CAPE CANAVERAL, Fla. (AP) _ Sen. Jake Garn says he's not bothered by the ribbing he's taking about his upcoming space shuttle flight from cartoonist Garry Trudeau in the ''Doonesbury'' comic strip.

''I've always liked Garry Trudeau; I'm glad he's having fun with the barf bag,'' the Utah Republican said Sunday after he and his six crewmates completed a successful practice countdown for their flight aboard shuttle Challenger in two weeks.

In the strip, Garn is interviewed by ''Doonesbury'' television commentator Roland Hedley, who refers to the senator as ''Barfin' Jake Garn, a man and his mission.'' The reference is to medical experiments Garn will undergo, some of which could make him sick.

Hedley also calls Garn's trip ''the most extraordinary junket in the history of Congress.''

The senator, chairman of a subcommittee that oversees funding for the National Aeronautics and Space Administration, will be aboard as a congressional observer.

The seven-member crew climbed aboard Challenger on Sunday to participate in the final two hours of the countdown rehearsal. They checked all spacecraft systems so there will be no surprises on launch day.

Commander Karol Bobko, the only veteran space traveler on the crew, told reporters after the test that he hoped the real countdown goes as well as the rehearsal.

The other crew members are pilot Donald Williams; mission specialists Rhea Seddon, David Griggs and Jeffrey Hoffman, and French astronaut Patrick Baudry, who will operate a French-developed cardiovascular monitoring system to study the body's adaptation to weightlessness.

During four days in orbit, the astronauts will release a Canadian communications satellite and a NASA tracking and data relay satellite.

The launch is scheduled March 3, but there may be at least a one-day postponement because of a delay in moving Challenger to the launch pad last week. A firm date will be set Thursday.

Asked about the date, Bobko said, ''Even if it's not the third, it will be shortly after that. We'll be ready for any day.''