Willamette University

We are All Star Stuff

NuSTAR and the New View of the Universe

By Adam Torgerson

“In 1900, if you would have asked physicists what there was left to know, they would have said there were just a few bits and pieces still to sort out, and that we understood almost everything,” says President Steve Thorsett.

“Now we look around and realize that we only understand a small portion of the universe.”

Thanks in part to Thorsett’s work with fellow CalTech post-doc Fiona Harrison, NASA will soon launch the NuSTAR mission. The Nuclear Spectroscopic Telescope Array, which Thorsett named, will probe some of the most exciting parts of our universe, including exploding stars. NuSTAR is designed to see high-energy, or “hard,” X-rays. Scientists want to use them the same way your doctor does — to look through the haze of cosmic dust and learn more about our universe’s most energetic phenomena, such as supernovae and black holes.

A space telescope is needed because Earth’s atmosphere blocks X- and gamma rays, while radio and visible-light rays pass through.

Thorsett has used radio telescopes to study pulsars, which are dense balls of neutrons remaining after massive stars explode. Beams of energy from the spinning star cores sweep across the sky like cosmic lighthouse beacons. By carefully observing these flashes, which appear as blips on a radio telescope, Thorsett confirmed a prediction of Einstein’s theory of general relativity and helped find the universe’s oldest known planet.

As part of Harrison’s seven-person project team, Thorsett also led the effort to describe to NASA the scientific potential of a space telescope focused on hard X-rays. The team submitted its first proposal in 1994.

“We went through a series of projects, refining our ideas, getting to various stages of selection competitions at NASA before finally putting together the NuSTAR proposal early in the last decade,” he says.

Interdisciplinary work with NASA on NuSTAR and other international collaborations shaped Thorsett’s perspective as a leader. “That was a clear step in my own understanding of what it meant to be an administrator and why it was interesting,” he says. “You can accomplish big things.” NuSTAR will focus on the biggest things — supermassive black holes at the center of galaxies, such as ours. But Thorsett is most interested in what NuSTAR’s X-ray vision will reveal about recent supernovae. These massive explosions forge the universe’s elements, and the satellite could yield insight into the process.

“We are all made of star stuff,” he says, echoing a famous quote by Carl Sagan. “Figuring out how that stuff gets out of stars and into us is one of the fundamental questions of the creation of life on Earth.”


Artist’s rendering of NuSTAR in orbit.

NuSTAR has a 10 m (30') mast that deploys after launch to separate the optics modules (bottom) from the detectors in the focal plane (top).

Image credit: NASA/JPL-Caltech