Urine is the No. 1 need right now for some of the builders of the United States' next spaceship, lots of urine.

Space program contractor Hamilton Sundstrand is seeking urine from workers at the Johnson Space Center in Houston, Texas, as part of its work on the new Orion space capsule that eventually would take astronauts to the moon, according to Nasawatch.com as quoted by media report on Wednesday.

The need is voluminous: 30 liters a day, which translates into nearly 8 gallons. Even on weekends.

Designers of the Orion, which will park unoccupied in space for up to six months while astronauts work on the moon, have to solve a pressing issue of getting rid of stored urine, said John Lewis, NASA's head of life support systems for Orion.

"Urine is a mess because urine is full of solids," Lewis said. Those solids clog the venting system for dumping pee, so keeping the waste disposal system clear is "really a challenge," he said.

NASA has a long-standing tradition of collecting samples from its workers to help design better space toilets because "you can't make fake urine," Lewis said.

The Connecticut-based company building the Orion toilet needs the large volume of urine (about the daily output of 30 people) to work on urine acidity problems, said spokesman Leo Makowski. The memo seeking daily contributions from July 21 to July 31 was not meant to go public, he added.