What is the difference between two sentence below?

[blueisthebest]

"It would have been removed from Mars when an asteroid struck the planet."
"It was removed from Mars when an asteroid struck the planet."

Thank you in advance.

 

[billmcd]

"It would have been removed from Mars when an asteroid struck the planet." It wasn't removed, but would have been if an asteroid had struck. But I don't like the choice of words. "Removed"suggests that it was taken from Mars and placed somewhere else. I don't visualize/understand how that could happen in that situation. Also, I would replace "when" with "if". It fits better with "would".
"It was removed from Mars when an asteroid struck the planet." OK except for "removed".

Thank you in advance.

b.

 

[Tdol]

The first could be used to make an assumption about how it was removed, BrE at least.

 

[blueisthebest]

Thank you two.