ON EARTH, THEY ALREADY EXIST. 4 HORSEMEN HAVE 4 DAYS IN ONLY 1 EARTH.

SERVO AMPLIFIER REACTION JET OMS DRIVER (AFT) MULTIPLEXER-DEMULTIPLEXER UNITS MASS MEMORIES MULTIPLEXER-DEMULTIPLEXER UHF RECEIVER RENDEZVOUS SENSOR ELECTRONICS ` ACCELEROMETERS ONE-WAY DOPPLER EXTRACTION S-BAND * PM DOWNLINK (96 kbps) KU-BAND e PM UPLINK (72 kbps) VOICE (2 x 32 kbps) COMMANDS 6.4 kbps (2 kbps INFORMATION ENCODED), AND 1.6.