As it became known recently, NASA is working on a project to capture an asteroid. It is going to be delivered first to the orbit of the Moon, and then the Earth, and to land astronauts on it. What for? There are several goals: to teach people to work in open space, prepare them for flights to other planets (in particular, to Mars) and take care of repelling the asteroid threat.
Whom to catch?
First of all, it was necessary to choose an asteroid suitable for capturing. To do this, the WISE infrared space telescope, which has not worked since 2011, was awakened from hibernation. During his service (from December 14, 2009), he discovered hundreds of thousands of small celestial bodies.
Dr. Michael Mommert of the University of Arizona (Flagstaff, USA) and his team studied the WISE catalog and began exploring mission-appropriate asteroids using the Spitzer orbiting telescope.
It turned out that out of more than 10,000 near-Earth asteroids known to astronomers, 370 are suitable in size - their diameter does not exceed 10 meters. However, scientists were satisfied with the orbit of only 14 of them. And of these 14, only four have been studied well enough. Of these, two candidates for capture were selected - asteroids 2009 BD and 2011 MD. Apparently, the 2011 MD nomination will be finalized.
A piece of Swiss cheese
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The orbit of 2011 MD is already known, its shape, size, density and mass. The diameter of the asteroid is only 6 meters (and not 10, as previously assumed), the mass is 50 tons, and the density is 1.1 grams per cubic meter.
Scientists just shrug their shoulders: such density is not typical for asteroids, only gas giants like Saturn or Jupiter can "boast" of it.
Dr. Mommert suggests that this asteroid is not so much made of rock as of voids that occupy 65% of its volume. Many people compare it to a piece of Swiss cheese with huge pores.
How to deliver
NASA's Lyndon Johnson Space Center in Houston is currently working on a project for a spacecraft that can capture an asteroid. So far, it is only known that such a ship will have xenon-ion engines and a special trap bag made of increased strength material.
It is assumed that the work on the project will be completed by 2017, and the asteroid 2011MD will arrive in the orbit of the Moon in 2021. And after some time (while no one has named the dates), the asteroid will be transferred closer to the Earth, and samples of its rock will be handed over to scientists.
But even if, contrary to expectations, the plan fails, humanity will still receive unique data on what microasteroids really are and how they arise in the vicinity of the Earth. Previously, it was believed that microasteroids (up to 10 meters in diameter) are something like debris that occurs when large asteroids collide.
But it is possible that microasteroids are formed from dust particles and rock fragments. And this means that they are unlikely to contain so many resources that their capture would become a profitable business for earthlings.