Don't be distracted by the 1960 Mercury shown below. Reading about Irene Fischer (also here, and mentioned in this answer) and seeing the Fischer 1960 Mercury Ellipsoid turn up in tables of ellipsoid piqued my interest.

Question: What is the Fischer 1960 Mercury Ellipsoid, and why is it called that?

The other kind of 1960 Mercury, this particular specimen believe it or not came with factory AC and power windows! (click for larger)

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    $\begingroup$ Is this a spacecraft? I may be wrong, but in my humble opinion this is a roadcraft. $\endgroup$ – Uwe Nov 30 '17 at 10:49
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    $\begingroup$ See this online converter $\endgroup$ – Uwe Nov 30 '17 at 12:41
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    $\begingroup$ @mike better wait to see the answer before you jump to conclusions. Let's see... was anything else named Mercury in the 1960's? $\endgroup$ – uhoh Nov 30 '17 at 12:50
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    $\begingroup$ "An Earth spheroid employed operationally by NASA in the 1960s bore her name." lol, it was used in the Shuttle Mission Simulator until 2011. $\endgroup$ – Organic Marble Nov 30 '17 at 12:54
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    $\begingroup$ Googling "fischer ellipsoid mercury" (no quotes) yields several helpful links. It appears to be an approximation to the Earth geoid as @Julio says and the word "Mercury" refers to the Mercury missions. $\endgroup$ – user7073 Nov 30 '17 at 15:24

The U.S. Department of Defense (DOD) 1960 World Geodetic System was produced by Irene Fischer and published in 1960. Today they are commonly known as 1960 Fisher Ellipsoids, as they are called today, is a mapping of the shape of the Earth, published by Irene Fischer in 1960. This was the best unclassified ellipsoid available at the time. As a result, NASA used them for the Mercury project, which had it's first manned launch in 1961. Thus they gained the nickname "Mercury Datum".


  • $\begingroup$ There were other Ellipsoids before, for instance the Hayford Ellipsoid from 1924. It was recommended for international use. This ellipsoid should be unclassified to be used internationally. The Bessel Ellipsoid from 1841 fits well for Europe and Eurasia but its axes are too short by 700 m. This error may be a problem for satellites orbits. The Bessel Ellipsoid is still used for Austria, Switzerland and Germany. $\endgroup$ – Uwe Nov 30 '17 at 16:52
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    $\begingroup$ Fair, I should have said it was the best unclassified ellipsoid available. $\endgroup$ – PearsonArtPhoto Nov 30 '17 at 16:56
  • $\begingroup$ Bingo! Excellent links, thanks! I hope to get a hold of a copy of her book, quite a story. $\endgroup$ – uhoh Dec 1 '17 at 0:20
  • $\begingroup$ You may use a special search machine for used old books like BookFinder or JustBooks or find-more-books $\endgroup$ – Uwe Dec 3 '17 at 10:49

Wikipedia seems to suggest that the relationship was more than "This was the best unclassified ellipsoid available at the time. As a result, NASA used them..."

Fischer became one of two internationally known women scientists in the field of geodesy during the golden age of the Mercury and Apollo moon missions. Her Mercury Datum, or Fischer Ellipsoid 1960 and 1968, as well as her work on the lunar parallax, were instrumental in conducting these missions.

Since the Mercury and Apollo missions required accurate orbital calculations both around the Earth and to the moon, the geometrical relationships and accurate 3 dimensional vectors between locations on Earth — especially the tracking stations — was extremely important.

The use of satellite data in Geodesy was in its very earliest stages at this point obviously, but using satellite tracking to define positions on Earth was critical to subsequent use of those positions on Earth to track Mercury and Apollo spacecraft!

I'll expand on this answer later today; in the mean time this bibliography offers some clues.

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    $\begingroup$ Also the Gemini missions required accurate orbital calculations around the Earth, especially for the rendevous maneuvers tests. $\endgroup$ – Uwe Dec 3 '17 at 10:27

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