This diagram illustrates why NASA's NuSTAR can see radioactivity in the remains of exploded stars for the first time. The observatory detects high-energy X-ray photons that are released by a radioactive substance called titanium-44.

This diagram illustrates why NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, can see radioactivity in the remains of exploded stars for the first time.

When stars blow up in supernovas, they fuse lighter elements together into heavier ones, seeding the universe with the ingredients that go into making stars, planets and even people. Some of the elements produced in supernovas are radioactive, which means they are unstable and decay into lighter elements. When this happens, the radioactive substances give off energy in the form of particles called positrons -- and light, which is made up of photons.

One of the radioactive elements created in supernovas is titanium-44 (44 denotes the total number of protons and neutrons in an atom). Titanium-44 decays into calcium-44, and in the process, gives off high-energy X-ray photons. NuSTAR is the first telescope capable of creating detailed pictures of these high-energy X-ray photons. As a result, NuSTAR can map the radioactivity in supernova remnants for the first time, revealing new details about how massive stars explode.

NuSTAR is a Small Explorer mission led by the California Institute of Technology in Pasadena and managed by NASA's Jet Propulsion Laboratory, also in Pasadena, for NASA's Science Mission Directorate in Washington. The spacecraft was built by Orbital Sciences Corporation, Dulles, Va. Its instrument was built by a consortium including Caltech; JPL; the University of California, Berkeley; Columbia University, N.Y.; NASA's Goddard Space Flight Center, Greenbelt, Md.; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory, Livermore, Calif.; ATK Aerospace Systems, Goleta, Calif., and with support from the Italian Space Agency (ASI) Science Data Center, Rome, Italy.

NuSTAR's mission operations center is at UC Berkeley, with ASI providing its equatorial ground station located at Malindi, Kenya. The mission's outreach program is based at Sonoma State University, Rohnert Park, Calif. NASA's Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.

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