The beauty of assembling at a Lagrange point is that the majority of the Delta V for a Trans Mars Injection burn is delivered before boil off becomes a concern ....
But there are all sorts of ways of skinning this cat. You don't have to use a very large HLV to do it (or a huge increase in launch infrastructure and launch rate).
Quote from: notsorandom on 01/02/2014 07:51 pmThe beauty of assembling at a Lagrange point is that the majority of the Delta V for a Trans Mars Injection burn is delivered before boil off becomes a concern .... Right. What about other burns ?
Thinking about it the idea of standard sized payload "pods" sized to the smallest launcher with mounting hardware to join pods together came (literally) off the top of my head.
The rest of the burns like entering and leaving Mars orbit can be handled with electric, storable methane and/or aerobreaking. I think that solar electric propulsion and staging out of an L-point is a pretty good solution. SEP can even be used to move bigger hardware to an L-point from LEO if time is not a factor.
That would be somewhere in 14ton to LEO range, including the "pod" of course, if you wanted to include as many companies with launchers as possible, worldwide. Incidentally, thats around what most ISS modules came in at.
I'm long convinced that this is how any bigger architecture should be put together, be it the next space station or a lunar base, or even mars sample return.
Methane is not storable, not currently, the tech does not exist and is not validated. No immediately obvious plans anywhere to get it done in next decade.
SEP only works for payloads that have plenty of time to get where they need to be, years.For everything else, hydrazine seems to be the morning fresh dairy for spacecraft for years to come.
AJ10-118K had a 319 sec specific impulse, but that's pressure fed and only 4.45 tonnes thrust. The Titan 4 second stage LR91-AJ-11 engine was pump fed. It produced 48 tonnes thrust at 316 sec ISP, but of course was not restartable. Ariane 5 has Aestus, with its 321 sec ISP and restart ability. Russia has more modern hypergolic pump fed engines, including some with staged combustion cycles. They have proven specific impulses of up to 327 seconds.
Although logically Methane should be not much harder than Lox if someone wants to do it.
Hypergolics are the pragmatic solution but there is no big engine to use them.
Quote from: john smith 19 on 01/03/2014 08:31 pmAlthough logically Methane should be not much harder than Lox if someone wants to do it. LOX isnt being used on any long duration mission either, so that doesnt get you further than methane.The proven technologies for deep space propulsion ( i.e beyond earth departure kick ) right now are - hydrazine - small SEP thrusters- solid kick stagesQuoteHypergolics are the pragmatic solution but there is no big engine to use them. You may want to ask Russians about that.
No, not just hydrazine but nitrogen tetroxide as well. The main propulsion systems on the larger probes like Cassini are bipropellant.
1. 2 ranges. KSC and CCAFS are the Eastern Range (one range). But depending on the orbit, Wallops may use resources of the Eastern Range.
2. No, it is pad/vehicle dependent. so no difference.
3. The issue isn't the supply of physical roadblocks. It is setting up and clearing out the areas that the roadblocks are to protect.
faster voice and data channel re-configuration processes are still limited by having to do physical voice checks on on all the channels at all the positions.
I guess I'm a bit surprised at that given the EELV's were designed to the same spec. I take it the range interfaces at the pad level, rather than the vehicle.
You mean someone has to physically speak some kind of message on each channel ? There is no "test" mode that connects a single microphone to all channels for a quick pass/fail test on them in one go?
Is there anything specialized about the people who do this? It sounds like anyone from the National Guard to a hired security firm could handle it on a one off basis. BTW if you knew you were doing 3 launches back to back could you not seal common areas for the whole week?
It is a security firm that does it, the same one that handle base security.
And no you can't seal off the common areas for a week because other facilities need to accessed, like other pads. People still need to their day jobs.
Yep. Because there are dozens of channels and dozens of consoles positions in many facilities. Not every channel goes to each console, nor can most consoles handle more than 20 channels.
In your opinion what's the long pole in the tent if you wanted to swap LV's in (say) 1 day instead of two?
Quote from: john smith 19 on 01/07/2014 08:59 pmIn your opinion what's the long pole in the tent if you wanted to swap LV's in (say) 1 day instead of two?manning to cover more than 5/40 per week