the screens seemed frozen.
“You are receiving telemetry from the comm system?” he asked the communications engineer in a quiet voice brittle with tension.
“Yes, sir,” the engineer said, looking up over his shoulder at Urbain. “The tracking beacon is coming through, too, loud and clear.”
“Very good. Run the diagnostics program, if you please.”
“For the whole comm system?”
Urbain thought a moment. “No. Merely the receiving antennas. Primary and both backups.”
The man pecked at his keyboard. Urbain noticed that his fingers were thick, blunt, the nails ragged and chewed down to the quick. The display screen flickered through long lists of alphanumerics faster than his eye could follow.
At last the engineer cleared his throat and said, “Diagnostics completed. All receiving antennas fully operational.”
“Good,” said Urbain. “Now I wish to send a very specific command to—”
“Hey!” a voice yelled. “It’s moving!”
Without being told to, the communications man punched up the satellite view of Titan with the blinking red dot showing where Alpha ’s beacon was located. The red pinpoint was inching across the screen.
“It’s moving,” Urbain breathed.
“Looks that way,” said the engineer.
Raising his voice to an angry shout, Urbain demanded, “Who gave the command to move Alpha? ”
No one answered.
“Well? Which of you did it?”
Dead silence.
The comm engineer cleared his throat again, louder than before, and jabbed a forefinger at one of his secondary screens. “Sir, here’s the communications log. No one’s sent any command of any kind to the lander since you ordered it to report its review of the propulsion system checklist.” He tapped his screen for emphasis, then added in a smaller voice, “Nobody’s said a word to the beast.”
My god, Urbain thought, staring at the screen. It’s moving on its own volition.
Titan Alpha ’s central computer was programmed to anticipate certain problems and, within carefully preset limits, to act on its own. Even though commands from the control center usually spanned the distance between habitat Goddard and the surface of Titan in less than six billion nanoseconds there was always the possibility of some immediate emergency—a sudden fault line opening in the icy ground, an avalanche, an electrical
storm shorting out communications—that would require action before the human controllers in Goddard could react. Then, too, there were periods when the habitat was on the opposite side of Saturn and commands had to be relayed to the lander through the communications satellites placed in equilateral positions around the ringed planet. There could be a lag of almost a hundred billion nanoseconds under those conditions.
Based on the latest commands reported by the main receiving antenna, Alpha ’s central computer anticipated that the propulsion system was to be activated. But such a command ran directly counter to the master program’s primary restriction. The computer pondered this conundrum for more than a thousand nanoseconds, then used its decision-tree logic program to resolve the problem.
Activate propulsion engines.
Engage tractor treads.
Automatically, the navigation and reconnaissance programs also activated. The central computer immediately became aware that the edge of the bluff loomed three thousand, seven hundred and twelve centimeters ahead.
Engage reverse gear.
Maintain speed at five centimeters per second.
Strain gauges and vibration sensors immediately began reporting data. Comparing their inputs to the structural diagnostics program, the central computer decided to proceed.
Titan Alpha lurched into painfully slow motion, backing away from the rim of the ice bluff, grinding over small round pebbles of ice, heading away from the dark encrusted sea.
In the control center aboard Goddard , Urbain stared at the satellite view in unrelieved horror.
“It’s moving,” he whispered, barely able to
“You are receiving telemetry from the comm system?” he asked the communications engineer in a quiet voice brittle with tension.
“Yes, sir,” the engineer said, looking up over his shoulder at Urbain. “The tracking beacon is coming through, too, loud and clear.”
“Very good. Run the diagnostics program, if you please.”
“For the whole comm system?”
Urbain thought a moment. “No. Merely the receiving antennas. Primary and both backups.”
The man pecked at his keyboard. Urbain noticed that his fingers were thick, blunt, the nails ragged and chewed down to the quick. The display screen flickered through long lists of alphanumerics faster than his eye could follow.
At last the engineer cleared his throat and said, “Diagnostics completed. All receiving antennas fully operational.”
“Good,” said Urbain. “Now I wish to send a very specific command to—”
“Hey!” a voice yelled. “It’s moving!”
Without being told to, the communications man punched up the satellite view of Titan with the blinking red dot showing where Alpha ’s beacon was located. The red pinpoint was inching across the screen.
“It’s moving,” Urbain breathed.
“Looks that way,” said the engineer.
Raising his voice to an angry shout, Urbain demanded, “Who gave the command to move Alpha? ”
No one answered.
“Well? Which of you did it?”
Dead silence.
The comm engineer cleared his throat again, louder than before, and jabbed a forefinger at one of his secondary screens. “Sir, here’s the communications log. No one’s sent any command of any kind to the lander since you ordered it to report its review of the propulsion system checklist.” He tapped his screen for emphasis, then added in a smaller voice, “Nobody’s said a word to the beast.”
My god, Urbain thought, staring at the screen. It’s moving on its own volition.
Titan Alpha ’s central computer was programmed to anticipate certain problems and, within carefully preset limits, to act on its own. Even though commands from the control center usually spanned the distance between habitat Goddard and the surface of Titan in less than six billion nanoseconds there was always the possibility of some immediate emergency—a sudden fault line opening in the icy ground, an avalanche, an electrical
storm shorting out communications—that would require action before the human controllers in Goddard could react. Then, too, there were periods when the habitat was on the opposite side of Saturn and commands had to be relayed to the lander through the communications satellites placed in equilateral positions around the ringed planet. There could be a lag of almost a hundred billion nanoseconds under those conditions.
Based on the latest commands reported by the main receiving antenna, Alpha ’s central computer anticipated that the propulsion system was to be activated. But such a command ran directly counter to the master program’s primary restriction. The computer pondered this conundrum for more than a thousand nanoseconds, then used its decision-tree logic program to resolve the problem.
Activate propulsion engines.
Engage tractor treads.
Automatically, the navigation and reconnaissance programs also activated. The central computer immediately became aware that the edge of the bluff loomed three thousand, seven hundred and twelve centimeters ahead.
Engage reverse gear.
Maintain speed at five centimeters per second.
Strain gauges and vibration sensors immediately began reporting data. Comparing their inputs to the structural diagnostics program, the central computer decided to proceed.
Titan Alpha lurched into painfully slow motion, backing away from the rim of the ice bluff, grinding over small round pebbles of ice, heading away from the dark encrusted sea.
In the control center aboard Goddard , Urbain stared at the satellite view in unrelieved horror.
“It’s moving,” he whispered, barely able to
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