The radar evaluation pod was a bank of instruments used to test the rendezvous radar, a vital instrument because rendezvous was a vital goal for the whole Gemini program. Without rendezvous, Apollo couldn't go to the Moon.
For more on the Gemini radar evaluation pod, here's the latest article on Vintage Space.
For some amazing images taken by the Gemini 5 astronauts, check out this awesome gallery up on Vintage Space.
And for more on rendezvous and why this tricky manoeuvre, here's a look at the lunar orbit rendezvous decision.
And there's a lot more Vintage Space over on Popular Science.
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