I am in two minds about this DSG. On the one hand NASA needs to find their next big project after ISS, on the other hand this has some of the hallmarks of a make work program to utilize the SLS/ORION.I general I like the idea of a way-station where spacecraft’s can refuel and astronauts rest/resupply before the next leg of a journey either to the moon or mars. For that reason, DSG is appealing. But it should not be a substitute for LEO infrastructure such as a zero-gravity research, tech-demo etc. such as what is happening on ISS. Now commercial might take over this role with after ISS, with NASA as anchor tenant, but NASA would probably still need to initiate a COTS type program for that to happen. NASA has forced itself out of LEO in some ways with all its talk of handing over LEO to commercial operators and SLS/ORION is for BLEO. SLS/ORION only justification other than pure pork lies in its superior per launch BLEO capability. So, given the need to justify and utilize SLS/ORION what to do in BLEO, that is within the flat budget profile?DSG allows NASA to utilize SLS/ORION to build an infrastructure capacity. A make work program for SLS/ORION that also delivers some permanent value. The big fear is that a DSG program under the SLS umbrella so to speak will mean its cost will be enormous and ends up never flying or constant being revised since political forces align to keep it going no matter the high costs and low return. Much like SLS and ORION.
Quote from: A_M_Swallow on 06/10/2017 04:47 amQuote from: su27k on 06/10/2017 04:21 amTo quote the article "“In terms of basic functionality, the DSG is being planned to support multiple NASA, commercial, and international objectives,” added the overview. “It would be designed for the deep space environment and would support a crew of 4 for total mission durations of up to 42 days with the Orion vehicle attached."Please explain how is a 42 days ECLSS qualifies as long term life support?After 10 visits that is 10 * 42 = 420 days. More than a year.The ECLSS in capsules can be serviced every time they return to Earth but the DSG's ECLSS can only expect its consumables to be replaced. NASA hopes to use the same design of ECLSS on its Mars trips.But if the ECLSS needs to be replenished every 42 days, you certainly aren't getting to Mars. Or am I missing something?
Quote from: su27k on 06/10/2017 04:21 amTo quote the article "“In terms of basic functionality, the DSG is being planned to support multiple NASA, commercial, and international objectives,” added the overview. “It would be designed for the deep space environment and would support a crew of 4 for total mission durations of up to 42 days with the Orion vehicle attached."Please explain how is a 42 days ECLSS qualifies as long term life support?After 10 visits that is 10 * 42 = 420 days. More than a year.The ECLSS in capsules can be serviced every time they return to Earth but the DSG's ECLSS can only expect its consumables to be replaced. NASA hopes to use the same design of ECLSS on its Mars trips.
To quote the article "“In terms of basic functionality, the DSG is being planned to support multiple NASA, commercial, and international objectives,” added the overview. “It would be designed for the deep space environment and would support a crew of 4 for total mission durations of up to 42 days with the Orion vehicle attached."Please explain how is a 42 days ECLSS qualifies as long term life support?
Quote from: Chalmer on 06/10/2017 04:48 amI am in two minds about this DSG. On the one hand NASA needs to find their next big project after ISS, on the other hand this has some of the hallmarks of a make work program to utilize the SLS/ORION.I general I like the idea of a way-station where spacecraft’s can refuel and astronauts rest/resupply before the next leg of a journey either to the moon or mars. For that reason, DSG is appealing. But it should not be a substitute for LEO infrastructure such as a zero-gravity research, tech-demo etc. such as what is happening on ISS. Now commercial might take over this role with after ISS, with NASA as anchor tenant, but NASA would probably still need to initiate a COTS type program for that to happen. NASA has forced itself out of LEO in some ways with all its talk of handing over LEO to commercial operators and SLS/ORION is for BLEO. SLS/ORION only justification other than pure pork lies in its superior per launch BLEO capability. So, given the need to justify and utilize SLS/ORION what to do in BLEO, that is within the flat budget profile?DSG allows NASA to utilize SLS/ORION to build an infrastructure capacity. A make work program for SLS/ORION that also delivers some permanent value. The big fear is that a DSG program under the SLS umbrella so to speak will mean its cost will be enormous and ends up never flying or constant being revised since political forces align to keep it going no matter the high costs and low return. Much like SLS and ORION.The prototype machines are being developed under Next Space Technologies for Exploration Partnerships (NextSTEP).https://www.nasa.gov/nextstep
We know that even though SpaceX is being paid to send two humans around the Moon, otherwise they are focused on building interplanetary spacecraft that can start to colonize Mars. So I don't see SpaceX themselves being interested in the DSG. Maybe a SpaceX customer would want to go, but I think there is a limited market for that.
Heck, *just from a public coolness point of view* (minor, but a point about public support) imagine the photos tweeted from those astros? Those photos from the ISS are probably the most viewed thing relating to NASA etc in the public arena.
Yep. Gerst hates it when people say "them vs us". He sees everyone as different parts of the same team.Per the DSG plan. I love it. I love the L2 Gateway and I love this. Great stepping stone approach to deep space human space flight. And building an outpost out there. Heck, *just from a public coolness point of view* (minor, but a point about public support) imagine the photos tweeted from those astros? Those photos from the ISS are probably the most viewed thing relating to NASA etc in the public arena.
... But again, even though you could do Mars with DSG, Gerstenmaier indicates that it really is just a test bed for a better craft down the line(DST). The engines and solar panels at the very least need to be tested long duration in the relevant environment. Wear levels on the solar panels in the precise radiological environment is something that needs to be 100% understood. NASA's Space Radiation Laboratory(NSRL) is only an approximation.
So, like playing catch between two as a minimal game, you have two mitts and a baseball. Two DSG's and a DST.
Might be hard to consider SLS as a minimalist's approach to Mars, but it is.
you'd be able to test the lander from DSG on the Moon before SEP'ing it off to Mars.
So what might keep the govt HSF (possibly all govts BTW ...) from getting irrelevant would be a tight mission focus that could keep it from dithering
just "at a distance" support from DSG in case of emergency.
Quote from: Space Ghost 1962 on 06/12/2017 06:43 pmSo, like playing catch between two as a minimal game, you have two mitts and a baseball. Two DSG's and a DST.If you mean put a DSG in lunar orbit and another DSG in Mars orbit, at that point, it probably makes sense to consider a cycler.
Rendezvous in Mars orbit is an unproven capability and adding them to Mars architectures will cause overall mission risk to jump for some time to come.
QuoteMight be hard to consider SLS as a minimalist's approach to Mars, but it is.1)Putting so many resources into a vehicle that will launch so infrequently certainly constrains options.2)It's not clear that a Mars surface mission or more than one lunar surface mission a year could be fielded without heavy involvement from other launchers, which begs the question of why bother with SLS.3)It also seems to put high-power electric propulsion on the critical path to Mars. Hopefully that will work out in time, but it should be an enhancer, not an enabler.
Quoteyou'd be able to test the lander from DSG on the Moon before SEP'ing it off to Mars.EDL at Mars is very different from EDL at the Moon. A Mars lander has to be demonstrated at Mars.
QuoteSo what might keep the govt HSF (possibly all govts BTW ...) from getting irrelevant would be a tight mission focus that could keep it from ditheringTight focus does not seem to be in the cards, unfortunately.
Quotejust "at a distance" support from DSG in case of emergency.1. There is some logic in having an independent shelter a little distance from a station. Rapidly bringing crews all the way back to Earth's surface under emergency conditions (from LEO or lunar orbit) is a risky proposition in itself. And there are failure modes where that would not be required or desirable.2. But a shelter, like insurance, has to be affordable -- a small fraction of the cost of the station (or an emergency crew return vehicle) itself. Unfortunately, our insurance for ISS cargo/crew and for other domestic HLVs and capsules is many times bigger than those costs.
...1. You use it because it is available, it advances your mission, and it allows political/industry to renegotiate the new landscape of technology. And if it fails, new launch capability will phase in from three sources that can eventually serve in the same capacity. 2. Logistical support of Mars/lunar DSG's can also be via commercial on long cycle trajectories to pre-position consumables/supplemental payload. The primary function of SLS will be the crew ride and exploration payloads.3. SEP/has been the only propulsion technology that has improved enough to allow reasonable mass margins for a near term HSF Mars mission. Short of Musk's approach to allow a much larger mission architecture, which is out of the scope of current plans....
{snip}2. DSGs (plural)? First DSG needs 4 SLS flights after EM-1, so late 2020s. And you think a second will be built?{snip}
Quote from: Space Ghost 1962 on 06/13/2017 04:02 am...1. You use it because it is available, it advances your mission, and it allows political/industry to renegotiate the new landscape of technology. And if it fails, new launch capability will phase in from three sources that can eventually serve in the same capacity. 2. Logistical support of Mars/lunar DSG's can also be via commercial on long cycle trajectories to pre-position consumables/supplemental payload. The primary function of SLS will be the crew ride and exploration payloads.3. SEP/has been the only propulsion technology that has improved enough to allow reasonable mass margins for a near term HSF Mars mission. Short of Musk's approach to allow a much larger mission architecture, which is out of the scope of current plans....1. Not available. Still many years away from any operations.
2. DSGs (plural)? First DSG needs 4 SLS flights after EM-1, so late 2020s. And you think a second will be built?
3. SEP will never be used for a HSF mission, let alone a near-term one. Improved enough for cargo... maybe the next generation of SEP. On orbit refueling is the only technology that will get anything to Mars beyond a flag and a couple people to make footprints.
DSG as conceived -- a multi-launch, SLS-only, DRO assembled/fitted out space craft -- will be stillborn.