This answer begins with:

It appears to have actually been a pole, not a cord.

Handrails and handholds, colored blue for quick identification, were located throughout Skylab.


In computer graphics choosing good colormaps is a thing, and Project Seaborn (also here) addresses this issue in a way that is also more inclusive to people with various kinds of color blindness.

The crewed spaceflight experience can be punctuated by critical moments where one needs to be able to access and absorb a lot of disparate pieces of information quickly, and color-coding can be extremely useful.

Color coding is also useful in warnings and reminders, e.g. "don't touch this unless you mean to".

So I would like to ask:

  • Has color blindness been an excluding factor for astronauts in the past?

  • What about currently for crews bound for space stations?

  • What about passengers for space tourism?

There seems to be some unofficial, non-diagnostic tests (for those interested in learning about the topic) available at https://www.color-blindness.com/color-blindness-tests/

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  • 1
    $\begingroup$ I used to share a flat with a guy who did wiring on new build nuclear submarines. He was colour blind. There are workarounds and checks :-) $\endgroup$
    – Rory Alsop
    Dec 15, 2021 at 18:38

3 Answers 3


Yes, there has been at least one color blind astronaut. Astronaut pilots cannot be color blind, but some color blindness is permitted with mission specialists.

Roger Crouch is one such example, he flew on STS-83 and STS-94. There's a short article on it on NASA's web site.

I don't know what kind of color blindness he has, I suspect if you have red/green color blindness it's still a no go.

  • $\begingroup$ Thank you for the data point; yes color blindness comes in a variety of "flavors". $\endgroup$
    – uhoh
    May 5, 2019 at 23:20
  • $\begingroup$ Note he was a payload specialist. $\endgroup$ May 7, 2020 at 0:50

No. I can't find a NASA source, but I can find one from the Canadian Space Agency, whose astronauts have to ride on NASA missions and therefore would meet the same requirements. It specifically states "Applicants must not be colour blind"source.

  • $\begingroup$ I do have a hunch that this could be the correct answer, but remember that half of the ISS is not NASA, and there are also other space stations and space agencies as well. $\endgroup$
    – uhoh
    May 5, 2019 at 12:13
  • 3
    $\begingroup$ There is no evidence that color blindness would be exclusionary for space tourism astronauts (third bullet in question). As long as they can pony up the cash. $\endgroup$ May 5, 2019 at 13:06
  • 1
    $\begingroup$ What a bummer! I have read that as many as 12% of peoole have red-green color-blindness. Sadly, +1. $\endgroup$ May 5, 2019 at 16:34

Yes. There has been at least one color blind pilot astronaut.

“Color Blindness” covers such a wide range of conditions, the term is almost useless. It would be counterproductive to disqualify all astronaut candidates with a detectable color defect. But it would be unwise not to accurately assess for significant defects.

At one end of the “Color Blindness” spectrum is a very rare condition called Achromatopsia (complete absence of color receptors in the eye). Those affected not only have no color sensation, but are severely disabled by normal daylight levels of light.

At the other end of the spectrum are Anomalous Trichromats (one or more color pigments with anomalous absorption spectra). They may be unaware they have abnormal color vision but the deficiency can be detected with specialized testing.

In-between are Dichromats who have two color pigments instead of the normal three. They may be unaware of their color vision deficiency and usually manage well using other clues. For instance, traffic lights are always arranged with the red light on top, a feature which many normally-sighted drivers have never consciously noted. If these people are presented with a colored light in the absence of other clues (such as a red or green navigation light), they may have significant difficulties.

Since there is no one-size-fits-all definition for “color blindness”, astronaut candidates should be tested for the level of color vision performance required for the specific job, as we do for visual acuity. Aviation pilots, mariners and railway engineers need to correctly identify the color of small, dim lights at distance. The appropriate test for this is Farnsworth Lantern Test. The familiar Ishihara Plate Test (which presents numbers made up of dots), works well for screening since most people are familiar with the appearance. Detailed testing for subtle defects requires a Farnsworth-100 test or Anomaloscope or computerized equivalents.

Daniel Brandenstein was Chief of the Astronaut Office 1987-92. He flew 4 space flights, including flights as a pilot astronaut. He failed the Farsworth in 1987. According to http://www.sotos.com/writings/deutan_mission_specialists.pdf he was “severely color deficient”, a fact that was widely known and the source of jokes in the Astronaut's Office. Other astronauts presented him with a black and white photograph titled "The World as Dan Sees It".

So, to answer the title question, yes, there can be colorblind astronauts.

  • 2
    $\begingroup$ @uhoh With the edit I think the answer is now relevant and a partial answer to the question. $\endgroup$
    – Ludo
    Dec 14, 2021 at 16:28
  • 1
    $\begingroup$ @Ludo thanks for the heads-up! I hadn't followed the question so didn't know there had been an edit. $\endgroup$
    – uhoh
    Dec 14, 2021 at 20:07
  • $\begingroup$ "Hauck said the allegation that Brandenstein is colorblind is ″absurd.″" apnews.com/article/ef16519b20a41a3a2b436c74cbbd2732 $\endgroup$ Aug 17, 2022 at 17:13

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