Question: In 19th century texts on astronomy, the planets are often represented by [symbols](http://en.wikipedia.org/wiki/Astronomical_symbols): ☿ for Mercury, ♀ for Venus, etc..

Did NASA ever use these symbols, or were they already obsolete by then? If they did use them, I'd expect it to be very early on.

Answer: 
They have absolutely used these, in various mission badges:

This was the logo for the Mercury project:

![](https://history.nasa.gov/project_mercury.jpg)

Here's a patch from the Viking program:

[![](https://i.stack.imgur.com/fi1mO.jpg)](https://i.stack.imgur.com/fi1mO.jpg)  

(source: [colostate.edu](http://rammb.cira.colostate.edu/dev/hillger/Viking_mission-patch.jpg)) 

And one from Mariner 2, to Venus:

[![](https://www.spacecollection.info/patches/mariner_2_patch.jpg)](https://www.spacecollection.info/patches/mariner_2_patch.jpg)

None of these are for any sort of technical reason; I'm sure the symbols aren't used for anything important, but as a little bit of astronomical history, they're not completely forgotten, either.
In the astronomical literature and therefore by NASA, at least the Earth and Sun symbol are used by standard to denote parameters like radius, mass, luminosity of the Earth and the Sun. It is customary to denote $\rm R\_{\oplus}$, and $\rm R\_{\odot}$, whereas for Jupiter (probably as it is not implemented in standard latex) one nowadays usually uses $\rm R\_{J}$ or $\rm R\_{Jup}$.