Deorbital

… continued from Periapsis

Anna squeezed the contents of the meal packet into her mouth, barely registering the pea protein and coconut oil texture as she gazed into the starry void. The ring station was now not much more than a thin line, glinting in the sunlight, arcing high overhead as the shuttle gradually ascended in its elliptical orbit. The half-disc of Kepler 62f’s larger moon loomed beyond the shining arc, while the smaller moon hung low, just above the horizon.

Seventeen hours had passed since the engine failure, and in that time the shuttle descended through the night to their closest approach to the planet, and now they ascended once again through the dawn’s light toward apoapsis. Anna had run what tests she could, and it now seemed clear that neither OMS engine would be usable. When the starboard engine exploded, shrapnel and hot gases ripped through fuel and control lines for all systems at the aft end, leaving only the forward RCS thrusters safe to fire. The shuttle would need drydock to effect repairs. Anna was sure Takashi would have been able to do it back in the docking bay inside Aniara, but out here? Even Tak would be stretched, and she was no Tak.

She sucked down the last of the paste, biting uselessly on the end of the tube, and with a curse thew the empty packet across the cockpit.

“Hey.”

Laxmi put her hand on Anna’s shoulder. Anna shrugged her off, keeping her gaze outside, focused on the larger moon. The meal packet bounced off the copilot console, ricocheted from a bulkhead, and then skittered across the cockpit window, losing momentum with each strike.

“Anna.”

The tumbling packet rebounded off one more control panel before Laxmi reached out and snagged it from mid-air.

“Anna, look at me. This isn’t your fault. There was nothing you could do, nothing any of us could do.”

“The moon…”

“Anna, are you listening to me? Look, I know you’re blaming yourself, but you have to stop…”

Anna’s fingers started flying across her console keyboard. David charted a lot of data about the two planetary moons while they were on approach, didn’t he? Was that data here in the shuttle computer?

“Anna…”

Yes, it was here. Size, estimated mass, distance from primary, orbital parameters. Would it work? Could she pull this off? She quickly charted some navigational parameters and ran burn scenarios through the computer.

Laxmi sighed and turned away.

“Laxmi, wait.”

Laxmi saw the changed look in Anna’s eyes and looked at her expectantly.

“I have an idea. It’s… unorthodox. But I think I can save us.”

“You found a way to get us back to Aniara?”

“Well… no. But I can buy us some time. But I need to run it by you and Jaci first.”

14221079550_f7ddea5aaa_k
image credit: NASA Johnson

***

“You want to do what!”

“I want to land on the planet.”

“How in the hell does that help us?” Jaci waved his arms around in the air. If he weren’t floating in free fall, he’d have been pacing back and forth across the crew compartment. “It’s an alien planet, Anna! It’s the absolute epitome of an unknown variable. We’ll probably die down there! And it’s certain that once we go down, there’s no way for us to ever lift off the surface again.”

“You’re right. It’s an unknown variable. But we have to match that against a known variable, which is the absolute certainty that we’ll die if we stay up here. Probable death against certain death… I don’t know, but those seem like better odds to me.”

Jaci huffed, but he didn’t say anything.

“Look, I know it’s a long shot, but I don’t have another option. But if either of you can think of something better to get us out of this mess, I’m all ears.”

Laxmi spoke up. “If we have enough fuel for a deorbital burn from this altitude, why aren’t we able to use that to get back to Aniara?”

“We don’t. At least not in the normal fashion. We have only forward RCS, and that’s enough to push us around a little bit, but not enough to either deorbit or raise our orbit significantly. But, there’s a small window of opportunity opening up. We can use the moon to push us down to the atmosphere.”

“The moon.”

“Yes. Well, specifically, the L1 Lagrange point between the planet and the larger moon. When the OMS failed, it pushed us a few degrees off from the equatorial inclination. And that, as it happens, means that our orbit now passes through the plane of the moon’s orbit. And, what’s more, just before we approach apoapsis this time, we’re going to pass through the L1 point.”

Anna looked at them both expectantly, but saw only puzzlement in their eyes.

“You know, the point of balance between the gravitational pull of both bodies?”

“We know what a Lagrange point is, Anna. We’re just not sure… well, I’m not sure… what that has to do with anything.”

Anna sighed. “It’s like when we use a hyperbolic trajectory during unpowered acceleration…”

“Anna. Layman’s terms, please.”

“Jaci, didn’t you have to learn anything to become an astronaut?”

“Yeah. I had to learn how to translate heretofore unknown languages. That’s why I’m here. You had to learn how to pilot starships. That’s why you’re here. So… hyperbolic trajectory.”

“All right, forget the hyperbolic trajectory. But you’ve heard of getting a gravitational assist, right? This is kind of like that. A well-timed burn while passing through a Lagrange point is a low-energy way of transferring to a different orbit.”

“Can’t we use that to burn to a higher orbit?” Laxmi asked.

Anna looked uncomfortable. “Well, technically, yes, but there’s a problem.”

“Yes?”

“To raise our orbit, we need to burn prograde while we’re at periapsis. The L1 is much, much closer to apoapsis.”

“So can’t we burn prograde then?”

“We can. But it won’t raise our orbit. It’ll raise our periapsis, making the orbit a little less elliptical. If we keep doing it, eventually it’ll circularize the orbit. And, if we keep doing it beyond that, then it’ll start to raise our apoapsis. But, even with the Lagrange assist, that’ll take many orbits to achieve, and many burns, and we’ll run out of fuel before we get to that point. But…”

Anna paused, looked both Laxmi and Jaci in the eye.

“But, since the Lagrange is so close to apoapsis, and our orbit is already highly elliptical, a retrograde burn there, even with the RCS, should be enough to decrease our periapsis altitude significantly. And, on a second pass, we can decrease it again enough that we’ll start to skim the upper atmosphere. That’s all it’ll take. From that moment, deorbit is inevitable.”

“Ok, can we come back to the part about alien planet, and so on?” Jaci asked. “What happens once we’re down?”

“We already know we can breathe the atmosphere. That was one of the first things we figured out when we arrived. Otherwise there’d be no point to this. But we can, so that solves the most immediate problem. We know there’s water down there — the surface is mostly water — and we should be able to use equipment on the shuttle to desalinate and purify it. So, that’s the second problem solved. We have emergency rations on board that we can stretch out to last the three of us at least a month. After that, yes, we’re going to have a problem. So, we’re going to have to hope that we can find something to eat after we get there. Laxmi, your job will be making sure whatever we find is edible and nutritious. That’s our biggest unknown, but we know that life developed on this planet, and that it developed in an environment of oxygen and water. That life ate something. So, I figure our odds are good that we can eat whatever they ate.”

“That’s a pretty big assumption, Anna,” Laxmi said. “But I concede your point. We have a better-than-zero chance of finding food and surviving. But after that? This would be a one-way trip. The shuttle can land, but it can’t lift off again. We’ll be stuck.”

“Yes, well… That’s a problem, I admit. Honestly, I don’t know. But I can try to set us down close to one of the elevator bases. That at least should give us something to investigate in hopes of finding a way to use the technology here.”

“The technology that already killed Takashi, and maybe killed David, and almost killed us?”

“Yes, that technology.”

entry
image credit: NASA

***

Four hours later the shuttle approached apoapsis, the highest point of their orbit, and as it did so it also approached the Lagrange-1 point between Kepler 62f and the planet’s larger moon. There was nothing to see through the cockpit window to indicate anything special about this spot in space, nothing that any of them could feel that was in any way different. Yet, at the appointed time, the shuttle computer fired the forward RCS thrusters, following the program Anna configured. The thrusters fired continuously for twenty-three minutes while Anna watched their calculated periapsis altitude decrease, until the rate of decrease dropped off and it was clear the Lagrange effect had ended.

Twelve hours after that, everyone gathered in the cockpit to watch as the shuttle accelerated quickly toward a far closer approach, a mere eight-hundred kilometers above the planet’s nightside. It seemed that almost as soon as the sun fell below the western horizon it popped back up above the east again, and indeed in less than ninety minutes the shuttle began its final ascent, slowing as it climbed back toward apoapsis, and back toward the Lagrange low-energy transfer point.

“One more time,” Anna muttered, and they ascended into the star-filled night.

Twelve more hours, an eight-minute burn at the Lagrange point, and they began their last descent.

With each passing hour, the shuttle fell faster and the planet loomed closer, dominating the cockpit view. The terminator approached, consuming the blue globe with greater speed as their orbital velocity increased.

Anna wondered if the others felt the same sense of foreboding as she did, watching the advancing line of darkness, turning blue to black, day into night. Perhaps they felt it more strongly, resigned as they were to leaving their fates in her hands. She knew they trusted her; she only hoped their trust was not misplaced. A part of her could not shake off the thought that it was, that she had failed them, that she was in the act of failing them right now. But was there any other option? No way Anna ran the numbers came up with them flying back to Aniara, so no, there was no other option.

The terminator merged with the eastern horizon behind them, the sun flared a final time before dipping below the glowing arc, and then darkness commanded. Anna felt the tiniest of buffets through the shuttle’s frame, and she knew it had begun.

“Ok, guys, time to strap in. We’re starting to feel the atmosphere. I’m retracting radiators and solar arrays, and buttoning up.”

“We’re good back here. All clear to proceed, Anna.”

Anna fired the RCS thrusters again, not forward but downward at the nose, to push the shuttle’s nose up forty degrees relative to the horizon. The buffeting began in greater earnest now, the heat-shielded belly and spread wings of the spaceplane taking the brunt of the airflow. An orange glow appeared around the nose cone and the leading edges of the wings, bright against the nightside darkness. At this altitude, two-hundred kilometers from the surface, the air was still so thin as to be practically nonexistent, but having accelerated to over twenty-eight thousand kilometers per hour during the hours-long fall from geostationary orbit, every molecule struck the shuttle with the force of a mallet swung by a giant.

“Seal helmets and turn on suit oxygen. It’s about to get rough.”

“About to? What do you call this?”

The shuttle streaked across the night sky at Mach 25, twenty times the velocity of a speeding bullet, trailing fire in its wake as the speed of their passage compressed gases into burning plasma. Anna, Laxmi, and Jaci felt the force of their deceleration pushing them hard down into their seats as the shuttle slammed belly first into the thickening atmosphere. The turbulence increased as they descended, and Anna fought to keep her grip on the control yoke light and steady.

At one-hundred kilometers altitude and Mach 5, the air became thick enough for the shuttle to respond to flight control surfaces. The trail of fire had burned off, and Anna eased the nose back down to level flight.

“Engaging scramjets. I have flight control.”

Dawn tinged the air rosy pink, and far below and ahead the black ocean turned to grey, and then iridescent blue, dotted with islands, strings of emerald and golden jewels. A few high cirrus clouds lay slung across the expanse below them, but otherwise the sky was clear all the way to the horizon. Far, far above a faint silvery line divided the sky, which Anna knew was the ring station forty-one thousand kilometers above. Somewhere up there Aniara coasted, silent and unseen. Somewhere up there David’s fate remained unknown.

At ten kilometers altitude, and Mach 1, Anna found what she’d been looking for. Far ahead she could make out a whisper-thin vertical line ascending to the heavens.

“I’ve located the elevator cable and I’m adjusting course toward it. It’s still too far away to see the base, but I estimate it’s about a thousand kilometers away. I’m going to look for a place to put down somewhere near it.”

Anna eased the yoke over to bank the shuttle gently to the right.

A red indicator began blinking on her console.

“What now?” she muttered, and pulled up a diagnostic screen. From somewhere behind, she heard a thump, then a loud bang, and the shuttle yawed wildly to the right before turning steeply downward. Anna pulled up hard on the yoke to level out their flight path, but the shuttle now unmistakably descended at a much faster rate.

“Guys, we’ve lost the scramjet. It must have been damaged in the OMS failure, and then further weakened during reentry.”

“Wouldn’t we have to have been here before for this to qualify as reentry?” Anna could hear the strain in Jaci’s voice as he tried to make light of their situation. “But hey, we didn’t explode, so this is an improvement in terms of catastrophic failures for us, no?”

“Huh. Improvement, sure. Ok, we’re not gonna make it to the elevator cable. We can glide a little bit, but in unpowered flight this thing is a like a pig with little stubby wings. We’re descending under control, but it’s a fast descent. There’s a bunch of islands down there; I’m gonna try to set down near one of them. I won’t lie, this is gonna be a rough landing.”

Anna pulled back a little on the yoke, trying for that perfect angle that maintained an optimal speed while providing enough lift to keep their glide path shallow. Still, the water seemed to be coming up more quickly than she cared for. She banked the spaceplane along a chain of islands, verdant and mountainous, passing across knife-edge ridges atop sheer cliffs. Flat land seemed so far to be in short supply.

“No chance of a ground landing; it’s too rough. No surprise there. It’s gonna be a water landing. I’ll get as close to shore as I dare. Stand by.”

That one. She liked the look of that island, with its high central mountain and a ring of sandy atolls encircling a wide lagoon. One kilometer to go, skimming two-hundred meters over the water. Still too fast. Still too fast.

“Thirty seconds. Extending flaps. Stand by… stand by… hold on, here we go.”

Anna barely registered waves crashing against a fringing reef before the spaceplane zoomed across an outer atoll, barely skimming over the tops of what certainly looked like trees before rushing over the flat, calm waters of the inner lagoon. She pulled back hard on the yoke, desperate to bleed off airspeed and lift, and the aft belly of the craft skipped once, twice across the water, before settling in. Once full contact was made, friction with the water brought their forward motion to a quick, rather abrupt halt, causing the nose to dig in, dousing the cockpit windows with a great splash. Momentum threw Anna hard against the straps of her seat, knocking the wind out of her and dazing her for a moment.

With a groan of pain, she released her seat restraints, then glanced across the many angry blinking red lights on her console.

“Guys, we’re down, obviously. Everyone ok back there?”

“We’re alive,” replied Laxmi.

“Alive, yeah,” said Jaci. “But… I think my leg’s broken.”

… continued with Lagoon


header image credit: user:bachstroem / pixabay.com


© Matt Fraser and mattfraserbooks.com, 2018. Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Matt Fraser and mattfraserbooks.com with appropriate and specific direction to the original content.

One thought on “Deorbital

  1. Pingback: WorkInProgress: Deorbital – Matt Fraser

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