Discovered a mysterious force pushing asteroids to Earth

15.12.2003

Discovered a mysterious force pushing asteroids to Earth

15.12.03, the


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Scientists from the United States and the Czech Republic for the first time were able to register a barely visible, but theoretically very important effect of non-gravitational origin acting on all the celestial bodies in the solar system.

This involved using a giant cosmic radioradarnogo rangefinder for a number of years to produce extremely fine measurements of the orbital path of one of the near-Earth asteroids. The force in question, arises from the so-called Yarkovsky effect (named in honor of the pre-revolutionary Russian engineer Ivan Yarkovsky, in 1900, for the first time in theory of reasoned action of this effect). The root cause is the solar energy that an asteroid absorbs his day party and re-emits into space at dusk. "Midday" quadrant of any solar system body (ie, the one side of it, which is longer than the others turned toward the light) is, naturally, more heat, it also emits more heat energy. This unbalanced thermal radiation produces a tiny acceleration that still had "not prudent." As a result of his actions there is a new factor, which forces scientists to closely monitor future developments of the trajectories of asteroids.

Asteroid 6489 under the number "Golevka" ("Golevka") on near-Earth maloprimeten standards, but such an object can lead to a serious accident in the event of a collision with the Earth (even a 100 — or 50-meter object can destroy a significant part of the city). Its diameter is about half a kilometer, but the weight — about 210 billion kg. Thus, the density of the asteroid — 2.7 g / cm3. Watching him were in 1991 (the year of discovery), 1995, 1999, and last May, during the record (16 million km) closer to Earth. An international team of astronomers, which included researchers from JPL (Jet Propulsion Laboratory — JPL)
NASA in Pasadena (California) used these data to produce a detailed analysis of the orbital path of the asteroid. Post this group appeared in the magazine on December 5 Science.


"For the first time we have shown that asteroids can literally propel themselves through space, albeit very slowly — said Dr. Steven Chesley (Steven Chesley), a scientist from the Jet Propulsion Laboratory, NASA, who led the study. — The force arises due to the Yarkovsky effect, in the case of Golevki seems very small (one ounce), especially considering the total mass of the asteroid. But in the 12 years that the observations were made, this small force has changed the orbit of the asteroid 15 kilometers (compared with calculations that take into account only the gravitational factors). When that same force acts tens of millions of years, it can have a huge impact on the orbit of a celestial body. So, asteroids that are in orbit between Mars and Jupiter (asteroid belt) may actually be a near-Earth object. " The real state of Golevki thus corresponds to the predicted given the force of the Yarkovsky (based on the location of the axis of rotation of the asteroid, its speed of rotation and surface properties including reflectance).


Yarkovsky effect has already become an important tool for describing many aspects of the dynamics of asteroids. Theorists have used it to explain the phenomenon of the movement of objects in the main asteroid belt to the inner solar system, to estimate the age of meteorites and the characteristics of the so-called "asteroid families" formed mainly by collisions of larger asteroids that break down, give life numerous offspring with similar characteristics. And yet, in spite of major theoretical importance, this force is still really did not show up for any of the asteroid. To show the complexity of the experiment, Dr. Chesley compared the radar survey carried out with the definition of an accurate (within one-half inch) distance to the field of basketball in New York City with the help of a radar dish the size of a ball in Los Angeles. The researchers used a model of the Yarkovsky effect, developed by Prague scientists (Dr. David Vokruhlitski (David Vokrouhlicky)), and the Arecibo Observatory radio telescope in Puerto Rico.

US-Czech team now plans to study other asteroids, and hopes that its new method will eventually become accepted in tracking these objects. Astronomers also believe that the measurement of the force of the Yarkovsky effect provides the only real opportunity to reliably determine the mass of Earth and the density of small (less than a kilometer) asteroid, which is important for assessing the potential threat posed by them. However, an effect that leads to the fact that the asteroids approach the Earth, may instead help them to "break up" in space, if such a potentially dangerous asteroid right "repaint"Some of the huge spray, as suggested by Joseph Spayteyl (Joseph Spitale) of the Lunar and Planetary Laboratory at the University of Tucson.

 

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