J. Phys. IV France 08 (1998) Pr3-175-Pr3-179
The telescope readout electronics for the Gravity Probe B satelliteH.P. Demroff1, S. Babu2, M.R. Bye3, K.L. Coleman1, N. Das4, D.B. DeBra5, P.D. Ehrensberger Jr.3, R.P. Farley1, D.K. Gill3, J.H. Goebel6, M. Jhabvala7, A. Kashani8, E. Romero3 and M.T. Sullivan3
1 Advanced Technology Center, GP-B Lockheed Martin Missiles and Space, Bldg. 251, 3251 Hanover Street, Palo Alto CA 94304, U.S.A.
2 Ball Aerospace and Technologies Corp., Boulder, Colorado, U.S.A.
3 W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford CA 94305, U.S.A.
4 Hughes/STX. Lanham, Maryland, U.S.A.
5 Aeronautics and Astronautics Department, Stanford University, Stanford CA 94305, U.S.A.
6 Sensors and Instrumentation Branch, NASA Ames Research Center, Moffett Field CA 94305, U.S.A.
7 NASA Goddard Space Flight Center, Greenbelt, Maryland, U.S.A.
8 Atlas Scientific, 713 San Conrado Terrace, Sunnyvale CA 94086, U.S.A.
The pointing and stability requirements for the Gravity Probe B (GP-B) Relativity Mission pose a number of challenges for the star-tracking electronics. Because the telescope-gyroscope assembly operates at 2.8 K, the detector circuit's Si JFETs at the telescope focal plane must be thermally isolated and heated to at least 50 K through self-heating or with the aid of heating resistors. We have designed a low noise, thermally stable photodetector circuit that meets the GP-B requirements as well as fabricated an isolator to give the required thermal isolation and mechanical stability. Test results of the detector - isolator assembly are presented.
© EDP Sciences 1998