Even if ITS launches are so cheap, that 4-5 a mission is not problem. Still have crew vehicle waiting in orbit on the refuelling flights, all of which need to successful without significant delays. If ITS only departs LEO with partial fuel load it becomes lot more inefficient as propellant mass fraction goes down.A separate lunar lander should have higher PMF as there is no heatshield, launch and reentry forces to factor in design. If ISRU infrastructure is in place to refuel ITS on surface then dedicated more efficient OTVs and landers would exist to service LEO -moon route.Where ITS will shine is as low cost cargo and tanker to LEO and maybe EML1.
Quote from: TrevorMonty on 07/24/2017 10:35 amThe problem with using ITS for lunar missions is takes about 4-5 ITS launches per mission. Using ITS as LEO tanker plus a smaller LV for crew would allow for more frequent trips. Using ACES derived, tankers, crew OTV and lander would allow 6 crew to do round trip from LEO using 100t of LH LOX. Alternatively a single launch of full lander would deliver almost 20t of cargo to surface plus a lander that could be converted to habitat.Methane lander would do about 14t to surface. A crew mission would be down to 2-3 at guess, havn't done the maths.SpaceX is developing ITSy to replace Falcon 9 and Heavy. So presumably would become cheaper per launch than either.That makes 4-5 ITSy launches cheaper than using a separely developed smaller lander.
The problem with using ITS for lunar missions is takes about 4-5 ITS launches per mission. Using ITS as LEO tanker plus a smaller LV for crew would allow for more frequent trips. Using ACES derived, tankers, crew OTV and lander would allow 6 crew to do round trip from LEO using 100t of LH LOX. Alternatively a single launch of full lander would deliver almost 20t of cargo to surface plus a lander that could be converted to habitat.Methane lander would do about 14t to surface. A crew mission would be down to 2-3 at guess, havn't done the maths.
No LAS is why ITS may never take crew to LEO.
Quote from: TrevorMonty on 07/24/2017 07:24 pmNo LAS is why ITS may never take crew to LEO.Do those certification requirements apply to non-Nasa flights too? If not, then ITSy can have a very busy life serving as a transport system for private industry, even if NASA remains unwilling to increase its risk tolerance slightly.
Does everyone realize this entire discussion is based on 3 sentences in an 80-minute discussion?"If you want to get the public real fired up we gotta..gotta have a base on the Moon. Its like that would be pretty cool, and going beyond that getting people to Mars."and"Having some permanent presence on another heavenly body, kinda the Moon base and then getting people to Mars and beyond."BTW each statement was followed up with "getting people to Mars." Anyone who think Elon's focus is wavering should pay closer attention.
So yes, the moon IS a stepping stone. It needs to be the HUB of interplanetary travel. It needs to be the departure and return point for interplanetary travel. It needs to be the source for provisioning and outfitting interplanetary spacecraft. It needs to be the source for provisioning and supplying fledgling planetary bases and settlements. We don't need just a few bases on the moon. We need cities on the moon. It's not a stop-over place. It is an entire world just begging to be settled, exploited, developed and used. Just because it's hard is not a reason not to do it. If we cannot do this on the moon then we have absolutely no business going anywhere else to try it.
Quote from: clongton on 07/21/2017 01:39 pmSo yes, the moon IS a stepping stone. It needs to be the HUB of interplanetary travel. It needs to be the departure and return point for interplanetary travel. It needs to be the source for provisioning and outfitting interplanetary spacecraft. It needs to be the source for provisioning and supplying fledgling planetary bases and settlements. We don't need just a few bases on the moon. We need cities on the moon. It's not a stop-over place. It is an entire world just begging to be settled, exploited, developed and used. Just because it's hard is not a reason not to do it. If we cannot do this on the moon then we have absolutely no business going anywhere else to try it.I totally agree. Add to that the symbolic value of a permanent human presence on the moon. The moon is visible in the sky to anyone anywhere on our planet. Boys and girls will look at the sky, imagine people on the moon, think of future cosmic adventures, and dream to participate. Some of them will do great things.
Quote from: giulioprisco on 07/27/2017 07:14 amQuote from: clongton on 07/21/2017 01:39 pmSo yes, the moon IS a stepping stone. It needs to be the HUB of interplanetary travel. It needs to be the departure and return point for interplanetary travel. It needs to be the source for provisioning and outfitting interplanetary spacecraft. It needs to be the source for provisioning and supplying fledgling planetary bases and settlements. We don't need just a few bases on the moon. We need cities on the moon. It's not a stop-over place. It is an entire world just begging to be settled, exploited, developed and used. Just because it's hard is not a reason not to do it. If we cannot do this on the moon then we have absolutely no business going anywhere else to try it.I totally agree. Add to that the symbolic value of a permanent human presence on the moon. The moon is visible in the sky to anyone anywhere on our planet. Boys and girls will look at the sky, imagine people on the moon, think of future cosmic adventures, and dream to participate. Some of them will do great things.When anyone can look up at a half moon at night, and see a city on the dark side... yea. It'll be "real" to everyone.
...you get points for correct use of "dark side."However, it seems basically impossible to me that you would be able to see even a lunar megacity with a half moon. There wouldn't likely be that many exterior lights, and it'd be drowned out by the sunlit part of the Moon.
I found this chart interesting, with 150 tonnes of payload the fully fueled BFS has 6 km/s ∆v. Not quite enough for a return to Luna surface and back from LEO but enough to get there from GEO.I guess they would refill the BFS in LEO, boost to some higher eccentricity orbit, refill from a tanker there and then head to the moon.
