Debbie Hahn, Mission Payload Manager

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Debbie Hahn, Mission Payload Manager
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George Diller: With more than 30 successful launches already under her belt, NASA's Space Shuttle Discovery once again graces Launch Pad 39B at the Kennedy Space Center in Florida.

Poised for liftoff in December, Discovery will carry seven astronauts who will continue building the International Space Station during STS-116.

Three spacewalks will be needed to deliver and install critical hardware and help rewire the station.

STS-116 payload Mission Manager Debbie Hahn explains more about what is packed inside Discovery's payload bay and how those payloads will be used.

Hahn: STS-116 is composed of three primary payloads: the P5 truss segment, the SPACEHAB single logistics module and the integrated cargo carrier with the service module debris panels and the DOD space transportation program deployable experiments. P5 will be used as a spacer, or a bridge, between large solar arrays. It will also allow for reconfiguration of the power and cooling systems.

The SPACEHAB logistics single module is a pressurized carrier. It provides approximately 1,100 cubic feet of volume for transportation of supplies, hardware and experiments to and from the International Space Station. Some of the hardware items stowed in the module on STS-116 for subsequent transfer to the space station are a video base ban signal processor, a rotary joint motor controller assembly, and an external TV camera group, and most importantly, some additional hardware of the oxygen generation system.

Diller: After Discovery undocks from the International Space Station, the crew will deploy three small satellites.

Hahn: Pico-satellites are very tiny, coffee-cup-sized satellites. The three deployable pico-satellites are the atmospheric neutral density experiment, called ANDE, the radar fence transponder, called RAFT, and the micro-electro-mechanical system pico-satellite inspector, called MEPSI. They are installed on the integrated cargo carrier in bay 13 of the shuttle. While undocked from the International Space Station, RAFT and MEPSI are planned to be deployed on flight day 10, and ANDE will be deployed on flight day 12. Diller: During the mission, racks of experiments, flight hardware, spacewalk equipment and supplies will be transferred from the SPACEHAB module to the station as needed.

Discovery's last payloads were carried inside a Multipurpose Logistics Module, or MPLM, but as Debbie explains, the MPLM is different than the SPACEHAB.

Hahn: The multi-purpose logistics module, MPLM, and the SPACEHAB perform a similar resupply function to the International Space Station. The MPLM is actually removed from the orbiter payload bay and attached to the station instead of staying in the payload bay, as SPACEHAB does.

Diller: Three spacewalks are scheduled for this mission in part, to rewire the station. But does this mean the space station will get a new electrical system?

Hahn: Well, it's not really a new electrical system. It's a reconfiguration of the power system from the space station early power configuration to the beginning of the final assembly complete power configuration. The successful addition of the P5 integrated truss segment is key to making all this happen. The overall configuration of the space station power system is quite complicated, and consists of power generation, energy storage, power management and power distribution equipment.

Diller: It takes teamwork from across NASA to prepare the payloads for flight. Once they are packed and ready to go, they must also be loaded into the space shuttle. We asked Debbie how it all happens...

Hahn: After the space shuttle arrives at the launch pad, the rotating service structure is moved into place around the orbiter payload bay. The payload changeout room is the major feature of the rotating structure. Clean-air purges and specially designed seals help ensure that the payloads being transferred from the payload canister into the payload changeout room are not exposed to the open air.

Prior to the arrival of the space shuttle at the pad, the payload is delivered to the payload changeout room by the payload canister. The payload is transferred from the payload canister into the payload grand handling mechanism, which is a large handling fixture in the payload changeout room. Hooks configured on the payload ground handling mechanism hold the payload by the same trunnions that will hold the payload in the space shuttle.

When the transfer of the payload to the orbiter payload bay occurs, the payload ground handling mechanism translates forward along the floor of the payload changeout room and the load of the payload trunnions is transferred from the hooks on the payload ground handling mechanism to the payload retention latches on the orbiter payload bay.

Diller: And, now that the SPACEHAB, the P5 truss and the deployable experiments are tucked inside Discovery's payload bay at the launch pad, it's time to wait and see the majestic launch of Space Shuttle Discovery as NASA continues constructing the International Space Station.

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