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Dec 26, 2021
Comet Hartley has a fairly short orbital period around the Sun - just over 6.4 years. Despite the fact that it was observed in 1991, 1997 and 2004, its return in 2010 was one of the most successful to study.
Position of Comet Hartley in the Solar System on October 20, 2010
The approaching comet was first noticed back in May 2008 by the astronomers of the Paranal Observatory in Chile. In August of the same year, it was studied by the Spitzer orbiting telescope in the infrared range. In 2011, the comet was explored by the Herschel Space Observatory. Thus, comet Hartley became the fifth comet visited by a spacecraft.
Studies have shown that the comet's nucleus is highly elongated and consists of two parts with a bar. Its length along the long axis is 2.2 km. The nucleus rotates along a complex trajectory with a period of 18 hours, which is possibly due to its unusual shape and uneven heating of different parts of the comet. The surface topography turned out to be very heterogeneous. A smooth bridge is adjacent to a hilly surface on two halves of the comet, which are covered with huge boulders up to 90 meters in size, with three times higher albedo than the surrounding surface.
Close-up photography of the Deep Impact probe, November 4, 2010
The core consists of frozen water mixed with ice, carbon monoxide and carbon dioxide. At the same time, the concentration of ice on the comet is uneven. Water vapor is released in the middle, and carbon dioxide degasses most intensively in the edge parts of the comet.
Analysis of the water showed that the ratio between heavy water and ordinary water is the same as in the oceans of the Earth. The main feature of Hartley's comet is its high activity during its approach to the Sun, when it loses thousands of tons of mass in a very short time. According to scientists, after 700 years, it will cease its cometary activity.
Source: Moscow Planetarium.
Related links:
ROSCOSMOS Press Release: https://www.roscosmos.ru/33691/
Moscow Planetarium: https://www.roscosmos.ru/tag/moskovskiy-planetariy/
Comet: https://www.roscosmos.ru/tag/kometa/
Images, Text, Credits: ROSCOSMOS/NASA/Moscow Planetarium/Orbiter.ch Aerospace/Roland Berga.
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