What kind of fuel to use? Part 4

A series about a self launching space station built on the moon.  Part 3 here.

A few questions arise from the latest post.

1. What kind of fuel will it use?
2. How big will the station be?
3. How will it dock in space?
4. What kind of missions will it perform?

These are the questions I can think of now.  Undoubtedly, there are many more.

What sparked this idea was that there's plenty of aluminum and oxygen on the moon.  That's the primary components of a solid rocket booster.  But there's more stuff, which kinda throws water on the idea.  If you can find chlorine, that'd be great.  But you also need a binder.  That makes up a considerable portion of the mass.

If you can find all of these materials, you still have to put it all together.  This would require some type of facility of the moon.  Like a permanent moonbase.  This may help to answer #4.  One mission would be as a bus that can transfer people back and forth.  Or it can stay in space for awhile if it is properly provisioned.  If it is to stay for a long time, it will need a lot more capabilities that I envision at the moment.

I was thinking it could have legs and with five separate tubes, it could be quite stable when it landed.

On the opposite end could be the docking ports.  One for each tube.  Each tube would have its own dock because there's no simple way to add a capability to move to one tube to the next when the thing is spun up in space.  It should be spinnable and unspinnable at will in order to allow docking and to handle contingencies.

This leaves question 2.  How big?  A lot depends on what you intend for the mission to do.  If it is just to be a bus, it need not be very big at all.  If it is to be a big station, it will have to be tall.  In fact, so tall that getting it into position to be launched may be something of a problem.

It could be a flexible design that would allow for growth in capabilities depending upon mission needs.