CHICAGO (CBS) — An astronaut who graduated from the University of Illinois will be going on a spacewalk later this week to fix the International Space Station.

WBBM Newsradio’s Bernie Tafoya reports astronaut and U.S. Air Force Col. Mike Hopkins has been preparing for as many as three spacewalks to repair a broken cooling line on the station.

His first six-hour walk, along with another American astronaut, has been scheduled for Saturday morning, when they’ll begin replacing a refrigerator-sized ammonia pump module. A second walk has been planned for Monday.

If needed, a third walk would take place on Christmas Day.

The station is using a backup cooling system until the main system is fixed.

Hopkins received a degree in aerospace engineering from the U of I in 1991, and was co-captain of the Fighting Illini football team.