Astronauts on the ISS finally managed to conduct a successful test on the equipment that turns urine into drinking water, a necessity for supporting the ISS’s crew, which will soon double, from three to six.

Space Station commander Mike Fincke told Mission Control early Tuesday morning that they have successfully tested the device. Astronauts had spent a frustrating five days trying to get the urine processor working. Unfortunately, until early Tuesday, the machine couldn’t last the four hours needed for a successful test run. Another test was planned overnight, while the seven astronauts on Endeavour and three space station crew members slept.

In order to deal with this problem, NASA added a 16th day to Endeavour’s mission, so astronauts could tinker with the urine processor before the shuttle returns to Earth, possibly with the troubled equipment packed aboard. If none of the tests would have been successful, NASA would have brought back the device for repairs. Now, Endeavour is set to undock Friday and land in Florida on Sunday.

The urine processor makes up a section of the $154 million water recycling system that was delivered to the space station by Endeavour. Samples of the processed urine, sweat and condensation will be tested on Earth before astronauts can start drinking the purified water next year.

In the process of fixing the problem, Fincke and Endeavour astronaut Don Pettit had removed vibration grommets which were used to mount a centrifuge in the urine processor, bolting the piece down. NASA also wanted to test if the four spacewalks the astronauts performed during this mission paid dividends.

They were made in the attempt of cleaning and lubricating a jammed solar-wing joint on the station’s right side, a joint that hasn’t worked properly for more than a year. The station’s crew members and Endeavour’s astronauts were asked to avoid creating vibrations during the test, and they were given an extra half hour to sleep in because of the test.