AP AEROSPACE WRITER

MARCIA DUNN

CAPE CANAVERAL, Fla. (AP)—Columbia and its seven astronauts blasted off on a belated mission Monday, carrying 48 rats that will be poked, prodded and in some cases decapitated by guillotine and dissected in orbit.

All in the name of medical science.

The astronauts quickly got started on their 14 days of space checkups, drawing blood from one another, measuring their blood pressure and noting any symptoms of motion sickness.

The mission—the longest ever planned for a space shuttle—is intended to help scientists develop measures for counteracting the debilitating effects of space travel.

Despite the tests, everyone was flying high.

‘‘As you can well imagine, there are seven very happy people up here,’‘ commander John Blaha said.

Astronaut-physician David Wolf was the first one to enter the pressurized laboratory module in the cargo bay, followed by the crew’s other medical doctor, M. Rhea Seddon.

NASA needed three countdowns to get Columbia off the ground. Equipment failures halted last week’s attempts.

‘‘Guys, the third time’s a charm,’‘ orbiter test director Brian Monborne assured the crew before liftoff.

Delayed 10 seconds by a stray Navy plane, the 2,000-ton spaceship rose from its seaside pad at 10:53 a.m. and tore through three decks of clouds on its way to a 176-mile-high orbit.

It is only the second mission in 58 shuttle trips focused entirely on medical research.

Scientists say they need more tests before they can draw any conclusions about avoiding such effects of space travel as shriveled muscles, weakened bones and weakened immune systems. And then there’s space motion sickness, which strikes two-thirds of all astronauts.

Two crew members had catheters threading through their veins for launch—Martin Fettman, the first U.S. veterinarian in space, and Shannon Lucid, a biochemist who became the first woman to fly in space four times. The catheters were hooked to white backpacks with floating cables, making the astronauts look like a pair of bees.

Fettman and Blaha looked a little silly Monday night wired up for an experiment simulating the sensation of falling. A skullcap recorded head movements and leg electrodes measured muscle movement as they took turns dropping about a foot by bungee cords.

Fettman is in charge of the rats, the most that’s ever flown on a shuttle. Half the rodents were slightly warmer than biologists desired because of an overheated enclosure; the crew turned off the thermostat in an effort to cool the unit.

Throughout the mission, Fettman and the others will draw blood from the 2- to 3-month-old male rodents, inject radioactive isotopes and hormones, and collect the animal droppings to measure calcium content, an indicator of bone loss.

On Oct. 30, Fettman will use a guillotine to behead five of the rats, six if there’s time. He and another astronaut then will perform the first animal dissections in space, preserving almost everything for postflight analysis: brain, eyes, inner ears, parts of the skull, spleen, heart, liver, kidneys, pancreas, thyroid, lungs, trachea, bones, muscles, blood, glands, testes.

Biologists say the only way to know exactly how weightlessness affects creatures is to dissect them before they’re re-exposed to gravity.

Columbia’s surviving rats will be killed for dissection after the flight, the same fate encountered by the more than 100 rats on previous shuttle missions in studies of space travel.

As for the nearly 1,000 rats that were on standby in case of further launch delays, NASA planned to kill the animals and donate them to a rehabilitation program for birds of prey.