Sen. Jake Garn (R-Utah), whose scheduled flight into orbit aboard the space shuttle Challenger was canceled last week, was named yesterday to the crew of a Discovery mission planned for this month.

The space agency said that Garn will make the next shuttle flight with all but one of the members of the crew he would have flown with this week on Challenger had electrical failures in a $100 million communications satellite in Challenger's cargo bay not forced cancellation of that four-day mission.

The dropped crew member is French scientist Patrick Baudry, who was reassigned to a June shuttle flight.

The National Aeronautics and Space Administration said it named Garn to the Discovery flight because it fit his "busy congressional schedule" and maintained his "direct involvement in the medical experiments" he is to perform with the crew he has been training with for more than two months.

At his request, Garn is to become the first member of Congress to go into space, in part because he is an experienced pilot and because he is chairman of the Senate Appropriations subcommittee that has responsibility for NASA's budget.

NASA gave no firm date for Discovery's flight, which will combine some portions of the canceled Challenger mission with others of the previously planned Discovery flight. Discovery will carry into orbit a Canadian communications satellite that would have been flown on Challenger and a Navy communications satellite that had been part of Discovery's original cargo.

Discovery also will not carry out its planned recovery of a 10-ton satellite, the Long Duration Exposure Facility.