Engineering topics

Cesarone, R. J.

Publications and source records attributed to Cesarone, R. J..

22 records · Page 2

NASA NTRS1984

Prospects for the Voyager extra-planetary and interstellar mission

An advance study has been conducted to examine the trajectory characteristics of Voyager 1 and 2 as they depart from the solar system and traverse interstellar space. A survey of the extraplanetary phase, commencing with completion of the final planetary encounters and ceasing with loss of spacecraft communication, considers the trajectory aspects attendant to a heliospheric investigation and possible sensing of a trans-Neptunian massive body. An analysis of departure telecommunications capability attempts to bound the inevitable time of communication loss. A study of the interstellar phase examines closest approaches of the spacecraft to the sun's stellar neighbours. A covariance analysis is provided to illustrate the statistical effect of stellar state uncertainties on these approaches. In addition to the Voyager spacecraft, data for Pioneers 10 and 11 are provided where appropriate.

Cesarone, R. J.↗

NASA NTRS1982

Voyager 2 navigation to Uranus and Neptune

Key navigation issues and capabilities relating to the Voyager 2 Uranus/Neptune mission are presented. Predicted navigation performance at each encounter body (Uranus, Neptune, and Triton) is examined relative to mission navigation requirements and science return capabilities. Orbit determination accuracies are presented for several radio data types and for combinations of radio data with two optical data types. Maneuver strategies designed to accommodate the orbit determination results and satisfy mission navigation requirements are examined. Possible alternate aimpoints and contingency strategies are developed for situations of unexpected loss of propellant or optical navigation capability.

Van Allen, R. E.↗

NASA NTRS1982

Voyager 2 Uranus and Neptune targeting

Targeting strategies are developed for the Voyager 2 flybys of Uranus and Neptune/Triton. The need to maximize science return, conserve propellant, and maintain spacecraft safety presents a challenge, given the difficulty in estimating the spacecraft orbit relative to these outer planets. Expected propellant usage, science return, and targeting complexity are presented for each targeting strategy. For the dual encounter of Neptune and its satellite Triton, split targeting conditions are proposed to fix the most important conditions at each body, and thus minimize science losses resulting from Triton ephemeris uncertainties.

Gray, D. L.↗

NASA NTRS1980

Voyager 1 Saturn targeting strategy

A trajectory targeting strategy for the Voyager 1 Saturn encounter has been designed to accomodate predicted uncertainties in Titan's ephemeris while maximizing spacecraft safety and science return. The encounter is characterized by a close Titan flyby 18 hours prior to Saturn periapse. Retargeting of the nominal trajectory to account for late updates in Titan's estimated position can disperse the ascending node location, which is nominally situated at a radius of low expected particle density in Saturn's ring plane. The strategy utilizes a floating Titan impact vector magnitude to minimize this dispersion. Encounter trajectory characteristics and optimal tradeoffs are presented.

Cesarone, R. J.↗