August 3, 2012

Scientists have gained a powerful new tool for finding and studying black holes and other violent objects that give off high-energy X rays–NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) space observatory. Black holes are regions of space whose gravitational force is so strong that nothing can escape from them. Because black holes trap even light, astronomers cannot see them directly.

Black holes “are sort of the Las Vegas of the universe,” said one scientist. “What happens in a black hole stays inside of a black hole. But on the outskirts of them, that is where there’s tremendous action.” That action occurs when a cloud of gas and dust–or even a star–gets close enough to the black hole to be captured and “eaten.” In the process, the material swirling into the black hole gets so hot that it glows and emits invisible high-energy X rays–the kind used in medicine to image the inside of the body and teeth. This radiation can reveal not only the location of a black hole but also its size. Scientists also plan to study mysterious black hole “burps,” which may be X rays that shoot from black hole if too much material is pulled in at once.

Galaxies appear in much sharper focus in a computer simulation showing NuSTAR’s view of an area of deep space (lower right), compared with an image taken by the European Space Agency’s INTEGRAL satellite (upper left). NuSTAR’s ability to capture high-energy X rays will enable scientists to find individual black holes currently hidden by clouds of dust. (ESA/NASA/JPL-Caltech)

Other targets of the NuSTAR observatory will be supernovae–massive exploding stars that create black holes–and active galaxies–galaxies with supermassive black holes in their nuclei (cores) that give off vast amounts of radiation. Scientists also plan to study the sun‘s atmosphere, which is much hotter than the surface below.

Since the June 14 launch of the $170-million space telescope, NuSTAR’s scientists have been calibrating its instruments and taking test images. Because NuSTAR has more than 100 mirrors for reflecting X rays, it will be able to produce images 10 times as sharp as those from current X-ray telescopes, even the orbiting Chandra X-ray Observatory.

Additional World Book articles:

• Electromagnetic waves
• Space exploration

June 14, 2012

A space observatory designed to search for and study one of the most powerful and mysterious objects in the universe was launched into Earth orbit on June 13. NASA‘s Nuclear Spectroscopic Telescope Array (NuSTAR) will be able to collect the high-energy X rays that surround black holes, regions of space whose gravitational force is so strong that nothing can escape from them. Because black holes are powerful enough to trap even light, astronomers cannot see them directly. But just before a cloud of gas and dust–or even a star–is sucked into a black hole, the material gets so hot that it glows and emits invisible high-energy X rays. Scientists use the rays given off by these doomed objects to identify, measure, and study black holes. Astronomers also plan to use NuSTAR data to study the effects of black holes on their host galaxies.

A supermassive black hole sucks in a swirling disk of matter, shooting out beams of particles, in this artist’s conception. (NASA)

The NuSTAR observatory includes the first focusing telescopes that will be able to image the sky in the high-energy X-ray region of the electromagnetic spectrum. Because of this ability to focus, the images NuSTAR produces will be 10 times as sharp as images from current X-ray telescopes, even the orbiting Chandra X-ray Observatory. NuSTAR’s instruments will be able to see through clouds of gas and dust that block low-energy X rays.

NuStar’s mission also includes gathering data on other high-energy-emitting targets (objects that give off high-energy X rays). Among them are supernovae, massive exploding stars that create all of the chemical elements heavier than the two lightest elements–hydrogen and helium–including iron, gold, and uranium. Astronomers also planned to investigate active galaxies, galaxies that give off vast amounts of radiation from their nuclei (cores).

NuSTAR (NASA/JPL-Caltech)

NuSTAR was launched in mid-air from a L-101 Stargazer aircraft atop a Pegasus XL rocket built by Orbital Sciences, a private company based in Dulles, Virginia. Such airborne launches require less fuel than a traditional surface take-off. The NuSTAR mission is part of NASA’s Small Explorer class of low-budget space flights.

Additional World Book articles:

• Astronomy
• Electromagnetic waves
• Space exploration