Explanation:

The Low-Density Supersonic Decelerator or LDSD is a re-entry vehicle designed to test techniques for atmospheric entry on Mars. The disc-shaped LDSD uses an inflatable structure called the Supersonic Inflatable Aerodynamic Decelerator (SIAD), which is essentially an donut-shaped balloon, to create atmospheric drag in order to decelerate the vehicle before deploying a large supersonic parachute. The goal of the project is to develop a re-entry system capable of landing 2- to 3-ton payloads on Mars, as opposed to the 1-ton limit of the currently used systems.