Author_Institution :
Down to the Metal, Dennis, MA, USA
Abstract :
What may well be the most famous ten-word utterance of the 20th century came to us from the Moon-or was it eleven words? Neil Armstrong intended to say, and thought he did say, “One small step for a man, one giant leap for mankind,” but everybody heard it without that minimal word “a”-or was it really everybody?. The answers may cast a shadow on digital messages exchanged by avionics suites in the 21st century. Armstrong, the most cool, calm, and collected of astronauts, generally did and said exactly what he intended. There must be a way he said what he meant but we all heard it the other way. This paper presents a new way to address the dilemma. At any given moment, only half the surface of the Earth is able to receive RF signals from a particular distant point in space, necessarily along a line-of-sight from the transmitter. The Manned Space Flight Network (MSFN) and the Deep Space Network (DSN) included antennas located around the world; the biggest being in Spain, California, and eastern Australia. Signals received at any of those places had to be routed through terrestrial communications networks to get to Houston, where somebody selected whichever feed promised the best quality. None of that would have affected the immortal sentence, were it not for the key fact that Australia had no undersea cables to the rest of the “terrestrial network.” All serious communications had to travel via geosynchronous satellite, a fifty-thousand-mile path taking a quarter of a second. Comparing that with the overland microwave link between California and Houston (seven or eight milliseconds), we find a time difference big enough to swallow a small word. Looking forward to the predominance of digital packet communications throughout the new century, I wonder if a hole big enough to swallow a small spoken word could conceal the very existence of a digital message.
Keywords :
aircraft communication; avionics; satellite antennas; satellite communication; California; DSN; Houston; MSFN; Neil Armstrong; RF signals; Spain; antennas; avionics; deep space network; digital messages; digital packet communications; eastern Australia; geosynchronous satellite; manned space flight network; overland microwave link; terrestrial communications networks; transmitter; Antennas; Australia; Earth; Moon; Space vehicles; Switches; TV;