Docking made easier

Click for larger imager
The DCA passive docking ring prototype has been manufactured and is ready for integration with an APAS assembly.
The International Space Station (ISS) Common Docking Adapter (CDA) will host the next generation in advanced docking systems for human spaceflight.

“The CDA is part of a larger effort at NASA to develop a NASA Standard Docking System, compatible with the emerging International Docking System Standard (IDSS),” said Skip Hatfield, manager of the project. “This will enable any country using an IDSS-compatible system to dock together. Today, there is no single standard allowing this.”

The ISS will provide an ideal platform to demonstrate this new system and gain operational experience. Any vehicle docking to the United States On-orbit Segment (USOS) portion of station will use the system. This includes new commercial crew vehicles.

Presently on station, there are two Pressurized Mating Adapters hosting the Russian-developed Androgynous Peripheral Attach System (APAS). The APAS is a mechanically-based docking system that traces roots back to the Apollo-Soyuz Test Project, the first time spacecraft from two nations docked together in space. The system was adopted as the primary docking system for the shuttle-MIR missions, and more recently has been the shuttle docking system for all of the shuttle missions to ISS.

The CDA will be installed on the axial and radial ports of the ISS’s Node 2 module to provide a new docking interface for a wide variety of visiting vehicles.
The CDA will be installed on the axial and radial ports of the ISS’s Node 2 module to provide a new docking interface for a wide variety of visiting vehicles.
The new IDSS standard is designed to use advanced low impact technology to enable a wide variety of vehicles to dock together, from very light to much heavier vehicles with significantly lower docking loads than today’s systems.

A universal system

Instead of each country or user developing its own unique docking system, the CDA creates a universal method for attaching to the ISS. This is a more efficient approach. The current station International Partners are working jointly to agree on the IDSS, which will allow any spacecraft with an IDSS-compatible docking system to connect together in space.

Current progress and estimated completion

“The initial CDA will be launched to station aboard a Japanese HII Transfer Vehicle cargo in 2014,” Hatfield said. “The second CDA will follow in 2016. In parallel, the NASA Standard Docking System is being developed and qualified to allow use by multiple visiting vehicles.”

The CDA has three major components –passive docking interface, tunnel assembly and common berthing mechanism.

Stimulus dollars at work

Click for larger imager
The CDA has three major components, as shown in this picture.
With $15 million of funding from the American Recovery and Reinvestment Act of 2009, development of the CDA will be accelerated faster than original budget projections permitted. In addition, a prototype of the passive IDSS compatible docking interface is being assembled to help potential users understand the system and its requirements.

Benefits to present and future space travel

“The benefit of the CDA along with the new international docking system standard is the development of a new generation of low impact technology docking system, with far greater flexibility than previous systems,” Hatfield said. “And, as mentioned, this system will be a truly universal system allowing collaborative exploration beyond ISS.”

Having a common system will allow spacecraft from any participating country to dock together. This will also allow not only exchange of crew and cargo, but also the assembly of larger spacecraft on orbit.

Neesha Hosein
Johnson Space Center, Houston

NASA Home JSC Home

For questions, comments and requests
about JSC Features please contact Catherine Ragin Williams.

Curator: JSC PAO Web Team
Responsible NASA Official: Amiko Kauderer

Web Accessibility and Policy Notices

Updated: 06/03/2010