Mitch Henderson works for NASA as Hermes Flight Director.

He was in charge of the well-being of the ARES 3 crew and wanted to tell the crew that Mark was alive but Vincent Kapoor and Teddy Sanders over-rode him.

After Rich Purnell pitched an idea to send the remaining crew back to Mars to save Mark, Teddy shot the idea down as he didn't want to risk the rest of the crew. Although never explicitly stated, it is heavily implied that he sent the crew an encrypted version of the Rich Purnell Maneuver and was asked to hand in his resignation for disobeying The Director and putting the crew in danger.