Leah nodded slowly. "I've been finishing up the work from the data they had stored to optical before the accident. They got enough data to fully model the ecology. It's dying."

"How?" I asked. "Why?"

"Oxygen," she said. "The oxygen level in the atmosphere is rising, slowly but inexorably. The photosynthetic forms simply out-compete the anaerobes, and the result is that oxygen is gradually acc.u.mulating in the atmosphere."

"But that's good," I said. "That's what happened on Earth. The biosphere is evolving."

Leah shook her head. "But Mars isn't Earth. The oxygen is starting to scavenge hydrocarbons out of the atmosphere, and after that it will begin to displace carbon dioxide. Just like on Earth, but for Mars, that will be catastrophic. A few tens of millibars less carbon dioxide, and--" she clapped her hands. "Frozen solid. End of story."

"But the Gaia hypothesis-- doesn't the presence of life regulate the temperature?"

She shook her head. "Bacteria are dumb. Gaia is a hypothesis; it's never been a proven theory. In this case, it happens to be a wrong theory."

"You're sure?"

Leah nodded. We were silent for a moment, and then I asked, "How long?"

"Hmmm? Well, couldn't say precisely. Not enough data."

"Give or take."

"I'd give it few thousand years at the outside. Probably less than a thousand."

She saw me smiling, and added, shaking her head, "The time may be uncertain, but the fact still is, it will happen."

That put a little different spin on it. We would all be dead before the planet returned to bare rock. No need to mourn for Mars, not for quite a while yet.

Later, alone with just Leah in the tiny sleeping cubbyhole, I made love to her slowly and deliberately. She closed her eyes and arched her back as I stroked her, in her own way sensuous as a cat, but still I couldn't tell what sort of feeling she had for me.

When it was over, and we were lying in the dark, I had to ask. "Do you feel anything for me? Anything at all?"

Leah turned over. "Quit asking meaningless questions. I unask your question.

Mu."

Much later, after I thought she had fallen asleep, she said softly, "It looks like I'm stuck with you. I suppose there are worse people I could get stuck with. Don't get in the way."

It was all I could ask for. I will follow her as long as she will allow it, love her, ask nothing in return. Maybe someday I will mean something to her, maybe some day as much as a comfortable pair of slippers or a favorite chair.

In the mean time, though-- It was a large universe. There would be places to go, no end of places to follow her to. That was enough.

In the morning, the lander would come, and I would follow her home.

END.