Once the Raptor engine is developed. Then, I have the following questions.1. Do you have the manufacturing infrastructure to build ITS?2. Do you have the transportation infrastructure to get ITS to the launch pad?3. Do you have the launch facilities to handle 20 million or more lbs of thrust?4. Do you have the landing facilities, either on land or on a ship for such a rocket to land, or is it going to land back at the launch pad? 5. What about sound and vibration of such a launch for nearby areas? Does such a launch facility need to be remote?, near the equator?, or such? As you can see, the infrastructure for such a beast is going to cost a lot. Probably more than one of the ITS rockets itself. Things to consider. Pads 39a and 39b are capable of 12 million lbs thrust now. Just some modifications needed for something that size or smaller. Anything larger than 12 m in diameter cannot fit the existing barge, river and inland waterway transportation system in America, and it is extensive already. I think it should be no larger than NASA's old Nova rocket of 12 million lbs thrust to use the existing facilities at the Cape. Maybe scale it down to 50 people and 50 tons to Mars. Unless Governments chip in and buy's launches for their colonization efforts to not be left out.
The test ITS tank seems to have failed cryo-testing. No details as yet, but it has definitely broken apart.https://imgur.com/a/bGHR6"Should they..." is probably only going to get messier based on the number of tanks they go through in testing.
Looking over the ITS plans and comparing them to either Mars Direct or SLS...it's on the verge of insanely ambitious. Bear in mind I'm not saying it's impossible (indeed I pray it succeeds, moreso ahead of the SLS/Orion mess), but the SLS, STS, and Saturn V all suffered growing pains in their development. Would it be easier to build a smaller version of ITS first beforehand or not? Say something either at 1/2 or 2/3 scaled compared to the full ITS.
Quote from: RotoSequence on 02/17/2017 02:05 pmThe test ITS tank seems to have failed cryo-testing. No details as yet, but it has definitely broken apart.https://imgur.com/a/bGHR6"Should they..." is probably only going to get messier based on the number of tanks they go through in testing.Are we sure this really is a picture of an ITS test tank? I'd expected something "stiffer." This looks like rubber. Also very surprised that is what Hawthorne or Texas looks like. The tanks seem to be a major part of ITS. Big composites, carrying sub cooled cryogens, multiple cycles of launch/transit/entry/ over decades.This is not a large soda bottle wrapped in string. It's a long way past the SoA, never mind the common SoP.
Both Musk and many people here think it would be wasted effort. I think it could have the advantage of building something to use as a fully reusable workhorse launcher (replacing the F9), especially since SpaceX is developing a scaled down Raptor engine contracted by USAF anyway. Then use more generous mass fractions to ease development of both stages -- you don't need 100t payload to LEO for any commercial payloads anyway and if you can go aluminum instead of composites things get much faster and easier. Then you could get something that you can debug and optimize on a smaller scale, while earning money with it.Personally I think that the span between what SpaceX is actually flying now on one end and ITS on the other end is so big that nobody really is convinced enough to give them the money to go there. And without money SpaceX will never get around to actually build ITS. They need to add a rung more to that ladder so they can climb it.From a purely engineering point of view ITS is a bit much to eat with one bite. Starting smaller and with more elbow room in terms of mass fractions would make this much more doable.
A typical mid-L/D Mars lander with 40mt payload has the dimensions 30m x 10m.ITS has the dimensions 50m x 12m. Only ~1/3 of that volume is available for the payload, so it's questionable whether SpaceX can land much more volume on Mars than a typical 40mt lander from NASA. DRM 5.0 needs 2 40mt landers.Making ITS smaller in terms of volume might not be an option if SpaceX plans to sells Mars flights to NASA.
Build the simpler to outfit 90 tonne ITS stage 2 Tanker version first.Equip with just the 3 SL Raptors to flight test them and the stage 2 airframe, TPS & avionics~700 tonnes of propellant and the 90 tonne craft can get up to ~5 Km/sec (rocket equation)Fly & recover, testing heat shield and airframe at lower stress and qualifying the avionics
Quote from: Oli on 02/17/2017 06:13 pmA typical mid-L/D Mars lander with 40mt payload has the dimensions 30m x 10m.ITS has the dimensions 50m x 12m. Only ~1/3 of that volume is available for the payload, so it's questionable whether SpaceX can land much more volume on Mars than a typical 40mt lander from NASA. DRM 5.0 needs 2 40mt landers.Making ITS smaller in terms of volume might not be an option if SpaceX plans to sells Mars flights to NASA.So about 1,800 m3 of volume for payload, at CRS payload densities that is over 200 tonnes, SpaceX say that they will land 100 tonnes (maybe more later).
Quote from: MikeAtkinson on 02/17/2017 06:29 pmQuote from: Oli on 02/17/2017 06:13 pmA typical mid-L/D Mars lander with 40mt payload has the dimensions 30m x 10m.ITS has the dimensions 50m x 12m. Only ~1/3 of that volume is available for the payload, so it's questionable whether SpaceX can land much more volume on Mars than a typical 40mt lander from NASA. DRM 5.0 needs 2 40mt landers.Making ITS smaller in terms of volume might not be an option if SpaceX plans to sells Mars flights to NASA.Yes, my mistake. Still anything over about 200 tonnes would require a greater density than CRS cargo to the ISS. Not impossible for bulk products (metals/chemicals, dry/frozen foodstuff, etc.)So about 1,800 m3 of volume for payload, at CRS payload densities that is over 200 tonnes, SpaceX say that they will land 100 tonnes (maybe more later).The IAC presentation says up to 450 tonnes landed. Nominally 300.
Quote from: Oli on 02/17/2017 06:13 pmA typical mid-L/D Mars lander with 40mt payload has the dimensions 30m x 10m.ITS has the dimensions 50m x 12m. Only ~1/3 of that volume is available for the payload, so it's questionable whether SpaceX can land much more volume on Mars than a typical 40mt lander from NASA. DRM 5.0 needs 2 40mt landers.Making ITS smaller in terms of volume might not be an option if SpaceX plans to sells Mars flights to NASA.Yes, my mistake. Still anything over about 200 tonnes would require a greater density than CRS cargo to the ISS. Not impossible for bulk products (metals/chemicals, dry/frozen foodstuff, etc.)So about 1,800 m3 of volume for payload, at CRS payload densities that is over 200 tonnes, SpaceX say that they will land 100 tonnes (maybe more later).
Quote from: MikeAtkinson on 02/17/2017 06:29 pmQuote from: Oli on 02/17/2017 06:13 pmA typical mid-L/D Mars lander with 40mt payload has the dimensions 30m x 10m.ITS has the dimensions 50m x 12m. Only ~1/3 of that volume is available for the payload, so it's questionable whether SpaceX can land much more volume on Mars than a typical 40mt lander from NASA. DRM 5.0 needs 2 40mt landers.Making ITS smaller in terms of volume might not be an option if SpaceX plans to sells Mars flights to NASA.So about 1,800 m3 of volume for payload, at CRS payload densities that is over 200 tonnes, SpaceX say that they will land 100 tonnes (maybe more later).The IAC presentation says up to 450 tonnes landed. Nominally 300.
Quote from: envy887 on 02/17/2017 07:37 pmQuote from: MikeAtkinson on 02/17/2017 06:29 pmQuote from: Oli on 02/17/2017 06:13 pmA typical mid-L/D Mars lander with 40mt payload has the dimensions 30m x 10m.ITS has the dimensions 50m x 12m. Only ~1/3 of that volume is available for the payload, so it's questionable whether SpaceX can land much more volume on Mars than a typical 40mt lander from NASA. DRM 5.0 needs 2 40mt landers.Making ITS smaller in terms of volume might not be an option if SpaceX plans to sells Mars flights to NASA.So about 1,800 m3 of volume for payload, at CRS payload densities that is over 200 tonnes, SpaceX say that they will land 100 tonnes (maybe more later).The IAC presentation says up to 450 tonnes landed. Nominally 300.Yeah, they're looking at non-Hohmann transfers. Which actually is pretty reasonable when you start digging down into the numbers. You get a lot of trip shortening with that first extra bit of delta-V (it's a case of diminishing returns after that). And from an economics perspective, they have a lot of sunk costs in that ship doing nothing when it's just drifting through space. The sooner they can get it back to earth and relaunch, the better their economics work out to be. So it's worth sacrificing cargo.
Quote from: redliox on 02/16/2017 11:03 pmLooking over the ITS plans and comparing them to either Mars Direct or SLS...it's on the verge of insanely ambitious. Bear in mind I'm not saying it's impossible (indeed I pray it succeeds, moreso ahead of the SLS/Orion mess), but the SLS, STS, and Saturn V all suffered growing pains in their development. Would it be easier to build a smaller version of ITS first beforehand or not? Say something either at 1/2 or 2/3 scaled compared to the full ITS.Are you suggesting 1/2 or 2/3 the diameter? Or 1/2 to 2/3 the mass and volume? There's a big difference since mass and volume scale as diameter cubed.1/2 scale by diameter could be easily launched on Falcon Heavy, while 1/2 scale by mass/volume would dwarf Saturn V.
Quote from: envy887 on 02/17/2017 03:25 pmQuote from: redliox on 02/16/2017 11:03 pmLooking over the ITS plans and comparing them to either Mars Direct or SLS...it's on the verge of insanely ambitious. Bear in mind I'm not saying it's impossible (indeed I pray it succeeds, moreso ahead of the SLS/Orion mess), but the SLS, STS, and Saturn V all suffered growing pains in their development. Would it be easier to build a smaller version of ITS first beforehand or not? Say something either at 1/2 or 2/3 scaled compared to the full ITS.Are you suggesting 1/2 or 2/3 the diameter? Or 1/2 to 2/3 the mass and volume? There's a big difference since mass and volume scale as diameter cubed.1/2 scale by diameter could be easily launched on Falcon Heavy, while 1/2 scale by mass/volume would dwarf Saturn V....Someone double-check my figures to be certain; however I think for a smaller mission this could suffice to get the ship to Mars even without the tanker Elon wants in the full version.