over 17 days, the payload failed to respond to commands. It was believed that the clock-based access codes got out of synchronization and the satellite would not respond to what it interpreted as unauthorized commands. See also List of communications satellite firsts References Further reading James E. Bartow, Thomas P. Mottley, Walter P. Teetsel, "The Courier Communications Satellite System". In Telecommunication Satellites (Theory, Practice, Ground Stations, Satellites, Economics), edited by K.W. Gatland. pp. 156-183 T.P. Mottley, D.H. Marx, W.P. Teetsel, "A Delayed-Repeater Satellite Communication System of Advanced Design". In IRE Transactions on Military Electronics, Vol. MIL-4, No. 2, April–July 1960, pp. 195-207. N.B.: IRE Transactions on Military Electronics is currently published as IEEE Transactions on Aerospace and Electronic Systems T. P. Mottley, W. P. Teetsel, P. W. Siglin, "Project Courier Final Report", AD224091, U. S. Army Signal Research and Development Laboratory, Fort Monmouth, New Jersey, July 24, 1961 Pierce W. Siglin & George Senn, "Courier Communication Satellite". In The Journal of the Institution of Electrical Engineers, Vol. 7, August 1961, pp. 504-508 G.F. Senn & P.W. Siglin, "Courier Satellite Communication System". In IRE Transactions on Military Electronics, Vol. MIL-4, No. 4, October 1960, pp. 407-413. N.B.: IRE Transactions on Military Electronics is currently published as IEEE Transactions on Aerospace and Electronic Systems'' External links Information on Courier 1A and 1B at Gunter's Space Page Courier 1B history at CampEvans.org (Home of InfoAge. Courier Page of SMC Heritage Foundation Communications satellites in low Earth orbit Spacecraft launched in 1960