Delta-v, page 44
“You’re not going to finish the ship if you’re dead.”
Adisa shielded his eyes against the light. “We were supposed to depart today. Each day we delay makes return less possible.”
“We’re working on it.”
“We must fly, or we will die. Overdosing hardly matters.”
Neither Tighe nor Jin reacted. They all knew they’d missed the ideal return orbital window. Earlier that morning Tighe had watched one of the ship’s cameras aimed back at Earth. Ryugu was close enough now for him to discern the Earth and Moon as two separate disks side by side. A finger’s width to the right were the Pleiades—which was 365 light-years away. The Earth might as well have been the Pleiades for how accessible it was to them.
Now each additional day of delay required more delta-v to reach Earth. Soon, they’d never be able to encounter Earth at all. Tighe didn’t want to know the day of their point of no return. The knowledge would only weigh on him.
He knew—as all of them knew—that their return ship still needed days of work. The metallic hull, hatches, plumbing, and engines were all complete, but the electronics were still a mess. The mismatched, cannibalized parts from the Konstantin and CRC’s mining robots caused difficult-to-pinpoint failures and errors. The guidance system was sketchy. And the ship was so stripped down that literally everything had to work—there were no redundancies.
Abarca prevented Adisa from sitting up. “Rest, Ade. Get some rest.”
* * *
—
More than a week later, Tighe, Jin, and Chindarkar stared at nothing as they sat numbly around the galley table in Hab 2. They’d each lost several more kilos of weight and looked haggard from overwork. The James Caird was still docked near the refinery.
Every day the bright disk of the Earth drew closer. Now it was just 58 million miles away. However, because it was coming closer, it also meant they might not be able to close the gap before it passed them by.
As of today, Tighe, Jin, Chindarkar, and Abarca had done all they could to prepare the vessel. They’d even loaded their scant personal belongings and other supplies onto the James Caird, ready to depart the moment it was finished.
The remaining work was software based and relied entirely on Adisa and mission control engineers. The astrogation, guidance, and fuel management systems were still only partially complete due to flaws that Earth-bound engineers had not yet been able to rectify. There was nothing more that Tighe, Jin, and Chindarkar could do to help.
As tired as they looked sitting around the table, they all knew Adisa was even more exhausted—even as he used his considerable intellect to wrestle with complex software integration problems.
Adisa’s voice came in over the comm link. “J.T., Han, Priya. I need you to prebreathe for another diagnostic, please.”
Tighe answered wearily. “Did mission control resolve the errors?”
Adisa had an edge in his voice as he replied, “I will not know until we run through the tests.”
They all exchanged looks and then went to retrieve oxygen masks.
Two hours later, they exited the lower airlock in their blue flight suits—all three of which had black Kapton tape sealing leaks from worn joints. They moved along the scaffolding where the James Caird was still moored near the Konstantin’s refinery. As sleek as the aerobraking vehicle was, the rest of the vessel was an ungainly gridwork of girders and piping, with twin rows of spherical tanks—all designed to withstand significant g-forces from acceleration. And yet, the ship was inert.
Jin keyed his mic. “Almost in position.”
“I copy.”
There was a standard docking hatch on the starboard side of the aerobraking craft, but it was easier to enter the ship by pulling themselves past the booster’s rocket engines, hand over hand across rows of fuel pipes, between fuel tanks, and then to enter the crew module. The hatchway here was square and much larger.
Once inside, they continued through another narrow hatchway and into the aerobraking vehicle itself. Here, there was room for four rows of two seats in a narrow compartment—although only five seats were installed. The ship had originally been designed to return the entire eight-person Konstantin crew. Every time Tighe saw the empty slots, he felt the absence of Clarke, Morra, and Tsukada.
Soon they strapped in, Jin in the pilot seat, Chindarkar as astrogator, and Tighe monitoring fuel systems. After tapping at a few virtual buttons, Jin instantiated a virtual windscreen. Tighe could now “see” through the steel hull of the vessel via the plenoptic cameras embedded in housings there.
Jin spoke over the comm link. “Ready for diagnostic check, Ade.”
“You are all seated?”
Jin looked around the cabin. “Affirmative.”
The vibration of turbopumps winding up reached Tighe’s inner ear. He exchanged confused looks with Jin and Chindarkar.
Jin stabbed at virtual controls. “We hear the fuel system pressurizing.”
Adisa said, “That is because I’ve launched a countdown timer.”
“A countdown timer?”
Tighe sat up.
“I am launching the James Caird. For real. Remain in your seats.”
Jin scowled. “Ade, what the hell are you saying? Isabel! Ade needs help. He’s suffering some sort of nervous—”
“I am not suffering a breakdown, Han. Everything else is. The return ship will launch in four minutes whether you are on it or not.”
Tighe shouted, “Why are you doing this?” He unbuckled and pulled himself out of his seat, floating back toward the crew module.
Chindarkar called to him. “J.T.! The ship’s on a countdown!”
Tighe exited through the rear hatch.
Abarca’s voice came in over the comm link. “Listen to Ade! He isn’t delirious. And this decision isn’t sudden. Adedayo and I made it some time ago.”
Chindarkar shouted through the link, “What are you talking about, Isabel?”
Tighe glided through the crew module as fast as he could, headed back toward the Konstantin.
Adisa’s measured, calm voice said, “Listen, all of you: we are out of time. I have reviewed the calculations with Isabel and confirmed them with mission control. If we wait even twelve more hours, none of us will ever reach Earth.”
Tighe shouted over his radio, “Then why aren’t you and Isabel on board?”
Adisa answered, “There are too many uncontrolled variables for this ship to fly a predictable trajectory without external aid—and the minute we launch from the Konstantin you will lose contact with Earth. An error of a fraction of a radian at the beginning and you will miss Earth entirely.”
Tighe exited the crew module and moved between the piping and fuel tanks. For the first time he noticed the tanks were wicking off white vapor—loaded and ready to go. He called over the comm link, “We are a crew, Ade. A family. We decide together!”
“J.T., there is no other reasonable choice. If we all stay here, we all die. There is not enough food. But if you three go, Isabel and I have over five years’ of supplies. You can send help for us.”
“Goddamnit! That’s too dangerous. Even if you live—” Tighe reached the Konstantin’s lower airlock and tried to slide the lever—but it was stuck. He looked up at the glass portal.
Abarca’s face stared back at him, the handle of her ice ax jamming the lever in the locked position. She shook her head, her voice coming in over the comm link. “Get back on the ship, J.T. You have less than three minutes.”
He pounded on the hatch. “Cancel the launch! This isn’t how we say good-bye! I know you can cancel it!”
Adisa’s voice: “That is where you are wrong, J.T. I have overfilled the fuel tanks with superchilled liquid oxygen and liquid methane. It is the only way to give you the higher delta-v you will need—over 20 kilometers per second. Without the added mass of Isabel and myself, or the food and oxygen we would need, you will go even faster. However, if you do not burn this fuel in the next five to ten minutes, it will expand as it warms. It will burst the tanks and possibly explode, killing everyone and destroying the Konstantin.”
Tighe looked back at the growing white clouds wicking off the fuel tanks.
“Jin and Chindarkar cannot fly the ship by themselves. Two people to handle the fuel-line switchover, and one to effect the course corrections I will provide by radio. You must go now, J.T. There is no stopping the launch.”
Abarca said, “Get on the ship, J.T. Or you’re killing us all.”
Tighe turned to look at Abarca’s face through the portal. “I understand why Ade is staying, but why would you?”
“Ade is here because of me. And I don’t leave until my entire expedition is off the mountain.”
Adisa’s voice: “Two minutes! You must board the ship, J.T. Please, I beg you!”
Tighe moved right up to the borosilicate glass, placing his glove on it. “Let me take your place, Isabel. I once left my diving partner to die. I won’t do it again.”
Abarca nodded to herself and smiled at Tighe as she placed her hand against his beyond the glass. “I think Richard Oberhaus would be proud of what you’ve done with his years.” She shook her head. “But you and Han are the most experienced on EVAs. I’ve barely been in a suit.”
Adisa shouted, “J.T. Board the ship!”
Tighe stared at her. “We will return for you.”
“I have no doubt.”
With one last glance, Tighe pushed off and moved across the scaffolding with practiced ease. He grabbed the piping of the James Caird and moved between the rows of steaming fuel tanks.
CHAPTER 47
Injection Burn
FEBRUARY 19, 2038
As James Tighe pulled himself aboard, he turned back for one last look at the Konstantin. He committed to memory the image of Abarca and Adisa floating near the ship’s core in their faded jumpsuits, the Far Star glittering in its perch beneath an LED light.
Tighe noticed Jin Han exit the crew module of the James Caird. Jin glided over the piping. He pointed urgently at the steaming tanks. “Take position for launch.”
Tighe nodded and moved to the first of three fuel-line levers on the port row of tanks. Here, a series of eyebolts were placed for him to clip in, along with spiral steps running the length of the starboard piping. Jin clipped in at the base of a second spiral stair on the port side.
Tighe spoke over the radio. “Adedayo Adisa, Isabel Abarca, Nicole Clarke, David Morra, Amy Tsukada—it has been an honor crewing with you.”
Adisa said, “You are all my brothers and my sisters.”
Chindarkar answered, her voice cracking. “I love you, Ade. I love you, Isabel.”
Abarca responded, “I love you, too, but don’t get too weepy just yet. For all we know, you’re the ones who are about to die, not Ade and me. If you have any chance to make Earth, you will need to remain focused and follow Ade’s radioed instructions closely for as long as you’re in range. Emotion comes later.”
Chindarkar sniffled. “Copy that.”
Adisa’s voice came in. “Releasing docking clamps . . .”
Clamps at the four corners of the scaffolding released the return ship, and cold-gas thrusters vented, pushing it slowly away from the Konstantin.
Tighe looked up at the black shadow of the asteroid Ryugu. The Honey Bees were still at work up in the sunlight above its horizon. A line of a dozen boulders waited there in a terminator orbit. The mining would continue.
The James Caird was still gliding slowly away from the Konstantin—not quite 20 meters away now. The larger ship’s radial arms swept past overhead. The lights on the girders of the Konstantin made it look like a refinery in the night.
Adisa said, “Priya, I will track your position using the Ka-band transmitter and advise you. Check your display for my trajectory adjustments. As of ten minutes ago, the James Caird will need to achieve a delta-v of 24.4 kilometers per second to encounter the Earth in forty days. Mission control knows to listen for you on or after March 31.”
Jin answered, “Twenty-four point four kilometers per second? Ade, can we achieve aerocapture at that speed?”
“You have no choice but to try. You will have to make adjustments, Han. If any of us can do it, it is you.”
Tighe looked at Jin’s anxious expression.
“It is time to go. . . .” Adisa began a countdown over the comm link. “Ten, nine, eight . . .”
Tighe studied the familiar form of the Konstantin, pirouetting, now 300 meters away. It was hard to believe that after all these years, the expedition would end so suddenly. “Godspeed, Konstantin.”
“. . . two, one, ignition.”
Nothing happened.
“Shit.” Tighe turned to Jin.
Chindarkar’s voice: “Ade, we’ve popped a circuit breaker. Fuel control system. J.T., Han, there’s a short somewhere. The computer’s preventing engine startup.”
“We’re on it.” Tighe pulled himself along the lattice framework as though climbing over monkey bars. “What subsystem?”
“Fuel Pump 2.”
Jin called out, “Here.” He motioned for Tighe to join him, and they pulled apart a section of cabling.
“Yeah, Priya, the shielding on the cabling’s damaged. We’ll wrap it.”
“Copy that.”
They started wrapping the cable bundle with Kapton tape. Tighe looked up at the fuel tanks wicking white vapor more furiously now.
Ade’s voice said, “You must hurry. The fuel is warming. We do not have much time to get the engines started!”
Tighe knew the six bladder tanks around him contained 180,000 liters of methalox rocket fuel each—more than a million liters in total. A thousand tons of explosive energy. If there was even a small spark among the engine piping, then the explosion might actually be visible from Earth.
In a few moments, he and Jin finished wrapping the ignition cable. They returned to their stations, clicked in their tethers, and held on to steel handles, bracing for acceleration.
“Ready! Try again!”
Chindarkar’s voice: “Begin the countdown, Ade!”
“No time for a countdown! Safe journey!”
“We—”
Suddenly the twin Starion rocket engines roared to life, their red-white exhausts forming interlocking cones. There was no sound—but the steel plumbing all around Tighe vibrated, and a bass rumble entered his middle ear.
He and Jin examined the piping for leaks. There were no telltale gas plumes.
“Good burn—both engines, Ade!” Tighe glanced back at the Konstantin.
They didn’t appear to be moving. His view of the black shadow of Ryugu behind them wasn’t changing either. Neither was he experiencing much in the way of acceleration. Yet, the James Caird’s engines—each capable of 430,000 foot-pounds of thrust—were at full throttle.
Jin said, “She is heavy!”
Tighe nodded. Ninety-five percent of the James Caird’s 1,200-ton weight was fuel, and they were going to burn through all of it in the next ten minutes.
Adisa’s voice came to them again. “Check your AR display. We have tank changeover in two minutes, forty-five seconds.” Tighe and Jin took up their positions across from each other at the first set of valve handles.
Although the process was ludicrously crude, Tighe and Jin would have to manually switch over the fuel tanks as they drained. The James Caird was a fly-by-AR vessel, piloted exclusively with virtual controls and monitored by virtual gauges. Even now a virtual row of fuel tank levels appeared in Tighe’s crystal display. His crystal had transferred to the Caird’s wireless network, and now he was looking at this ship’s telemetry readings. They were traveling at 6 meters per second and accelerating.
Each fuel tank would burn for three minutes and thirteen seconds. The valves had to be manually switched from one tank to the next before the rocket’s fuel source ran dry. Once started, if the engines were not properly shut down, any sudden loss of pressure would cause the engine to explode—which would in turn cause their entire ship to explode, killing everyone.
“We can’t screw this up, Han.”
Jin nodded.
Tighe and Jin would do the cutover with an eight-second buffer. As each tank emptied, they would unlatch the brackets holding the empty bladder tank in place—and it would pull free from its fuel hose and fall away behind them as they accelerated away, shedding several tons of deadweight.
As the total mass of the James Caird dropped, g-forces from acceleration would increase. Mission control engineers estimated they would endure a maximum of 3 g’s acceleration. However, with the extra fuel Ade had loaded, it was anyone’s guess what the final acceleration would be.
Looking back between the exhaust plumes, Tighe could see they were now noticeably accelerating, pulling away from the Konstantin and from Ryugu. He never imagined that leaving the asteroid would be bittersweet.
The James Caird continued to pick up speed. Suddenly they moved out from the shadow of Ryugu and into the sunlight, and most of the stars and nebulae faded to invisibility.
Adisa’s voice came in over their local comm link. “You are approaching 10 kilometers’ distance from us and will soon be out of voice radio range. After this, we will only be able to communicate with you through a Ka-band data channel. I am sad to say that this is, for now, good-bye.”
Abarca’s voice came in over the radio. “Don’t be sad. You will need all your focus for the challenges ahead. Ade will guide you. Reach out to us, and we will be here.”
Tighe spoke over the comm link. “Isabel, Ade, take care of yourselves.”
Moments later the radio link to the Konstantin disappeared in a fuzz of static.
But there was no time to mourn as the first fuel tanks emptied, and Tighe monitored his gauge and performed the cutover, then watched the rocket plume as the new fuel tank took the place of the first. To his relief it went smoothly.
