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Docking system agreement key to global space policy

Posted: October 20, 2010

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An agreement on a common docking interface for the International Space Station is pushing the program's partners closer to a global transportation policy, one that officials say is imperative for a collaborative exploration effort.

File photo of a space shuttle docked to the Harmony module on the International Space Station. Credit: NASA
The station's five partners agreed to technical standards for the docking and berthing mechanism during a Multilateral Coordination Board meeting Sept. 21, according to NASA and European Space Agency officials.

Representatives from the United States, Russia, Europe, Japan and Canada approved a document with the new standards, which will be compatible with future docking systems for space station and deep space exploration applications.

"The goal was to identify the requirements to create a standard interface to enable two different spacecraft to dock in space during future missions and operations," said Bill Gerstenmaier, MCB chair and NASA's associate administrator for space operations. "This standard will ease the development process for emerging international cooperative space missions and enable the possibility of international crew rescue missions."

Aboard the space station, the International Docking System Standard would permit visiting spacecraft to use any available port on the complex.

More refinements of the IDSS technical document are possible over the next few years. The system is capable of receiving propulsive dockings or robotic arm berthings.

NASA plans to launch two Common Docking Adapters to the space station in 2014 and 2016. Both docking systems will be carried to the outpost on H-2 Transfer Vehicles and bolted to the Harmony module at the forward end of the complex, according to NASA officials.

"We are trying to operate a standard docking system after the shuttle withdrawl on the U.S. segment of the station, and later on for exploration," said Marco Caporicci, chief of the human orbital transportation and re-entry division in ESA's human spaceflight directorate.

File photo of a Russian Progress resupply ship and its docking system. Credit: NASA
The new docking ports, called CDAs, will replace the station's Pressurized Mating Adapters used by visiting space shuttles.

Although future docking commercial and NASA vehicles will use the CDAs, NASA plans to keep the shuttle docking ports at the station for extra storage room.

NASA is developing the Low Impact Docking System, or LIDS, for next-generation exploration and crew rescue vehicles. The LIDS system will fly on the Orion spacecraft and commercial crew capsules later this decade, and the new CDA system will be able to receive those vehicles.

The LIDS design is not compatible with the station's existing androgynous docking system used by space shuttles.

The European Space Agency's International Berthing and Docking Mechanism will also meet the international standards agreed to last month.

"This is a good example how to proceed, not only for ISS but also exploration, because being able to have a standard interface (among) the five partners, it's never happened before," said Simonetta Di Pippo, ESA's director of human spaceflight.

ESA hopes to incorporate the IBDM on its next unmanned cargo freighters, either on new orders of the Automated Transfer Vehicle or a re-entry version named the ARV.

File photo ESA's Automated Transfer Vehicle approaching the space station. Credit: NASA
According to Caporicci, the common docking standard could enable ATV or ARV missions to dock with the U.S. segment of the station. The first set of European resupply craft use a Russian docking system and arrive at the Zvezda service module.

Jean-Jacques Dordain, ESA's director general, told reporters at the International Astronautical Congress in Prague that a viable global exploration strategy requires cooperation on transportation, beginning with a common docking interface.

Every space agency has its own launch vehicles and spacecraft with their own strengths and weaknesses, Dordain said.

"From there, can we find common interfaces? The fact that we have no common transportation policy means we have no common interface," Dordain said, highlighting the urgency of the new docking standard.