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  • 1
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    Orbit Determination Accuracy Analysis of the Magnetospheric Multiscale Mission During Perigee Raise (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Goddard Space Flight Center (GSFC) Flight Dynamics Facility (FDF) will provide orbit determination and prediction support for the Magnetospheric Multiscale (MMS) mission during the mission's commissioning period. The spacecraft will launch into a highly elliptical Earth orbit in 2015. Starting approximately four days after launch, a series of five large perigee-raising maneuvers will be executed near apogee on a nearly every-other-orbit cadence. This perigee-raise operations concept requires a high-accuracy estimate of the orbital state within one orbit following the maneuver for performance evaluation and a high-accuracy orbit prediction to correctly plan and execute the next maneuver in the sequence. During early mission design, a linear covariance analysis method was used to study orbit determination and prediction accuracy for this perigee-raising campaign. This paper provides a higher fidelity Monte Carlo analysis using the operational COTS extended Kalman filter implementation that was performed to validate the linear covariance analysis estimates and to better characterize orbit determination performance for actively maneuvering spacecraft in a highly elliptical orbit. The study finds that the COTS extended Kalman filter tool converges on accurate definitive orbit solutions quickly, but prediction accuracy through orbits with very low altitude perigees is degraded by the unpredictability of atmospheric density variation.
    Keywords: Astrodynamics
    Type: GSFC-E-DAA-TN16122 , AIAA Space 2014; Aug 04, 2014 - Aug 07, 2014; San Diego, CA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Partial Derivatives of the Lambert Problem (2014)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A procedure for deriving analytic partial derivatives of the Lambert problem is presented. Using the universal, cosine based Lambert formulation; first order partial derivatives of the velocities with respect to the positions and times are developed. Taking advantage of inherent symmetries and intermediate variables, the derivatives are expressed in a computationally efficient form. The added cost of computing these partials is found to be approximately 10% to approximately 60% of the Lambert compute cost. The availability of analytic partial derivatives increases optimization speed, efficiency and allows for trajectory optimization formulations that implicitly enforce continuity constraints via embedded Lambert problems.
    Keywords: Astrodynamics
    Type: AIAA SPACE 2014 Conference and Exposition; Aug 05, 2014 - Aug 07, 2014; San Diego, CA; United States
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Improving FermiI Orbit Determination and Prediction in an Uncertain Atmospheric Drag Environment (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Orbit determination and prediction of the Fermi Gamma-ray Space Telescope trajectory is strongly impacted by the unpredictability and variability of atmospheric density and the spacecrafts ballistic coefficient. Operationally, Global Positioning System point solutions are processed with an extended Kalman filter for orbit determination, and predictions are generated for conjunction assessment with secondary objects. When these predictions are compared to Joint Space Operations Center radar-based solutions, the close approach distance between the two predictions can greatly differ ahead of the conjunction. This work explores strategies for improving prediction accuracy and helps to explain the prediction disparities. Namely, a tuning analysis is performed to determine atmospheric drag modeling and filter parameters that can improve orbit determination as well as prediction accuracy. A 45 improvement in three-day prediction accuracy is realized by tuning the ballistic coefficient and atmospheric density stochastic models, measurement frequency, and other modeling and filter parameters.
    Keywords: Astrodynamics
    Type: GSFC-E-DAA-TN14296 , International Symposium on Space Flight Dynamics (ISSFD); May 05, 2014 - May 09, 2014; Laurel, MD; United States
    Format: application/pdf
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  • 4
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    Improving Fermi Orbit Determination and Prediction in an Uncertain Atmospheric Drag Environment (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Orbit determination and prediction of the Fermi Gamma-ray Space Telescope trajectory is strongly impacted by the unpredictability and variability of atmospheric density and the spacecraft's ballistic coefficient. Operationally, Global Positioning System point solutions are processed with an extended Kalman filter for orbit determination, and predictions are generated for conjunction assessment with secondary objects. When these predictions are compared to Joint Space Operations Center radar-based solutions, the close approach distance between the two predictions can greatly differ ahead of the conjunction. This work explores strategies for improving prediction accuracy and helps to explain the prediction disparities. Namely, a tuning analysis is performed to determine atmospheric drag modeling and filter parameters that can improve orbit determination as well as prediction accuracy. A 45% improvement in three-day prediction accuracy is realized by tuning the ballistic coefficient and atmospheric density stochastic models, measurement frequency, and other modeling and filter parameters.
    Keywords: Astrodynamics
    Type: GSFC-E-DAA-TN14297 , International Symposium on Space Flight Dynamics (ISSFD); May 05, 2014 - May 09, 2014; Laurel, MD; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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