Person 1 has file A, which person 2 wants to download. Person 2 connects to person 1 and starts to download which makes person 1 a seeder. If person 1 has file A but doesn’t seed, person 2 can’t download file A since there is no seeder.
When you seed you make sure that others can download that same file, but yes, they establish a connection with you to download it. If I have understood it correctly.
Didn’t they discover water molecules on the moon a couple of years ago?