Quote from: envy887 on 05/01/2017 02:03 pmThe ITS booster isn't going to exist without the ITS spaceship. If the ITS spaceship exists what's point in developing the Mars Direct departure, transit, EDL and Earth return hardware? It's all grossly out-classed by the ITS ship. The Mars Direct surface ops and refueling hardware would still be useful, but could at that point just be delivered to the surface by ITS.Every now and then I do seem to see hints that SpaceX is building the ITS spaceship first rather than the booster. Doing the opposite would make better sense to me. I will admit though, if the spaceship is up and running and operating with the same engines it would serve as a SSTO LEO launcher which could be where Elon seeks to get most of his money; the booster solo would be overkill for a small-payload-rich v.s. large-payload-poor economy.
The ITS booster isn't going to exist without the ITS spaceship. If the ITS spaceship exists what's point in developing the Mars Direct departure, transit, EDL and Earth return hardware? It's all grossly out-classed by the ITS ship. The Mars Direct surface ops and refueling hardware would still be useful, but could at that point just be delivered to the surface by ITS.
They clearly need to be designing and building the booster and ITS in parallel.It's not a question of which comes first - they need to ensure that they are both ready to go at the same time. You cannot have one without the other. I'd expect the ITS to start manufacture first since it is more complicated and therefore clearly on the critical path.
Quote from: JamesH65 on 05/03/2017 11:56 amThey clearly need to be designing and building the booster and ITS in parallel.It's not a question of which comes first - they need to ensure that they are both ready to go at the same time. You cannot have one without the other. I'd expect the ITS to start manufacture first since it is more complicated and therefore clearly on the critical path.On the contrary: you certainly can have the ITS Spaceship and Tanker without the booster. Both can launch and undergo testing (suborbital testing, at least) without the booster.
Quote from: sevenperforce on 05/03/2017 02:19 pmOn the contrary: you certainly can have the ITS Spaceship and Tanker without the booster. Both can launch and undergo testing (suborbital testing, at least) without the booster.But you cannot do the job they are being built in any sensible timescale for if you do one then the other. If you want to go to Mars, you have to have both ready at the same time.
On the contrary: you certainly can have the ITS Spaceship and Tanker without the booster. Both can launch and undergo testing (suborbital testing, at least) without the booster.
... you cannot do the job they are being built in any sensible timescale for if you do one then the other. If you want to go to Mars, you have to have both ready at the same time.
Quote from: JamesH65 on 05/03/2017 03:38 pm... you cannot do the job they are being built in any sensible timescale for if you do one then the other. If you want to go to Mars, you have to have both ready at the same time.For Mars, they will both have to be operational at the same time. That does not mean they have to be in simultaneous development. That would, in fact, be inadvisable for several reasons. Technology difficulties related to the first can be avoided for the second. One team of engineers can design the first, then design the second with compatible technology. Separate teams working at the same time may drift into divergent technology; they require twice the salaries and work space. Sequential development is far more prudent.Post Script. Multiple parallel development was required for the Apollo program, but that was necessary in order to meet Kennedy's deadline. In regards to differential technology, look at the problem Apollo 13 had with non-compatible CO2 scrubbers. Having one team develop ITS and its booster sequentially allows engineers to utilize commonality.
But takes twice as long.
Quote from: JamesH65 on 05/04/2017 09:55 amBut takes twice as long.Whereas parallel development costs twice as much. I'm not sure Elon has the money to do this all at one time. Apollo was only going to the moon, and the parallel development cost 4.5% of the entire federal budget. I think parallel development is cost prohibitive.