The plaque they sent on the Pioneer PROBE
had a drawing of a naked man and woman.
The Big Bang Theory Season 8, Episode 21
He helped launch the
New Horizons space PROBE.
The Big Bang Theory Season 12, Episode 5
Is this about the PROBE
he's working on without you?
The Big Bang Theory Season 8, Episode 21
And, of course, it's Gravity Probe B.
The Big Bang Theory Season 1, Episode 13
Voyager the space PROBE,
or Voyager the Star Trek TV show?
The Big Bang Theory Season 8, Episode 6