One mile above the ground, explosive bolts will jettison the parachute and six retrorockets
will slow the craft to just 1.
Some of these inventions that didn't make the cut make sense to us today, such as the use of retrorockets
for heavy air-dropped cargo and vehicles.
As Columbia fired its retrorockets
at midmorning to pull itself out of orbit and re-enter the atmosphere, traffic was halted on the base.
As a commercially-viable spacecraft would have to be reusable, the design would also have to cram in a heat shield, retrorockets
and perhaps parachutes into the ten per cent of solid matter take-off weight.
Early visitors to Mars used retrorockets
for this maneuver.
Electrical problems near the end of the groundbreaking mission meant that he had to manually fire his retrorockets
and successfully steer the capsule through re-entry.
When Phoenix's robotic arm imaged the lander's footpads on the fifth day after landing, scientists discovered that the retrorockets
had exposed a flat layer of bright ice.
Every inch of the craft must be protected by a rigid aeroshell, which bears the brunt of the fastest portion of the descent before parachutes and retrorockets