Friday, June 22, 2012

NuSTAR Reveals The Universe In X-Rays

An Orbital Sciences technician completes final checks of NASA's NuSTAR inside the Orbital Sciences processing facility at Vandenberg Air Force Base.

Over a century ago, Wilhelm Rontgen made an amazing discovery - X-rays. Never in his wildest dreams could he ever have imagined the many uses this form of electromagnetic radiation would have inspired. It has evolved from basic medical uses to the furthest reaches of outer space. Now an orbiting NASA telescope has been launched and it will provide us a look at the Universe that we've never seen before. This new telescope was developed with help from researchers from SLAC National Accelerator Laboratory and Stanford’s main campus and the views it will provide will be hard. Hard X-rays!

NuSTAR - the Nuclear Spectroscopic Telescope Array is the brainchild of a consortium of scientists and engineers under the leadership of Fiona Harrison from the California Institute of Technology. At its heart is a system of nested X-ray mirrors which will image the Universe in hard X-rays - the penetrating view which passes through solids, liquids and uncompressed gases. NuSTAR will be able to focus this portion of the electromagnetic spectrum into images "10 times sharper and 100 times more sensitive than any previous X-ray telescope."

Needless to say, members of the joint SLAC/Stanford Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) are on the NuSTAR science team and are eager to get their first glimpse through this new telescope's eyes. “Every time there is a new instrument with significantly better sensitivity than any previous instrument, significant discoveries are bound to follow,” said SLAC astrophysicist Greg Madejski, who is leading the KIPAC contingent. Dr. Madejski was also part of the creative team that created NuSTAR's scientific parameters - both before the telescope was built and while it is in operation.

“The most important study will involve the cosmic X-ray background -- understanding the individual phenomena that contribute to it,” Madejski said.

Just what will NuSTAR look at? Imagine scanning the event horizon of a black hole where particles are crammed together like soapsuds going down a drain. Or peering into a high energy Universe where jets of material spew from active galactic nuclei. NuSTAR will go beyond information sent back by telescopes like the Fermi Gamma-Ray Space Telescope. The gamma rays captured by Fermi don’t provide enough information to fully explain what powers these jets; according to Madejski, the hope is that NuSTAR will be able to measure the jets’ contents and reveal some of the high-energy processes that accelerate the contents to such great speeds.

"NuSTAR can convert high-energy X-ray photons into sharp images because of its innovative telescope design." said SLAC engineering physicist Jason Koglin, who currently helps users of the Linac Coherent Light Source get the information they need from the LCLS X-rays. Previously, he was at Columbia University working with the team that developed NuSTAR’s mirrors. “The whole telescope is basically a set of nested reflective mirrors,” which are designed to deflect light onto the special solid-state detector, said Koglin. "Each of its two identical optics modules is made of 133 layers of concentric, cone-shaped shells, each shell built of between 12 and 24 individual segments, all molded from ultra-thin glass similar to what’s found in laptop screens and glazed with hundreds of layers of reflective coatings."

Although this technology is cutting-edge, the advanced mirror design can on deflect X-rays to a small amount. Within a week of launch, a specialized lightweight gantry will be employed. This maneuver will increase the "space" between the modules and the main telescope by an additional 33 feet. This will enable the deflected X-rays to converge in a perfect position.

Holding his breath, Koglin patiently waits with the other KIPAC scientists to decipher the messages that NuSTAR will deliver. “Multi-band studies are so important,” he said -- in other words, studying the same phenomenon in NuSTAR’s hard X-rays and Fermi’s gamma rays, or in the less energetic X-rays detected by the Chandra X-ray Telescope. “It’s like looking at different colors in a very broad spectrum,” he said. “If one of the colors isn’t there, you can’t even tell you’re missing something.”

Thanks NuSTAR, the bare bones of the Cosmos will soon be ours to discover.

Contributed by Tammy Plotner. Original Story Source: Stanford University News Release.

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