An Experiment Of Observing The Reentry Capsule SHENZHOU-7Using Weather Radar Network And Prediction Of Its Trajectory Deploying A Parachute Based On A Fine Wind Filed

The China Meteorological Administration conducted an experiment involving Weather Radar network monitoring the SHOUZHOU-7Reentry Capsule, high-resolution wind observation, analysis and prediction its trajectory deploying a parachute based on a fine wind field between21and28September2008over the Siziwangqi Ulan Qab League of the Inner Mongolian Autonomous Region.This paper tries to make a study on the Reentry Capsule of the SHENZHOU series of spacecraft in the reentry phase from the following three perspectives.Firstly, based on the actual measuring data of C-band radar, the article made a system analysis on the mechanism of the plasma stealth of reentry target. Various branches of knowledge were used in this article such as reentry physics, theory of propagation of electromagnetic wave, characteristics of radar target. The inevitability of temporary target loss during the tracing of reentry capsule under the centimeter wave radar detecting technology was illustrated. The integrated description of electromagnetic scattering characteristics of the Reentry Capsule during the whole reentering proces was presented.Secondly, An experiment of observing the reentry capsule SHENZHOU-7using weather radar network was studied. The algorithms for the fixed theoretical trajectory of the reentry capsule SHENZHOU-7and the monitoring parameter of the weather radars along the recovery line of spacecraft were studied. The monitoring parameters have been used to guild the radar operator to real-time monitor the reentry capsule SHENZHOU-7on September28,2008. After experiment, the trajectory was given by fitting analysis of the observation data of the weather radar was intercompared with the theorectical trajectory and the real observed from the Beijing Aeroplane Control Center. The experiment proved the partial weather radar stations are able to trace back and detect the SHENZHOU-7reentry capsule, this is an effective supplementary to our space tracking network. The algorithm and program in this paper accumulated value experience for observing the spacecraft using weather radars in the future, but also meet some problem in the experiment need to be further discussion, solving the problem how to detect the spacecraft in the blackout area, there are so many place need further study in the future.Finally, the characterization of the horizontal wind plays an important role in predicting the trajectory of the manned spacecraft SHENZHOU-7when employing a parachute was analyzed, an algorithm for tracking a spacecraft deploying a parachute is studied. High-resolution wind profiles obtained from a numerical weather model, upper-atmosphere soundings and mobile incoherent Doppler wind lidar are compared. Forward and backward trajectory predictions based on various wind profiles, as well as their differences, are presented. In addition, the trajectory of SHENZHOU-7is predicted using different wind profiles, and the predicted parachute-opening and landing points are compared with the observed points. Results indicate that a high-resolution numerical weather model and fine observation data can offer more-detailed wind information for the prediction of spacecraft trajectories and can thus help in the editing and sending of flight commands, consequently increasing the accuracy and reliability of landing on an assigned spot and reducing the search area and rescue time.