NuSTAR

NuSTAR. The Nuclear Spectroscopic Telescope Array is a space-based X-ray telescope that operates in the high-energy X-ray band. Launched in 2012, it is the first orbiting telescope to focus light in the hard X-ray region of the electromagnetic spectrum, providing an order of magnitude improvement in sensitivity and resolution over previous instruments. Its primary mission is to conduct deep observations in this energetic regime to study some of the most extreme environments in the universe.

Overview

The mission is led by principal investigator Fiona Harrison of the California Institute of Technology, managed by the Jet Propulsion Laboratory, and implemented with significant contributions from international partners including the Italian Space Agency and Danish Technical University. Unlike previous hard X-ray missions like INTEGRAL and Swift, which used coded-aperture masks, it employs true focusing optics, a technological leap pioneered for this energy range. This capability allows it to make sharp images and precise spectroscopic measurements of cosmic sources such as black holes, neutron stars, and the remnants of supernovae.

Development and launch

The concept was selected under NASA's Small Explorer program in 2003, following a competitive proposal process. A key innovation was the development of segmented Wolter telescope optics coated with depth-graded multilayers, enabling the reflection of high-energy photons. The spacecraft bus was built by Orbital Sciences Corporation, and the mission faced a cancellation threat in 2006 before being reinstated. Launch occurred on 13 June 2012, via an L-1011 Stargazer carrier aircraft that released a Pegasus XL rocket over the Kwajalein Atoll in the Pacific Ocean. The successful deployment of its long 10-meter mast, which separates the optics from the detectors, was a critical post-launch event.

Instrumentation and capabilities

The observatory's core instrumentation consists of two identical, co-aligned grazing-incidence telescopes. Each telescope module contains 133 concentric shells of glass optics, coated with alternating layers of platinum and silicon carbide to act as mirrors for hard X-rays. The focal plane is equipped with cadmium zinc telluride detectors, developed in collaboration with the Columbia University and the Goddard Space Flight Center. These detectors provide high spectral resolution across its operational band of 3 to 79 kiloelectronvolts. The long deployable mast, provided by ATK, creates the necessary focal length for high-angular resolution, achieving half-power diameter of less than one arcminute.

Scientific objectives and discoveries

Its primary scientific goals include surveying black hole populations across a range of cosmic distances, understanding the dynamics of particle acceleration in supernova remnants like Cassiopeia A, and probing the dense interiors of neutron stars. A landmark discovery was the detection of the radioactive isotope titanium-44 in the remnant of Supernova 1987A, providing direct evidence of recent nucleosynthesis. The telescope has also been instrumental in studying the coronae of black holes, identifying hidden supermassive black holes obscured by dust, and contributing to multi-wavelength campaigns with observatories like the Chandra X-ray Observatory, XMM-Newton, and the Hubble Space Telescope.

Mission operations and status

Mission operations are conducted from the University of California, Berkeley, which hosts the Science Operations Center, while the Jet Propulsion Laboratory manages the spacecraft. Data is archived and distributed through the High Energy Astrophysics Science Archive Research Center at NASA's Goddard Space Flight Center. Originally designed for a two-year primary mission, the observatory has remained highly productive for over a decade, with its mission extended multiple times by NASA. It continues to be a vital facility for the global astrophysics community, participating in coordinated observations with newer missions like IXPE and contributing to time-domain astronomy.

Category:Space telescopes Category:NASA space probes Category:Explorer program