In this AP/WISN news item Air leak at International Space Station temporarily plugged by a thumb they show a file photo of German astronaut Alexander Gerst at the Baikonur cosmodrome, making what looks like a gesture with his two hands, possibly forming the letter "K".

Question: What does it mean? Are there many hand signals used on the ISS? Is there a standard reference for such?

Member of the International Space Station (ISS) expedition 56/57, German astronaut Alexander Gerst gestures as his space suit is tested in the Russian-leased Baikonur cosmodrome on June 6, 2018. SOURCE: Vyacheslav Oseledko/AFP/Getty Images

German astronaut Alexander Gerst

  • 2
    $\begingroup$ From another angle it might look like an A or triangle. Maybe, he's just in the middle of gesticulating $\endgroup$
    – Dragongeek
    Sep 3 '18 at 0:34
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    $\begingroup$ @Dragongeek I'm thinking "K" for OK perhaps"? $\endgroup$
    – uhoh
    Sep 3 '18 at 1:17
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    $\begingroup$ Well I can tell you what it's not: A common German gesture or American one. I don't think it's standard sign language either and all other photos I can find of Gerst gesturing are easy to identify and none are similar to this. Maybe it's K for Kosmonaut? $\endgroup$
    – Dragongeek
    Sep 3 '18 at 22:26
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    $\begingroup$ I am unaware of any ISS specific sign language. I can think of some gestures that could be used, for example, when someone takes the last piece of fresh fruit from a shipment. $\endgroup$ Mar 11 '19 at 12:21
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    $\begingroup$ There would be significant downsides to using two hands for any common signal gesture, so unless he happens to be signing, I suspect he's illustrating something. It looks to me like he's demonstrating a particular spatial attitude with his left hand with respect to two orthonormal reference axes indicated with his right hand, e.g., "so if this is our up and left, we're oriented like this..." $\endgroup$ Feb 22 at 5:26

Update: At this point I have reviewed the only video i can find of the time of his hand signal.

The point in time is when he is seated, awaiting his turn for the leak-check of his suit, (helmet and gloves will be fitted, hence his skull cap is ready, and his blue ventilation box is by his side).

His commander (Sergei Prokopyev) is undergoing the test, his other crew mate (Serena Aunon-Chancellor) will be after Gerst.

His seat is right at the back of the room, nearest the door he came in from, after suit fitting.

At great distance is the glass separator, in the middle of the room, with crew family & friends and press on the other side.

The crew can only talk verbally when they are closest to the glass screen (with the mic) after completing their leak check.

So during this time, if they want to communicate with their family & friends, they are using hand signs or other forms of non-verbal communication.

(Whilst waiting, Gerst also talks to his back up crew, and towards his family (and bearded friend) he gestures to his legs and also talks to support staff about his ventilator box)

  • and this is the point where Alexander makes the hand signal. (which is now off-screen)

So, it might really just be a gesture known only between himself and his family (and the bald chap with the beard who seems to be a close friend).

And.. it might be a reference pertaining to the surprise appearance to play along with Kraftwerk later on during the mission..

Video is here: preflightactivities


--> original answer (based on 2 news articles) follows:

ok, not with any real source other than this and a number of other bits of speculation:


which translated to:


which was referring to 2018 FIFA World Cup football match between his home country Germany and Mexico, which he then watched from the ISS.

...and then we get to my speculation:

He hails from Künzelsau, Baden-Württember in Germany, and in honor of his achievements and what he means for his home town he was made an Honorary Citizen of the city and an observatory was built in his name.


He received a Welcome Home party there after his second mission.

(Zurück in seiner Heimatstadt Künzelsau plant er schon seine nächste Mission: in drei Tagen zum Mond. Welcome-back-Party am 18. Mai 2019 mit Alexander Gerst in Künzelsau.)




He studied at Karlsruhe Institute of Technology, and unfurled and displayed a special KIT banner whilst on the ISS.


German electronic music group Kraftwerk, of which Alexander is a fan, had a lo-fi K as a logo early in their career, and Gerst made a surprise appearance from the ISS when Kraftwerk performed at a festival in Stuttgart in 2018.

After both Gerst and founding member Ralf Hutter addressed the crowd they then played a special duet version of the track 'Spacelab', for which Alexander had a tablet computer configured with virtual synthesizers on board.


I guess you can see where I went with this...


His other half's name starts with L though.. :/

(and doesn't seem to be a krautrock or gang sign either..)

  • 1
    $\begingroup$ Excellent, thank you for reviving this! My (significantly) older brother introduced me to Autobahn when it first came out, along something else that went along well with listening to it and was a fan for the following decade or two. But I didn't know about this ISS/ESA event until now. So being the SE junkie I've become, I've just asked Did Kraftwerk have a “lo-fi K” symbol on their early albums? If so, which ones, and what does it look like? $\endgroup$
    – uhoh
    Jun 22 at 14:19
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    $\begingroup$ I am thinking I could be wrong about the single k logo as I cannot find what I thought I saw, and I am beginning to think Kraftwerk never used just a k.. oops $\endgroup$ Jun 22 at 14:29
  • $\begingroup$ Okay thanks, we'll see how things go there. $\endgroup$
    – uhoh
    Jun 22 at 14:30
  • $\begingroup$ The article seems very irrelevant with respect to the image. It was written much later about something that took place 10 days after the image was taken... $\endgroup$
    – asdfex
    Jun 22 at 18:13
  • $\begingroup$ i did find a second article, about the same thing, only this time Gerst was watching the playback of the game on the ISS, and it included a 2nd photo taken at the same time as the one above, only not with the hand sign. Seems to have been a theme at the time. $\endgroup$ Jun 22 at 19:20

K might be short for Klaar ("Clear" in German) but:

It's the wrong way round from his perspective;

It's unlikely that the crew he is working with knows German - they are more likely to communicate in English than in Russian, but both are more likely than his mother-tongue.

If we had this as a video clip, I believe we would see him make an O shape immediatly beforehand.

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    $\begingroup$ Is this answer based on anything other than speculation? $\endgroup$ Mar 11 '19 at 17:04
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    $\begingroup$ "Clear" in German is "klar", but "OK" is much more commonly used in such a situation. But without a video of the context and the full gesture, this answer is just speculation. $\endgroup$
    – ahemmetter
    May 20 '19 at 11:35
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    $\begingroup$ Being the wrong way round from his perspective merely means he's signing to someone else. I've certainly worked in places where 'OK' was indicated by 'K' in chats etc. $\endgroup$
    – user21103
    Oct 25 '20 at 13:10
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    $\begingroup$ The common signal for 'OK' is just a circle formed by thumb and index finger (i.e. the 'O' part) - originally used by divers but now virtually universal. I don't see why he would go out of his way to make a 'K' as well (or instead of). $\endgroup$
    – GordonD
    Jun 22 at 8:39
  • $\begingroup$ in the video he is sat at the back from the glass, at this point awaiting his leak-check. He is at great distance form the glass, and so can only communicate to family with hand signals. Clearly his mother is on the other side of the glass and perhaps his sister. Everyone else is either for the other crew or press. $\endgroup$ Jun 23 at 8:31

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