What goes on at the edge of a black hole? NASA launches NuSTAR to find out. (+video)
NASA will launch the orbiting X-ray observatory NuSTAR Wednesday in hopes of plunging deeper into the secrets of black holes and supernovae.
A new space telescope is set for launch Wednesday on a quest to explore the inner workings of black holes, the mechanisms driving some of the most mighty explosions in the cosmos, and the poorly understood processes heating the sun's corona to more than 1 million degrees.Skip to next paragraph
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These phenomena reveal their secrets via X-rays – a form a light substantially more energetic than visible light and capable of piercing enshrouding clouds of cosmic dust. Known as the Nuclear Spectroscopic Telescope Array (NuSTAR), the $170 million X-ray observatory will allow scientists to observe activity around black holes and other sources of X-rays with greater sharpness and clarity than any telescopes currently available.
Its trick is a 33-foot-long mast that extends out from the spacecraft in space. Two sets of optics on the end of the mast will deliver the X-rays they pick up to detectors on the spacecraft in a tightly focused group. As a result, NuSTAR not only will be able to create images 10 times sharper than those from other orbiting X-ray observatories, but it will also be able to see X-ray sources 100 times fainter.
This means that its targets will be "some of the hottest, densest, most energetic phenomenon in the universe," says Fiona Harrison, an astrophysicist at the California Institute of Technology in Pasadena and the project's lead scientist.
This includes regions near the point of no return for matter falling into supermassive black holes at the centers of large galaxies. As dust and gas get closer to this so-called event horizon, the matter is compressed and heated, eventually reaching the point where it emits radiation as X-rays. Existing X-ray telescopes can detect emissions from fairly close to the event horizon. But NuSTAR is designed to detect more-energetic X-rays, in effect giving it a window on conditions even closer to the event horizon.
NuSTAR will also open new vistas on supernovae – some of the most powerful explosions known and events that are thought to produce all the chemical elements in the universe heavier than hydrogen and helium. NuSTAR scientists will in effect act as a cosmic bomb squad, teasing from the expanding cloud of element-rich matter ejected new details about how the explosions happen, says Daniel Stern, project scientist for NuSTAR at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
To do this, the team plans to train the telescope on two supernova remnants: Cassiopeia A and SN 1987A.
In Cass A's case, the type of star that exploded is unknown. But supernova 1987A involved a star some 20 times the sun's mass. When a star at least 10 times the sun's mass explodes, the object that remains after a supernova is a neutron star – essentially a solid core of neutrons with as much mass as the sun but packed into an object the size of Manhattan. But if a far more massive star goes supernova, the result is a black hole – an object so dense and with gravity so intense that not even light travels fast enough to escape it.
The Chandra X-ray Observatory has detected a neutron star at the heart of Cass A, but it can't detect key features of the expanding remnants of the progenitor star that can help answer key questions scientists have regarding supernovae explosions. Scientists have not yet located anything at the core of SN 1987A, but one hypothesis is that a neutron star could be shrouded in dust, making it impossible to see at visible wavelengths.