One thing I thought might limit us is if in-orbit assembly is more complicated than just docking the components listed above together. They are already required to come apart and some are already designed to reconnect in orbit. for the ascent, descent, command and service stages/modules, we could make them 3-5 times bigger than Apollo while still remaining in the 20-30 ton range per launch.
Got any numbers on that?I guess it has one problem that the lunar module is not available for back up life support and thrust, as used by Apollo 13.
Was just trying to find stats on the constellation earth departure stage to see if it would fit, but couldnt find any masses here.http://en.wikipedia.org/wiki/Earth_Departure_Stage
This paper suggests a 25% - 33% increase in net delivered payload using single impulse ballistic trajectories.http://ccar.colorado.edu/nag/papers/AAS%2006-132.pdfIt appears this technique could be used to pre-position the entire lander.
Quote from: Bill White on 05/14/2010 02:20 amThis paper suggests a 25% - 33% increase in net delivered payload using single impulse ballistic trajectories.http://ccar.colorado.edu/nag/papers/AAS%2006-132.pdfIt appears this technique could be used to pre-position the entire lander.How about this one?http://www.universetoday.com/2010/03/06/astronomy-without-a-telescope-%E2%80%93-the-hitchhikers-guide-to-the-solar-system/"Edward Belbruno proposed a low energy lunar transfer to get the Japanese probe Hiten into lunar orbit in 1991 despite it only having 10% of the fuel required for a traditional trans-lunar insertion trajectory. The manoeuvre was successful, although travel time to the Moon was five months instead of the traditional three days."
Ah yes I have heard of ITN and how it can allow cheap slow transport to the moon. Im guessing that this would make the fuel to get the lander and ascent stage relatively negligible. I wasn't confident I would get the math right figuring how much this would reduce the EDS and service module mass, total and dry, if their sole purpose was to taxi the command module to-from the moon.
Another trick might be to split the EDS into two parts one launch brings up the main H2 tank and engines and another the main O2 tank.The H2 side would have a small LOX tank as well.The masses just don't split well since LOX is most of the mass in a lH2 rocket. Use a vehicle like F9-H or Atlas phase two and it should be possible to assemble a 60T EDS in two launches.Fuel transfer at least LOX might be easier then joining two halves of a rocket stage in orbit.One simple refuelling solution might be to have an Ares I US equipped with a sun shade launched on a Delta IV-H with just enough lox to get it's self in orbit and then have several modified F9 upper stages refuel the LOX tank.The CxP EDS was designed to spend up to four weeks in orbit.
Nothing important about restricting ourselves to two launches. Just an example. Having a range of options, including a minimalist one, is what makes it interesting.
We have a (dormant) thread on the mathematics behind it:Online study group for dynamical systems theory and innovative trajectories