Cryptic crossword No 3,129

Great theme. Took me until the penultimate answer to twig - and it was staring me in the face all along ;-) 3d and 28a new to me. Of course 11a can be made with one (or both) of the themes.... Big fan of themed crosswords, especially when theme isn't signposted (well, other than the cryptic picture in this case). I once tried reading Green Mars, but it wasn't to my taste. And kudos on 8d - brilliant clue. (I've only just now realised 17d is another one.... might be a few more I'm unaware of)

Fabulous work Dave, loved it. Some really smooth surfaces too. My favourites: 9a, 12a, 16a, 21a, 14d and 19d. Thanks!