Very little indeed of what some returning astronauts anticipated? (1,4,2,3,5)
I believe the answer is:
a drop in the ocean
'very little indeed' is the definition.
(I've seen this before)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for a drop in the ocean that I've seen before include "result of walking the plank?" , "going with the tide?" , "Drink for a drifter" , "Certainly no effect of global warming" , "something insignificant" .)