Translated material
Dawn has been postponed
The first flight to the dwarf planet will begin in September
NASA was forced to postpone the launch of one of the most promising interplanetary stations, Dawn, to September. The device was going to be sent into space this weekend, but competition for a place at the Cape Canaveral Space Center was too high. Now Dawn will launch only in the fall, when it will not interfere with either the Endeavor shuttle or the new Mars mission.The hubbub of space launch vehicles at Cape Canaveral may be noteworthy, but only insofar as it reflects a hyperactive NASA and an enviable intensity of the American space program. But the Dawn mission itself is more interesting: the device was specially created for a thorough study of the “first among the small” - the giant asteroids Vesta and Ceres.
In the last century, interplanetary stations in the overwhelming majority of cases were sent either to the Moon closest to us, or to the planets - Mars, Venus, Jupiter, and so on. Second in line for study were the planets' satellites. It came to smaller asteroids and comets later, when the number of the same Martian programs began to number in the dozens. Among the well-known missions, one can note, for example, the recent flight to the asteroid Eros (the American program Near Earth Asteroid Rendezvous), when in 2001 an artificial vehicle for the first time managed to land on the surface of a small planet, the Deep Impact station, which was forced to crash into comet Tempel-1, or, say, the Japanese Hayabusa probe, which studied the Itokawa asteroid. True, we have not yet flown to the largest of the small planets.
Ceres and Vesta, known to astronomers since the beginning of the 19th century, were chosen for the Dawn mission. Both celestial bodies are found in the asteroid belt between Mars and Jupiter, in company with several other large and a huge number of small fragments of stones and dust. This is one of the construction dumps of the Solar system, where “garbage” was collected that was not useful in the formation of large planets. Ceres is the largest body in the belt, its diameter ranges from 909 to 975 km. Vesta is slightly smaller, no more than 578 km in diameter, and has a more irregular shape.
When Dawn Station was designed and built, it was thought that it would go out to study simple asteroids. But shortly before the end of the preparatory work, the status of the celestial bodies unexpectedly changed: last year the International Astronomical Union upgraded Ceres to a “dwarf planet.” So “Dawn” unexpectedly turned out to be a multi-purpose device (albeit only from a formal point of view): first it will examine the ordinary asteroid Vesta, and then for the first time it will approach the dwarf planet closest to us.
But, as astronomers suggest, these two celestial bodies differ not only in status and size, they are also structured slightly differently. So, Vesta is apparently just a rocky block in the sky, like most of the smaller asteroids in the belt between Mars and Jupiter. And the larger Ceres consists not only of cosmic dust, but also about a quarter of ice. If this is true, then it turns out that there is more fresh water on this dwarf planet than on our Earth.
In addition, scientists are intrigued by the giant crater on Vesta: in the area of the south pole of this small planet there is a recess 13 km deep. It is assumed that in ancient times this asteroid was hit by a smaller neighbor. A huge amount of debris scattered across space in all directions, increasing the amount of rock debris in the solar system. Surely some of these pieces of Ceres have reached us, and it is possible that some of the meteorites found on Earth will someday be recognized as the “lost property” of this asteroid.
According to the preliminary plan, Dawn should reach Vesta in October 2011. Before that, for more than four years, it will move in an orbit gradually moving away from the Sun towards the asteroid belt. In 2009, the device will fly near Mars (the gravity of this planet should have added speed to Rassvet). In addition to Mars, acceleration will also be provided by xenon ion engines: these extremely low-power accelerators will operate for 2 thousand days and gradually accelerate the device to enormous speed. Dawn will reach the final point of its journey - Ceres - only in 2015, having flown more than 5 billion km in space. Postponing the launch will probably push back these deadlines somewhat, but two months will not be too noticeable against the backdrop of the eight-year period it will take to complete the entire program.