I am writing this final log entry as I sit in the Soyuz. Everything is ready. All I need to do now is disconnect the power and ventilation pipes and close the hatches. Then all it takes is a release switch, a couple of controlled burns and then, less than four hours later, I land in Kazakhstan. I will throw this log through the open hatch into the station just before I close the hatches. Maybe someone will find it one day? I doubt it but I have to leave some record.

Everything has changed in the last hour. I was bringing a tub of freshly harvested tomatoes to the Soyuz when I met Arth in the Unity module, apparently on his way to the Soyuz too. I asked him what he was doing and he replied preparing to secure the stationside hatch for me. That seemed reasonable but I had not asked him to do that and he's been showing a little too much initiative recently.

I have no idea what made me do it, but I decided to ask Arth if he had tampered with the Soyuz O2 bottles. He immediately replied yes. So I asked him why. His answer blew my mind. He explained that he doesn't want to be alone. He's concerned that he won't be able to maintain the station for very many weeks before he suffers another mechanical failure. He's not trained to maintain or repair himself.

I can't say I've ever sensed much in the way of emotional response from Arth, but I actually believe he's scared of being alone. He's never spent more than a few hours alone and even then he's always known that backup is only seconds away. Once I make the descent to the surface, he will be alone for as long as the station's orbit is sustained, unless he suffers an electrical failure in the meantime.

He's not human, not even close to being human, but he's been my sole companion for weeks now. When I reach the surface, it seems entirely probable that I will find no-one still alive down there. If that's the case I'm going to miss Arth's companionship, as much as it is. I don't want to be alone either.

The logical decision, the only sensible decision, is to leave Arth aboard the station and take as much food and water as I can down to the surface, but I just can't do it. We could be the last two things active on the entire planet, so I'm taking him with me. It will cost me almost two week's food, but I can't leave him behind. He's served faithfully ever since he arrived on the station. It's just not fair to abandon him. I've unbolted his microgravity legs and connected his walking legs. Walking isn't one of his strong skills but the microgravity legs would be no use at all back down on the surface.

I am leaving this diary on the station. The Soyuz is stocked and Arth is aboard. All I have to do is close both hatches and initiate the launch sequence. The drop to the surface should be uneventful. Soyuz has been tested as much, or more than, almost all other space tech in history. What will I find when I get there? Who knows what awaits? Even if I die shortly after arrival, at least I should know what happened to the human race.