CAPE CANAVERAL, Fla.—With just two more days together, the astronauts of the linked space shuttle and space station busily collected as many recycled urine samples as possible from a machine that they coaxed into operation.

The device for turning urine into drinking water—a critical part of the space station’s new water recycling system—seemed to be working fine Tuesday after several days of tinkering by the astronauts. They laughed and described the process as turning “yesterday’s coffee into today’s coffee,” and labeled a few bags as such.

“Now we’re not going to be drinking this today,” shuttle commander Christopher Ferguson said, holding up the first batch of processed urine. The samples need to be returned to Earth by Endeavour and thoroughly tested before the recycled water in orbit is declared fit for human consumption.

“Beginning probably, oh, maybe next spring or so, we’ll get the green light to go ahead,” Ferguson said in a series of TV interviews.

By the time Endeavour undocks Friday, six one-liter containers of recycled urine and condensation should be packed aboard the space shuttle, said flight director Holly Ridings. Additional samples will be returned on the next shuttle flight in February.

Astronaut Donald Pettit, who worked on the urine processor, said it’s normal to have a few hiccups with new equipment. Endeavour delivered the $154 million recycling equipment on Nov. 16, along with other home improvement gear that will allow NASA to double the size of the international space station crew next year.

“You have to remember that this is serial number zero-zero-one for a brand new technology which we’re testing out here on space station,” Pettit said.

NASA officials were just as thrilled with the way a newly repaired rotary joint was working.

The joint—needed to point the solar wings on the right side of the space station toward the sun—appeared to operate fine during a three-hour test Tuesday. It had not been used in the automatic mode for more than a year because of metal grit that clogged its inner workings.

Endeavour’s astronauts spent four spacewalks cleaning and lubing the joint, and installing new bearings.

Space station program manager Mike Suffredini said Tuesday’s joint test went better than he could have hoped.

“We’re well on our way” to achieving a full six-person space station crew by May or June, he said.

Suffredini stressed that months of testing remain. It’s possible that nothing more will need to be replaced in the joint and that a lube job every year or so by spacewalking astronauts will keep it functioning until at least 2015.

Endeavour and its seven-person crew are scheduled to land Sunday. NASA extended the flight by a day to give the astronauts more time to work on the urine processor.