Author Topic: ASAP on board with NASA's DSG as stepping stone to Mars  (Read 39619 times)

Offline A_M_Swallow

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #120 on: 10/18/2017 11:57 AM »
]

The DSG could be used to build the lunar base. For example the SLS would throw 40 tonne habitats to the DSG. The station's reusable lander would take the habitats down to the lunar surface. Same for heavy cargoes going to Mars.

Building the DSG 10 tonnes at a time is just using Orion on SLS as a Shuttle building the ISS. With a heavy lift launch vehicle lift most of the spacestation in a single launch, like SKYLAB. Enhancements like refuelling facilities may need additional launches.

Agreed it would be better the assemble DSG from Skylab sized sections since SLS can lift them.

I think it would be best to assemble DSG in LEO then attach an ion tug or a mostly full EUS to it and take it to lunar vicinity.

LEO rendezvous and assembly is old hat.


The block 1 SLS can lift 70 tonnes to LEO, later versions 105 tonnes. IMHO That is a reasonable size for a mini spacestation.

The first module of the DSG is the Power and Propulsion Element (PPE). With a few minor changes, like the guidance system, that is a space tug in its own right.

Whether a 50kW SEP (Solar Electric Propulsion) is sufficient to push 105 tonnes out of LEO I do not know. The SEP will probably have been sized for station keeping in lunar orbit.

Online envy887

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #121 on: 10/18/2017 05:20 PM »
]

The DSG could be used to build the lunar base. For example the SLS would throw 40 tonne habitats to the DSG. The station's reusable lander would take the habitats down to the lunar surface. Same for heavy cargoes going to Mars.

Building the DSG 10 tonnes at a time is just using Orion on SLS as a Shuttle building the ISS. With a heavy lift launch vehicle lift most of the spacestation in a single launch, like SKYLAB. Enhancements like refuelling facilities may need additional launches.

Agreed it would be better the assemble DSG from Skylab sized sections since SLS can lift them.

I think it would be best to assemble DSG in LEO then attach an ion tug or a mostly full EUS to it and take it to lunar vicinity.

LEO rendezvous and assembly is old hat.


The block 1 SLS can lift 70 tonnes to LEO, later versions 105 tonnes. IMHO That is a reasonable size for a mini spacestation.

The first module of the DSG is the Power and Propulsion Element (PPE). With a few minor changes, like the guidance system, that is a space tug in its own right.

Whether a 50kW SEP (Solar Electric Propulsion) is sufficient to push 105 tonnes out of LEO I do not know. The SEP will probably have been sized for station keeping in lunar orbit.

By my calcs (2.5 N per 50 kW, 8.0 km/s dv required) it would take a 50 kW thruster 10 years to move 100 tonnes from LEO to LLO.

But with a much larger 1.5 MW array and 75 N worth of state-of-the-art ion thrusters it could be done in about 4 months.

Offline MATTBLAK

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #122 on: 10/18/2017 10:43 PM »
How much damage to the arrays would happen if they lingered too long in the Van Allen belts; even with an optimized trajectory minimizing exposure? Assuming a slow SLS launch rate; what about an SEP bus that could move it to LLO in a bit less than a year?

I'm impressed and a little excited by the prospects of SEP. The best thrusters available and the largest gallium-arsenide arrays possible should be able to shift a lot of stuff around efficiently. A chemical (hypergolic or LOX/CH4)/SEP combo would bring a lot of capability to bear. A 500kw array would be how large compared to the ISS 'acreage' of panels?
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Offline savuporo

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #123 on: 10/19/2017 12:18 AM »
A 500kw array would be how large compared to the ISS 'acreage' of panels?

https://trs.jpl.nasa.gov/bitstream/handle/2014/45034/11-2964_A1b.pdf

That's for 300kw

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Offline Patchouli

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #124 on: 10/19/2017 12:31 AM »


By my calcs (2.5 N per 50 kW, 8.0 km/s dv required) it would take a 50 kW thruster 10 years to move 100 tonnes from LEO to LLO.

But with a much larger 1.5 MW array and 75 N worth of state-of-the-art ion thrusters it could be done in about 4 months.

50 KW would be much too small for SLS sized payloads.

But the parking orbit need not be at ISS altitudes it can be higher or even elliptical so you may not need 1.5 MW either.
Since SLS Block IB can throw the 37,300Kg Skylab II into a lunar trajectory and just a simple tug maybe even one with chemical engines would be enough to place it where's it's needed I feel that concept is probably be the right one to go with.
If the EUS had IVF added to it a large SEP tug may not be needed at all even for Skylab II as the EUS could take it through TLI and place it in a high lunar orbit.
Just use the SEP engines to lower it down to LLO.
« Last Edit: 10/19/2017 12:32 AM by Patchouli »

Offline MATTBLAK

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #125 on: 10/19/2017 12:38 AM »
Helpful examples above, thanks. So a 500kw solar array using modern methods and technology would not be out of the question and still probably be smaller than the ISS size-spread.
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Offline Steven Pietrobon

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #126 on: 10/19/2017 06:16 AM »
The block 1 SLS can lift 70 tonnes to LEO, later versions 105 tonnes. IMHO That is a reasonable size for a mini spacestation.

The 105 t is the IMLEO, including the EUS. The payload mass is about 93 t.
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Offline A_M_Swallow

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #127 on: 10/19/2017 06:35 AM »
The block 1 SLS can lift 70 tonnes to LEO, later versions 105 tonnes. IMHO That is a reasonable size for a mini spacestation.

The 105 t is the IMLEO, including the EUS. The payload mass is about 93 t.

93 t - we will have to put the spacestation on a diet.

Offline Proponent

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #128 on: 10/19/2017 12:31 PM »
The DSG could be used to build the lunar base. For example the SLS would throw 40 tonne habitats to the DSG. The station's reusable lander would take the habitats down to the lunar surface. Same for heavy cargoes going to Mars.

NASA has no plans to build a moon base and is unlikely to have funding for such in foreseeable decades.  While a base could conceivably be staged through a station in high lunar orbit, I challenge you to find a single proposal for a moon base, from the many decades' worth of such proposals, that involves such a station.  If nobody from Goddard (and he proposed mining lunar water!) on thought it a good idea, why is it a good idea now?

Offline ncb1397

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #129 on: 10/19/2017 05:33 PM »
13 payloads

No.

Only five are partially or fully funded through HEOMD.

Whether it comes out of JAXA's budget or HEOMD, effect on overall NASA led exploration may be the same/similar.

The Administration's proposed cut to NASA's 2018 topline was based on program terminations and content reduction, not old development programs ending. 

The NASA 2017 budget request put cargo and crew transportation to the ISS(including development of domestic crew vehicles) at 2.758 billion. This component was fully funded, was it not? The NASA 2018 budget request put Cargo and Crew transportation to the ISS at 2.415 billion(a drop of 343 million without accounting for inflation). If this drop hadn't occurred, and education wasn't taken out, there would be basically no drop in NASA budget keeping all other funding the same(and not accounting for inflation). This drop is most attributable to the projected end of development in the 2018 time frame of major development programs. The specific funding for commercial crew development drops ~$500 million. This likely also reflects reductions in payments to Russia for missions in 2019+(that won't occur) because of end of development of domestic alternatives.

For 2018, the White House proposed eliminating NASA's entire education program, terminating several earth science missions in development, and turning off earth science instruments on other operational missions.

Even if you don't count the end of the education program, we are still talking about a pretty large drop, especially when you account for inflation. U.S. Inflation in 2017 was about 2.2%, which means the 2017 budget of 19.653 billion would be equivalent to the 19.993 billion(assuming 2018 inflation is equal to 2017 inflation). Adding education back in yields a budget for 2018 of 19.155 billion, a fall of $838 million which can be attributable to the completion(cancellations count) of several development programs. Again, without major new development program(s) to replace ones that are ending, the budget falls substantially. This could be the Europa lander, lunar lander, DSG or something else. It seems that there is a trade between bumping Planetary Science to account for new development programs and bumping Exploration spending to account for new development programs in order to maintain NASA's current funding levels. Your multi-billion dollar required increase to NASA's topline budget to fund any additional exploration equipment is simply incorrect especially considering the most expensive components of a lunar surface program are already funded (based on actual data from Apollo..this isn't theoretical). If a major billion dollar exploration program was created in FY 2018 roughly equivalent in size to the Orion crew vehicle, the result wouldn't have been a multi-billion dollar increase in NASA's top line budget. The result would have been an essentially flat budget(give or take 1%).
« Last Edit: 10/19/2017 05:49 PM by ncb1397 »

Online UltraViolet9

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #130 on: 10/19/2017 08:26 PM »
Whether it comes out of JAXA's budget or HEOMD, effect on overall NASA led exploration may be the same/similar.

No.

If an entity outside HEOMD is paying for an activity -- especially a foreign space agency -- then HEOMD will see no funding freed up when that activity ramps down or ends.

Quote
Even if you don't count the end of the education program, we are still talking about a pretty large drop, especially when you account for inflation. U.S. Inflation in 2017 was about 2.2%, which means the 2017 budget of 19.653 billion would be equivalent to the 19.993 billion

Unfortunately, this is unrealistic for planning purposes.

NASA's budget has not kept pace with inflation for decades.

Quote
The NASA 2017 budget request put cargo and crew transportation

May all be accurate.  I'm just pointing out there were terminations and content reductions, not just programs ramping down.

If it's accurate, there's a lesson here that HEOMD or NASA can't expect to keep every dollar freed up in future-year budgets from old developments ramping down or old programs ending.

For planning purposes, we shouldn't bet on retaining every dollar in the current budget and on inflation on top of that.

Either the older, more routine elements of the space exploration enterprise become more efficient with time or there will be less and less funding for new elements that actually do the exploring.

« Last Edit: 10/19/2017 08:27 PM by UltraViolet9 »

Offline ncb1397

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #131 on: 10/19/2017 09:12 PM »
Even if you don't count the end of the education program, we are still talking about a pretty large drop, especially when you account for inflation. U.S. Inflation in 2017 was about 2.2%, which means the 2017 budget of 19.653 billion would be equivalent to the 19.993 billion

Unfortunately, this is unrealistic for planning purposes.

NASA's budget has not kept pace with inflation for decades.

Plugging NASA's 2000 funding amount into a government CPI calculator yields a different conclusion:

https://data.bls.gov/cgi-bin/cpicalc.pl?cost1=13428&year1=200001&year2=201701

NASA budget from beginning of the century to 2017 was inflation adjusted and then some. I used CPI for my inflation calculations above.

edit:
It is also good to keep Apollo costs in mind in these discussions:

ranked by expense:

Saturn V: 6.4 B
CSM: 3.7 B
LEM: 2.2 B
Skylab: 2.2 B
LRV: .038 B

You could almost fund the LEM, Skylab and the LRV for the cost of the CSM. Likewise, you could possibly get away with funding the DSG, a lander and a rover for what is spent on Orion( $1.2 B/year). For reference, this would be a 2018 budget of 2017 enacted + inflation + $400 million. Not several billion dollars.
« Last Edit: 10/19/2017 11:38 PM by ncb1397 »

Offline Proponent

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #132 on: 10/20/2017 01:44 AM »
Even if you don't count the end of the education program, we are still talking about a pretty large drop, especially when you account for inflation. U.S. Inflation in 2017 was about 2.2%, which means the 2017 budget of 19.653 billion would be equivalent to the 19.993 billion

Unfortunately, this is unrealistic for planning purposes.

NASA's budget has not kept pace with inflation for decades.

Plugging NASA's 2000 funding amount into a government CPI calculator yields a different conclusion:

https://data.bls.gov/cgi-bin/cpicalc.pl?cost1=13428&year1=200001&year2=201701

NASA budget from beginning of the century to 2017 was inflation adjusted and then some. I used CPI for my inflation calculations above.

edit:
It is also good to keep Apollo costs in mind in these discussions:

ranked by expense:

Saturn V: 6.4 B
CSM: 3.7 B
LEM: 2.2 B
Skylab: 2.2 B
LRV: .038 B

You could almost fund the LEM, Skylab and the LRV for the cost of the CSM. Likewise, you could possibly get away with funding the DSG, a lander and a rover for what is spent on Orion( $1.2 B/year). For reference, this would be a 2018 budget of 2017 enacted + inflation + $400 million. Not several billion dollars.

The CPI is not a good measure of inflation for NASA programs, unless, perhaps, you want to compare the amounts of consumption that Americans sacrificed for NASA programs at different time.  The difference between the CPI and a more relevant inflation index, such as the NASA New-Start Index (NNSII) , has decreased in recent years, but NASA programs from the 1960's turn out to be far more expensive in today's dollars with the NNSII.

Offline yg1968

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #133 on: 10/26/2017 03:04 PM »
« Last Edit: 10/26/2017 07:29 PM by yg1968 »

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #134 on: 10/26/2017 10:04 PM »
NASA budget from beginning of the century to 2017 was inflation adjusted and then some.

No.

Based on a CPI website, NASA's FY 2017 budget gets NASA back to its FY 2000 budget, plus inflation. 

But that's the wrong inflator for NASA or the aerospace sector overall; FY 2000 is a low point in NASA's annual budget; and most importantly, there was no steady inflationary increase year-on-year during this time period.  The area under the curve that matters much more than the endpoints.

Even with a cherry-picked inflator and starting point, NASA's buying power in the intervening years did not keep pace with inflation.  In fact, in some of these years, NASA's budget actually shrank, even in constant dollars (forget inflation). 

« Last Edit: 10/26/2017 10:49 PM by UltraViolet9 »

Offline ncb1397

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #135 on: 10/27/2017 06:07 PM »
NASA budget from beginning of the century to 2017 was inflation adjusted and then some.

No.

Based on a CPI website, NASA's FY 2017 budget gets NASA back to its FY 2000 budget, plus inflation. 

But that's the wrong inflator for NASA or the aerospace sector overall; FY 2000 is a low point in NASA's annual budget; and most importantly, there was no steady inflationary increase year-on-year during this time period.  The area under the curve that matters much more than the endpoints.

Even with a cherry-picked inflator and starting point, NASA's buying power in the intervening years did not keep pace with inflation.  In fact, in some of these years, NASA's budget actually shrank, even in constant dollars (forget inflation).

I think we are in agreement then. I don't really count a inflation adjustment as a budget increase, because it just counteracts the fall in the value of the dollar. But yes, they need some sort of yearly increase(in nominal terms) in order to fund additional exploration elements ultimately totaling several billion dollars on an annual basis. I mean, going back to the 1966 budget of ~6 billion USD just isn't feasible. Obviously, NASA is screwed without a "cost of living" adjustment. But they are getting, on average, yearly increases given the 1966 budget of 6 billion and the 2017 budget of ~19-20 billion. Goes without saying that it didn't keep up with inflation, especially between those two end points. But more recently, on a long term basis, it has more or less kept up with CPI after the recovery from Shuttle/Constellation/ISS construction ending in the same timeframe
« Last Edit: 10/27/2017 06:25 PM by ncb1397 »

Offline Coastal Ron

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #136 on: 10/27/2017 06:32 PM »
Even with a cherry-picked inflator and starting point, NASA's buying power in the intervening years did not keep pace with inflation.  In fact, in some of these years, NASA's budget actually shrank, even in constant dollars (forget inflation).

I think we are in agreement then. I don't really count a inflation adjustment as a budget increase, because it just counteracts the fall in the value of the dollar. But yes, they need some sort of yearly increase(in nominal terms) in order to fund additional exploration elements ultimately totaling several billion dollars on an annual basis. I mean, going back to the 1966 budget of ~6 billion USD just isn't feasible. Obviously, NASA is screwed without a "cost of living" adjustment. But they are getting, on average, yearly increases given the 1966 budget of 6 billion and the 2017 budget of ~19-20 billion. Goes without saying that it didn't keep up with inflation, especially between those two end points.

I found the following on the "Budget of NASA" Wikipedia page:



The trend for NASA's budget since 1991 has been a decrease both in 2014 Constant Dollars (a way to take into account inflation) and as a percentage of the Federal Budget.

From Wikipedia regarding Space Station Freedom:

Quote
NASA signed final ten-year contracts for developing the Space Station in September 1988, and the project was finally moving into the hardware fabrication phase.

Which corresponds with the bump starting in 1988. And not that the DSG would require the funding profile of the ISS, but NASA's overall budget would have to take into account operational funding for one or more yearly SLS and Orion flights (and all of the production associated with them), as well as the production of the DSG hardware itself, and the DSG operational budget.

If the official goal becomes to land humans back on the Moon again, then you have to add development for all of that hardware, as well as funding the production of more SLS and Orion required to support the planned missions - and all of the funding required for ongoing operations (including the permanent staff required to be kept between flights).

We should get a hint about whether this is a possibility soon, when NASA responds back to the NSC.
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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #137 on: 10/27/2017 06:39 PM »
But yes, they need some sort of yearly increase(in nominal terms) in order to fund additional exploration elements ultimately totaling several billion dollars on an annual basis.

That, or a wedge has to be carved out of the SLS/Orion/GSE budget approaching $4B/yr.  Based on FY 2022 and STS experience, that does not seem possible without retiring one or both of those flight elements.

Without a plus-up or SLS/Orion/GSE retirement, it's hard to see much of a budget wedge opening up for DSG and/or lunar landers until after ISS retirement in 2024-2028 or later.

Offline yg1968

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #138 on: 10/28/2017 02:45 PM »
European space officials outline desired contribution to Deep Space Gateway:
http://spacenews.com/european-space-officials-outline-desired-contribution-to-deep-space-gateway/
« Last Edit: 10/28/2017 02:46 PM by yg1968 »

Offline redliox

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #139 on: 10/28/2017 03:31 PM »
European space officials outline desired contribution to Deep Space Gateway:
http://spacenews.com/european-space-officials-outline-desired-contribution-to-deep-space-gateway/

In that article their emphasis seems to be on a space tug, presumably SEP.  Might be within their capability.
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