When the spacecraft returns to the earth through the atmosphere, it will friction with the atmosphere and cause the temperature to rise sharply. In order for the spacecraft to safely return to the earth by overcoming the "thermal barrier", a foreign research institution made a new technical attempt on recovering the micro satellite EGG. During the descent, the hemispherical heat-insulation parachute formed by the expansion and expansion of carbon dioxide was opened, and then the atmospheric resistance it received increased significantly, and it slowly entered the atmosphere and fell smoothly. The premise of the above technology attempt is based on:. ['Spacecraft surface material needs to be able to withstand ultra-high temperature.', 'The cost of researching spacecraft heat-resistant materials is higher than the cost of a parachute.', 'Overheating when a spacecraft falls into the atmosphere is a common problem in the descent process.', 'Spacecraft entering Earth at a slower speed reduces friction-induced heat.']