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Wallops' Low Elevation Link Analysis for the Constellation Launch/Ascent LinksPrior to the redirection of the Constellation Program, the Wallops 11.3-meter ground station was tasked to support the Orion's Dissimilar Voice (DV) link and the Ares's Development Flight Instrument (DFI) link. Detailed analysis of the launch trajectories indicates that during the launch and ascent operation, the critical events of Orion-Ares main engine cut off (MECO) and Separation occur at low elevation angle. We worked with engineers from both Wallops Flight Facility (WFF) and Johnson Space Center (JSC) to perform an intensive measurement and link analysis campaign on the DV and DFI links. The main results were as follows: (1) The DV links have more than 3 dB margin at MECO and Separation. (2) The DFI links have 0 dB margin at Separation during certain weather condition in summer season. (3) Tropospheric scintillation loss is the major impairment at low elevation angle. (4) The current scintillation models in the Recommendation ITU-R P.618 (Propagation data and prediction methods required for the design of Earth-space telecommunication systems), which are based on limited experimental and theoretical work, exhibit idiosyncratic behaviors. We developed an improved model based on the measurements of recent Shuttle mission launch and ascent links and the ITU propagation data. (5) Due to the attitude uncertainty of the Orion-Ares stack, the high dynamics of the launch and ascent trajectory, and the irregularity of the Orion and Ares antenna patterns, we employed new link analysis approach to model the spacecraft antenna gain. In this paper we discuss the details of the aforementioned results.
Document ID
20150008556
Document Type
Conference Paper
External Source(s)
Authors
Cheung, Kar-Ming (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Ho, Christian (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Kantak, Anil (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Lee, Charles (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Tye, Robert (NASA Wallops Flight Facility Wallops Island, VA, United States)
Richards, Edger (NASA Wallops Flight Facility Wallops Island, VA, United States)
Sham, Catherine (NASA Johnson Space Center Houston, TX, United States)
Schlesinger, Adam (NASA Johnson Space Center Houston, TX, United States)
Barritt, Brian (NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
May 20, 2015
Publication Date
March 5, 2011
Subject Category
Space Communications, Spacecraft Communications, Command and Tracking
Meeting Information
2011 IEEE Aerospace Conference(Big Sky, MT)
Distribution Limits
Public
Copyright
Other

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