Rather than keeping it as simple as possible I think redundancy is more important. The flexibility of a liquid system would allow emergency operation immediately, while solids would pretty much limit your options. Dual, autonomous propullsion systems with individual redundancy in systems makes more sense. <br /><br />As for hypergolics they have proven very effective, but they are also highly corrosive and have limitations as far as storage time, Soyus being an example. Shuttle seems to handle them much better but it only has to do so for a relatively short time. I would bet pergolics would prove limiting also if we are talking about a vehicle that could be refurbished and relaunch on a regular basis.<br /><br />I also think, if the plan is to use a parafoil landing system the shock absorbing provisions of the seats would not have to be too exotic, more in line with that required for business or airline seat construction.<br /><br />While it is a plus to keep cable runs to a minimum, putting the avionics in the front defeats the dynamics of a capsule design. The major mass should be as close to the back as possible to increase the inherent stability. What I would think would work far better would be two pilots forward and four passengers side by side behind them, then major components, electronics, propellant and such behind the passengers and in front of the heat shield. I also think putting a docking adapter on the front is the best idea that would require putting as much mass in the rear as possible to counter act it's mass.<br /><br />I've been thinking it might be possible to have a maneuvering stage that attaches to the docking adapter for launch and acts as an escape system in an emergency. Once reaching a destination it could be dettached to allow docking and either reattached to allow return, burning up in the atmosphere or de-orbit the vehicle and return to the station for re-use, sort of the Tug idea in it's early stages.<br /><br />I still think we should conce <div class="Discussion_UserSignature"> </div>