Every morning for the past 16 years, solar physicist Säm Krucker sat down at his desk to check the latest data from NASA’s RHESSI. Had the solar observatory seen a flare overnight? If there was a new flare, Krucker, RHESSI principal investigator at University of California, Berkeley, since 2013, would pore over the data, each recorded X-ray telling him something about the giant explosion on the Sun.

Now, many years after launching on Feb. 5, 2002, the RHESSI — short for Reuven Ramaty High Energy Solar Spectroscopic Imager — mission has ended; Krucker, and many other scientists, will no longer check the spacecraft’s data returns each day. In anticipation of losing touch with the spacecraft’s aging receiver, mission operators sent the spacecraft commands to decommission on Aug. 16, 2018.

“It does impact everyday life that way,” Krucker said. Though it’s appropriate timing for RHESSI to stop operations now, he said, while the Sun nears solar minimum, the lull in its activity over an approximately 11-year cycle. “The next two to three years would have been quite boring.”

RHESSI’s job was to watch the Sun for solar flares, some of the most dramatic events on the Sun that can sometimes fling solar energy toward Earth.

Read about the History of this prolific Solar Observatory