Lucas Zhang whistled softly to himself as he double-checked the seals on his EVA suit. The tune – an old pop song from decades ago – echoed in his helmet, mingling with the quiet hiss of the suit's oxygen regulator. He always whistled before stepping outside; it was a little ritual to steady his nerves. Not that he'd admit to being nervous – he'd done dozens of extravehicular outings on this mission – but something about this morning's developments had put a knot of tension in his gut.
He glanced across the airlock antechamber at Mira, who was similarly suited up and performing her own pre-check. The small room was lit by harsh white panels, illuminating the utilitarian gray walls scuffed by years of use. Two large pressure doors – one leading back into the base, the other to Charon's surface – framed the space. Between them, Lucas and Mira methodically went down their checklists.
"Comms test, channel 3," Lucas said, tapping the side of his helmet.
"Copy, I read you," Mira's voice sounded in his ear, slightly tinny through the suit radio but clear. Her face was visible through her bubble helmet – focused, eyes on the heads-up display projected in front of her.
"Vitals nominal on both," came Dr. Alva's voice from Control over the general channel. Sora was monitoring their suit telemetry from inside. "Lucas, your heart rate's a bit elevated, but still within safe range."
Lucas chuckled once. "All good here, Doc. Just my morning workout climbing into this suit." That earned him a faint smile from Mira. Truthfully, his heart was beating faster than usual, but he chalked it up to a mix of anticipation and unease about what they might find out there.
He gave Mira a thumbs-up. "Ready when you are."
She returned the gesture. "Beginning airlock cycle. Standby."
Mira pressed the panel to cycle the airlock. With a muffled clunk, the inner hatch sealed shut, locking them away from the base's warm confines. A red light blinked as pumps began evacuating air. Lucas's ears popped during the brief pressure drop. The atmosphere in the chamber thinned, the hum of the base's ventilation replaced by the quiet internal sound of his suit's life support.
In moments, a green light indicated they'd reached vacuum. The outer hatch slid open with a metallic rumble, revealing the stark landscape beyond. Lucas instinctively gripped one of the safety handrails beside the door. Outside was darkness relieved by a dim bluish twilight, and a horizon jagged with crater rims and ice outcrops.
He took the lead, carefully stepping out onto the greyish-brown regolith of Charon. The ground was a mix of hard-frozen water ice and rocky dust. His boots left shallow imprints that would likely last eons in the near-total stillness of this airless moon. Even with magnetic soles, every movement had to be slow and deliberate – one push off the ground and he could sail unmoored, given Charon's weak gravity.
Mira followed, each of them tethered to the airlock by thin rewind-capable lines – their lifeline back to safety. Lucas's suit lights automatically switched on, a beam cutting into the darkness ahead. Above them, the sky was a spray of brilliant stars, unhindered by any atmosphere. And dominating the sky, exactly where it always hung, was Pluto. The dwarf planet took up a large portion of the view, a great pale orb with faint hints of its famous heart-shaped region gleaming under scattered sunlight. Seeing Pluto so huge and static overhead always made Lucas feel both awed and uneasy – like living beneath a massive silent guardian. Or a grave marker, he sometimes thought, if mood was bad.
He turned his gaze away to focus on the task. "Tethers secure. Signal is good," he said into comms. "Let's move."
The communications array was located about 30 meters from the main habitat, connected by a heavy power and data conduit. It consisted of a high-gain radio dish and a cluster of antenna masts. In the faint Pluto-shine, the dish's rim glinted softly.
Mira and Lucas began their trek across the surface. Each step was more of a controlled hop – in one-sixth Earth gravity even a gentle push launched them upward in a slow arc. They both had plenty of practice: the trick was not to overdo it and risk a hard landing or drifting off if untethered.
They walked in silence for a minute, just the crunch of boots over icy dust audible through vibrations in their suits. Lucas scanned around, looking for any irregularities. Charon Base was a collection of squat cylindrical modules connected by tube-like corridors, half-buried under regolith berms for radiation protection. In the twilight, the base looked like a series of low mounds with a few protruding domes and the occasional blinking status light. Beyond, the terrain stretched into darkness, broken by a ridge silhouette and the yawning black sky.
"Seems quiet enough," he muttered to Mira privately on their suit-to-suit channel. "Hard to believe anything's wrong when it's this still, huh?"
Mira was a step ahead, carrying a small toolkit. She responded, "The calm ones are when things sneak up on you." Her tone was light but the meaning wasn't lost. Out here, disaster often struck without warning.
They reached the base of the communications mast. Mira's voice came on general channel: "Base, we're at the comm array junction. Beginning inspection."
"Roger that," Commander Patel answered from Control. "We see you on the external cams."
Lucas craned his neck up at the dish. It was a five-meter wide parabolic antenna mounted on a swiveling base. Right now it was idle, pointed roughly toward the ecliptic where Earth would be far beyond the horizon. Next to it, two tall rod antennas for other frequencies jutted into the sky. They looked intact.
He knelt (more like crouched gently, careful not to spring upward) to check the heavy cabling at the base. The thick bundle snaked from under the regolith – part of it was buried for insulation. At the junction box, he noticed something odd. "Mira, look at this."
She stepped over. Where Lucas pointed, a panel on the junction box was slightly ajar. It wasn't gaping open, but it wasn't flush as it should be. He could even see a tiny rim of frost around the opening – perhaps moisture from inside that had flash-frozen.
"I swear I closed that latch after the last maintenance," Lucas said. "No way I'd leave it open out here."
Mira nodded. "I remember. I was with you. It was definitely closed." Using a tethered screwdriver from her kit, she carefully pried the panel fully open. Crystals of ice flaked away, sparkling as they drifted in the suit lights. Inside was a tangle of colored wires and optical lines, as well as a diagnostic port. Mira anchored herself by slipping her boot under a strut and leaned in to examine. "It doesn't look damaged… Could have popped loose if something tugged on the cables."
Lucas frowned. "Tugged? Like an impact or… or a drone messing with it?" As soon as he said it, he realized it was a real possibility. If DV-5 had come out here on that mysterious errand, could it have tampered with this?
"I'll run a continuity check," Mira said, plugging a cable from her suit's diagnostic pad into the port. Her voice turned businesslike as she talked through it. "Reading power line integrity… There's a minor voltage drop across segment 12B. That could have caused a surge reading if something drew load unexpectedly."