Crew Dragon (without a crew) just docked to the ISS for the first time last night. Most of the news reports on it are using the below photo. I thought it was supposed to dock to the Harmony module's International Docking Adapter, but this picture doesn't look at all how I would expect if that were the case. In the photo, Dragon appears to be about to dock to a structure with two large converging cylindrical booms. What is that structure?

Dragon docking


1 Answer 1


User DarkDust provided this explanation and video link:

As you can see in the video of the approach at about 08:00 this structure is appearing. It's in the foreground, Dragon is moving towards the forward port of the Harmony module which is outside the viewport of this camera and would be somewhere on the lower right.

Ignore the position of the horizon in the next two pictures. Also, the Crew Dragon rendering in the software is not very detailed as of yet.

This picture shows the line of sight in the video (from the high-def camera mounted at CP8).

enter image description here

This is a re-created image of the one in the question. It is looking along the line of sight drawn in red on the picture above.

enter image description here

The structure in the field of view is the elbow joint of the JEM RMS (the Japanese Experiment Module robot arm). You can tell which robotic arm joint it is by the handrail and the roller-bearing-like latch striker on the elbow.

The module at the right of the image in the question and the re-creation is the Japanese experiment logistics module pressurized section (ELM-PS).

Here is the elbow joint of the JEMRMS and shuttle arm. The ELM-PS is at the top left of this image.

enter image description here

Here is the SSRMS elbow joint.

enter image description here

Cropped from NASA pictures 1 and 2

  • 1
    $\begingroup$ Oh, nice find! I've removed my answer but I think the video of the approach is still worth mentioning since it's showing that the Dragon module is passing behind the structure (starting at about 08:00). $\endgroup$
    – DarkDust
    Mar 3, 2019 at 17:09
  • $\begingroup$ excellent chart brut! $\endgroup$
    – tedder42
    Mar 6, 2019 at 20:32

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