Next NASA Mission :The Nuclear Spectroscopic Telescope Array

Figure: NuSTAR (Credit: California Institute of Technology)

The NuSTAR mission will deploy the first focusing telescopes to image the sky in the high energy X-ray (6 - 79 keV) region of the electromagnetic spectrum. Our view of the universe in this spectral window has been limited because previous orbiting telescopes have not employed true focusing optics, but rather have used coded apertures that have intrinsically high backgrounds and limited sensitivity.

During a two-year primary mission phase, NuSTAR will map selected regions of the sky in order to:

(1) take a census of collapsed stars and black holes of different sizes by surveying regions surrounding the center of own Milky Way Galaxy and performing deep observations of the extragalactic sky;

(2) map recently-synthesized material in young supernova remnants to understand how stars explode and how elements are created; and

(3) understand what powers relativistic jets of particles from the most extreme active galaxies hosting supermassive black holes.

In addition to its core science program, NuSTAR will offer opportunities for a broad range of science investigations, ranging from probing cosmic ray origins to studying the extreme physics around collapsed stars to mapping microflares on the surface of the Sun. NuSTAR will also respond to targets of opportunity including supernovae and gamma-ray bursts.

The NuSTAR instrument consists of two co-aligned grazing incidence telescopes with specially coated optics and newly developed detectors that extend sensitivity to higher energies as compared to previous missions such as Chandra and XMM. After launching into orbit on a small rocket, the NuSTAR telescope extends to achieve a 10-meter focal length. The observatory will provide a combination of sensitivity, spatial, and spectral resolution factors of 10 to 100 improved over previous missions that have operated at these X-ray energies.



Figure: NuSTAR focal plane motherboard with one of the four CdZnTe detectors installed. NuSTAR will have two such units, providing for a total of two 4K high energy X-ray cameras.

NuSTAR has two detector units, each at the focus of one of the two co-aligned NuSTAR optics units. The optical units observe the same area of sky, and the two images are combined on the ground. The focal planes are each comprised of four 32×32 pixel Cadmium-Zinc-Tellurium (CdZnTe, or CZT) detectors manufactured by eV Products. CZT detectors are state-of-the-art room temperature semiconductors that are very efficient at turning high energy photons into electrons. The electrons are then digitally recorded using custom Application Specific Integrated Circuits (ASICs) designed by the NuSTAR Caltech Focal Plane Team.

A NASA Small Explorer (SMEX) mission, NuSTAR is currently in Phase C/D and is scheduled to launch into low-Earth equatorial orbit in February 2012.