Comet 67P / Churyumova-Gerasimenko became a frequent guest in media reports after 2003, when it was decided to send the Rosetta apparatus with the Fila descent module to it. The goal, without exaggeration, of the grandiose project was to land the apparatus on the object and study its characteristics. Today, in April 2015, we can already say that the mission was successfully completed. And this was preceded by voluminous work both on the creation of the spacecraft and on the study of the comet.
Opening
Comet Churyumov-Gerasimenko, the trajectory, size, and other parameters of it, were well studied even before it was chosen as the object of the Rosetta mission. The opening day of this cosmic body is considered to be October 23, 1969. The first images of comet Churyumov-Gerasimenko, however, were obtained a little earlier, on the 11th. Then, the future discoverers Svetlana Gerasimenko and Klim Churyumov, as part of a group of astronomers from Kiev State University, observed the movement of comets in the sky over the vicinity of Almaty.
On October 11, Svetlana Gerasimenko took a picture of the comet Comas-Sol, which showed a strange speck, presumably a marriage of a photographic plate. However, after some time, Klim Churyumov, studying this and other images from this part of the sky, found that the spot is present at all and noticeably shifts against the background of stars. Photos were sent to Cambridge to Brian Marsden, who calculated the orbit of the new comet. It was named after the discoverers. In scientific publications, the cosmic body is designated as comet 67P / Churyumova-Gerasimenko.
Flight characteristics
As it turned out, the open cosmic body is a short-period comet. This does not make it unique: in the solar system there are more than one hundred objects of the same type as the comet Churyumov-Gerasimenko. Its flight path is such that the perihelion of the orbit (the place of the smallest distance to the Sun) is located between the orbits of Mars and the Earth, and the aphelion (the place of the greatest distance to the Sun) is located beyond the orbit of the gas giant Jupiter. The circulation period is slightly less than 6.6 years.
The neighborhood with such a large planet as Jupiter is not in vain for anyone. Comet Churyumov-Gerasimenko is no exception. The trajectory of her flight was constantly exposed to the gravity of the giant. According to scientists, some time ago, one revolution of this cosmic body around the Sun took about three years more, but 10 years before its discovery, the comet came too close to Jupiter. The result was a reduction in the rotation period.
Mission object
If we return to the Roseta probe, then comet 67P became the goal of the project for several reasons:
- 40 years have passed since the discovery, during which the object was constantly monitored: astronomers know its orbit well and can predict almost any possible effects on it;
- the comet’s orbit is deviated from the ecliptic plane by only 7 °, which means there is no need for an additional energy resource to lift the spacecraft above the ecliptic.
Nevertheless, the comet Churyumov-Gerasimenko, whose size, orbit, and other characteristics are excellent for such a mission, was not the first candidate. Initially, the probe was supposed to go to the comet Virtanen, similar in its parameters to 67P. The situation has changed due to the failure of the engine of the Arion-5 launch vehicle. The planned start had to be postponed, and the favorable launch moment was missed. At that moment, it turned out that in about a year it would be possible to direct Rosetta to another object - comet Churyumov-Gerasimenko.
Long 10 years
The Rosetta probe was supposed to go into the tail to the comet, having previously equalized the speed with it, become its satellite, determine the possible landing site and lower the Fila module onto it. In order for all this to happen, the device had to circle the solar system for 10 years. During her trip, Rosetta photographed Mars and the Earth from several angles, repeatedly crossed the asteroid belt and met with two of its representatives, also filming them. In addition, during the rapprochement, Rosetta took pictures of comet Churyumov-Gerasimenko, which helped clarify its shape. It turned out that 67P is visually divided into two parts connected by a fairly narrow isthmus. In articles on 67P you can find a mention of a rubber duckling, which comet Churyumov-Gerasimenko resembles in form. The dimensions of the “head”, the smaller part, are 2.5 × 2.5 × 2.0 km, the “body” is 4.1 × 3.2 × 1.3 km.
mission Possible
Without going into details, we can say that the first in the history of mankind spacecraft landing on the surface of a comet was generally successful. The Fila module did not land exactly where it was planned, and pretty soon it ran out of energy, but was able to transmit a ton of information to Earth.
Comet Churyumov-Gerasimenko, whose surface photo was filmed by Fila during the landing process, suffered a lot from the apparatus: it was tapped, drilled, shone, and so on. Researchers obtained data on composition, topography, and gravity. This information is also valuable because the comet is of the same age as the solar system, which means it can reveal some secrets of its formation.
Results in brief
Comet Churyumov-Gerasimenko, whose landscape photo helped to map the surface, was divided into zones according to the features of the relief. Among the formations resembling rocks and dunes, three-meter hills were found, often found on the entire surface. Presumably they are characteristic of other comets.
During the study, it was found that the density of the substance of the comet is half that of water. Also, scientists were able to establish the ratio of organic compounds and water molecules. The former turned out to be more, which differs from the assumptions of the researchers. These data forced a revision of the hypothesis about the origin of the comet: it was believed that it formed in the vicinity of Jupiter. New data convincingly indicate that the comet came from a more remote part of the solar system, from the Kuiper belt.
Comet Churyumov-Gerasimenko, whose trajectory and features were suitable for the grandiose Rosetta project, has not yet revealed all its secrets. The device that delivered the Fila still accompanies her and still transfers the data. And therefore it is quite possible that soon we will learn a lot about the 67P.