Author Topic: ASAP on board with NASA's DSG as stepping stone to Mars  (Read 37183 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.


Offline 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.

Offline 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 »

Tags: DSG JAXA