UPDATE: NuStar's launch was a success. "NuSTAR spread its solar panels to charge the spacecraft battery andthen reported back to Earth of its good health," Yunjin Kim, the mission's project manager at NASA's Jet Propulsion Laboratory, said in a release. "We are checking out the spacecraft now and are excited to tune into the high-energy X-ray sky."
At the center of our galaxy lies a supermassive black hole, and that black hole spews forth high-energy X-rays. Yet astronomers who study such powerful phenomena with current space telescopes often compare it to a farsighted person trying to read a book without glasses.
"The view of the center of our galaxy ... is a rather fuzzy image. We think it's much more complicated," physicist William Craig of the University of California, Berkeley, said during a NASA press conference Monday.
To bring an unprecedented view of the X-ray sky, NASA engineers built a new space telescope called NuSTAR, short for nuclear spectroscopic telescope array. This morning around 11:30 am EDT, NASA plans to launch it into space from the belly of an airplane. (Watch NASA's live coverage on the web starting at 10 am EDT.)
Ultimate X-ray Vision
High-energy X-rays come from a variety of astronomical objects and processes. Black holes, for example, emit X-rays while feeding on captured matter from stars, planets, and other celestial objects. As the celestial debris builds up in a disk around the black hole, it travels progressively faster and gets progressively hotter. Before it passes the event horizon—the point of no return, even for light—that matter gets hot enough to glow in the X-ray part of the spectrum.
Other X-ray sources include the cooling remnants of supernovas and particles traveling between galaxies. NuSTAR's team members say that studying these is crucial to understanding how galaxies, stars, and solar systems form.
"One of NuSTAR's primary science goals is to study ... the extreme physics near black holes, where spacetime is very distorted and particles are accelerated close to the speed of light," Fiona Harrison, an astrophysicist at Caltech and another NuSTAR team member, said during the press conference. "It will also help us understand how black holes are distributed throughout the universe."
Thankfully for life on Earth, our atmosphere blocks out X-rays. So researchers must launch space-based observatories to see them. Several X-ray observatories already exist, including NASA's Chandra and the European Space Agency's XMM-Newton. However, these spacecraft record X-rays at relatively low-energy wavelengths (imagine if an optical telescope couldn't see in blue or green). NuStar will be able to observe higher-energy X-rays, and in better resolution.
"It opens up a new window into the high-energy universe," Craig says. "For the first time, [we'll be able to] look at the energies of these exotic objects."
NASA's budget is tight and getting tighter, and so NuStar won't be riding into space aboard a big, fiery rocket blasting off from Cape Canaveral. "We couldn't have afforded a rocket ... to launch something the size of a school bus," Craig says.
Instead, the telescope will be launched from the air. NuStar is currently tucked into the nose cone of a smaller 58-foot-long Pegasus XL rocket, which itself is strapped to the bottom of Stargazer airplane. When the aircraft reaches an altitude of about 40,000 feet above Kwajalein Atoll, near Earth's equator, the rocket will fall away and launch into orbit. (Here's a video simulation.) Several commercial space companies, most notably the Paul Allen-backed mega jet called Stratolaunch, are trying to use this piggyback method of launching a rocket because it drastically cuts down launch costs—NuStar will tally a relatively cheap $170 million.
The problem is making the telescope compact enough. Focusing fuzzy X-ray light sources into crisp images on its sensors requires NuStar to have two "light buckets," or lenses, about 33 feet from the camera. The Pegasus XL rocket's nose cone, however, fits something only as tall as 7 feet. So the engineers designed a new collapsible mast for NuSTAR's light buckets. A week after the spacecraft settles into orbit, the spacecraft will unfurl its mast and open up for business.
If all goes well, the telescope will rival the capabilities of Chandra and XMM-Newton in imaging distant, high-energy objects. Harrison noted that combining data with those from other X-ray telescopes will provide a complete look at the mysterious objects.
"Together they can study the entire X-ray spectrum, breaking the X-ray light into its colors," Harrison says. "We can watch matter circulate near a black hole, observe how spacetime distorts our view of these objects and even tell how fast the black hole is spinning."