(433) Eros
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( 433 ) Eros is an asteroid that was discovered on August 13, 1898 by the German astronomer Gustav Witt. He was the first well-known near-Earth asteroid and in 1900 and 1930 used for the precise determination of the earth's orbit radius, analogous to Venus transit.
It was named after celestial bodies Eros, the god of love in Greek mythology.
Eros is the first asteroid from a spacecraft - orbits (2000) and loaded a friend ( 2001) - NEAR Shoemaker.
Discovery
The asteroid was discovered on a photographic plate, the Gustav Witt and his assistant Felix Linke (1879-1959) had illuminated on the night of August 13, 1898 at the Berlin Urania Observatory. Also Auguste Charlois in Nice had taken the asteroids in the same night, he did not recognize the track that had left on the photographic plate, the asteroid, though initially.
Train
Eros was the first known asteroid whose orbit extends partially within the orbit of Mars. It thus belongs to the class of near-Earth asteroids from the Amor type. It orbits the Sun in just 1.76 years at a distance of 1.133 ( perihelion ) to 1.783 ( aphelion ) astronomical units, so that over the decades he can get close to 22 million km of the Earth. The orbital plane is inclined at 10.83 ° to the ecliptic, the orbital eccentricity is 0.223.
Soon after the discovery of the asteroid fell on his highly fluctuating brightness, from which one could infer the rotational period and an extremely elongated shape. Model calculations of the 1960s resulted in proportions of approximately 15 × 30 km, in 2001 differed from the measurements of the NEAR spacecraft just about 2-3 km.
Published in 1999, the Viennese astronomer Rudolf Dvorak the result of his long-term numerical forecasts. Thus Eros is 20 million years remain relatively stable path, then rush but by chaotic acting perturbations in the sun.
Construction
Eros is an irregularly shaped celestial body with 33 × 13 × 13 km stretch. It has a relatively bright silicate-containing surface with an average albedo of 0.16 ( or 0.25 according to JPL data). Its density is 2.4 g / cc as the density of silicate rock.
In about 5 hours and 16 minutes to rotate around its own axis. Measurements have shown that the temperature on the side facing the sun ( daylight side ) of the asteroid increase to 100 ° C, while they fall on the night side at -150 ° C. While the opposition it reaches a brightness of 8.3 mag. Eros was examined on 14 February 2000 to February 12 2001 intensively by the NEAR Shoemaker spacecraft. The probe had been placed on an orbit around the asteroid and eventually landed on its surface, detailed images were created. It turned out that Eros craters littered and is crisscrossed by grooves and crevices. The asteroid was obviously exposed to violent collisions with other celestial bodies. Almost everywhere lying around rock debris that may be partially associated with the impact craters.
According to the scientists of the NEAR mission most of the larger boulders come from a crater, which was formed probably a billion years ago in a collision. This impact could also be responsible for a small craters strewn below 500 m region, which accounts for 40 % of the surface of Eros. A large part of the surface of fine dust, regolith coated. Originally, it was assumed, therefore, that the ejection of the collision has filled the smaller craters. An analysis of the crater density of the surface, however, shows that distribute crater poorer areas within 9 km of the point of impact. Some of the less cratered areas are on the opposite side of the impact, but are still within the distance of 9 km. It is believed, therefore, that spread on impact seismic waves through the asteroid and the smaller crater einebneten.
Near the narrowest point of the asteroid is a large crater 5.5 km in diameter, which accounts for almost half the diameter thus the " peanut " shape. It is still unclear why Eros is not broken due to this impact.
At the flyby, the probe was easily distracted by the gravitation of the minor planets, from which its mass was determined to be about 7.2 × 1015 kg. Because of its irregular shape of the gravitational acceleration varies on Eros between different points on the surface very strong; in the middle of his attraction only about 0.06 percent of that on the Earth's surface. Nevertheless, it was at the crater walls seem to slide down scree. The cause of the scientists suspect vibrations of the asteroid body that are triggered by impacts of small chunks and lead to reduced friction.
Raw materials
Eros contains 20 billion tons of aluminum and similar amounts of gold and platinum and other rare metals in the earth's crust.