At 2:03 a.m., the main computer completed the analysis of the rear camera images obtained over the last three weeks. It had compared these images to those from the forward-looking telescope obtained immediately prior to the course change. This comparison was daunting, even for a computer with enormous processing power because it was looking for dust from angles almost 155 degrees apart and without star targets for standardization. As an afterthought almost, astronomer Savanna had also programmed the computer to look at their new trajectory from images acquired prior to course change and after.
A soft beeping sounded in Lucinda’s cabin as well as in Savanna’s. The sound started very low, thirty decibels, and slowly increased in intensity until silenced. They awoke about the same instant and silenced the tone. On screen in both rooms was a generated message in red letters.
ATTENTION: POTENTIAL IMPACT PREDICTED IN ONE TO TWO WEEKS. HUMAN ANALYSIS OF IMAGES IS RECOMMENDED. A COURSE CHANGE IS RECOMMENDED AND WILL COMMENCE WITHIN 24 HOURS UNLESS OVERRIDE SEQUENCE IS INITIATED. CONTINUE FOR MORE INFORMATION.
Both women looked at additional data. Lucinda saw that Savanna had been notified and had viewed the alert. She threw on her standard one-piece zip-up medical suit and walked the two flights up to Science. Savanna, without changing from her scant sleepwear, walked over to Cyrus’s cabin and entered. She touched him on the shoulder, awakening him. He looked at her in confusion as the veil of sleep lifted. He started to smile.
“It’s not what you think, Cyrus. We have a collision warning. I need you in CAC.”
“What?”
“Look at your screen.” Savanna took a couple of steps and activated the screen and tapped the flashing warning icon. “See you up top in a minute.” Savanna left as quietly as she entered. Cyrus rousted himself and read.
After Savanna dressed, she walked up to Science, where she found Lucinda going over the images on a one-meter rectangular screen in a room lit primarily by red lights. She was toggling a marker by tapping a key. She was studying closely a corner of the screen. “What do you see, Luc?”
“If it were me looking at these images, I would have seen nothing. But in this area,”—she hit a function key and pointed at an elliptical blue mark—“there is a faint, vague streak hiding in all these stars. As my eyes accommodate better and as I look at it longer, I am more certain it is real.”
“If I see what you see, it doesn’t look like it is in front of us.”
“That’s because these images were taken prior to a course correction of twenty-five degrees. Now,”—she stroked a different key—“you see it is ahead. This was taken yesterday. It is moving and in our flight path.”
“What does the computer say we should do?”
“I have not looked yet. I wanted to see the images first.”
“Are these pictures available to all computers?”
Lucinda tapped a dozen keys. “They are now. But this screen and the ones in CAC and CAN have the best images. I’m not sure they will show up on the others.”
“Can you enhance them?”
“The computer has already done it,” Lucinda said as she touched another icon. The almost-invisible streak became colorized in amber against the black-and-white array of stars, its brightness tripled and now elegantly visible. “We’re in comet heaven.”
“It could be hell for us,” Savanna replied.
“Not with a course correction.”
“I woke up Cyrus. I’m going to meet him in CAC.”
Savanna left as Lucinda was mumbling, “Let’s see what additional information I can coax out of old Bitelzebub.”
Savanna noticed the lift was in operation as she passed the door and reentered the stairwell ascending. She and Cyrus arrived on CAC about the same moment.
Thirty minutes later, Lucinda came up. The colorized image was displayed on the large main screen. Cyrus was immersed in sines and tangents, thetas, alphas, and betas. Savanna had the course change recommendation in front of her on one screen and her share of navigation computations on the other.
“You called. I’m here,” Lucinda announced. Savanna looked up.
“Good,” she said. “Talk to me.”
“It looks like we are headed into a comet trail, probably on the edge but still fatal at our velocity. Our course is at a thirty-degree angle to the comet. The computer estimates it at 250 hours away with a 98 percent margin of error of seventy hours either direction. You guys are the pilots, but a two-degree course change toward Arcturus started now and completed in twenty-four hours would put us well outside the dust trail.”
“We were just debating if a two-degree change was safe enough,” Cyrus said. “I would rather make a larger correction.”
“It is up to you, guys. I’m the medic struggling to keep the science lab running. Do not let me fly this thing.”
“I think the computer’s recommendation of two degrees is overkill.” Savanna opined. “If this obstacle is just 150 hours away, at a two-degree change, we will still miss the center by, what, 2.8 billion kilometers or so. That’s huge. A one-degree change gives us 1.5 billion clicks away, still huge, and our course recorrection is obviously less. If it is three hundred hours away, a one-half-degree change seems totally safe.”
“The sooner we change, the less the change is, right?” Lucinda asked.
“Yes,” Cyrus and Savanna answered simultaneously.
“So if you started the change now instead of waiting for the computer to initiate tonight, that would mean a smaller change. How far do we travel in twelve hours?”
“About six billion kilometers,” Cyrus answered after doing the math. “I guess a one-degree correction started now would give us a huge margin of safety.”
“Then, Cyrus, initiate a course correction of one degree over one hour toward Arcturus. Program to recalculate route in three hundred hours.” She had a twinge of misgiving that she brushed away immediately, which she would later regret.
“Acknowledge.”
“One of us should stay on the bridge until correction is complete and verified,” Savanna said.
“I’ll stay,” Cyrus volunteered. He focused on the screen before him as he accessed the computer generated course correction and modified it, which took about two minutes to make the correction and another two minutes to override the security features. “Correction initiated,” he said as he hit the return icon. There was no perceptible change in the ship.