Sedna told Newt, "What Marian said she had in mind was this. On Earth there are bacteria that get oxygen out of carbon dioxide without photosynthesis. They originated deep underground where the energy gradient came from heat rising from the core. She wondered if Mars has a similar deep biosphere. I couldn't find a Q link to anything living deep like that. So I thought we might want to try going down the volcano chimney to see if we can find it."

Newt said, "Okay, if you think you're really onto something. But we should talk to Frogo before we go down the main vent. He has a lot of experience mining lava tubes. Maybe he's explored deep vents before."

Sedna agreed. "But you know I still can't understand a word he says in that muffled West Texas drawl of his. I always have to link up with his thoughts in the Q."

They weren't sure where they'd find Frogo so they hooked up with him on the QAR link. The system brought up his image on the wall of their room. He was sitting in a recliner, like he'd been operating his drone. 

"Hi," he said. "Whusup?"

Newt said, "Hi Bullfrog. Did we interrupt anything?"

"You know I don't go by that anymore."

"Jeremiah then?" Sedna asked him.

"Please don't call me that either."

"It's your name, isn't it?"

"How did you know?"

"I've been around."

"Okay, then Frogo," said Newt. "What's up with you?" 

"Nothing deep. I just parked my drone and was deciding what to do next. Maybe you're gonna tell me?"

"The grapes you're growing in the farm are looking mighty fine," Sedna told him.

"Can't make fine wine without fine grapes. You ought to come over and help me drink it sometime. But that's not why you called, is it."

"Well, Sedna and I want to explore the main vent of the volcano. We thought maybe you've done that before."

"That's deep enough. But why would I do that? An eruption always scours the main vent clean. Nothing there but old lava rock. The minerals I look for collect in the side vents. So that's where I look for them."

"Oh. We were hoping to go down and see if we could find some natural Mars life. You know, like in the deep biosphere of Earth? There are things that live off the temperature gradient instead of photosynthesis."

"What sort of things?"

Sedna answered this. "Marian said archaebacteria. Primitive things that live on CO2. No one has found any native life on the surface here, not even in the lava tubes. Our farm plants do fine on CO2 as long as we give them light. But maybe the deep environment is friendly to more primitive things that get their energy from something else."

"Don't our tube farms already have primitive things, lichens and such?"

"I don't know. I suppose there could be some things like that in the soil. But they would be from Earth. We're hoping to find something native to Mars."

 "Okay, maybe I can help. Don't bother."

 "What? Why not?"

 "Because our vent is plugged."

 "Plugged? How could you know that?"

"It's old. Older than these lava tubes we live in. There haven't been any lava flows here for millions of years. Not since the Annunaki left."

"Right, we all know that. But what about other vents? Are they all plugged?"

"If they aren't they'll be too hot. Nothing can live in magma." 

"Don't they find all kinds of evidence of deep hot life on Earth? Doesn't that come from volcanoes?"

"Nope. It mostly comes from oil wells. You drill down deep to get oil. The oil can be pretty hot. But not so hot that nothing can live in it. Or in the rock it comes up through."

"Has anyone drilled down deep like that here?"

"Why would they want to? Fifty years ago maybe, when they might have wanted to make rocket fuel. Now we only need to drill for water. Besides, methane leaks out of the ground here in lots of places, and that makes good rocket fuel."

"So no one actually knows what's down there."

"Oh they know in a general way, from seismic readings. They know about the deep hot part. Just not the biosphere. Seems like there should be, though, because it comes with the oil, and the oil comes when the planet is forming. The methane probably comes from the biosphere."

"So we really are the only Martians on the surface."

"I suppose that's right, if you put it that way."

 "Well, then, thanks, Frogo. You just saved us from doing something even dumber than we thought it was."

"Always glad to help. Joy."

When their wall went back to normal Sedna turned to Newt. "Back to square one?"

He said, "Oh, no, I think we've checked off a lot of squares. We just keep finding more of them."

"Right. If Mars isn't going to give us what we need there must be plenty of things on our farm that would be happy to oblige."

"You know we could always carry a tank of air with us. Like a SCUBA tank. Underwater becomes Under CO2."

"That would be a last resort for me, though. But it does make me wonder how big a bush I'd have to carry."

"Seems like a good place to start. Let's ask the Q."

"This could be a different kind of plunge."