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Emergency Communications for NASA's Deep Space MissionsThe ability to communicate with spacecraft during emergencies is a vital service that NASA's Deep Space Network (DSN) provides to all deep space missions. Emergency communications is characterized by low data rates(typically is approximately10 bps) with the spacecraft using either a low-gain antenna (LGA, including omnidirectional antennas) or,in some cases, a medium-gain antenna (MGA). Because of the use of LGAs/MGAs for emergency communications, the transmitted power requirements both on the spacecraft andon the ground are substantially greater than those required for normal operations on the high-gain antenna (HGA) despite the lower data rates. In this paper, we look at currentand future emergency communications capabilities available to NASA's deep-space missions and discuss their limitations in the context of emergency mode operations requirements.These discussions include the use of the DSN 70-m diameter antennas, the use of the 34-m diameter antennas either alone or arrayed both for the uplink (Earth-to-spacecraft) and the downlink (spacecraft-to-Earth), upgrades to the ground transmitters, and spacecraft power requirements both with unitygain (0 dB) LGAs and with antennas with directivity (>0 dB gain, either LGA or MGA, depending on the gain). Also discussed are the requirements for forward-error-correctingcodes for both the uplink and the downlink. In additional, we introduce a methodology for proper selection of a directionalLGA/MGA for emergency communications.
Document ID
20150008559
Acquisition Source
Jet Propulsion Laboratory
Document Type
Conference Paper
External Source(s)
Authors
Shambayati, Shervin
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Lee, Charles H.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Morabito, David D.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Cesarone, Robert J.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Abraham, Douglas S.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
May 20, 2015
Publication Date
March 5, 2011
Subject Category
Communications And Radar
Meeting Information
Meeting: 2011 IEEE Aerospace Conference
Location: Big Sky, MT
Country: United States
Start Date: March 5, 2011
End Date: March 12, 2011
Sponsors: Institute of Electrical and Electronics Engineers
Distribution Limits
Public
Copyright
Other

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