Today we went back to work and boy, did we ever. We had our morning meeting at 8:00 am to divide clean-up chores and plan this crew's ninth EVA consisting of Dave, Simone and Elia. The Hab had started to get a bit disheveled and it was time to straighten up and get our living space in order for our final week.

We drew straws for bathroom detail and Dave Scott was the unfortunate recipient of the short one. The rest of us received more humane details and went off to work. We had hoped to get the EVA team onto the surface by 11:00 am or so but due to the extent of the clean-up work, we did not get them out there until around noon. Fortunately simulated Mars was still waiting for them.

We keep referring to this simulation we are in, but unless you are intimately involved with the work, it is hard to know what that means. We are following mission operations primarily described in two NASA publications: The Mars Surface Reference Mission: A Description of Human and Robotic Surface Activities edited by Stephen J. Hoffman and The Mars Project: Avoiding Decompression Sickness on a Distant Planet by Conkin.

Obviously there are some things we cannot simulate in Utah's desert, Mars' gravity field for one. But wherever possible we live under manned Mars mission constraints that are consistent with the published manned Mars mission documents.

The highlights of the rules for the simulation are these:

1) No going outside without a spacesuit. Two team members who have started to call themselves "mutants" are allowed to go outside briefly without a suit to do required equipment maintenance that would be dangerous in simulation. But the rest of the team follows this rule.

2) The spacesuits only have 6 hours of consumables; so long EVA's must not be of longer duration than this and need to include a safety factor. Sure we could make believe that more air, power and water are carried on the ATV's or that we have stored caches of supplies along the route. But that would require using invisible equipment. We have nothing appropriate to simulate something that extravagant and so we aren't.

3) When not on EVA or taking a day off, crewmembers must exercise for 1 hour. As mentioned previously in other dispatches, it is difficult to find the time and space to satisfy this protocol.

4) Water rationing is in place and so crewmembers can only shower every other day at a maximum. The showers must be low water consumption showers, either sponge baths or navy showers.

5) Contact with mission support is delayed by the time appropriate to the current distance between Mars and Earth.

6) Every six days the crew gets a day off.

7) Before going outside in a spacesuit, the astronauts have to spend 30 minutes in the airlock for a prebreathe protocol. This is to avoid decompression sickness when out on the Martian surface and actually relies on the most optimistic assumptions for Habitat pressure and space suit design. In reality the protocol will probably require a duration at least 3 times longer.

8) EVA teams must always be within walking distance of the Habitat, except when using the pressurized rover, with the amount of consumables remaining in their suits. This is a safety constraint just in case an ATV breaks down.

A lot of these rules assume a kind of bare bones type human Mars mission but the requirements are consistent with a mission that might take place in the next 10-20 years. We could work and live under more optimistic assumptions that rely on technology yet to be developed or perfected but why? It would make our time here easier but is thoroughly uninteresting from a research standpoint. Constraints yield insights.

For instance, with our EVA today we started to push the limit of the suits' life support. The walking distance safety constraint required us to plan the EVA route very carefully. It was challenging to do. And in fact it would probably be an interesting area of research to develop a software planning tool to assist teams in planning their EVA. The terrain affects what your route can look like. For instance, on flat terrain an EVA would be easy to plan with a circular or oval shape. MDRS though, a location with some topography, requires a different strategy. We basically chose a linear path with the site the longest distance away being visited first. And then sites nearer to the Hab were visited later.

Another interesting consequence of the simulation constraints relates to the size and arrangement of the main airlock. The EVA teams here rather quickly complained about having to stand in the airlock for 30 minutes without space to move around in. So after the first few EVA's the teams started to bring small seats into the airlock with them while they waited. The interesting thing about this is that only 3 seated astronauts can fit in the airlock at a time. If a short prebreathe and decompression time is simulated, then 4 standing astronauts fit in the airlock without complaint. Without the simulation constraint we probably would not have realized that the main airlock space is not optimum for 4 astronauts to use on a regular basis. And for a longer prebreathe protocol it would be completely inadequate for a team that size.

The strict simulation constraints also shape the activities that take place during an EVA. Typically now the first hour of an EVA is spent doing things around the Hab before ever leaving on scouting or sampling trips. Trash needs to be disposed of, readings need to be taken, outside equipment needs to be fixed. And when teams return from their excursions, there are usually other similar tasks that require attention before the crew enters the airlock.

This is the simulation philosophy of Crew 18. We came here to work and live as though we are one of the early crews to explore Mars. Our human factors study requires it.

We could make it less mentally, emotionally and physically straining on ourselves by bending the rules at times. But if we did that, what would be the point? We are not interested in dressing up for Halloween and driving around the desert on ATV's for 14 straight days. We came here to explore the details of settling Mars. Science and engineering are all about the details. Acting is for Hollywood.