NASA's InSight Mars lander is scheduled to touch down on the Red Planet tomorrow afternoon (Nov. 26), and mission team members and agency officials are understandably nervous about the make-or-break moment. … The difficulty for landed missions stems chiefly from the fact that Mars features both a relatively strong gravitational pull and a wispy atmosphere, which is just 1 percent as thick as that of Earth, said Tom Hoffman, InSight project manager at JPL. So, approaching spacecraft get accelerated to high speeds and then have a hard time dissipating enough energy to slow down before landing, he explained during today's...