Error analysis for apollo earth parking orbits using range rate and angle measurements
A. Marlow · NASA Technical Reports Server (NASA) · 1965
Parametric studies a r e made of RMS e r r o r s in position and velocity for an Apollo Earth Parking Orbit (launch azimuth go", height 200 km), using uncertainties in range rate of & O .l m/s and k0.03 m/s; and in angles of k2 X radians, and k2 x radians.radians, f 6 X Range rate and angles a r e measured every second by a tracking ship located at 26" 40' N and 49" 20' W in order to provide tracking during the time the spacecraft is inserted into the parking orbit.In order to compare the RMS e r r o r s in the state vector, two separate sets of e r r o r analyses are made which include and exclude the effects of an uncertainty in the tracking ship's location.For this study a total uncertainty in the tracking ship's location of approximately *450 meters was assumed, It was found thatwhen range rate and angles are measured, the angles a r e the dominant influence; i. e., that the position and velocity e r r o r s a r e approximately the same whether S t = *O.lm/s o r k0.03 m/s.For examp!<; with optimum tracking and an angular uncertainty of *2 X radians, the RMS e r r o r inposition is 144.2 meters when S i = *0.1 m/s and 143.8 meters when 8 : = f 0.03 m/s.Corresponding velocity e r r o r s a r e 0.821 m/s and 0.819 m/s.When the angular uncertainty is &Z x radians, the position e r r o r s a r e 16.6 meters and 14.7 meters and the velocity e r r o r s a r e 0.097 m/s and 0.084 m/s for the respective uncertainties in range rate.However, when station location e r r o r s a r e included, these become the dominant influence and even with a minimum amount of tracking, the RMS e r r o r s in position approach the level of the sta-11 tion location error.