William Kraushaar, a pioneer in high-energy astronomy and a former physics professor at MIT and the University of Wisconsin, died March 21 in Scarborough, Me., of complications from Parkinson’s disease. He was 87.

Kraushaar, who devoted much of his career to the study of interstellar matter, began in 1955 a decade of work on the detection of cosmic gamma rays that promised to open new ways to investigate high-energy processes in the universe.

In 1958 he proposed what would become known as Explorer 11, the first orbiting astronomical observatory. Launched in April 1960, it operated for several months, mapping gamma rays coming from outside and inside the galaxy that bathed Earth’s atmosphere in high-energy but invisible light waves.

A subsequent experiment yielded the first definitive all-sky map of high-energy gamma rays from directions in the Milky Way where interactions of charged cosmic rays with interstellar matter were most abundant.

At Wisconsin, he established a research group in X-ray astronomy whose work revealed a hot and violent part of the universe, one that contained previously unsuspected black holes, neutron stars and million-degree gas.

Because his work could not be done from Earth or with high-altitude balloons, he used “sounding” rockets that broke out of the atmosphere and gave researchers the first sense of where these rays were coming from.