🚀 go-pugleaf

>Dave Jones (dj@ekcolor.ssd.kodak.com) wrote:

>One day, I'm going to sit down and work out if Asimov's Martian Way really
>would have worked....soft land a chunk of Saturns Rings on Mars, when just
>getting into Earth orbit takes 90% of your starting mass?  Hmmm....... 

While your mulling that one over Dave, here is some food for thought.
While it takes roughly 90% of your starting mass to get into LEO, it 
only takes about 60% of your starting mass to escape Earth's gravity
from LEO.  It is very different moving something from orbit than moving
something from the surface (or whatever) of a planet.  Secondly your
number assumes an engine with an Isp of about 350 sec--something like a
chemical rocket.  If you can use nuclear propulsion you can get an Isp
of around 1000-3000 sec and if you can use electric propulsion you can have
an Isp of around 10,000 sec.  With an Isp of 10,000 for example, your 
original mission requires only 8% of your initial mass.  Granted electric
propulsion is not going to launch anything from Earth but it would be 
well suited for moving large things around in space.

Tej