I wanted a taste of how it might be to be an astronaut, living on the surface of Mars, and the MDRS simulation has provided much to think about. The first night 'in sim', I felt very aware of the near vacuum beyond the portholes, a kind of isolation and confinement that you can't feel on Earth. The Mars-suits and airlock procedures, the radios bringing the whole crew perpetually within earshot, and even the taping of the headset onto the ear for security: these really do allow you to consider yourself on another planet where the only possibilities are suit or Hab. I could feel my dependence on these things, and my vulnerability. The landscape at the site is truly spectacular and indeed alien. Until the very last days, I felt excited to be exploring this unearthly terrain, even to the point that I would sometimes wonder whether there could ever be a place on the real Mars so engrossing. I took over a thousand photographs, and it was only time that stopped me taking more, not subjects. The few days without our ATV rovers were the hardest for me - every hour of roving had brought a breathtaking new discovery, but the books in the Hab, however interesting, were no substitute.

I would like to see the simulation evolve to become ever more rigorous. The problems we had with various generators particularly highlighted the unrealism of this element of the MDRS. A real station will handle energy much more carefully: here we have 5 kW of continuous supply - the only thought we need give to our consumption is not to use the toaster simultaneously with the water heater and hot-plate. I'd like to see a move to some kind of battery system, so that we have to manage the number of kWh we consume. Then the Hab power - on Mars, our lifeline - needn't be cut when we come to change the generator oil: we make a planned and controlled switch over. In case of failure, we'd have some time to make repairs before essential systems went down. Being in the desert, we could certainly make more use of solar power - the existing single panel for the GreenHab works very well, and diverted through an inverter, we managed to power various essentials during the failures. Supplemented with perhaps a wind generator, and the diesel, we'd have a diverse system that could be reliable enough to live from.

The water treatment processes in the GreenHab are very important, and appear (to my inexpert eye) to be working pretty successfully. The present goal of providing water for the toilet system is less ambitious than it could be. At the moment, we are using potable water for showering. I think it could be a feasible step to be completely recycling the shower water, the main consumption.

Some parts of the simulation are 'assumed'. For example, there's an assumed tube leading to the GreenHab, to the generators, and perhaps to the observatory. From the point of view of the psychology of the experiment, I think this doesn't work too well - it gives you the possibility to go and sit in the tube for a while to get some fresh air. Assumed tubes don't really confine you the way a real one would; their paths deviate depending on exactly where you need to go. Returning from EVA to see a couple of people working in assumed tubes certainly breaks the illusion of regaining the safety of the Hab. Real tubes might be an answer; even a ribbed framework might be sufficient (and less susceptible to wind).

I've enjoyed the mission greatly, thanks most of all to the company of my five crewmates Gus, Kathleen, Gregorio, Steve and Alyssa. Thanks also to those at Mission Support, and to all who helped bring this place into being.