Author Topic: Mars Orbital mission with only DSH and Orion  (Read 12637 times)

Online woods170

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Re: Mars Orbital mission with only DSH and Orion
« Reply #40 on: 04/25/2017 06:33 PM »
Falcon Heavy can put 64 tonnes in LEO. For 100 mill.

You don't get it. Launch cost is only a minority percentage of the total cost. Development of the DSH and final development of Orion will be considerably more expensive. You don't buy an additional mission by switching from SLS to FH. The cost saving is just not big enough given that Orion is, and DSH will be, horrendously expensive to develop and build.

Online woods170

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Re: Mars Orbital mission with only DSH and Orion
« Reply #41 on: 04/25/2017 06:37 PM »
What most people fell to appreciate is that the Falcon 9 Heavy, with its kerolox upper stage, has low performance beyond LEO. nothing beats LH2 there.
And that's not a problem given that FH will not be used to fly the really important missions beyond LEO. FH is for the pre-cursor missions like Red Dragon. It's performance is good enough for those. SpaceX is optimizing for cost, not for performance. Given that mantra it is silly to put a LH2/LOX stage on FH.

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Re: Mars Orbital mission with only DSH and Orion
« Reply #42 on: 04/27/2017 02:10 PM »
Instead of 3 Orions, why not have another ICPS for boost operations?

i'm thinking along these lines too.  Maybe I'm missing understanding something but two top level observations:

-you seem to be leaving a lot of SLS 1B performance off the table if you are only launching Orion to GTO. 
-are you doing anything with those two extra orion crew modules?  seems awfully wasteful to launch all that extra mass if you don't need it for something.

If you are assuming you have block 1b, then you have EUS.  it's designed to be an in space stage to do the kinds of boost maneuvers you talk about, with the exception maybe of the long term storage you need for any burns that happen late in the mission.  Why not use those instead? If you need more "storable" delta-V, use a second Orion SM but don't waste another CM.  Or better yet just take extra prop and consumables to replenish the first SM. 

Online AncientU

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Re: Mars Orbital mission with only DSH and Orion
« Reply #43 on: 04/27/2017 06:55 PM »
What most people fell to appreciate is that the Falcon 9 Heavy, with its kerolox upper stage, has low performance beyond LEO. nothing beats LH2 there.

Refueling beats LH2* hands down.
We have to get out of the APOLLO mindset if we are going anywhere BEO.

SLS/Orion is particularly a failure of this sort -- fundamentally a failure of vision which is totally expected given its political backers.

* compared to traditional launch-everything-on-one-booster mode
"If we shared everything [we are working on] people would think we are insane!"
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Online ncb1397

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Re: Mars Orbital mission with only DSH and Orion
« Reply #44 on: 04/27/2017 07:09 PM »
Falcon Heavy can put 64 tonnes in LEO. For 100 mill. Surely NASA should drop the SLS and just work out a way to send the DSH , Orion etc up on top the falcon heavy, just think of the extra exploration missions they could run with the money they saved. SLS is dead in the water, 40 year old technology with a huge price tag.

Many of the NASA exploration parts could be put into space with falcon heavy recovery of the first stages. That should make it cheaper again.

The 100 million price is not for the full performance of the Falcon Heavy. Last time I checked, $90 million is for up to 8 mT(could be dated) to GTO while the full performance was ~3x that. Common misconception on the internet. NASA tends to pay a lot more than the published prices regardless.

Online Coastal Ron

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Re: Mars Orbital mission with only DSH and Orion
« Reply #45 on: 05/04/2017 07:33 PM »
The 100 million price is not for the full performance of the Falcon Heavy. Last time I checked, $90 million is for up to 8 mT(could be dated) to GTO while the full performance was ~3x that. Common misconception on the internet.

An expendable Falcon Heavy would be more than $100M, though chances are it's still in a pretty reasonable range (i.e. less than $150M).

Quote
NASA tends to pay a lot more than the published prices regardless.

Only because NASA asks for additional products and services for their launches, not because SpaceX is charging NASA higher prices because they are the government.  For instance, from a SpaceNews article on the Surface Water and Ocean Topography (SWOT) spacecraft launch contract award to SpaceX last year:

"NASA spokeswoman Cheryl Warner said that the award values can differ from contract to contract depending on the specific requirements for each mission. “The specific launch service price is considered competition and procurement sensitive information,” she said Nov. 22."

The same would apply to SLS launches too, it's just that the costs would be hidden deep in NASA's budget.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

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