NASA aborted an attempt to deploy a temporary habitat at the International Space Station after it failed to inflate to full size on Thursday.

The new room, known as the Bigelow Expandable Activity Module (BEAM), is part of an experiment to test expandable habitats astronauts might use on the Moon or Mars in the coming decades.

NASA astronaut Jeff Williams took charge of the inflation early Thursday in cooperation with mission control in Houston.

However, the module made little progress despite two hours of effort.

"Flight controllers informed NASA astronaut Jeff Williams that BEAM had only expanded a few inches in both length and diameter at the time the operation ceased for the day," the US space agency said in a statement.

Fully expanded, the module should reach a size of 13 feet long (four meters) by 10.5 feet (3.23 meters) wide.

NASA said it would not try again Friday, but would hold a news conference at 12 pm (1600 GMT) to discuss the problem.

"NASA and Bigelow Aerospace are working closely to understand why the module did not fully expand today as planned," a NASA spokeswoman said.

"Engineering teams will monitor the module overnight for structural changes that could result in either larger volume or lower internal pressure before meeting on Friday morning to discuss options moving forward."

The crew at the ISS is safe and "both BEAM and the space station are in a stable configuration," she added.

- First test -

The oblong habitat, developed by Bigelow Aerospace under an $18 million contract with NASA, is being tested in space for the first time.

Astronauts were scheduled to enter it for the first time on June 2, according to the initial timeline.

The plan called for the crew on board the space station to venture into the module several times a year to collect data from interior sensors -- particularly to see how well it protects people against radiation in space.

The inflation process may be better described as "unfolding" since it takes very little air to bring the pod to full size, experts said.

The space station crew was to expand BEAM by introducing a small amount of air from the orbiting lab via a manual valve on the BEAM bulkhead.

Only about 0.4 pounds per square inch (psi) was supposed to be needed to expand BEAM to its full shape.

Eight air tanks inside BEAM, once activated, were set to bring the pod to full pressure, requiring about 42 pounds of air to fully pressurize BEAM's internal volume of 565 cubic feet (16 cubic meters).

Expandable habitats' benefit lies in the little space they take up in spacecrafts' cargo holds while providing greater living and working space once inflated.

But key questions that remain to be answered include how well pods would protect people against solar radiation, space debris and the temperature extremes of space.