CAPE CANAVERAL, Fla. (AP)—NASA rewarded the Columbia astronauts’ energy-conservation efforts by adding a day to their mission, and a shuttle robot scored a space first Sunday, catching a floating object on command.

The seven astronauts were thrilled about the flight extension. They had been working in near darkness, curtailing television views of the shuttle and turning off unnecessary computers to save energy.

German space officials and researchers at the science control center in the Bavarian town of Oberpfaffenhofen also were delighted, though the extension means delaying the post-flight celebration at Kloster Andechs, a monastery near Munich famous for its beer.

‘‘We will drink an extra beer for the extra day,’‘ said Hans Bolenger, a crew interface coordinator at the control center.

‘‘That sounds like a good deal,’‘ replied astronaut Jerry Ross.

The German-sponsored laboratory research mission is now scheduled to end with a Kennedy Space Center landing on Thursday.

German payload official Walter Brungs said the extra day in space will allow scientists to meet and possibly exceed their flight objectives. Equipment problems had delayed several of the 88 planned Spacelab experiments.

German researchers said their 2^4-foot-long robot arm, called Rotex, pulled an aluminum die not quite an inch in size from its holder and let it float inside the enclosure around the arm. After knocking it away once, grippers on the end of the jointed arm succeeded in clamping onto the die, holding it fast.

German space officials said it was the first time a robot commanded from Earth caught a free-floating object in space.

Researchers hope robots eventually will perform routine chores in space, lightening the astronauts’ work load.

A fourth astronaut was infused with saline solution Sunday, completing another experiment.

Only astronaut-physician Bernard Harris Jr., who was infused Saturday night, seemed to have a bad reaction. NASA said he was in no medical danger. He became chilled because the saline solution, although heated to body temperature, had cooled down by the time it was injected into his body.

Researchers hope the half-gallon infusions will compensate for the body fluid lost by astronauts in space. Blood and other fluids accumulate in the chest and head in weightlessness, resulting in dehydration and, at the end of a flight, reduced blood pressure and dizziness.

The astronauts had to get out their plumbers’ gloves again.

While flushing urine and other waste water into space from a backup storage system, the astronauts reported an odor coming from the large, rubber-lined bag containing the fluid. The bag has been used since Tuesday, when the regular tank broke and waste water had to be rerouted.

Mission Control instructed the crew to move the bag—one of two on board—into an unused trash compartment beneath the floor so odors could be vented to the outside.