A google search with "NASA" and the id usually works pretty well. Otherwise if you post images here you'l be sure to get answers
In order to sell the photos on eBay there's not really any need for you to work out what the image is. The buyers know what they're looking at.
What's most important is to be very clear about the watermark on the back - "A KODAK PAPER" and "THIS PAPER MANUFACTURED BY KODAK" are very different things - and the condition.
It's not always clear from a photo or scan if the surface of a photos has creases, half-moon dings, surface gloss loss, or discoloration/fading. This is information you should provide for each photo listed.
Make sure you allow international bids. Flat rate envelopes work well as long as you put in some serious protection against bending (a sandwich of heavy duty card or foamboard).
Finally, don't use a buy-it-now price or allow anyone to trick you into ending an auction early to sell direct. I know you know this already but it's always worth stating for the sake of others who might be thinking of selling for the first time.
If you start NASA photos at say $9.99 they'll all find their own price level.