Math interlude

mass fraction equation:

want to know for every 10k pounds of wet mass, what must be fuel.  I put this in a spreadsheet before, but it is a hassle to go look for it again, so I have to derive it here for my purpose.  Would like to know how much equipment you can land on Ceres based upon this.  For example, if Ceres has delta v escape velocity of .51 km/sec, how much fuel are you going to need to land on it?

This thing destroyed my calculations that I just had here, so let's just state it simply like this.  The moon requires about a pound of fuel to land a pound.  With a much weaker gravitational field, you should be able to land on Ceres more than a pound for each pound of fuel.  That means more equipment and so forth.

The derivation of the above equation gave me a number of ln( mass fraction ) = .0001.  That seems to small of a number, so I may have screwed up.

Damn it all.

Update:

Yeah, that must have been an error.  Anyway, I found the spreadsheet and its 13% fuel fraction if you use a methane / lox engine and its ISP is 380.

Update:

Looks like a Falcon Heavy could deliver a 1 ton payload, which is about the mass of the Curiosity Rover.

If you landed a Rover there, you could inspect for water sources with an eye towards a refueling station on the planetoid.