NASA and the Italian Space Agency are planning to strip the Leonardo cargo module of unnecessary parts and beef up shielding to equip the barrel-shaped spacecraft for a permanent stay at the International Space Station.

File photo of the Leonardo module inside the space shuttle's payload bay. Credit: NASA

Leonardo will fly on the final space shuttle mission scheduled for launch Sept. 16 next year.

The reusable module has flown six times since 2001, delivering internal cargo, experiments and crew supplies to the complex on space shuttle missions. Leonardo is slated to fly once more on the shuttle Discovery in March before undergoing final outfitting for its new permanent role at the station.

The new module is called the Permanent Multipurpose Module, or PMM.

Engineers are modifying the module as part of an agreement with the Italian Space Agency, which provided the Leonardo, Raffaelo and Donatello logistics carriers to NASA.

The Multipurpose Logistics Modules are designed to ferry pressurized material to the station and return waste, experiment racks and failed equipment to Earth. The MPLMs are berthed to the complex for up to a week while the shuttle is docked, then returned to the payload bay for landing.

Officials decided to modify Leonardo to give the station more room for storage.

The modules measure about 21 feet long and 15 feet in diameter, weighing about 9,000 pounds empty.

Italian space officials could not provide a cost estimate on the changes, but NASA managers say they are only doing mandatory work to limit the price tag.

"We were (determined) that the only modifications we would make was to make it survivable on orbit," said Mike Suffredini, NASA's space station program manager. "What that essentially meant was we needed to beef the shielding up, so that it can stay on orbit longer and have the micro-meteorite protection."

Astronaut Don Pettit works inside Leonardo during a 2008 space shuttle mission. Credit: NASA

Dan Hartman, manager of space station integration and operations, said the PMM will probably be first attached to the space-facing, or zenith, port of the Harmony module.

That location would expose the PMM to a more hostile environment for space junk and micro-meteoroid impacts.

Suffredini said the PMM would likely be eventually moved to the Earth-facing port on the Unity module to reduce the impact threat.

Mission planners are attempting to fit as much equipment as possible inside the PMM for delivery to the station on the last shuttle flight.

Engineers will remove old components from Leonardo to free more space for extra cargo to keep the station operating after the shuttle's retirement.

"Way back when, we were planning to carry a bunch of refrigerators and freezers up, so there was a lot of plumbing, there were a lot of pumps involved, that we are going to strip out of this vehicle to give it more up mass capability," Hartman said.

NASA reportedly rejected an earlier European proposal to modify an MPLM for a permanent stay at the space station.

Suffredini said officials were concerned they would need to use an MPLM to return unneeded cargo from the station on the last shuttle flight.

"But our failure rates have been very positive, so we won't have enough failed ORU's (hardware) to justify a whole MPLM," Suffredini said. "That allows us to fly this one up and leave it on orbit and use it for storage. We'll get all the hardware down we need to without having to return a whole MPLM."