The utility model discloses a semi -rigid machinery expandes to get into speed reduction landing gear belongs to the spacecraft and gets into and return the field. Prevent heat exchanger mechanism including main part, control ring, rigidity nose corn, the semi -rigid heat exchanger of preventing, the semi -rigid heat exchanger control mechanism of preventing and flexibility, the main part links firmly with the control ring, is connected actuating mechanism between control ring and the rigidity nose corn, and actuating mechanism control encircles and relative motion is made to the rigidity nose corn, the semi -rigid heat exchanger of preventing covers and to install on the semi -rigid heat exchanger control mechanism of preventing, semi -rigidly prevents that heat exchanger control mechanism is articulated mutually with main part and rigidity nose corn respectively, the semi -rigid heat exchanger's of preventing of control expansion or draw in in, the semi -rigid heat exchanger's of preventing outside edge is equipped with can prevent heat exchanger mechanism to the flexibility that outside secondary launched. The utility model discloses the whole area after the expansion is greater than developed area one time, and keeps less volume under drawing the transmission shape attitude in, has improved taking in of device and has compared, has improved pneumatic face speed reduction effect, has reduced the system complexity, has realized that the two -stage is slowed down and the organic unity of landing buffering.