“They’ve probably targeted the missile to strike just above the surface of the asteroid, hoping that the explosion and radiation will heat the rock, vaporizing some of it and turning it into ejecta, which would act like a rocket exhaust and push the asteroid onto a new path. The ejecta would go one way, the asteroid the other.”
“I remember most of that from our preflight briefings. If they vaporize enough of the rock, it moves into a completely new orbit and misses the Earth entirely,” Gesling said as he moved closer to Hui whose voice had grown softer while making her explanation.
“Except that in this case, the bomb will likely vaporize enough rock to cause the asteroid to split into two pieces instead of diverting. It’s like trying to hold a cookie that is cracked along the middle. You must carefully pick it up or it will break off before you can eat it. Then the crumbs fly off in different directions. We’re in the same situation here. When the nuclear device detonates on our cookie”—she pointed out the window at the asteroid and then continued—“our cookie is going to break in half and then the smaller piece of the asteroid may get enough delta-vee to miss hitting the Earth, but the big one may not be moved enough to cause it to miss the planet. Without knowing the mass split between the two, the yield of the bomb, when the bomb will get here, and several other factors there is simply no way to know for sure.”
“If it does split, and either piece hits the planet, a lot of people will die.”
“Wait a minute. The missile Mikhail thinks they’ve launched won’t arrive for another two months. That’s plenty of time for the asteroid to be nudged into a new orbit. It won’t be where they think it would be when they launched and the missile will miss us entirely, flying through empty space instead of hitting the rock. I’ve been running trajectories for our return home and looking at what will happen to the rock once the thrusters begin working. Even with the small thrust the electric propulsion system provides, this rock will be on a different course than when we got here,” Gesling said.
“Paul, that’s all well and good. But what if that the missile is not a fire-and-forget type weapon? Which I highly doubt it is. It likely has its own sensors and navigation capability. It will use some sort of onboard radar or optical sensor to find the target and remain locked onto it until the mission is complete. This is all standard technology for either of our countries’ missile defense programs.”
“Even if it is in a new orbit and obviously not a threat?”
“It may have sensors and be smart, but it likely isn’t smart enough to run all the orbital mechanics calculations and determine that it doesn’t need to strike. I know my government. They prefer simple systems with few options. Systems that usually get the job done.”
“In this case, the job is likely to kill us in the process. We need to stay close by as long as possible to make sure those thrusters keep working.”
“That is certainly likely.”
“Then we need to contact them and have them stop the missile. Surely it can be detonated or diverted if commanded to do so,” said Hui.
“I’m sure you are correct. My government would not launch such a weapon without the ability to turn it off.”
“Then we need to contact them and tell them to call off the missile strike,” Hui said as she looked expectantly at Gesling.
Gesling would have squirmed had he been in a seat and able to do so. As it was, he could only grimace. He didn’t have good news.
“Hui, we don’t know for sure that the electric thrusters are working yet. And it will be several more days, or even weeks before we know that they are working well enough to actually divert the asteroid. With the high-gain antenna destroyed and only the low-gain antenna to work with, we’ll have to boost away from the asteroid and point the ship in the correct direction to beam a radio signal to Earth. That will take propellant. I don’t believe we should do that until after we’re sure the thrusters are working well enough to be left behind and operate on their own. We are so low on propellant we may not make it back home as it is. If we go out far enough to send the signal home, then we might not have enough fuel to return here and fix or adjust the electric thrusters and then get home. Once we leave this rock, we’d better be darned sure we don’t need to come back. Or we’ll end up riding it all the way to Earth the hard way. That being said, Mikhail is almost finished with the omnidirectional antenna and we will start broadcasting soon. Hopefully, they will hear us sooner than later.”
“Paul, that should still be okay if they don’t pick up the low power omnidirectional signals. Even if it takes three weeks to be sure the electric thrusters are working well enough to leave, that would still give us several weeks to radio back home and tell them to call off the missile strike.” Mikhail sounded optimistic about their situation for the first time since realizing that a missile strike was likely on its way toward them.
“Mikhail, I wish I shared your optimism. Even if everything is working as it should and we stop the missile strike, if there is one, I’m still not sure we have enough attitude control propellant to get home. I’ve been plotting various trajectories and almost all of them will likely require too many small correction burns, each requiring that we use propellant to adjust the ship’s attitude before performing to make sure we’re pointed in the right direction. Even if we save the planet, we may very well go into permanent orbit around the Sun instead of heading home to be in the Rose Bowl parade.”
The three astronauts were silent as they looked at each other in the cramped confines of their suddenly, seemingly, smaller spacecraft. Mikhail was the first to respond.
“Paul, you said almost all of the possible trajectories require too many burns. That implies that there are some that don’t require as much. What of those?”
“The only ones I’ve found that fit somewhat into our projected capabilities all require that we stay on the asteroid until about a week before it flies by the Earth, or hits it, whichever the case may be. If we depart then, we should have enough propellant to get home.”
“Does that include the propellant we’ll use to call off the missile strike?” asked Hui.
“No. That assumes we don’t do anything until we’re ready to depart for home. If we hop off, radio home, and then come back, the margin gets less. My best guess in that case is that we’d have to wait until one or two days before closest approach.”
“In both of those cases, you’re assuming that the new electronics works and the electric thrusters do their job as designed. Based on the data so far, I can’t assure you that will be the case.”
“Then I suggest you get back to it,” Gesling said.
CHAPTER 27
Paul looked out the small window into the blackness of space. As the Sun vanished behind the bulk of the massive rock that was Sutter’s Mill, the star field burst upon his awareness as his eyes grew accustomed to the darkness. For Paul, who frequently stargazed in the Nevada desert near where the Dreamscape took off and landed, it was a magical and spiritual experience. When he looked at the stars, he could almost feel the vastness of empty space separating him from the stuff out of which he and all life was made. He felt connected and disconnected at the same time—to him, it was a fleeting glimpse of eternity. And it was meant to be savored.
Paul hadn’t heard anything from home about Carolyn’s condition in the three weeks since they lost radio communication with Earth. While Mikhail had built a low-gain dipole antenna and Hui and he had done an EVA to attach it, they had yet received any word back. It was possible that the low-gain antenna couldn’t pull a signal out of the background noise all the way from Earth, but Paul wasn’t sure. He was an aerospace guy, not a radio guy. Mikhail had assured him that if they were listening with the big dish in Arecibo, Puerto Rico that they would hear them. At least maybe Earth knew they were alive. Maybe not. He couldn’t assume any of it.
Paul’s mind was continuously busy now with figuring out how to get them home safely. He had less and less time to let himself dwell on the fa
ct that he had no idea how his wife was. He still missed her but he wasn’t spending as much time being morose and thinking of her constantly. When he realized he hadn’t thought of her in a while, he immediately felt guilty. When he was thinking of her, he felt as if he was neglecting the rest of the crew and indulging in self-pity. It was a truly no-win situation.
As Paul looked at the stars and momentarily thought of Carolyn, he took satisfaction at having proved the psychologists back home wrong on at least two points. The first was his ability to lead and function on the mission with his wife being injured and comatose back home. He’d talked to the psychiatrists extensively before departure and he was confident that they’d recommended against sending him on the mission. But someone, probably Childers, had used his influence to overturn that inevitable recommendation, to assure that he was on the trip. The second was their sometime stated, but mostly implied, belief that a mixed-gender crew couldn’t manage to be in deep space away from home without some sort of sexual liaison occurring. So far as he knew, Hui and Mikhail had not “hooked up” during the voyage and given the fact that there was virtually no privacy to be had on their small ship, he was fairly certain he would know if they had. Hui was an attractive and assertive woman. He and Mikhail were both red-blooded heterosexual males. The psychologists tended to believe that their sex drives would overcome their intellect and ego. What the experts didn’t fully appreciate was that they were all three professionals who placed the importance of the mission far ahead of personal satisfaction, whether it was physical or a matter of ego. If the impulse was there, they were exceptionally good at controlling it. Or maybe they just weren’t into each other in that way. Psychologists didn’t know everything about how personalities work even if they thought they did. Paul didn’t care one way or the other as long as it didn’t impact the mission negatively.
He didn’t have long to let his mind wander before he moved his head out of the small shadow and back into the sunlight. The glare of the sun obscured the stars and brought him out of his reflection. He looked around and saw Hui behind him, and, from what he could tell, mostly by her silence, she was having a moment of deep thoughts as well. Or maybe they were both just really bored or going stir crazy. They’d all been in space a really long time now and only Mikhail had experience like that.
Mikhail, as he had done every day for the past few weeks, was looking at lines of data, software code and engineering specifications. He’d installed the new electronics in the electric thrusters that were to divert the asteroid and they weren’t working as designed. From what Paul could tell from the ship’s instruments, they weren’t working at all. It was at this moment that Mikhail broke the news.
“I cannot fix the problem. I know what’s wrong but I don’t know how to fix it.”
Hui was the first to respond. “What’s wrong with them?”
“The unit is drawing power from the solar arrays, processing it and sending it to the thrusters. But the voltage is far too low to provide the acceleration needed to meet the propulsion requirements. It’s only about twenty-five percent of what they need to operate. The performance of these systems isn’t linear. You can’t run it at twenty-five percent power and get twenty-five percent of the thrust. If you run it at twenty-five percent or even fifty percent power, you get zero net thrust. They simply aren’t going to work.”
“Would another EVA help? Is there anything you can do to them physically that will get them to a hundred percent?”
“No. I’ve looked at that. These are complex electronic circuits, fabricated in clean room conditions, and there is no way I can rewire or jump start them. Something is wrong with the hardware and there is simply nothing else I can do. We’d get more thrust out of them by throwing them off the asteroid a piece at a time!” Mikhail sounded frustrated and at his wit’s end.
“Well, then, we’re screwed,” said Gesling, being uncharacteristically negative.
“The rock isn’t being diverted, so Armageddon is still on. The people back home still think we’re dead as far as we know and there is the hypothetical nuclear missile that may be headed our way. I guess I now hope they did launch it. And in fact, hope they haven’t heard our signal yet so they don’t feel like they are sentencing us to death.”
“We can still leave, can’t we?” asked Hui.
“Not until a week before the impact. Remember we don’t have enough attitude control propellant to leave now and get safely home. If we do, we may get away from the missile strike, but we’ll be entombing ourselves in solar orbit for the next several million years. I’d just as soon not do that.” Gesling was feeling the weight of hopelessness bearing down upon him as he looked at the also-helpless looks on his colleagues’ faces.
“But what if they didn’t launch a missile? Then this rock will hit and kill millions. We can’t just give up and sit here.”
Paul looked again at his colleagues and saw the faces of defeat. He, too, felt defeated.
Silence.
“Paul, Hui, I have an idea. What if we land, and I mean physically land and tie down the ship to the asteroid and then fire our main engines while we are attached to the asteroid? The thrust would provide an impulse to the rock and perhaps get it to move enough from its path to miss Earth. I wasn’t going to suggest it unless it looked like we had no other choice and it is certainly starting to look like that now,” Mikhail suggested.
“Wow, that’s a Hail Mary play if I ever heard one,” Gesling replied, taking a deep breath before continuing. “It’s a long shot, but it might just work. I ran the numbers just after we arrived. When Bill and I were on the Moon and working to get Hui and her comrades home, we were always thinking of alternatives should what we were doing not work for some reason. I always want to have a backup plan. We’re still far enough out that we should be able to nudge the asteroid off course enough to miss Earth—if we can find a way to attach the engines to it.”
“What about after? How do we get home?”
“We don’t. Once we light up the engines and push this rock out of the way, we’re here for the duration. We’ll have one hell of a view of Earth as we pass by.”
“So we’ll be stranded and just remain here until we run out of air.”
“Most likely. If the people back home knew we were alive, then they might be able to mount a rescue effort. Maybe they could get something out to get us before we suffocate, but it would be another long shot. And it’s a longer shot since they don’t know we’re still alive. I would bet no one is planning a mission based on a small chance we’re still out here and stranded.”
“Can we move the ship to another part of the asteroid so we can get our signal back home?”
“We keep broadcasting the omni and hope they hear us. Otherwise, it’ll be long ride.” Gesling waved his arms, manipulating the virtual control panel in front of him, and the 3D projection of Sutter’s Mill momentarily vanished and reappeared with it and the Tamaroa now clearly visible. On the asteroid, about two hundred meters aft of the ship, their appeared a white flashing “X” with an arrow emerging from it and canted about seventy degrees off the normal.
“According to the geometry of the asteroid and the trajectory we’re on, the best hope we have for pushing it in the right direction means we need to have our thrust vector pointed in the direction of that arrow. And we need to do it as soon as possible. Every minute we wait decreases the probability of successfully diverting the asteroid. This kind of thing only works if you thrust as far away as possible from the impact point.”
“Show us the Earth,” asked Mikhail.
Gesling again manipulated the wispy virtual control panel and the 3D image of Earth appeared on the other side of the cabin.
“And the geometry of where we are now, the thrust point and the Earth are all correct?”
“Yes. The rock will be between us and home almost all the way in,” Gesling said as he moved his hands above the virtual controls. A fraction of a second later, the holographic projection was
in motion. Sutter’s Mill slowly followed a curved path toward a point in space well ahead of Earth, which was also moving toward the same point. In a few seconds, they were both converging on that point in what looked like it would be a collision, but at the point of almost impact, Sutter’s Mill moved across the path of the Earth moments before the two could collide.
“That’s the best case. And you can see that we won’t be in a line of sight and have enough power to use the low gain antenna to communicate with Earth until after we pass and are on our way into deep space. By then it will be too late for anyone to come after us.”
“But we’ll be able to let them know we’re alive and what we’ve done,” said Mikhail.
“Yeah, we’ll be able to do that. And say our goodbyes.”
“And there is a chance that they’ll notice the asteroid is no longer on a collision course, call off the nuclear strike and send a rescue ship. Or pick up the omni signal, but it is likely the asteroid is blocking it and will be until it is too late.” Hui tried to sound optimistic but was having a hard time doing so. There were just too many variables working against them.
“That’s a lot of miracles but we can always hope. I suggest we take one step at a time and if a miracle happens, or multiple miracles, then all the better,” Gesling said and immediately thought of the miracle he was still praying for each day—that Carolyn would wake up and return to a normal life. Yes, he did need multiple miracles. “Mikhail, is there any chance of finding enough cabling that we could walk the low-gain antenna around the asteroid and point it at Earth?”
“Sorry, Paul. While we might find that much cabling in the ship, it would take salvaging it from almost every system and rigging it all together. Not sure it would work then anyway.”
“What about just taking a radio around the asteroid?” Hui asked.
“Maybe we could pull one from the ship, but that would take some time.”
On to the Asteroid Page 16