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Burkhart, P.

Publications and source records attributed to Burkhart, P..

10 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

The Strategy for the Second Phase of Aerobraking Mars Global Surveyor

This paper focuses on and describes the strategy developed for the second phase of aerobraking MGS. This description includes the baseline aerobraking flight profile and the key trajectory metrics that were monitored in order to successfully guide the spacecraft to its desired mapping orbit.

aerobraking↗
NASA NTRS1999

Navigating Mars Global Surveyor Through the Martian Atmosphere: Aerobraking 2

The Mars Global Surveyor (MGS) spacecraft was successfully inserted into an elliptical orbit around Mars on 9/12/97, 01:53:49 UTC. This orbit was near polar (inclination=93.26 deg) with an orbital period of 44.993 hours and apoapsis and periapsis altitudes of 54,025.9 km and 262.9 km respectively. After 201 orbits and 196 days after Mars orbit insertion, the first phase of aerobraking (AB), called AB 1, has ended; after the AB 1 termination maneuver, the orbital period was 11.64 hours with apoapsis and periapsis altitudes of 17,870.3 and 170.7 Ian respectively. Thereafter, MGS was in a science phasing orbit (SPO) and acquired data from the science instruments from 3/28/98 to 9/22/98 (orbits 202 through 572). The second phase of aerobraking (AB2) began on 9/23/98 with the first descent into the atmosphere on P574 and ended with the aerobraking termination maneuver (ABX) on 2/4/99 on A 1284. Just prior to ABX, the apoapsis and periapsis altitudes were 456.5 km and 116.7 km respectively with an orbit period of 1.973 hours, a local mean solar time (LMST) at the descending node of 2 hours, 3.6 minutes and an inclination of 92.9 degrees. AB was responsible for circularization of the MGS orbit. However, two additional orbital conditions had to be satisfied simultaneously. These were a) complete AB2 when the LMST at the descending node was close to 2:00 am and b) the inclination was at 93.0 degrees. This paper describes the navigation of MGS throughout AB2; a companion paper describes the strategy and plan for aerobraking. Navigation challenges involved: a) the estimation of an atmospheric density model for every drag pass or periapsis-passage by analyzing doppler tracking data, b) the generation of a short-term, that is over one to several orbits, accurate atmospheric density predictions, c) maintaining the spacecraft's orbit within upper and lower bounds of atmospheric density or dynamic pressure during each periapsis-passage, and d) the prediction of accurate periapsis-passage times (Tp) over one to fifteen orbits. The density estimation and analysis procedure, evaluation of almost 700 atmospheric densities throughout AB2, the variation and accuracy of density predictions, the Tp prediction accuracy and how effectively we terminated AB2 are the basis of this paper and shall be presented in detail. A summary overview of AB2 is given.

Esposito, P.↗
NASA NTRS1998

Navigation and Guidance for the Mars Surveyor 1998 Mission

Mars surveyor 98 is part of NASA's Mar Surveyor Program, a scientifically aggressive but tightly cost-constrained program of robotic Mars exploration, with the goal of sending two spacecraft to Mars every two years form 1997 to 2006.

navigation↗
NASA NTRS1998

Navigation and Guidance for the Mars Surveyor 1998 Mission

In December, 1998 and January 1999 NASA will launch two spacecraft to Mars as part of the overall Mars Exploration Program managed at JPL. One is an orbiter that will arrive at Mars in October of 1999 carrying a science payload for remote sensing.

navigation↗