ACuriousMind has given a good answer to your question in general.
To address your proposed question specifically, searching the tag gravitational-waves for "detect" brings up this poor question and this better question among about four hundred others. The question as you describe it here sounds like an exact duplicate of the first, but a helpful flagger might link it to another more comprehensive question like the second.
For what it's worth, repeatedly asking "would such-and-such a question be on-topic?" is not really a good use of Meta. It's worked out for you twice now, but a better long-term strategy is for you to spend more time reading good questions on the subjects that interest you.