So I propose that we actually refuel the MCT in LEO (something we would already routinely do) for partially propulsive Earth Entry.
As Jim said earlier somewhere, Dragon is too small to have a rover.
From the last thread:Quote from: Impaler on 06/11/2015 05:34 amSo I propose that we actually refuel the MCT in LEO (something we would already routinely do) for partially propulsive Earth Entry.Your fuel needs to get into LEO. If other MCTs on BFRs are launching fuel to LEO depots, then, pretty much by definition, those MCTs will need to be able to handle a full LEO reentry, so the TPS problem would need to be solved before you can use this to solve the program that you are trying to solve by using this. (So to speak.)
Quote from: Paul451 on 06/14/2015 08:34 amFrom the last thread:Quote from: Impaler on 06/11/2015 05:34 amSo I propose that we actually refuel the MCT in LEO (something we would already routinely do) for partially propulsive Earth Entry.Your fuel needs to get into LEO. If other MCTs on BFRs are launching fuel to LEO depots, then, pretty much by definition, those MCTs will need to be able to handle a full LEO reentry, so the TPS problem would need to be solved before you can use this to solve the program that you are trying to solve by using this. (So to speak.)Only if one tries to imagine that MCT is used as a Tanker to LEO, which is very silly and wasteful. Tankers will be a stretched upper stage of the BFR without any cargo on top and will use its low ballistic coefficient and retro-propulsion with residual propellents and likely some parachutes to perform re-entry and landing, all while delivering far MORE propellents.
Lots of people have been pushing this idea of MCT is the ONLY thing that BFR will ever have placed on top of it and that is must do EVERYTHING we want done from LEO all the way to Mars, this is completely unrealistic and dose not save any money as the MCT would be 10x harder to design and build when it has so many requirements put on it.
Dang it, we really need one spot that has all known information about MCT that comes from SpaceX. I'm not sure if he said 80-100 or 50-100. Not that it makes an enormous difference, but it's annoying.
MCT and BFR are supposed to be based on the same kind of platform. MCT will HAVE to have similar mass efficiency of an upper stage (in fact Musk has said MCT needs to be capable of Mars surface to earth in a SINGLE stage, though with far less payload), and essentially that's what it is. So whether you call the tanker a modified MCT or a stretched BFR upper stage may be a distinction without much difference.
Quote from: Robotbeat on 06/14/2015 05:58 pmMCT and BFR are supposed to be based on the same kind of platform. MCT will HAVE to have similar mass efficiency of an upper stage (in fact Musk has said MCT needs to be capable of Mars surface to earth in a SINGLE stage, though with far less payload), and essentially that's what it is. So whether you call the tanker a modified MCT or a stretched BFR upper stage may be a distinction without much difference.Show me the quote for this, because I've never heard any such thing. Rather I think direct single stage Earth return is rather a possible (and the most aggressive possible) interpretation of some of Musks statements but it is far from set in stone.And even if Elon had said this was his goal we should have SERIOUS doubts if such a goal would survive contact with real engineering as the vehicle capable of doing all that would put a single stage to Earth orbit vehicle
Quote from: Robotbeat on 06/14/2015 05:58 pmMCT and BFR are supposed to be based on the same kind of platform. MCT will HAVE to have similar mass efficiency of an upper stage (in fact Musk has said MCT needs to be capable of Mars surface to earth in a SINGLE stage, though with far less payload), and essentially that's what it is. So whether you call the tanker a modified MCT or a stretched BFR upper stage may be a distinction without much difference.Show me the quote for this, because I've never heard any such thing. Rather I think direct single stage Earth return is rather a possible (and the most aggressive possible) interpretation of some of Musks statements but it is far from set in stone.
All this talk about avoiding costs by not developing a 2nd stage are silly, SpaceX MUST have a use for the BFR other then launching for Mars related travel. The rocket would be completely useless for any other purpose if it's payloads were volumetricly constrained by needing to be inside a MCT cargo-hold which is likely no more then 500 m^3, SLS should have a payload fairing in excess of 2000 m^3.
A second attempt at a Mars Colonial Transporter. Not a first generation ship, but perhaps second or third generation of 10m core rockets. Youtube playlist should show 18 little videos covering the whole trip. A few very speculative items have crept in, for fun.For some unknown reason, you need to restart the playlist after the first video. Sorry.Michel Lamontagne
Quote from: Robotbeat on 06/14/2015 05:58 pmMCT and BFR are supposed to be based on the same kind of platform. MCT will HAVE to have similar mass efficiency of an upper stage (in fact Musk has said MCT needs to be capable of Mars surface to earth in a SINGLE stage, though with far less payload), and essentially that's what it is. So whether you call the tanker a modified MCT or a stretched BFR upper stage may be a distinction without much difference.Show me the quote for this, because I've never heard any such thing. Rather I think direct single stage Earth return is rather a possible (and the most aggressive possible) interpretation of some of Musks statements but it is far from set in stone.And even if Elon had said this was his goal we should have SERIOUS doubts if such a goal would survive contact with real engineering as the vehicle capable of doing all that would put a single stage to Earth orbit vehicle to shame. You can hand wave away the incredible difficulty and mass costs of EDL on Mars and Earth and the costs of keeping a vehicle alive during interplanetary transit.All this talk about avoiding costs by not developing a 2nd stage are silly, SpaceX MUST have a use for the BFR other then launching for Mars related travel. The rocket would be completely useless for any other purpose if it's payloads were volumetricly constrained by needing to be inside a MCT cargo-hold which is likely no more then 500 m^3, SLS should have a payload fairing in excess of 2000 m^3.
With suitable mission kits MCT could perform the following missions:- Tanker flights to LEO- Propellant depot- Satellite and space station (up to BA 2100 size at least) delivery- Tourist launch to LEO (~300 passengers)- Cargo/crew delivery to space stations anywhere in cis-lunar space- Moon landings- NEO visits.MCT may not be the most efficient system to perform such missions, but it is capable enough.