The reusable hauler of supplies to the International Space Station was delivered to the launch pad this morning, ready for shuttle Discovery to truck the cargo-laden module to the orbiting outpost next month.

Credit: Ben Cooper/Spaceflight Now

Known by its nickname Leonardo, or more formally as the Multi-Purpose Logistics Module, this cylindrical structure is packed with new equipment, science gear and provisions for the station.

Discovery's upcoming mission, slated for blastoff April 5 at 6:21 a.m. EDT (1021 GMT), will attach Leonardo onto the station so that the astronauts can unload what amounts to a space-age moving van.

And once the racks of hardware and bags of supplies are pulled from Leonardo, items either no longer needed on the space station or looking for a ride back to Earth will be stashed inside the module before it's returned to Discovery's payload bay for ferrying home.

Leonardo was moved out of Kennedy Space Center's Space Station Processing Facility last week tucked within a special transport canister shaped like the shuttle's 60-foot-long payload bay. After a layover at the rotation building, where the container was turned upright, the module reached pad 39A before dawn today.

Ground crews went to work hoisting the canister up the gantry to place the payload into the pad's cleanroom for its eventual insertion into the shuttle bay next Wednesday.

Clay Anderson, a former space station resident and now flying as a Discovery crew member, says Leonardo really is like a moving van.

"If people can use the analogy that we're moving stuff from one house to another, if you will, and it's our U-Haul, it's our cargo carrier," he said. "And instead of driving it into the driveway and opening the back and carrying all the stuff out, we do it a little differently and we bring it up in the space shuttle and hook it up to the bottom of the station."

The space station's arm will be used to hoist Leonardo out of the shuttle, maneuver it around and then mount the module to the Harmony connecting node's downward-facing port.

"Once it's plugged in, we hook it up, make sure it's airtight, open the door and go inside and start to transfer all that cargo," he said.

Discovery mission specialist Naoko Yamazaki, an astronaut from the Japan Aerospace Exploration Agency, serves as the "load master" during the flight to oversee the transfer of items from Leonardo.

"Load master seems to be a challenging job," she said in a pre-flight interview. "The transfer activities will take about more than 120 hours, so it is very challenging to orchestrate all the activities in order. Some hardware has constraints, so some hardware needs to be transferred in certain order and in a certain way. So I need to understand the hardware very well.

"It's like moving into a new house. Some items needs to be treated very carefully and some items need to be transferred in a certain order. I believe it will go well with all my great crew members' help."

File photo of Leonardo being lifted from the shuttle bay. Credit: NASA

The Italian-built module is packed with items large and small for the station, including a new crew sleeping compartment, a supercold laboratory freezer, an exercise machine, a window observation assembly, assorted experiment equipment and multiple racks holding bags of supplies.

The challenge facing Discovery's astronauts and their fellow crewmates from the Expedition 23 team living aboard the station is getting all the transfer work done during the week the shuttle is docked.

"It has to be removed in a certain amount of time and we have to get it to a place within the station where it's not in the way, and stowage is a big problem inside the station these days," Anderson said.

"Then we have to take all the stuff the station guys don't need any more and put it back, pack it securely so that we can bring it home. So the big activity of transferring, of bringing all that stuff on and taking all the stuff off, it may sound very simple but it has to be quite uniquely choreographed because we want to make sure that we don't forget anything."

The other members of Discovery's crew includes commander Alan Poindexter, pilot Jim Dutton and mission specialists Rick Mastracchio, Dotty Metcalf-Lindenburger and Stephanie Wilson.

Also along for the launch besides Leonardo in the payload bay is a bridge-like structure holding an ammonia coolant tank that Discovery's astronauts will spend three spacewalks swapping out with a depleted reservoir on the station's truss backbone. The ammonia is used in the station's thermal control system.

Assuming an on-time launch, Discovery will rendezvous and dock with the station on April 7 at 3:50 a.m. EDT. The following flight day is devoted to mounting Leonardo onto the Harmony node and opening up the hatchway, with attachment targeted for April 8 at about 12:15 a.m.

The mission's three spacewalks by Mastracchio and Anderson are slated to begin at 1:41 a.m. April 9, 2:16 a.m. April 11 and 3:11 a.m. April 13. The first excursion moves the new ammonia tank from the shuttle into a temporary holding spot on the station, the second EVA removes the depleted tank and installs the new one, and the third spacewalk stows the old tank in the shuttle bay for return to Earth. A handful of other odds and ends are included in the timelines for each of the 6.5-hour EVAs.

Leonardo will be closed up and then detached from the station around 8:45 a.m. April 15, and Discovery undocks from the outpost at 4:03 a.m. April 16.

Landing at the Kennedy Space Center is targeted for Sunday, April 18 at 8:38 a.m. EDT.

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