors and analyzers.
During its journey, Rosetta made three maneuvers around the orbit of the Earth and one around Mars. The device approached the orbit of the comet on August 6, 2014. For your long haul The device managed to perform a number of studies. So, in 2007, flying past Mars at a distance of a thousand kilometers, he transmitted to Earth data on the planet's magnetic field.
In 2008, in order to avoid a collision with the Steins asteroid, ground specialists corrected the ship's orbit, which did not prevent it from photographing the surface of a celestial body. In the pictures, scientists found more than 20 craters with diameters of 200 meters or more. In 2010, Rosetta transmitted photographs of another asteroid, Lutetia, to Earth. it heavenly body turned out to be a planetesimal - the formation from which planets were formed in the past. In June 2011, the device was put into sleep mode to save energy, and on January 20, 2014, Rosetta “woke up”.
Philae probe
The probe is named after the island of Philae on the Nile River in Egypt. There were ancient places of worship, as well as a plate with hieroglyphic records of queens Cleopatra II and Cleopatra III. As a place to land on the comet, scientists chose a site called Agilika. On Earth, this is also an island on the Nile River, where some of the ancient monuments were transferred, which were threatened by flooding as a result of the construction of the Aswan Dam.
The mass of the Philae descent probe is one hundred kilograms. Linear dimensions do not exceed a meter. The probe carries ten instruments needed to study the comet's nucleus. With the help of radio waves, scientists plan to study the internal structure of the nucleus, and microcameras will make it possible to take panoramic pictures from the surface of the comet. The drill installed on Philae will help to take soil samples from a depth of up to 20 centimeters.
Philae batteries will last for 60 hours of battery life, then the power will be switched to solar panels. All measurement data will be sent online to the Rosetta spacecraft, and from it to the Earth. After the descent of Philae, the Rosetta apparatus will begin to move away from the comet, turning into its satellite.