Across:
   3. 30, they say, which may appear out of thin air? (3)
   8. Kerfuffle as university's public relations tool used in a row (6)
   9. Model student in pre-exam flurry (8)
  10. Plato and Socrates perhaps at layer one, and not quite second (9)
  11. Large Turner or such (4)
  12. Give credit to storing hydrogen in appropriate container? (5)
  13. Dates bold lunatic with impressive locks (9)
  17,4dn,18. Brave, hale, we push to moon... but change scheme with this announcement (7, 2 4 1 7)
  18. see 17
  21. Transformed Niven into a child of necessity (9)
  25,23. Loud radical has captured one, Earth's first lunar module pilot (4 5)
  27. 7's partner embracing male sweetheart who was in 20 of 6 28 (3 6)
  28. see 6 down
  29. Stinging insects get cross chasing one's kids perhaps (6)
  30. 3 said to be warranted (3)
Down:
   1. How 6 28 ended, with small whiplash after first three landed (10)
   2. 12s being interrupted by old major who played 27 (3 5)
   3. No one gets into this craft but medic and I (5)
   4. see 17 across
   5. Checks on return of battlers (4)
   6,28ac. Moved relation to help mission (6 8)
   7. Bowlers often try to get just as 'high' as this Mr Swigert on 6 28 (4)
  14. Dungeon, primarily refuge for the unilluminated (4)
  15. What 'they' might reflexively target? (10)
  16. Brag about abandoning second vessel (4)
  19. Worked hard at being cultivated despite carrying hangover? (8)
  20. Punctuation needed at both ends for instruction (7)
  22. Ultimately, live under, suffering (6)
  24. Method I've developed for 6 28 perhaps (5)
  26. Kaiser hurt containing uprising of Dortmund region (4)
  27. Euphoria welcoming Earth's first young passenger on bouncy but cosy ride (4)