Ceres. Source: ESO / L.Calcada / NASA / JPL-Caltech / UCLA / MPS / DLR / IDA / Steve Albers / N.Risinger
Water-bearing minerals are widely distributed in Ceres
. Scientists believe
that this may be indirect evidence of the existence of the ocean in the distant past planetoid. Most likely, the ocean covered a significant part of the surface of Ceres.
The Dawn probe team was able to determine the composition of the asteroid's crust thanks to the apparatus. It turned out to be a mixture of water ice, salts and hydrated rocks. In addition, traces of recent geological activity were found on the planetoid (recent by geological standards).
Scientists believe that Ceres is not a dead world at all. This is a rather complex, dynamic planetoid with a rich past, in which there was a large amount of water. Perhaps some of the water in the form of ice has survived below the surface Anyway, thinks so Julie Castillo-Roges, the representative of the command of the probe Dawn.
Unfortunately, it is not possible to get direct, but not indirect evidence of the existence of Ceres in the ocean millions of years ago. Sending to the object of the spacecraft is associated with significant technical difficulties. In addition, it can threaten the planetoid pollution (in particular, biological). Instead, scientists study Ceres remotely.
In the course of the research, experts used information on the structure of the planetoid surface and its gravitational characteristics. These data were previously transmitted by the probe itself, and now they are still being studied. The results of the study of Ceres were published by experts in the Journal of Geophysical Research.
The team involved in studying the information transmitted by the apparatus, believes that Ceres could have been geologically active earlier. Perhaps this activity is manifested even now, but it is not possible to track its manifestations. At least for now.
During the study of Ceres, three craters were discovered on its surface - Occator, Kerwan and Yalode. In addition, on the surface of the planetoid there is also a high mountain, Ahua Mons. All these objects are associated with gravitational anomalies. This means that the assumed gravity characteristics of Ceres are different from the real ones.
“There are many gravitational anomalies on Ceres, which are associated with its geological features,” the team of scientists says. In the end, experts have found that the density of the crust is relatively low, according to this indicator it is closer to water ice than to rocks. At the same time, there should not be too much ice here, the bark of Ceres does not consist entirely of water ice. But what is its exact mineralogical composition?
The results of a study conducted by Roger Foo from Harvard University help to clarify this. He has long studied the characteristics of the bark of Ceres, trying to understand what it is. According to Fu's calculations, the bark of a planetoid is a mixture of water ice, rocks, clathrate hydrate (gas hydrates) and salts. Clathrates
are crystalline compounds formed under certain thermobaric conditions from water and gas. The name "clathrates" (from the Latin. Clat (h) ratus - "closed lattice, planted in a cage").
Scientists believe that at Ceres there used to be many geological formations that smoothed out over time. Well, this smoothing, according to Fu and his colleagues, was manifested due to the influence of such a factor as the ocean. According to experts, for some time it was liquid. This is confirmed by the temperature model of the planetoid.
The implementation of the Dawn project began in 1992, when the ion engines of the device were first introduced. Their main advantage, compared with rocket - a long work. The authors of the project received three refusals
from the leadership of NASA, but in 2001 the mission nevertheless received approval. As part of the mission, the Dawn probe was to visit the two largest objects in the asteroid belt: Vesta, the largest asteroid in the solar system, and Ceres, the dwarf planet.
The project turned out to be very successful - the probe fulfilled all the tasks, adding to the piggy bank of scientific knowledge. Information transmitted by the device to Earth will be decrypted for a long time. The last stop of the probe is Ceres, the device will not fly further. The probe is going to put into a stable orbit around the asteroid, where it will remain. The height of the apparatus above the surface of the planetoid will be 200 km.
Scientists believe that the probe will remain in working condition at least until the middle of next year. The main tasks of the device are the study of the chemical composition of the surface, as well as the assessment of the amount of water ice in the Ceres bark.