The chang’e-5 probe successfully landed at Siziwang Banner landing site in the early morning of December 17 in Xi’an. The TT & C center of Xi’an Satellite and all TT & C stations successfully implemented the TT & C mission of the probe’s return phase. < / P > < p > “find the target!” at about 1:00 on the 17th, an active TT & C station in the northern Tibetan Plateau with an altitude of 4500 meters quickly completed the target acquisition, and successfully implemented the telemetry data receiving of the return device and the uplink remote control task. < / P > < p > it is understood that the chang’e-5 spacecraft, which returns at the second cosmic speed, has to go through the black barrier twice to slow down the reentry speed as much as possible. For this reason, Xi’an Satellite TT & C Center for the first time set up an active TT & C field in the northern Tibet Plateau, which is in the trajectory of return trajectory, as the first station for the returner to fly over China, so as to complete the TT & C work within a very limited time after the first time of the returner out of the black barrier, and ensure the returner to return home smoothly. < p > < p > Wang Qing, director of an activity measurement and control station, said that more than four months ago, they completed the transfer of nearly 5000 kilometers of railway and highway from the hinterland of the Central Plains and arrived at the preset destination. At the same time, they broke the double records of the longest single transfer distance and the highest altitude in the mission area in more than 50 years since their establishment. < / P > < p > “recovery No.2 found target!” “Recovery four, find the target!” A few minutes later, the returner went out of the black barrier for the second time, and another TT & C unit in Siziwang Banner of Inner Mongolia took over the baton. < / P > < p > in this recovery mission, the TT & C unit is mainly responsible for the TT & C and key command sending after the second black barrier of chang’e-5, as well as providing the optical live recording task before and after the parachute opening. Through the unit’s optical theodolite, a bright spot with a long tail appeared in front of the operator. < / P > < p > at the same time, in the first command Hall of Xi’an Satellite TT & C center, technicians are rapidly calculating and predicting the landing point through the telemetry data of the returner from the TT & C unit, and accurately providing it to the land and air search and rescue units. < / P > < p > “since the returner has no downlink signal in the black barrier area, we can’t directly determine its target position, so we can only search and capture through the waiting point set in the early stage and the theoretical trajectory sent by the center. In order to capture the returner quickly and accurately, we strengthen the ability to capture the target at night by tracking the international space station, signal bombs and other targets, so as to ensure that the measurement and control task in the return phase is safe. ” Measurement and control technician Wang Yuxiang said.