X-37 can fly in the same orbit as ISS but can they dock?


2 Answers 2


Yes and no. The current X-37 as flown by the US Air Force is not equipped with any docking ports (PMA, CBM or APAS) as described by @geoffc, nor does it have an attachment for the SSRMS (aka Canadarm) to grab it.

However, Boeing, the manufacturer, have published designs that would permit it to be so equipped at some future time. These plans are described in detail in an article on nasaspaceflight.com. This was part of their COTS proposals. You can get the sense of how this would work from these illustrations:

X37 docking with ISS

X37 as crew transport

  • 6
    $\begingroup$ I stand by the "No" since this is vapour ware, never built hardware. :) $\endgroup$
    – geoffc
    Commented May 21, 2015 at 20:54
  • $\begingroup$ Wouldn't there be legal problems with X-37 docking to ISS? AFAIK, the ISS (contrary to its predecessor, the Mir space station) must not be used for any kind of military purposes and X-37 seems to be a military vehicle. $\endgroup$
    – user3049
    Commented May 22, 2015 at 6:25
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    $\begingroup$ @DmitriPisarenko is "resupplying the ISS" a military purpose? Is there a problem with NASA astronauts who are active duty USAF or USN being on board the ISS? $\endgroup$
    – user5932
    Commented May 22, 2015 at 13:40
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    $\begingroup$ @DmitriPisarenko The X-37 started as a civilian program before the USAF took over after NASA dropped it. There's nothing technical that would stop it from either returning to the white world entirely, or to build an additional X-37 for civilian use. Depending on the wording of the ISS treaties using the same craft for either civilian or military purposes on different launches may be possible. I know the space shuttle carried a number of military cargos before ISS construction started. space.stackexchange.com/a/1399/157 $\endgroup$ Commented May 22, 2015 at 13:58

The ISS has 3 basic docking port types.

  • 2 PMA's - used by Shuttle. With addition of LIDS adapter (coming on SpaceX CRS-7 in June 2015) the CST-100 and Dragon Crew will dock to it.
  • 2 CBM ports - HTV, Dragon Cargo, Cygnus, and ISS modules berth to these.
  • 4 APAS ports - Russian segment has 4 ports. ATV, Soyuz, and Progress use these.

You can see a description of these ports (US Segment on one answer, and Russian segment in the other) in Will the ISS need more docking ports?

Stealing an image from there that sort of shows many examples.

enter image description here

X-37B carries no ports compatible with these systems at this time. No doubt if there was serious demand something could be added. The variety of available ports make that a greater possibility. (The Russians apparently will sell you a Kurs rendezvous system if you want, that is how ATV docks)

But as of now, no.


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