Originally Posted by N C More

I agree, we need to go to other planets and do a great deal more investigation before we reach any conclusion about the possibility of life having been in our solar system in the past.

However, some seem to sort of "put the proverbial cart before the horse" in this area. For example, Richard Hoagland uses questionable (very questionable) images that he says are evidence of artificial structures indicating past civilizations. This just isn't going to "cut it". Speculation about past life in our solar system is one thing, evidence of said, past life, is quite another thing.