Aero shell protects the system during the voyage in space and from the heat during landing due to friction of the atmosphere . The aero shell, together with the lander and the rover, forms the entry vehicle.
The aero shell consists of:
The heat shield
The back shell
The heat shield is used to protect the craft from the intense heat during landing and slows down the craft.
The back shell carries a parachute, the back shell electronics and batteries, a Litton LN-200 Inertial Measurement Unit (IMU), three large solid rocket motors called RAD rockets and three small solid rockets called TIRS.
A parachute is used to reduce the speed of the rocket. (See parachutes)
The back shell electronics and batteries fire off pyrotechnic devices like separation nuts, rockets and the parachute motor.
The Litton LN-200 Inertial Measurement Unit (IMU) is a device that monitors and reports the orientation of the back shell as it swings under the parachute.
The Rocket Assisted Descent motors assist the parachutes in reducing the speed of the spacecraft.