Free A Darkling Sea by James Cambias

through a trip out to view the waste incinerator, and tried to stand patiently as the female human went on endlessly about the accursed thing.
    “The shell’s just hull plating we scavenged from some of the cargo drop pods. Inside it’s all lined with native basalt. Satoshi and I spent two weeks in the crawler dragging a sled full of rock back from the nearest outcrop. There’s a pure oxygen feed and a hydrogen plasma torch; anything organic gets completely burned up in minutes. No contamination.”
    “But it produces much soot,” said Tizhos. “One can see it from orbit.”
    The female made a gesture with her shoulders. “The original plan was just to dump all the waste on a piece of rocky surface somewhere and let it sit there for the next billion years. But you guys wanted us to burn everything. Burning stuff makes ashes.”
    “You could take it all away from this world.”
    “Are you kidding?” her voice was shrill over the radio. “That’s what, ten kilos of fuel for each kilo of garbage? We’re already mining as much ice as you guys will let us.”
    Tizhos looked over at the station and saw that the elevator capsule was just emerging from the top of the shaft.
    “I have enjoyed speaking with you, but I see the elevator coming up. I need to go now.”
    Despite their best efforts to make the humans hurry, it was more than an hour before Gishora and Tizhos could board the elevator, and then more delays as their gear was loaded and two of the Terrans checked out all the onboard systems. So when the ice wall began sliding upward past the tiny porthole in the hatch, Tizhos felt a tremendous sense of relief.
    The elevator was a little self- contained habitat unit, almost as big as the surface station. It had four human-sized beds, a table, a little waste-disposal unit, and a cabinet stocked with dehydrated Terran foods. The two Sholen had their own foodmaker and distilled water to drink, and plenty of time for conversation. The descent took thirty- six hours to give their bodies time to adjust to the pressure.
    Tizhos actually enjoyed the elevator descent. She and Gishora had complete freedom to talk about their work—Ilmatar and the Terrans. It was almost like being a student again. Tizhos could simply enjoy the company of another smart, curious Sholen for the better part of three Shalina days. Their sexual play became more than just an official duty.
    She briefed him about the planet and its inhabitants. “Of course,” she cautioned, “most of what we know about Ilmatar comes from the Terrans. They may well have learned more since my last opportunity to read their findings.”
    “I must ask you to compare what you have read with what we see here,” said Gishora. “Note any differences. If you find anything the Terrans have concealed, let me know at once.”
    “I believe you said we did not come here to judge.”
    “True. But we must strive for accuracy and impartiality. Just as I cautioned against too much suspicion, we should also avoid trusting them too much.”
    “I understand.”
    “Please proceed,” said Gishora.
    Tizhos called up an image on her terminal. “The moon Ilmatar orbits the giant planet the humans call Ukko. I believe these names derive from the mythology of a human culture exterminated long ago by a more aggressive one. Ilmatar fits a standard model for giant planet moons far outside the life zone of the central star: a rocky core covered by a thick layer of water ice. Diameter of 6,400 kilometers. Tidal heating has liquified the interior, creating an ocean two kilometers deep, buried under a crust of ice a kilometer thick.”
    “Hence this long ride down. I understand the physical details. Tell me about the things which live here.”
    “Life on Ilmatar resembles similar ecosystems on other subglacial ocean moons. We know of three others. On all of them, volcanic vents on the seafloor serve as energy sources, giving off warm water and carbon or sulfur compounds. The native