Author: Thomas J. Wong

Publisher:

Published: 1961

Total Pages: 24

ISBN-13:

Entry corridors for manned vehicles returning from the moon are defined consistent with requirements for avoiding radiation exposure and for limiting values of peak deceleration. It was found that the use of lift increases the depth of the entry corridor and, hence, reduces guidance accuracy requirements. Mid-course guidance requirements appear to be critical only for the flight-path angle. Increasing the energy of the transfer orbit increases the required guidance for the flight-path angle. To correct a trajectory for an error in target perigee point, it was found that application of the corrective thrust essentially parallel to the local horizontal produces the maximum change in perigee altitude for a given increment of velocity. It was also found that the energy required to effect a given change in perigee altitude is not strongly dependent on the energy of the orbit, but it was found to vary inversely with range measured from the center of the earth. For this reason, it is important to detect and correct any errors in approach trajectory at the largest possible distance from the earth.