Parachutes cannot open at 15000 feet on earth - the air pressure is not there. Why do they open at an air pressure equivalent of 120000 on Mars? And even if t

Parachutes cannot open at 15000 feet on earth - the air pressure is not there. Why do they open at an air pressure equivalent of 120000 on Mars? And even if they did open, they would only be able to carry a miniscule weight. You realise that in a pure vacuum, a feather drops as quickly as a ball bearing?