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Design of Superconducting Gravity Gradiometer Cryogenic System for Mars MissionMeasurement of a planets gravity field provides fundamental information about the planets mass properties. The static gravity field reveals information about the internal structure of the planet, including crustal density variations that provide information on the planets geological history and evolution. The time variations of gravity result from the movement of mass inside the planet, on the surface, and in the atmosphere. NASA is interested in a Superconducting Gravity Gradiometer (SGG) with which to measure the gravity field of a planet from orbit. An SGG instrument is under development with the NASA PICASSO program, which will be able to resolve the Mars static gravity field to degree 200 in spherical harmonics, and the time-varying field on a monthly basis to degree 20 from a 255 x 320 km orbit. The SGG has a precision two orders of magnitude better than the electrostatic gravity gradiometer that was used on the ESAs GOCE mission. The SGG operates at the superconducting temperature lower than 6 K. This study developed a cryogenic thermal system to maintain the SGG at the design temperature in Mars orbit. The system includes fixed radiation shields, a low thermal conductivity support structure and a two-stage cryocooler. The fixed radiation shields use double aluminized polyimide to emit heat from the warm spacecraft into the deep space. The support structure uses carbon fiber reinforced plastic, which has low thermal conductivity at cryogenic temperature and very high stress. The low vibration cryocooler has two stages, of which the high temperature stage operates at 65 K and the low temperature stage works at 6 K, and the heat rejection radiator works at 300 K. The study also designed a second option with a 4-K adiabatic demagnetization refrigerator (ADR) and two-stage 10-K turbo-Brayton cooler.
Document ID
20160008979
Acquisition Source
Goddard Space Flight Center
Document Type
Presentation
Authors
Li, X. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Lemoine, F. G. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Shirron, P. J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Paik, H. J. (Maryland Univ. College Park, MD, United States)
Griggs, C. E. (Maryland Univ. College Park, MD, United States)
Moody, M. V. (Maryland Univ. College Park, MD, United States)
Han, S. C. (Creare, Inc. Hanover, NH, United States)
Zagarola, M. (Creare, Inc. Hanover, NH, United States)
Date Acquired
July 12, 2016
Publication Date
June 19, 2016
Subject Category
Fluid Mechanics And Thermodynamics
Spacecraft Design, Testing And Performance
Report/Patent Number
GSFC-E-DAA-TN32907
Meeting Information
Meeting: International Cryocooler Conference (ICC 19)
Location: San Diego, CA
Country: United States
Start Date: June 20, 2016
End Date: June 23, 2016
Sponsors: Cryogenic Society of America, Inc.
Distribution Limits
Public
Copyright
Public Use Permitted.

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