I think after several cargo mission, first with FH and then MCT. When MCT successfully land on Mars. First crew will arrive without specified return day. There task will be prepare infrastructure and ask for additional resources in preparation of infrastructure for return trip. Setup ice collection and build and maintain devices to create fuel,build tank for fuel. At the moment finishing task and prepare rocket for return trip some of the crew will start their trip back to Earth. I think when first crew will arrive there will be not enough fuel to bring them back, they have to build their "return ticket".
Quote from: Ionmars on 01/28/2016 08:39 amQuote from: BSenna on 01/28/2016 12:39 amQuote from: Ionmars on 01/27/2016 11:10 pmBlah,, blah... blah......Undesrtood!If you were to do a 3D model of the Depot it would just be a 2D (x,y) skeletal frame that is repeated into the third (z) dimension. Below is a sketch of the forward frame for one berth. The small circle is a "pad" for connecting to the nose of the MCT and the large circle is an imaginary volume representing one berth where one MCT is docked. The frames are connected by beams of a certain length in the z dimension. Then this 3D image is duplicated side-by-side to the right to make 5 additional berths until they join on the left side of the first berth. Voila!Is this?http://imgur.com/a/KJRna
Quote from: BSenna on 01/28/2016 12:39 amQuote from: Ionmars on 01/27/2016 11:10 pmBlah,, blah... blah......Undesrtood!If you were to do a 3D model of the Depot it would just be a 2D (x,y) skeletal frame that is repeated into the third (z) dimension. Below is a sketch of the forward frame for one berth. The small circle is a "pad" for connecting to the nose of the MCT and the large circle is an imaginary volume representing one berth where one MCT is docked. The frames are connected by beams of a certain length in the z dimension. Then this 3D image is duplicated side-by-side to the right to make 5 additional berths until they join on the left side of the first berth. Voila!
Quote from: Ionmars on 01/27/2016 11:10 pmBlah,, blah... blah......Undesrtood!
Blah,, blah... blah......
An international depot presupposes everyone using the same fuel, which doesn't look like the case at all. Assuming ULA gets ACES tankers off the ground they look to supply LH2. SpaceX is of course going methane. The Russian Fenix looks to be a methane "Zenit" (Sputnik News) and clustered for a heavy, but do we know what they'll use once in space if they even use tankers? China??
Crazy idea number 854: Could a fuel depot like this dip a "very long" stiff hose into the atmosphere, pump air up, and make fuel by processing CO2 and/or capturing methane? Granted it might take a really long time, but is it even technically possible? I assume the power supply to run this would have to be solar. since if it is anything else, you use more fuel than you make most likely.
The first stage of Vulcan and Blues own launcher, and their uppers use LH2. I haven't seen anything about a BE-4 Vac.
No word of a depot from SpaceX.Depots have a big advantage with hydrogen since hydrogen wants to boil-off really bad, and it takes fancy equipment like a mult-layer sunshield and an active cooler to stop that. But both methane and oxygen are space-storable, meaning with the right type of paint and by keeping your tanks out of direct sunlight (point the long way, butt to the Sun), you can get passive zero boil-off.So I really don't think SpaceX is planning a depot. But things change.
Well, if an MCT is going to act as the second stage of the BFR, it has to refuel in orbit. And if people launch on the MCT, it can't wait for multiple tanker MCTs to come and fill it up.
Quote from: Pipcard on 01/30/2016 12:26 amWell, if an MCT is going to act as the second stage of the BFR, it has to refuel in orbit. And if people launch on the MCT, it can't wait for multiple tanker MCTs to come and fill it up.Why not? They're going to be in space for the whole trip to Mars, what's a few more weeks in LEO? (Speaking of which, do we know if the refuelling is to be in LEO or somewhere else?)
Waiting around in LEO when you're supposed to go to Mars is wasteful for the life support systems.
Quote from: Pipcard on 01/30/2016 12:32 amWaiting around in LEO when you're supposed to go to Mars is wasteful for the life support systems.Really? Seems like a much cheaper option than depots. Don't get me wrong, I'm all for depots - but because they imply a different architecture to "biggest rocket evar".
What if...ionmars'll gonna hate that... The fuel carriers 2, 3 and 4 transfer The fuel directly to carrier 1 each time, then 1 transfers to the incoming MCT? Os that feasible?
Quote from: BSenna on 01/30/2016 01:16 amWhat if...ionmars'll gonna hate that... The fuel carriers 2, 3 and 4 transfer The fuel directly to carrier 1 each time, then 1 transfers to the incoming MCT? Os that feasible?I was just about to suggest exactly that. One tanker *is* the depot; you end up doing N launches to put a completely full tanker in orbit, then launch a crew+cargo MCT, fill it from the full tanker, and off we go..alternatively, you could daisy-chain:launch tanker #1launch tanker #2 to rendezvous with #1; transfer from #1 to #2; land #1launch tanker #3 to rendezvous with #2; transfer from #2 to #3; land #2(repeat until there is a full tanker in orbit)launch cargo/crew vessel to rendezvous with tanker #N; transfer fuel, land #NWith that scheme, you do more pumping, but all tankers spend about the same amount of time in orbit..