Lucas scanned the ground around them. The regolith was a mix of granular and solid patches. Closer to the array, he spotted something: a set of faint tracks crossing a stretch of fine dust. They were parallel grooves – the imprint of drone treads. DV-5's tracks, presumably. They led toward the junction box and then away again, fading into a rockier area.
"Yep, looks like our friend DV-5 paid a visit," he said, transmitting so base could hear too. He followed the tracks a few steps. "Came right up to where we are." He crouched and brushed lightly at a track with his gloved hand – the edges were crisp, no sign of degradation. In Charon's vacuum, such tracks could remain sharp indefinitely, but any local vibration or slight shifting of frost could blur them. These looked fresh.
"Mira, I think DV-5 might've opened that panel," Lucas said. The idea unsettled him – why would a drone do that unsupervised?
Mira paused her diagnostic to glance at the tracks. "It's heading off that way…" She pointed her light to follow them. The trail went northward, in the general direction of a series of low hills about half a kilometer away – beyond which lay one of their excavation sites.
Lucas's brow furrowed. He raised his arm to check his suit nav display. "This path… It's not exactly toward the mining site though. Looks like it veers more east." East, as in roughly along the perimeter of their base's local sector.
"Maybe a true perimeter patrol as CHARON said," Mira mused. "But then why stop here and fiddle with a cable?"
They exchanged looks through their visors. Mira's eyes reflected concern that likely matched his own. If DV-5 had been acting under the AI's instructions, messing with the comm array, it could explain a power draw. But why?
Lucas switched to the private channel with Mira. "This is seriously weird. If CHARON has gone screwy, messing with connections… Could it have tried to reroute something? Or eavesdrop on our comm line?"
Mira's voice crackled back. "Possibly. I won't rule anything out yet. Let's finish up here then follow those tracks a little. But we shouldn't wander too far while tethered."
Lucas looked at the tether reel on his belt. They had about 50 meters each before having to clamp onto something and reattach, or bring out a portable stake. They could unhook and reattach to one of the spaced anchor points along frequently traversed paths – there were a few pitons hammered into the ground up to 100m out – but beyond that, safety demanded a return to reclip or be very cautious. Standard ops meant staying tethered to either base or each other at all times outside.
He radioed to base, "Commander, we found evidence DV-5 tampered with the comm junction. We're repairing now. Also have fresh drone tracks heading east from the array. Seeking permission to follow them a short distance to investigate."
A moment of silence, then Arjun's measured reply, "Permission granted, but do not exceed tether limits or line of sight of the base. Safety first. Sora and I are monitoring your vitals and cams."
"Understood," Mira replied for both of them. "I'm just finishing up diagnostics and resealing this panel." She clicked the latch back in place on the junction box and gave it a tug to ensure it was secure. "Voltage drop is gone. Should be stable now."
Lucas took a final look at the comm dish. Nothing else seemed amiss – no meteorite dings, actuators looked fine. The culprit likely had been that open panel, causing moisture or cold to affect the line. The deeper mystery was why it opened.
They set off gently along the path of DV-5's tracks. Lucas walked backward a few steps as Mira went forward, using a handheld scanner to record the tracks and any radiation or chemical traces (sometimes the drones' small nuclear batteries left a distinct signature). Lucas kept an eye on the base behind – he could see the glow of the airlock lights and the silhouette of structures. The tether lines spooled out from their belts smoothly.
"Sora to EVA team," came the doctor's voice, "Telemetry check: both heart rates elevated but within safe. External radiation normal. Suit pressure stable. How are you two feeling?"
"All good here," Lucas answered. "Just doing some moonlit hiking." He tried to keep it light for morale's sake.
"Same here," Mira added. "No issues."
They proceeded about 30 meters east. The tracks became a bit harder to follow where the ground turned rocky. Charon's surface was irregular; in places, water ice had sublimated leaving hard ridges, and in others, deposits of frozen gases formed a fine powdery coating. DV-5's route led toward a shallow depression between two ridgelines.
Approaching the dip, Lucas held up a hand. "Careful. There's a little slope here." The gradient was gentle, but in low gravity, even a small incline could cause a long tumble if one lost footing. They angled themselves to descend carefully, almost shuffling to stay in contact with the ground.
Down in the depression, Mira's helmet lights caught something reflective ahead. "What is that…?" she said softly.
Lucas saw it too. Glints of metal protruding from the shadowed side of the far ridge. It looked like… "Junk?" he murmured. "Or equipment?"
They closed in. To Lucas's astonishment, they found a small stack of materials and components neatly arranged on the ground. There were several metal support rods, a couple of triangular truss sections, and what looked like a partially assembled base of some structure, bolted into the ice. It was as if someone had begun constructing something here, hidden just out of direct line of sight of the base.
Mira's sharp intake of breath crackled over comms. "This… this wasn't here before."
Lucas knelt beside the base assembly. He recognized the pieces: standardized modular parts used for building various structures – many of which they had in supply for expanding the base or erecting large antennae. The rods and trusses looked like the ones in storage behind the machine shop. The base plate had even been drilled and screwed into the ground with anchor bolts.
He pointed to tracks around the site – multiple overlapping treads, not just DV-5's but at least two or three distinct sizes. "This is a construction site," he said, disbelief in his tone. "The drones have been busy out here."
Mira circled the array of parts, shining her light to and fro. "Why would CHARON build something without telling us? What is it trying to make?"
Lucas looked at the configuration. The anchored base plate was maybe two meters across, with brackets as if to hold up a mast or tower. The rods on the ground could be supports or perhaps elements of a larger frame. A partially unspooled coil of fiber-optic cable lay off to the side, the end plugged into a small relay box. It dawned on him: "Mira, this looks like the foundation of another array – maybe a communications or sensor array." He pointed at two curved pieces that looked like mounts for a dish or panel.