In a word, no. Musk said his system could go to the moon or Mars, with no mention of a DSG. What do you infer?
Quote from: A_M_Swallow on 09/30/2017 03:53 amQuote from: Proponent on 09/29/2017 09:31 pm{snip}But the thing that bugs me most is how the goalposts have been moved. I invite the people who are now saying that DSG is a great idea to ask themselves why they weren't advocating years ago. While I'm at it, let me just mention a few other people who did not advocate a crewed cis-lunar station as a gateway to the moon or beyond: Wernher von Braun, Sergey Korolev, Mike Griffin and Elon Musk*.Did all of these very intelligent people miss something? Have the facts changed in some fundamental way, so that a DSG now makes sense, when it didn't in the past?{snip}The lunar lander in '2001 A Space odyssey' was nuclear powered and commuted between the lunar surface and the big wheel spacestation in LEO orbit. None of our proposed landers use high thrust nuclear propulsion so they need lower ISP chemical propellants. To increase the payload, by reducing the lander's delta-V, the staging has to occur nearer the Moon.One of the DSG jobs is acting as the return point for a solar electric propulsion Mars transfer vehicle. A high Earth orbit staging removes the need for the vehicle to have a heat shield and the months required to slow down to LEO velocity.The need or desirability of a station, much less a station with a long-term crew at the "return point" has not been established.
Quote from: Proponent on 09/29/2017 09:31 pm{snip}But the thing that bugs me most is how the goalposts have been moved. I invite the people who are now saying that DSG is a great idea to ask themselves why they weren't advocating years ago. While I'm at it, let me just mention a few other people who did not advocate a crewed cis-lunar station as a gateway to the moon or beyond: Wernher von Braun, Sergey Korolev, Mike Griffin and Elon Musk*.Did all of these very intelligent people miss something? Have the facts changed in some fundamental way, so that a DSG now makes sense, when it didn't in the past?{snip}The lunar lander in '2001 A Space odyssey' was nuclear powered and commuted between the lunar surface and the big wheel spacestation in LEO orbit. None of our proposed landers use high thrust nuclear propulsion so they need lower ISP chemical propellants. To increase the payload, by reducing the lander's delta-V, the staging has to occur nearer the Moon.One of the DSG jobs is acting as the return point for a solar electric propulsion Mars transfer vehicle. A high Earth orbit staging removes the need for the vehicle to have a heat shield and the months required to slow down to LEO velocity.
{snip}But the thing that bugs me most is how the goalposts have been moved. I invite the people who are now saying that DSG is a great idea to ask themselves why they weren't advocating years ago. While I'm at it, let me just mention a few other people who did not advocate a crewed cis-lunar station as a gateway to the moon or beyond: Wernher von Braun, Sergey Korolev, Mike Griffin and Elon Musk*.Did all of these very intelligent people miss something? Have the facts changed in some fundamental way, so that a DSG now makes sense, when it didn't in the past?{snip}
QuoteI suspect the brains trust did not expect to get the money for a cis-lunar spacestation so designed it out. This may have changed.(emphasis added by proponent)The amount of money available has not suddenly increased. CxP was projecting huge budgets but did not envision a crewed DSG. My key question boils down to: is there any evidence that a DSG was designed in in the first place?EDIT: Added emphasis to to final quote and added final sentence.
I suspect the brains trust did not expect to get the money for a cis-lunar spacestation so designed it out. This may have changed.
Quote from: Proponent on 09/30/2017 01:35 pmIn a word, no. Musk said his system could go to the moon or Mars, with no mention of a DSG. What do you infer?He steered clear of any commentary on such publicly owned systems such SLS and the political realm entirely.
DSG is political compromise as much as technical. NASA can't afford to do Mars on its own and its international partners aren't interested in funding a 15-20yr Mars development program while being stuck in LEO. For lunar missions Orion can't reach LLO, so it has stage at a HLO. Apollo style missions are not possible with 1x SLS 1B which means 2xSLS a few months apart. Have problems with 2nd launch and whole mission could be a writeoff, especially the already flown 1st launch. Without lunar surface refuelling any reusable lunar architecture will need HLO staging point for storing lander, DSG NRO is a good as any. In end it is DSG or nowhere BLEO.
Quote from: Proponent on 09/30/2017 10:42 amQuote from: A_M_Swallow on 09/30/2017 03:53 amQuote from: Proponent on 09/29/2017 09:31 pm{snip}But the thing that bugs me most is how the goalposts have been moved. I invite the people who are now saying that DSG is a great idea to ask themselves why they weren't advocating years ago. While I'm at it, let me just mention a few other people who did not advocate a crewed cis-lunar station as a gateway to the moon or beyond: Wernher von Braun, Sergey Korolev, Mike Griffin and Elon Musk*.Did all of these very intelligent people miss something? Have the facts changed in some fundamental way, so that a DSG now makes sense, when it didn't in the past?{snip}The lunar lander in '2001 A Space odyssey' was nuclear powered and commuted between the lunar surface and the big wheel spacestation in LEO orbit. None of our proposed landers use high thrust nuclear propulsion so they need lower ISP chemical propellants. To increase the payload, by reducing the lander's delta-V, the staging has to occur nearer the Moon.One of the DSG jobs is acting as the return point for a solar electric propulsion Mars transfer vehicle. A high Earth orbit staging removes the need for the vehicle to have a heat shield and the months required to slow down to LEO velocity.The need or desirability of a station, much less a station with a long-term crew at the "return point" has not been established.Trevor Monty answered that question in reply #20https://forum.nasaspaceflight.com/index.php?topic=43834.msg1729525#msg1729525QuoteQuoteI suspect the brains trust did not expect to get the money for a cis-lunar spacestation so designed it out. This may have changed.(emphasis added by proponent)The amount of money available has not suddenly increased. CxP was projecting huge budgets but did not envision a crewed DSG. My key question boils down to: is there any evidence that a DSG was designed in in the first place?EDIT: Added emphasis to to final quote and added final sentence.It is standard practice to design things out without writing them down. For example skis are a traditional method of moving across ice but I doubt any launch vehicle's requirements documents say that skis have been designed out because that they are not needed.
Quote from: TrevorMonty on 09/30/2017 05:09 pmDSG is political compromise as much as technical. NASA can't afford to do Mars on its own and its international partners aren't interested in funding a 15-20yr Mars development program while being stuck in LEO. For lunar missions Orion can't reach LLO, so it has stage at a HLO. Apollo style missions are not possible with 1x SLS 1B which means 2xSLS a few months apart. Have problems with 2nd launch and whole mission could be a writeoff, especially the already flown 1st launch. Without lunar surface refuelling any reusable lunar architecture will need HLO staging point for storing lander, DSG NRO is a good as any. In end it is DSG or nowhere BLEO.I certainly agree that this is largely about doing something -- anything -- that is politically possible. But it's not clear that a crewed outpost in HLO is desirable for supporting lunar-surface operations, and, in any case, such operations are far in the future. It could easily be that the cost of maintaining the DSG makes going back to the moon itself harder, not easier.
Just sending one Orion/SLS to DSG every year probably costs $3-ish billion -- that's not too different from the ISS budget.
"We will refocus America's space program toward human exploration and discovery," Pence wrote. "That means launching American astronauts beyond low-Earth orbit for the first time since 1972. It means establishing a renewed American presence on the Moon, a vital strategic goal. And from the foundation of the Moon, America will be the first nation to bring mankind to Mars."There are several notable phrases in there. The first, "on the Moon," is fairly obvious. In recent years NASA has talked about sending humans to a space station near the Moon but not landing astronauts there.
ArsTechnica:Quote"We will refocus America's space program toward human exploration and discovery," Pence wrote. "That means launching American astronauts beyond low-Earth orbit for the first time since 1972. It means establishing a renewed American presence on the Moon, a vital strategic goal. And from the foundation of the Moon, America will be the first nation to bring mankind to Mars."There are several notable phrases in there. The first, "on the Moon," is fairly obvious. In recent years NASA has talked about sending humans to a space station near the Moon but not landing astronauts there. https://arstechnica.com/science/2017/10/its-official-trump-administration-turns-nasa-back-toward-the-moon/
Quote from: Proponent on 10/03/2017 04:06 pmJust sending one Orion/SLS to DSG every year probably costs $3-ish billion -- that's not too different from the ISS budget.And that would accomplish what?