by Issui Ogawa
“Don’t forget, we’re going after a gold mine here…Okay, we’re getting close. Take a seat in the corner over there.”
Hibiki broke off the conversation and turned to his console. Sohya sighed. “A gold mine. I guess he’s right. The only reason we’re going through the trouble of sending a probe is to find water. It’s ironic. NASA just showed how important that is.”
“If Serpent brings back samples, I bet they offer us a million dollars for them.”
“No way. Ten kilos is all Serpent can carry. And we’re paying for it.”
“I’m paying for it, actually,” said Sennosuke with an innocent air. He laughed quietly and turned back to the mission screens.
Serpent was scheduled to bring back no more than ten kilograms of lunar material—a stark testament to the difficulty posed by a round-trip to the moon.
Eve I was forty-one meters long and weighed 148 tons fully loaded. It was capable of carrying fifty tons of payload into low earth orbit, ten times as much as other vehicles of similar size. For lunar orbit, its payload was ten tons. But since this was Eve’s first launch, the payload was limited to 20 percent of maximum: two tons. That determined Serpent’s total weight and the payload it could ferry back to Earth.
Half the probe’s weight was accounted for by the orbital module. This was the heart of the probe, containing the satellite bus—power supply, communications gear, and attitude controls—as well as the engine, propellant for insertion into lunar orbit, a small relay subsatellite christened Figu, and a remote-sensing system for surveying the lunar surface. Using the capabilities of this module, Serpent made several passes over the south pole, using lasers and a spectrometer to pinpoint promising locations for water ice.
The remaining ton of mass was accounted for by the landing module. After the landing area was selected, this module would separate from the orbital module, maintain communication with Earth via Figu, and land on the moon.
Half of the landing module’s mass was propellant: nitrogen tetroxide and hydrazine. This would allow the module to hover over the surface and carry out a more detailed search for the best landing area. Once the area was selected, the module would fire its engine, lower itself to the surface, and collect samples.
The mission’s goal was to explore the nature of the ice-bearing material. It was virtually certain ice would be found, but its form was unknown. Water molecules deposited over hundreds of millions of years might be distributed like snow or as frozen lakes with an overblanket of regolith. It might be buried deep beneath the surface or mixed with particles of regolith in a kind of permafrost. It might even lie in scattered basins separated by tens of kilometers free of ice. Scientists had proposed a variety of such scenarios. Before the water could be utilized, Serpent had to determine which if any of these models was correct.
Great care had been taken to configure the landing module so it could return with samples regardless of the nature of the ice deposits. First, Serpent had to touch down on an ice deposit. To ensure this, it was equipped with active sensors in everything from microwave to infrared frequencies, and it was equipped with drills that would allow it to access ice on, as well as below, the surface. To prevent the torque of drilling from rotating the lander in the weak gravity, the drills would operate simultaneously. If one of them were to break, a sample could still be obtained. Even if drilling proved impossible, a contingency sampler—a collection bucket fired onto the surface with a small explosive charge and then reeled back with a wire—could recover a sample by scraping the surface.
Serpent’s collection hardware totaled around a hundred kilograms. More than half of the remaining four hundred kilos was propellant to send the upper half of the landing module, known as the return module, back into lunar orbit. The descent engine, landing struts, and sampling gear would all be left behind. The lunar escape velocity is 1.68 kilometers per second, around Mach 5. But because of the moon’s weak gravity, attaining this velocity would be comparatively easy.
Once back in orbit, the module would execute a trans-Earth injection burn and leave the moon behind. The propellant it carried was required to take it to this point.
Now reduced to one-hundred-odd kilos, the module would reenter Earth’s atmosphere a few days later, deploy a parafoil, and glide to New Tanegashima Airport. Its final weight, after loss of its parafoil and the ablation shield to protect it against the heat of reentry, would be just over forty kilos. The weight of the sample was ten kilos.
This was the reality of round-trip lunar travel. One hundred and forty-eight thousand kilos launched, forty-odd kilos returned. To escape from the gravitational pull of two celestial bodies and make a journey of over a million kilometers, a huge amount of propellant was required for multiple engine burns.
Still, the terms of space travel could be improved. Eve had demonstrated only a fifth of its lifting capacity. This first mission incorporated many design approaches that were proven but not especially efficient—for example, using the same type of hydrazine engines that had served the Apollo program over half a century earlier. Optimizing these systems on subsequent missions with more advanced hardware would mean more efficient round-trips. Two Eve rockets would be launched simultaneously, allowing five passengers and a pilot to make the round-trip journey to the moon. Yet space travel would still be similar to a solitary, perilous journey across a desert in which one was forced to carry all needed provisions.
But the moon’s water could turn everything on its head.
The moon receives continuous sunlight. Convert that sunlight to electricity, and water could be electrolyzed into oxygen and hydrogen, two extremely efficient chemical fuels for powering a rocket returning to Earth. Not only that, since the fuel required for the last leg of the journey need not be ferried to the moon, fuel requirements for the outbound leg would be that much less. It would be as if there were an oasis at the midpoint of the desert journey, waiting with provisions required for the journey’s second half. Provisions that before were necessary just to supply the energy required to carry supplies to the midpoint would not be needed either. Travelers could set out across the desert with a deceptively light amount of baggage.
The moon’s water would not only make concrete production possible. It would transform lunar travel as well as the viability of settlement on the surface. TROPHY was essential to make use of atmospheric oxygen for escape from the atmosphere, but carrying a heavy load of oxygen into space still imposed significant limitations. Oxygen could be recovered from the moon’s regolith, but only through complex processes. Electrolysis of water was straightforward. Oxygen produced at low cost in large volume was the best news people living on the moon could have. There was more than the future of Sixth Continent on the line; space agencies around the world were closely monitoring this mission to see if the moon’s water could be easily accessed.
At 1830, Flight Director Hibiki gave the word. “Separate LM. Initiate descent.”
“Undocking LM. Starting descent.” Then, “First LM descent burn complete. Serpent is in the corridor.”
“Figu nominal. LM telemetry is five by five.”
“LM passing moon’s limb. Starting countdown to loss of signal. Five, four, three, two, one, LOS. LOS error, minus 0.2 seconds.”
“Signal handoff to Figu.”
“LM to auto control,” said Hibiki.
“Handing off LM to auto control.”
From now on, the lander would be engaging in critical maneuvers that could not wait for signals from Earth, so control was handed off to Serpent’s own computer. Beyond that, there was nothing to do but trust the AI, the same program refined through four years of hard work and used by Gotoba’s dozers. The software had already proven itself.
The landing module descended rapidly from its altitude of one hundred kilometers. There was no video feed; this would occupy too much transmission bandwidth. But the numerical data flowing in from the lander allowed the controllers to track its progress as if they were watching it with thei
r own eyes.
“Twelve thousand…eleven thousand…ten thousand. LM is in permanent shadow zone.”
“LM pitch over. Floodlights on. Ground radar on. Spectrometer engaged.” The lander flew over several pitch-black craters. Everyone’s nerves were taut.
“Getting solid returns. We’ve got clear absorption lines close to 2.15 microns near-infrared.”
“Ice on the surface,” Hibiki murmured, relaxing slightly. Checking for near-infrared absorption lines was the best way to confirm the presence of ice, but it required a light source. In the eternal darkness of the shadow zone, the lack of sunlight had made such investigations impossible. Serpent’s floodlights allowed readings to be taken for the first time. Furthermore, it seemed the ice was not buried. “Verify ground radar telemetry,” barked Hibiki. “I don’t want to get this far and plow into a mountain.”
“We’re fine,” said the GNC officer. “Readings from the last orbit confirm no areas of major elevation…Altitude eight hundred. Down at ten, fifteen forward.”
“Scanning for touchdown point. Fuel consumption is running slightly ahead of schedule. Should we move up touchdown?”
“No. Let Serpent decide. I’d rather risk a few extra burns to avoid a hard landing.”
“Roger.”
“Tae, do you know what’s going on?” Sohya saw the answer in her faint smile.
“Yes. It’s going well, isn’t it?”
“Seems like it.” Sohya nodded and looked at the displays.
Then it happened. GNC raised the first warning. “We’ve got metal!”
“What?” Hibiki craned forward in his chair. “What metal? What’s the data, what telemetry are you looking at?”
“Ah…I don’t know, the radar spiked suddenly. Like bouncing off a car.”
“Probably a flat boulder. Don’t worry about little anomalies.” But as Hibiki was dismissing the reading, shouting came from Flight Dynamics and INCO.
“LM pitch over complete! AI has initiated touchdown sequence!”
“Telemetry off nominal! Range finder spike!”
Again Hibiki responded instantly. “Terminate descent! Camera on! Altitude?”
“Eighty!”
“What’s going on? Did Serpent confirm the touchdown point?”
“No. She skipped confirmation. She’s proceeding with the landing sequence.”
“What is that, a system error? Give me a visual!”
“That will use most of our bandwidth.”
“I don’t care!” shouted Hibiki. “Forget the spectrograph. If we go down, I want to see it with my own eyes!”
GNC brought the feed from the lander’s belly camera onto the center display. The image that loomed into view was met with stunned silence.
Hibiki stared, face frozen in surprise. “What is that? Gold dust?” he whispered.
The image before them looked like flecks of gold scattered across the bottom of a river, or perhaps countless golden breakers whipped by the wind. Against a brown background, the fine particles spread endlessly, sparkling in the lander’s floodlights.
Hibiki stiffened. “It’s getting closer! Are we descending?”
“Yes! The hover command was ignored. Kill the autopilot?”
“No—wait! Velocity?”
“One point one down. Right on the money.”
“Let her go!” Hibiki gave the command without hesitation. The lander’s computer might be malfunctioning, but he decided to leave it in control of the descent. “Passing twenty. We’re beyond the abort limit. On your toes, gentlemen!”
The controllers were huddled in front of their screens, faces drained of color. The lander descended smoothly toward the sparkling surface. It was hard to believe it might be malfunctioning.
The halo of illumination from the floodlights narrowed toward the center of the display. At the same time, the surface began to blur, concentric circles of pale dust radiating rapidly outward. The room started buzzing.
“Steam?” called out Hibiki.
“No. Ice crystals. The vacuum is too high to sustain the liquid state. The ice sublimates and freezes again instantly.”
“Diamond dust!”
“Maybe dry ice?”
“She’s touching down,” said Hibiki. “Don’t sink…” He swallowed hard. The room fell silent again. This was a worry. Even if the surface could not support the weight of the lander, it would be viable as long as it sank only as far as the landing struts. If the sinkage were any worse than that, there would be no liftoff.
There was no sound, but everyone imagined it: three landing pads making hard contact with the surface. That was how abrupt the shock of contact was. The image jerked. The stream of fog kicked up by the lander engine abated. The LM engine shut down on sensing contact. Fine white dust streamed in all directions in a classic parabola and slowly fell to the surface. When the rain of particles ceased, the image cleared. The surface was clearly visible.
The controllers were glued to their monitors. Then, as if coming to his senses, one of them began calling out the data at his position.
“Flight, we have contact! Elevation, zero. Slope, zero. Sinkage, zero. Touchdown successful.”
“Success?”
“Success!” The room shook with triumphant cheering.
“Quiet!” Hibiki rose slightly from his chair and pounded his console. “Figu won’t be overhead for long. There’s no time for celebration. DPS! Disengage autopilot. Don’t go to backup yet! GNC, check telemetry and diagnose the dropout prior to touchdown. C&R, deploy the contingency sampler. Then the drills! Hurry!”
The controllers began calling out a stream of status updates. After a few moments the Data Processing Systems engineer advised, “Telemetry analysis points to a dropout triggered by circuit noise.”
“Noise? From where?” pressed Hibiki.
“Flight, I think I have it!” GNC put a ground radar plot on one of the forward screens. “The metal reading. That was clearly anomalous—the reflection was so strong it interfered with auto control. We didn’t expect this. The circuits are well shielded.”
“All problems are unexpected,” snapped Hibiki. “Can you recover?”
“Primary, secondary, and tertiary system diagnostics are all nominal. Whatever it was, it was transient.”
“Go to secondary just in case. Are we going to have the same problem on the way out?”
“No. We won’t be using ground radar on the way back to orbit.”
“All right then! Good so far…” For the first time, Hibiki sat back in his chair and took a deep breath. Then he turned to his visitors.
“Shall we take a look at the scenery?”
“By all means,” said Sennosuke.
“Hold it. Aren’t you Mr. Toenji?” said Hibiki, finally noticing the project sponsor. “Perfect timing.” He grinned. “Take a look at your new continent.”
He engaged the color CCD camera atop the 120-centimetertall lander. Something appeared on the main display, but the image was nearly dark. The lower half was a white blur.
“Is that a camera malfunction?” asked Sohya.
“No. The default sensitivity is very low. Once an Apollo astronaut fried his camera by accidentally pointing it at the sun. Let’s bring it up slowly…” As he spoke, the image gradually brightened and sharpened.
The white portion was the surface, illuminated from the underside of the lander. The long shadow of a landing strut cut across a fine carpet of sparkling particles, like a ski slope at night. Beyond the circle of light lay impenetrable darkness. There was no sign of surface, horizon, or space.
Tae’s voice broke the silence. “So this is the three-billion-year night of the shadow zone.”
“Yes,” said Hibiki. “Let’s switch on the floods.” The lander’s two-hundred-thousand-candlepower LED floodlights flashed on. For the first time, the team saw where they were.
It was a titanic, naturally occurring coliseum. The floor of the crater was draped in glistening white, like a blanket of snow
reflecting light in all directions. Softball-size rocks were scattered across the surface. A wall of jagged cliffs was visible just above the horizon. Hibiki panned the camera. The cliffs stretched unbroken around the compass. That must have been the crater rim. The lander had touched down in the center of the crater.
“Radar puts the height of the rim at 140 meters. If they’re on the horizon, that makes the crater diameter four kilometers. How steep are those cliffs?” said Hibiki.
INCO answered, “Slope is thirty degrees. Might be difficult to lay cables from the solar array over the rim.” If ice were detected where the lander touched down, the equipment to gather it would need power. To supply power in the darkness of the crater, solar panels would have to be set up outside the crater, where sunlight was available, and cables laid into the crater. One of Serpent’s goals was to locate a crater where this would be feasible.
Then one of the controllers spoke up. He was looking at a detailed map of the terrain.
“This is too good to be true. The height of the rim doesn’t matter. In fact, we’re lucky it’s so high.”
“What do you mean?” said Hibiki. The controller was rotating the map. The controllers on either side of her were staring at it as well.
“The crater’s elevation is slightly higher than average. It’s relatively isolated. That means sunlight will strike all along the rim. If the rim were lower, the crater wouldn’t be in shadow.”
Hibiki was skeptical. “There must be other craters with that profile.”
“Yes, but they’re at least twenty or thirty kilometers across. They’d need panel arrays on opposite sides of the crater to maintain power as the moon rotates with the earth around the sun. Here the panels can be spaced around a circumference of twelve klicks or so. The cables can be shorter. People on the surface will have less ground to cover.”
“This is prime south pole real estate!”
