Parafoil

A parafoil is a triangular parachute in the shape of an airfoil, which is similar to the shape of airplane or glider wings. Spartan-IIs on descent from low-orbit may use them to land safely on the planet's surface instead of using HEVs.

Operation
The parafoils are most likely made from extremely strong materials, as it would take more durable materials to hold over 1,000 pounds of armor and soldier in the air.