The crew celebrated other hard-fought wins as the number of days until Earth Orbit Insertion dwindled.
Roger was checking the bracing that locked the ullage dampers against the walls of the aft cavern when his helmet speakers beeped quietly. He checked his heads-up display. It showed a call request from Benjamin Zabor. “Accept,” he said.
“Commander, you asked me to let you know fifty hours before ignition for EOI.”
“Damn. So soon?”
“Yes, sir. I've verified our location and velocity. We're actually a bit early, and our velocity is under what it should be by about one-oh-three meters per second.”
“When do we stop approaching Earth and begin to recede?” he asked.
“Fifty hours, sir, it’s…” said Benjamin. “Uh. Fifty.”
“You were about to tell me that's why it was called the fifty-hour mark, Ben,” said Roger. He laughed. “Don't worry about it. I'm staring at a huge tank that softened the blast from a nuclear weapon and passed it on to Perseus, and I still can't believe we rode that unique kind of thunder to get back home. Okay, since I'm obviously not up to speed, tell me what happens next.”
“Sir, we must configure for orbital insertion. This means getting the reactors online, and ramping up their heat production for steam generation. We have to make sure the Perseus is rigged for acceleration, but it's not going to be anything over about point zero three g.”
“That low?” asked Roger. “We lack what, in terms of mps, to gain orbit?”
“In the range of seven hundred and fifty meters per second, sir. We're going to have to blast for about forty minutes.”
“Long time.”
“It's going to expend about one-sixth of our water,” said Benjamin. “But it can't be helped, sir. A nuke is too crude an impulse, this requires precise control, particularly at the end, when we're warping for a particular orbit.”
“Right, right,” said Roger. “It's coming back now. Final orbit?”
“We're aiming for an eccentric one, perigee about three hundred kilometers, and apogee around three thousand kilometers.”
“Inclination?”
“Zero. We'll be right on the equator. I used the final precession maneuver around Venus to ensure that we did the right change-of-plane approach. We're only off by about thirty minutes of arc.”
Roger whistled in his helmet. “Damn, Benjamin. That's tricky stuff.”
“Great nav computer,” Benjamin replied. “Well, really, a great astrogation computer. I just figured out where I wanted to see the stars when I was on the right course, spun the magic wheel, and these numbers popped up. Thank the computer.”
“Fifty hours,” said Roger.
“Forty hours, fifty minutes, now, sir,” said Benjamin, with just the slightest hint of reproof.
“Slave driver,” muttered Roger. “Cross connect me to Michael.”
Hill Sphere
Aboard Perseus, High Earth Orbit, January 19 2087, 2311 GMT
The maneuver wasn't violent enough to notice, but it did entail some adjustments to the work in progress. Several workers were missing; manning the reactors or the water tanks and injectors, or watching the readouts up in the Control Room.
Forty minutes later, the subliminal whistling of the attitude thrusters ceased, and Benjamin hung over the astrogation computers like a nervous day-trader. The numbers flickered as the inertial navigation units compared their precessing gyroscopes and spring-loaded masses with the expected numbers from the computer.
“We're in,” said Benjamin. “We're within Earth's Hill Sphere—the Perseus is officially the first asteroid to be piloted into orbit around the Earth.”
Roger blew out a breath that he didn't realize he had been holding. He put his finger on the intercom switch. “Sure?”
Benjamin nodded happily. “Oh, yes, sir. We're home.”
Commander Smithson announced the historic event to the crew. The cheers from the ground were audible five hundred meters up in the Control Room.
“Congratulations, Benjamin,” said Commander Smithson, his eyes glistening with a bit more moisture than anyone had ever seen before.
***
“Good job, Roger,” said McCrary. “We've got your orbital elements, and we're loading the Tank now. Launch in about two days, and we'll be there in about five. I'll send the coordinates when we clear the Flinger.”
“Good luck, McCrary. We'll be on continuous comms watch here. Perseus out.” Roger toggled the circuit off and floated out of the Control Room to the slideway down to the surface, where he was certain to find Michael, bossing the frantically working interior crew.
“Glad we put this in,” he muttered, as he placed a raw fiber mat on the slick aluminum surface and pushed off. He laid down and enjoyed the ride as the enormous slide dropped in a helix around one of three trusses connecting the original axial truss to the surface. Originally emplaced to assist in moving bulky objects to the inside surface of the fore cavern, it was routinely used by people to rapidly travel from the axis to the surface, and thereby freeing up the new elevator for upward-bound loads.
Michael's powder-blue jumpsuit made it easy to spot him.
“Michael, a word?” said Roger when he got close. The two of them moved off while the crew gave them space.
“McCrary called. They launch in about two days, rendezvous five days from today.”
“Damn. We're not going to be ready.”
“I'd concentrate on the aid station and the convalescent parts,” suggested Roger.
“My thoughts exactly. Those people are going to be hurting plenty.”
“Where's Harel or Doctor Gulotta? Or have you asked them about the micronutrient problem already?”
“The good doctor has already looked into it. We've got enough medical supplies for the most serious cases. The problem is one of services. It doesn't help if you've got an IV stand and a bed for a patient, but don't have walls or electrical sockets for the monitoring equipment for them. That's what I mean when I say we're lacking.”
“Sounds like I'm just slowing you down. I'm off to the aft cavern to do some final checks on the cradle and receiving tubes. I can't imagine that they're spending the entire flight in their spacesuits. Oh, since we're down here and not upstairs, I've asked Ragesh and Mickey to do a heel and toe watch on McCrary's signal and send it directly down here. Channel six.”
“I'll be delayed—I am not going to wear my helmet just to get a signal,” said Michael.
“I've also asked them to turn on the ship's flashers whenever they get a signal from the Moon. Coordination meeting at 1900?”
“Sounds good. Scat!”
Roger waved and loped towards the aft truss, one kilometer distant. He passed two hundred meters of green growing things, then the fields abruptly ended and the rough iron surface, colored a blue-black by the phosphate solution they had added to the steam back during inflation, stretched in a complete circle above his head. As he rode the elevator up to the central axis, he marveled at the little world that the crew had created inside this lump of cosmic slag. From seven hundred meters away, the individual plants blended together, and the rows between the plants were almost indistinguishable, lending a fuzzy green softness to the areas covered with plant life, growing and thriving under the LED lighting flooding down from the central axis.
For the awake crew that had seen nothing but harsh white and black for years, the green was a welcome presence, gradually emerging on the surface of the fore cavern. They had time to get used to it. The crew of the Collins, on the other hand, were going to get hit with it all at once. Roger hoped that they didn't start running barefoot through the fields, ruining the crops.
Then he snorted. McCrary would put a stop to that with a word.
He changed into his spacesuit in the robing chamber just fore of the first airlock and began the three-minute sequence that would take him through three different lock chambers and into the vacuum of Earth orbit.
***
Four days later, Roger was hovering over Benjamin's console in the Bradbury. “Status?”
“In the groove, sir. That Flinger is really something. Their trajectory is within half a meter per second in velocity, and the errors in positioning are less than one meter. It's really astonishing. They should begin retrofire in three hours.”
“You can do a lot when you have a long baseline of lineac magnetic motors. Speaking of, how is our own lineac going? It's not going to do the Perseus, or those airlocks, any good to have the Tank hit them at five meters a second.”
“Stop worrying, boss. Passed with flying colors, as best we can do without handling an actual load. We just took the controls from the Ring and hooked them up to the new hoops Jeff installed in the aft cavern.”
Roger smiled. Enormous hoops of iron-nickel, cooled with liquid hydrogen and hooked directly to the electrical output of both the thorium reactors powering the Burroughs and Bradbury, circled the interior of the aft cavern, forming a Flinger of their own that was two kilometers long. It was going to be ridiculously easy to capture the Tank as it came near the Perseus and slow it to a complete stop.
“Good to hear. Still, I'm worried about lateral velocities. Impact just one of the hoops, and the short circuits will trash the entire structure.” Roger gnawed at a knuckle subconsciously.
“That's why I've got the attitude control system online as well. Look, boss, give it a rest, will you? Jeff, Scott, and I have wargamed this six ways from Sunday, including all the abort procedures and parameters. We're not going to lose them here, so close to Earth.”
“Yeah, but...”
“Dammit, Roger,” said Benjamin, shocking the other man. “I've got at least fifty things to monitor here, as well as the input from Jeff and Scott. It's all my ass here. Their safety, our safety. I can't ensure that and answer your questions, too. Go bother Scott, or better yet, just watch from your office.”
Roger raised his hands in surrender. “You're right, Ben, I deserve that. I'll head back to my office and keep my fingers off the intercom button for Astrogation. Good luck, man. No hard feelings.”
Benjamin didn't smile when the Commander left his area. Already, he had slipped back into that place only few humans know, becoming one with the machines under his delicate control.
***
“Attention,” said Benjamin, his voice echoing from the speakers of countless commpads. “Tank retrofire is due within the next ten minutes. We are replicating radar data, and will go to visual when the retro sequence has concluded.”
He let go of the button and called over his shoulder. “Ragesh, give me Gatson.”
Ragesh, manning the communications console once again, flicked a couple of switches, routing channels. “Go, Ben.”
“Jeff, Ben. Is the aft cavern clear?”
“Clear. All men are inside their chambers and are under strict orders not to look out of the bullseyes.”
“Good. We don't need to blind people. I'll let you know when the Tank has secured their launcher.”
Jeff nodded to himself. “Aft, standing by.”
“Eight minutes, fifty, just so you know. I'll be giving a time check at five, two, and one minute, then going into the standard countdown. No abort, you know.”
“Yeah. Their bombs better work.”
Benjamin laughed. “You don't know?”
“Know what? I've been busting my ass back here for the past three weeks. My spacesuit interior is a horror.”
“They've already fired one. They work.”
“When?”
“Four years ago. A big-assed rock was going to sit on them. Very unfriendly. So they shot a bomb off just underneath it. It was over their local horizon so they were okay. But they burned out a bunch of telescopes on Earth. Fried the imagers. And I think a couple of folks lost an eye because they were looking at the Moon at the wrong time.”
“That's terrible!”
“Yeah. Politicians freaked out. Calls for the demilitarization of space, crap like that.”
“Same kind of crap we're about to get, no doubt. How long?”
“Six minutes. Time for me to concentrate.”
“Good luck, Ben. Aft cavern out.”
***
“One minute to retro sequence,” said Benjamin. “Sequence should last five minutes. Do not, repeat, do not look at the Tank. Watch on a monitor only.
“Forty-five seconds. Interior interlocks on bomb launcher released. Arming sequence commencing. Thirty seconds. Launcher swiveling into position. Twenty. Arming sequence complete. Fifteen. If bombs do not fire, Tank will begin reentry within ten minutes. Eight, seven, six, five, first bomb launched, two, one, detonation!”
On the monitors, there was a sudden glare of white, partially hidden behind a black angular shape. Five seconds later, another blast. Nine bombs exploded, then a long pause ensued, then a final detonation.
“Retro sequence complete, awaiting confirmation from the Tank.”
Benjamin's eyes flickered abnormally fast as he compared the numbers streaming in from the Tank's sensors, the radar on the Perseus, and the predicted trajectory. His hands flew over the control panel, setting up a correction maneuver.
“Ragesh, command circuit!”
“Go!
“Commanders, we must maneuver within the next thirty seconds. Delta-v X, minus two hundred cms, Y, plus three fifty, Z, thirty-two. Out.”
“Ragesh, intercom!”
“Go!”
“Secure for maneuvering! Lateral sequences in five, four, three, two, one, blast!”
A subliminal shuddering twitched Perseus, aligning it up with the altered trajectory of the Tank. Benjamin watched as the differences on his monitors decreased. He swung the thrusters on their gimbals as the deltas closed on zero. His hand tapped carefully as vents of steam blew out of the nozzles at either end of the Perseus.
He tapped the thrust control to zero and tripped a more complex program that reran the entire rendezvous computation from zero, using current data. The new numbers flickered on the screen.
“One more maneuver. Three, two, one!” Again, the delicate shuddering, swiftly decreasing in intensity.
“Aft crew reports cavern secure for impact. Tank has completely entered the aft end and has two kilometers to travel to berth. Internal Flinger activated and is absorbing differential velocities. Tank impact in one hundred seconds. Brace for acceleration.” The Perseus surged minutely as the relative speed of the Tank inside the cavern slowed dramatically.
“Impact with Tank in ten seconds. Delta is one meter per second, dropping. Brace for impact. Five, four, three, two, one, impact.”
The Perseus twitched once, minutely.
“Ragesh, give me Jeff!”
“Go!”
“Jeff, is the Tank secure? I can't tell!” Benjamin cycled through every camera inside the aft cavern.
“Did you turn off the Flinger?” asked Jeff. “I don't want to throw any men out the back!”
“Damn. Thanks. Flinger powered off. Check the Tank out. Ragesh! Give me Reactor Control.”
“You've got it, Ben. Good job.”
“Thanks. Duane, Ivan, you can start to dial down the reactors. Maneuvering complete, and I've shut off the Flinger.”
Ivan growled. “About time, we were starting to get to redline there. Reactors are dialing down.”
“Make sure you leave me enough power for some orbital burns. Those need to take place soon.”
“Ragesh, command circuit.”
“You're on.”
“Commanders, the Tank has been captured. Jeff's men are checking out the docking. Request a week of vacation.”
Roger and Michael stepped all over each other offering congratulations, until Michael let Roger speak.
“Good job, Benjamin. I think you have to regularize our orbit first, though, don't you?”
“Already in the works, sir. First burn is on the next orbit. I figured we'd want to get the Collins folks out of the Tank before we start blasting
.”
“Good. Michael? I'm headed back to welcome them into their temporary home. Smithson out.”
“Excellent job, Ben,” said Michael. “I'm proud of you.”
“Thank you, boss. I'm pretty happy everything worked out.”
Recovery
Aboard Perseus, High Earth Orbit, February 18 2087, 1011 EDT
“You saved us, McCrary. You saved us all.” Roger Smithson lifted a glass made from one of the Tank's silicon ingots. “Without you, there would be four hundred more dead up in space—our two hundred, and all of yours.”
McCrary frowned slightly at the praise. “Thank you, Commander, but I am nobody special.”
The men gathered around him in the communal dining hall growled their disapproval. One of the sleepers, Norman Radding, stood up.
“I was one of the sleepers on the Mars Expedition. If you didn't work with the awake crew, I would never have woken up. We'd be right about where we are right now, but in a flimsy spaceship instead of this impervious suit of armor.”
As if to punctuate his remarks, a loud bong rang out, the sign of a piece of lunar debris impacting the fifty-meter-thick skin of the Perseus.
“Hear, hear!” called out the men of the Mars Expedition. They had begged McCrary to leave the Collins group for a special dinner in his honor. He reluctantly accepted, but was stoically enduring their praise.
Dinner was a relatively quick affair. After all, there was only so much that could be done with vegetables and fruit. McCrary ate with relish. Michael noticed.
“How are the Collins crew responding to treatment?”
McCrary swallowed a bite and chased a cherry tomato around the plate. “Pretty good, I think. They all still want to get back to Earth, but I think we can convince them to hang around a bit while we turn the Perseus into a true shield. I am happy you've got a bunch of lasers built. We'll strip out the Tank, and add its defenses to yours.”
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