Does anyone have knowledge of the name of the"weird" sound effect instrument used in the theme song and also used for Martin's levitation finger? I'm wondering if it was the Ondes Martenot which was the first electronic keyboard invented in 1928!

Here is the information which is featured on my website:

According to the book "TV’s Biggest Hits" (Schirmer Books, 1996), a musical instrument, a combination of a thermin and ondes martinet was used to provide the sounds which accompanied the Martian's antennae rising or when he used his levitation powers. This same instrument's sounds were incorporated into parts of George Greeley's musical scores as well.

Hope this helps.
Jh harison

My MFM website has a page on the history of the series:

http://members.tripod.com/~jhh_2/HISTORY.htm