During the entry, descent and landing of NASA’s Perseverance rover on Mars, teams referred to that phase as “7 minutes of terror.”
When asked how those in Mission Control think about Orion’s entry, descent and landing, which will take about 13 minutes, flight director Jeff Radigan said it’s “about an hour and a half of things that have to go right.”
He went down the checklist of what occurs during that crucial 90-minute window before splashdown, including separation of the service module from the crew capsule, the release of the forward bay cover, the subsequent releases of three different sets of parachutes, achieving the right touchdown angle and of course, the heat shield has to protect the astronauts during the blistering heat of reentry.
The service module includes the engines responsible for the burns that have kept the capsule moving along the right trajectory in space, and separation will expose the heat shield.
The release of the forward bay cover is simply a means to enable parachutes to deploy. First, drogue parachutes will release to begin slowing down Orion’s descent, followed by pilot parachutes that are responsible for unfurling the capsule’s three main parachutes that further reduce Orion’s speed from 130 to 17 miles per hour (about 200 to 30 kilometers per hour) before splashing down in the Pacific Ocean off the coast of San Diego.