Atom & Cosmos

Clearing out space junk with dust, plus new black holes, sonic-boom star birth and more in this week’s news

Dust to clean up space junk Scientists have devised a controversial way to get rid of small space junk —material about 10 centimeters wide that can harm spacecraft. Gurudas Ganguli of the Naval Research Laboratory in Washington, D.C., and his colleagues propose removing the material by sprinkling about 20 tons of fine tungsten dust in a thin shell around the Earth. Atmospheric drag would force the dust to descend from an altitude of 1,100 kilometers, and the space junk would come down with it. In 10 years, all the material would fall far enough to ultimately burn up in Earth’s atmosphere, the researchers report online April 11 at arXiv.org. The team says that the dust, about 30 micrometers in diameter, wouldn’t harm spacecraft, but satellite solar arrays would need thicker cover glass. — Ron Cowen New class of black holes A natural mechanism to make a previously unknown class of dwarf black holes has been proposed by two University of Maine astrophysicists. Previous simulations showed that when stars die in supernova explosions, they produce small clumps of material. The researchers propose that some of the clumps might get compressed enough by their surroundings to form small black holes, which would then get kicked into space by the supernova explosion. These roaming black holes could account for some of the dark matter thought to make up most of the cosmos’ mass, the researchers suggest in an article posted online April 14 at arXiv.org. — Ron Cowen Shocking star birth Sonic booms that penetrate and compress cold clouds of gas may trigger star birth, observations with the European Space Agency’s infrared Herschel space observatory suggest. The telescope found that nearby interstellar clouds contain a network of tangled filaments all about one-third of a light-year in width. That uniform length scale is a strong hint that the filaments were shaped by shock waves. Moreover, Herschel found that the densest parts of the filaments often contain newborn stars — in one case a cluster of about 100 newborns. An international team of astronomers describes the findings in the May Astronomy & Astrophysics . — Ron Cowen First image of close-in planet For the first time, astronomers have imaged a planet whose line-of-sight distance to its parent star is less than Jupiter’s average distance from the sun. The feat offers hope that the glare from a parent star can be overcome to image planets that lie at relatively close distances. The planet, which orbits the star Beta Pictoris, was first discovered in images taken when the orb was much farther from the star. The new image was unveiled by Thayne Currie of NASA’s Goddard Space Flight Center in Greenbelt, Md., at an April 12 Goddard workshop on signs of extrasolar planets. — Ron Cowen

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