NASA Docking System

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NASA Docking System (Passive on the left, active on the right) before 11/13/2012
IDAs shown connected to PMA-2 and PMA-3 on the Harmony node

The NASA Docking System (NDS) is a spacecraft docking and berthing mechanism developed by NASA for future US space exploration vehicles, such as the Orion Multi-Purpose Crew Vehicle and the Commercial Crew vehicles. The NDS was to be NASA’s implementation of the International Docking System Standard (IDSS), an attempt by the ISS Multilateral Coordination Board (MCB) to create an international docking standard. NDS was also known as the (international) Low Impact Docking System (iLIDS or LIDS).[1] In 2012 NASA chose to adopt an alternative design sourced from Boeing over the iLIDS NDS design.[2]

The NDS docking mechanism is androgynous, the first system to use low impact technology and the first system to allow both docking and berthing.[3] It supports both autonomous and piloted dockings and features pyrotechnics for contingency undocking. Once mated the NDS interface can transfer power, data, commands, air, communication and in future implementations will be able to transfer water, fuel, oxidiser and pressurant as well. The passage for crew and cargo transfer has a diameter of 685 millimetres (27.0 in), which can be increased to 813 millimetres (32.0 in) by removing the petals of the capture mechanism after mating.[1]

In form and function NDS bears some resemblance to the Androgynous Peripheral Attach System (APAS-95) mechanism already in use on the Pressurized Mating Adapter (PMA) attached to the International Space Station, but is not compatible with it so International Docking Adapters (IDA) will be attached to the PMAs, one at Node-2 forward, the other at Node-2 zenith.[4] They are scheduled to be delivered to ISS by Dragon on separate Commercial Resupply Services missions in 2015.[5]

The mechanism is covered by US patent 6354540,[6] titled "Androgynous, Reconfigurable Closed Loop Feedback Controlled Low Impact Docking System With Load Sensing Electromagnetic Capture Ring."


Johnson Space Center began development in 1996, then it was known as the Advanced Docking Berthing System[7] and eventually the X-38 Low-Impact Docking System.[8][9] The X-38 was canceled in 2002, development of the mating system continued but its future was unknown. In 2004 George Bush announced his Vision for Space Exploration and NASA's 2005 Exploration Systems Architecture Study was created in response, recommended to use the Low Impact Docking System (LIDS) on the Crew Exploration Vehicle and all applicable future exploration elements.[10] The Hubble Space Telescope received the Soft-Capture Mechanism (SCM) on STS-125. The SCM is meant for unpressurized docking, but uses the LIDS interface to reserve the possibility of an Multi-Purpose Crew Vehicle docked mission. The docking ring is mounted on Hubble's aft bulkhead. It will be used for safely de-orbiting Hubble at the end of its service lifetime.[11]

In February 2010 the LIDS program became modified to be compliant with the IDSS and became known as the international Low Impact Docking System (iLIDS) or simply the NASA Docking System (NDS).[3] In May 2011, the NDS critical design review was completed and qualification is expected to be completed by late 2013.[4]

An internal memo dated on November 13, 2012,[12] announced to the development team that NASA had decided to retire and archive the design, instead contracting Boeing to develop their narrow ring design, SIMAC. According to this memo, work is not to be immediately shutdown, but current work was going to be finished and the documentation cleaned up and finished for archiving. Apparently, iLIDS was not the optimal design for the ISS, but NASA decided to keep the design, or the developed technology, as an option for the future. Under the Request of Proposals for the Commercial Crew Transportation Capability (CCtCap) NASA bought 5 docking systems, one of which is to be fitted to the ISS.[13]:p. 8


Bigelow Aerospace has expressed interest in licensing the LIDS technology from NASA for its space station technology development program. As of 2007 Bigelow was planning to equip its Sundancer and BA-330 expandable space modules with both a Soyuz-style docking system on one end and the NASA-standard Low Impact Docking System on the other.[14] During the summer of 2011, news had been made available that Bigelow was considering to use NDS on their modules.[15]


  1. ^ a b Parma, George (2011-05-20). "Overview of the NASA Docking System and the International Docking System Standard". NASA. Retrieved 11 April 2012. 
  2. ^ NASA Decides to Adopt Boeing SIMAC Design for Docking and Is Retiring the iLIDS Design
  3. ^ a b NASA Docking System (NDS) Technical Integration Meeting (2010-11-17)
  4. ^ a b Bayt, Rob (2011-07-26). "Commercial Crew Program: Key Drving Requirments Walkthrough". NASA. Retrieved 27 July 2011. 
  5. ^ "Dragon C2, CRS-1,... CRS-12". Gunter's Space Page. Retrieved 2014-01-17. 
  6. ^ US 6354540 
  7. ^ Low Impact Docking System (2009-02)
  8. ^ Advanced Docking/Berthing System - NASA Seal Workshop (2004-11-04)
  9. ^ Advanced Docking Berthing System
  10. ^ NASA's Exploration Systems Architecture Study - 5.3.4 Docking Mechanism/ISS Docking Module Trades (November 2005)
  11. ^ NASA (2008). "The Soft Capture and Rendezvous System". NASA. Retrieved May 22, 2009. 
  12. ^ Johnson Space Center (2012-11-13). "NASA Decides to Adopt Boeing SIMAC Design for Docking and Is Retiring the iLIDS Design". SpaceRef. Retrieved 15 November 2012. 
  13. ^ "NASA Commercial Crew Transportation Capability Contract CCTCAP Draft RFP". SpaceREF. July 19, 2013. Retrieved July 22, 2013. 
  14. ^ Covault, Craig (2007-04-08). "Bigelow Reveals Business Plan". Aviation Week. Retrieved 2010-07-20. "equipped with a Soyuz type docking system at one end and a new NASA developed advanced lightweight Low Impact Docking System on the other end" 
  15. ^ John Cook, Valery Aksamentov, Thomas Hoffman, and Wes Bruner (2011-09-02). "ISS Interface Mechanisms and their Heritage". The Boeing Company. Retrieved 6 September 2011. "The mechanism to be used for the interface between the CST-100 and the Bigelow module was originally an APAS, but the NDS platform is also consideration due to its implementation as part of the International Docking System Standard (IDSS)" 

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