Lampyridae - 2/4/2008 8:01 AMQuoteOnce the transfer vehicle works make a larger version and use it to send astronauts to Mars.If you say so, but the transfer vehicle is a short-term taxi, not a multi-year self-contained life support. Maybe some of the hardware could be carried over but it's still not really viable, IMHO.
Once the transfer vehicle works make a larger version and use it to send astronauts to Mars.
tnphysics - 4/4/2008 4:24 AMOne must ensure that an SEP failure doesn't strand the crew w/o return propellant.
Zach - 5/4/2008 3:11 PMI’m not convinced that reusable, either for the tug or the depot, is the way to go, at least not from the beginning. The depot concept presented by Frank is very light weight and inexpensive. Why would one want to haul it back to LEO? Just replace it once the propellant has been consumed. I envision a regular train of “depots” being brought from LEO to supply the propellant requirements. For the electric tug, once you get a ~100 kw power plant to LLO I would much prefer for one to get creative on how to use this there rather than bring it back to LEO.{snip}
A_M_Swallow - 5/4/2008 12:30 PMOnce the depot is in place it does not move. Fuel and customers come to it. This makes reuse relatively easy.
A_M_Swallow - 5/4/2008 12:30 PMAs for reuse of the SEP ferries, on launch costs alone it is cheaper to fly them back to LEO than to launch a second. The manufacturing cost would be on top of that.
Zach - 5/4/2008 6:50 PMYou make the assumption that the alternative to bringing the SEP back to LEO for reuse is to throw it away. A lunar base is going to require 100's of KW, or potentially many WM of power with any form on insitu production or food growth.
One has the choice of launching dedicated missions to provide the power infrastructure, or using the solar arrays from the SEP. By reusing the SEP for this lunar base power, you get the benefit of the solar arrays during transit to the moon as well as at the moon and you aren't further burdened by needing to provide the tonnes of propellant for the SEP return trip. Likewise, the SEP only must survive one series of trips through the Van Allen belts, not multiple.
A_M_Swallow - 5/4/2008 11:59 PMSolar power satellites supplying energy to the Earth are described as searching for the holy grail in the Advanced forum on this newsgroup because the systems are so complex. Doing it on the Moon is even harder. It is much easier to just aim solar panels straight at the sun.
Zach - 6/4/2008 10:00 AMQuoteA_M_Swallow - 5/4/2008 11:59 PMSolar power satellites supplying energy to the Earth are described as searching for the holy grail in the Advanced forum on this newsgroup because the systems are so complex. Doing it on the Moon is even harder. It is much easier to just aim solar panels straight at the sun.I don’t want to turn this into a SPS discussion, but how do you aim solar panels straight at the sun during the 2 week lunar night? Yes, there are a few mountains at the poles that get more illumination, but that winds up being very limiting. SPS’s competing with 10c/kwh power on Earth doesn’t make any sense. A little more promising in a few nitch markets on Earth. But what is a kwh worth on the moon during the lunar night? $100? $1,000? A lot more than here on Earth. The alternatives aren’t very attractive. Try supporting 100 kw through the lunar night using fuel cells and you wind up with 100’s of tones of fuel required. Nuclear is really the other viable alternative.
Zach - 6/4/2008 3:50 AMQuoteA_M_Swallow - 5/4/2008 12:30 PMAs for reuse of the SEP ferries, on launch costs alone it is cheaper to fly them back to LEO than to launch a second. The manufacturing cost would be on top of that.1. You make the assumption that the alternative to bringing the SEP back to LEO for reuse is to throw it away. 2. One has the choice of launching dedicated missions to provide the power infrastructure, or using the solar arrays from the SEP. 3. By reusing the SEP for this lunar base power, you get the benefit of the solar arrays during transit to the moon as well as at the moon and you aren't further burdened by needing to provide the tonnes of propellant for the SEP return trip.
Mr Natural - 29/4/2008 12:55 PM{snip}Orion CEV - however SM and EDS combined into one. Restartable EDS stays with Orion till Earth re-entry. Potential to fuel at L1 for LLO and TEI for return home. {snip}I ended up taking segments from all three main architectures. The combination of the EDS/SM only hit me a few hours ago.
Mr Natural - 29/4/2008 6:55 AMI'm getting closer to defining my baseline architecture and am looking for a bit more discussion. I'll try to summarise it succintly.CREWLaunch System - DIRECT and EELV (Propellant depot at L1) - Commercial companies contracted to create, maintain and service L1 propellant depot using Ion propulsion.Orion CEV - however SM and EDS combined into one. Restartable EDS stays with Orion till Earth re-entry. Potential to fuel at L1 for LLO and TEI for return home. CARGOLaunch System - DIRECT takes RSLAM and 20 mT Cargo to L1 using Ion Propulsion. CEV RSLAM rendezvous at L1 - both vehicles sent to LLO- RSLAM lands drops, off cargo - 7 days lunar surface activities - ascends with 5mT cargo, LOR - transfer to L1 - Cargo pod rendezvous with SEP while Crew return home - Direct Entry. EDS/CM burn up in atmosphere Cargo returns to Earth a few months later. I ended up taking segments from all three main architectures. The combination of the EDS/SM only hit me a few hours ago. One theme that seems less important in existing architectures is International Participation. It was one of the requirements of the VSE.
PaulL - 30/4/2008 10:44 AMThe idea of combining the SM and EDS is interesting, specially if you have a high payload capable rocket such as the J-120 to start with. However, I don't see why you want to send the CEV from L1 to LLO. That would cost a lot of delta V and force you to do LLO rendez-vous after ascent. If you are returning the RSLAM to L1, you may as well use it to return the astronaut at L1 too where they can transfer to the CEV waiting there.PaulL
Zach - 5/4/2008 6:44 PMOne must contain the LH2 or LO2 in something that can very efficiently store it during the 3+ month SEP transfer from LEO to LLO. The "depot" concept outlined by Frank can also simply be considered an efficient storage vessel. If the SEP can provide >10E-5 G's during the transit, this would be enought to settle the liquid, enabling settled pressure control.