Author Topic: ASAP on board with NASA's DSG as stepping stone to Mars  (Read 43364 times)

Offline yg1968

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #140 on: 11/04/2017 02:56 am »
NASA issues study contracts for Deep Space Gateway element:
http://spacenews.com/nasa-issues-study-contracts-for-deep-space-gateway-element/

Offline calapine

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #141 on: 11/04/2017 08:25 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.

As per a CNES study Ariane 6 could deliever 6 tons in 3 months (chemical) or 10 tons in 1 year (SEP) to the DSG.

Should be good enough to deliver entire modules.


Online brickmack

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #142 on: 11/07/2017 05:28 pm »
Got a link to that study? 3 months seems awful long for chemical unless they're using some fancy low energy transfer (but then 6 tons sounds low...)

Online TrevorMonty

Got a link to that study? 3 months seems awful long for chemical unless they're using some fancy low energy transfer (but then 6 tons sounds low...)
Quick 3day transfer to DSG is about 3.7km/s, slow 3 month transfer is about 3.1 km/s.

Online envy887

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #144 on: 11/07/2017 11:17 pm »
Got a link to that study? 3 months seems awful long for chemical unless they're using some fancy low energy transfer (but then 6 tons sounds low...)
Quick 3day transfer to DSG is about 3.7km/s, slow 3 month transfer is about 3.1 km/s.

3.1 km/s only gets it a Hohmann transfer to EML1 altitudes, how does it insert to NRHO?

Online TrevorMonty

Got a link to that study? 3 months seems awful long for chemical unless they're using some fancy low energy transfer (but then 6 tons sounds low...)
Quick 3day transfer to DSG is about 3.7km/s, slow 3 month transfer is about 3.1 km/s.

3.1 km/s only gets it a Hohmann transfer to EML1 altitudes, how does it insert to NRHO?
I was thinking of EML1, not sure about NRO.

Offline Patchouli

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #146 on: 11/08/2017 05:06 am »
Got a link to that study? 3 months seems awful long for chemical unless they're using some fancy low energy transfer (but then 6 tons sounds low...)
Quick 3day transfer to DSG is about 3.7km/s, slow 3 month transfer is about 3.1 km/s.

Why even bother with such a slow transfer when the 3 day one only requires 600 m/sec more delta V?
« Last Edit: 11/08/2017 05:06 am by Patchouli »

Offline calapine

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Offline Proponent

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #148 on: 11/08/2017 12:38 pm »
Why even bother with such a slow transfer when the 3 day one only requires 600 m/sec more delta V?

When the delta-V is comparable to or greater than the effective exhaust velocity, a small change can have a pretty big impact on payload.

For example, suppose a Centaur (Isp 450.5 s, inert mass 2,316 kg, propellant mass 20,830 kg) is the trans-lunar injection stage.  Assuming residuals of 0.5%, I get a payload 18,100 kg to 3.1 km/s but just 13,500 to 3.7 km/s.  In other words, lowering the delta-V by 13% increases the payload by 34%.
« Last Edit: 11/08/2017 12:46 pm by Proponent »

Offline Proponent

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #149 on: 01/27/2019 08:35 pm »
Bob Zubrin is totally not on board. I'm shocked <video link elided -- Proponent>

Thanks much -- that was actually quite interesting.  Zubrin tears into DSG, pointing out, among other things, that never before in the history of planning for missions to Mars (or the moon), dating back to von Braun, has anyone said that a cis-lunar station is desirable.

Though I believe Zubrin's general point is very much correct, I have recently found an explicit example of a recommendation to build a station in lunar orbit as a way station to the lunar surface.  It's an interesting piece of out-of-the-box thinking produced by Goodyear Aircraft in 1962,  Aside from rotating inflatable stations in both LEO and LLO lunar orbit, it depended on Gemini spacecraft, Titan launch vehicles and lots and lots of Agena stages.

EDIT:  Replaced "LLO" with "lunar orbit," per Steven Pietrobon's precis, below.
« Last Edit: 01/28/2019 12:58 pm by Proponent »

Offline Steven Pietrobon

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #150 on: 01/28/2019 06:26 am »
Very interesting. Their space station mass (both LEO and Lunar) is only 3086 kg! The Lunar station is at an altitude of 1600 km. After expansion, the station would have a 12.2 m diameter. The study even has a budget! Total cost is $3B. Total number of Titan II's is 1815 to 1968!
« Last Edit: 01/28/2019 06:34 am by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline tea monster

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #151 on: 01/28/2019 10:12 am »
I thought this was really cool. I did a quick render of what the ship may have looked like on the surface. The Gemini is from NASA's 3D Resource page.


Offline Robotbeat

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Re: ASAP on board with NASA's DSG as stepping stone to Mars
« Reply #152 on: 02/06/2019 03:19 pm »
A couple of notes on DSG:

Quote
Crusan: "for the first time ever, we have refueling baselined in our human space flight architecture."  Finally. Whoo hoo!!  #leag2017

https://twitter.com/george_sowers/status/917744545340764161

Quote
Jason Crusan asked how DSG is fueled. His answer: "I do not care where the fuel comes from" for Deep Space gateway. #LEAG2017

https://twitter.com/NASAWatch/status/917743640730132480
*cough* Salyut 7, Mir, ISS *cough*
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Tags: DSG JAXA