[tsimionescu]

Basically, discovering DNA is sufficient but not necessary to discovering life.

And if we did find DNA (itself a monumental discovery), sequencing it would be the next most important bit of information we could want, since it might allow us to check if there is some relation to life on earth.

[sandpaper26]

But I guess my question is this: we're going to spend $XB to send a probe to a distant moon. Once it lands, we get to ask exactly two questions. Question one is confirm/deny organic life (the microscope). Why is question two's ability to provide a meaningful answer so contingent upon a very specific outcome of question one?

Is this a combo of a) the cost of the second question (i.e. the weight and size of sending the DNA sequencer) is fairly small, b) we're confident enough about question one that putting resources toward question two is worth the opportunity cost of asking a different question, or c) we have no other questions that we can reasonably ask for the same amount of resources?

[Aeronwen]

If you don't ask question two, there's no point in asking question one.

Unless they find the place teeming with life, which nobody expects, it's more likely that anything they find hitched a ride from Earth instead of originated on the planet. So if they're not willing to rule that possibility out, they'll just end up causing decades of speculation and conspiracy theories.