You can't.

You can't always fight nature, you cant fight gravity. No matter how many times you play Halo Reach you can't save them. Everyone has tried to or even believed they could, but you can't. You have to learn to let go, to learn to move on. The more you focus on the past the harder it will be to move forward and focus on the future. As much as I love these characters and love seeing them on screen. They will die in the end, its just nature. You can't have halo reach without the deaths of Noble Team, if you believe that Noble 6 survived in a hole somewhere, you are in denial. Even if he did survive, narrative speaking the whole game is to remember you and your team's sacrifices and if you live, you have to live with all of that death and guilt. Halsey's speech would mean nothing to the Noble 6 still alive living in a hole in the ground. Your body, your armor will always burn and turn to glass no matter how many skulls are on, how difficult it is, and no matter how many people try to help save reach. You can't.