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RGClark

Member

From: Philadelphia, PA

Registered: 2006-07-05

Posts: 765

Website

SpaceX COULD have done a manned lunar mission this year…

For several years I’ve been thinking of mission architectures that could get us back to the Moon by the 50th anniversary of the Apollo manned lunar missions. We missed the Apollo 11 50th anniversary, but we MIGHT have been able to make the Apollo 17 50th anniversary of Dec. 2022. 

This is where it gets controversial. The SpaceX architecture of making 8 to 16 refueling flights for Moon or Mars flights is a bad architecture. There is a reason why the Apollo missions used a launcher with 3 stages and then 2 more stages for the lander for their round-trip missions. For missions with that high a delta-v requirement multiple stages are critical. SpaceX by using multiple refueling flights is acknowledging that, just in a very inefficient manner.

The point of the matter SpaceX could have manned Moon or Mars flights with a single launch IF they have given their launcher a 3rd stage. The 3rd stage could have been comparable size to the Starhopper. Yes, I know the actual Starhopper was not space-worthy but the point of the matter is by continuing it’s development along side the Starship they would have had a space-worthy vehicle capable of lunar landing and return by now.

Robert Zubrin also says the SpaceX plan of multiple refuelings for lunar or Mars flights is a bad idea. He says using the Starship as a lunar lander is like using an aircraft carrier for white water rafting. He also suggests using a smaller “mini Starship” that would stage off the Starship to do the landings. He notes this way you could do the missions with no refueling flights required. Plus the Starship not having to land on the Moon or Mars would be rapidly reusable. Zubrins refers to his approach as Mars Direct 2.0:

Mars Direct 2.0 - Dr. Robert Zubrin - IAC 2019.

https://www.youtube.com/watch?v=z5k7-Y4nZlQ

SuperHeavy+StarShip+StarHopper single launch missions to the Moon or Mars. It would have been so beautiful …

See here: 

Saturday, July 27, 2019
Starhopper+Starship as a heavy-lift launcher. Triple-cored Starship for super-heavy lift. 2nd UPDATE, 9/2/2019: Starhopper as a lunar lander.
http://exoscientist.blogspot.com/2019/0 … -lift.html

  Robert Clark

Last edited by RGClark (2022-06-22 11:40:12)

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Old Space rule of acquisition (with a nod to Star Trek - the Next Generation):

      “Anything worth doing is worth doing for a billion dollars.”

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: SpaceX COULD have done a manned lunar mission this year…

Zubrin had put for before starship a plan in 2018 to build a moon base with just 4 falcon heavies.
http://newmars.com/2018/03/moon-direct- … our-years/

we do have a topic with this being discussed http://newmars.com/forums/viewtopic.php?id=8473

Calliban

Member

From: Northern England, UK

Registered: 2019-08-18

Posts: 3,793

Re: SpaceX COULD have done a manned lunar mission this year…

SpaceX's Raptor 2 looks revolutionary.
https://m.youtube.com/watch?v=nMktmbcZYYQ

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"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

GW Johnson

Member

From: McGregor, Texas USA

Registered: 2011-12-04

Posts: 5,801

Website

Re: SpaceX COULD have done a manned lunar mission this year…

I'm not at all sure how "revolutionary" the Raptor-2 is,  but it is a big improvement no matter how you slice things. 

It's the same basic design,  but with the powerhead plumbing greatly simplified by redesign,  including the turbopump assemblies.  It was inadequate delivery from the Raptor-1 turbopumps that kept thrust (and specific impulse) achievables well below the original design intentions.  Inadequate massflow is lowered pressure,  which is lowered thrust.

The new turbopump assemblies are good enough to reach the intended 4400 psia = 303 bar (abs) chamber pressures,  despite a slight increase in throat diameter.  That and 150:1 expansion ratio gets you to 250 metric tons-force thrust and almost 380 s Isp in vacuum.  At 107:1,  you can fire it in the open air,  but thrust and Isp are a tad lower. 

The same powerhead fitted with a 40:1 expansion bell is the sea level engine.  Thrust levels and Isps's are lower,  but the disparity between vacuum and SL performance is not high,  unlike what happens if you try to use the 107 vac engine at SL.

I just published all this reverse-engineering data on my "exrocketman" site for the 1 October posting. 

GW

Last edited by GW Johnson (2022-10-02 16:18:34)

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GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

Mars_B4_Moon

Member

Registered: 2006-03-23

Posts: 9,776

Re: SpaceX COULD have done a manned lunar mission this year…

2022, 2023 for the Moon would have been early

quote

orbit might be positive perigee, 21 x 214 km, rather than my earlier estimate of -50 x 235 km. But still plus or minus about 30 km on that estimate

https://x.com/planet4589/status/1798695263839867376

Flight 4 and Finally reusable launch system development program and ambition of colonizing Mars.

https://x.com/spacex/status/1798715759193096245

it looks like tough craft a little beaten up but fine

Last edited by Mars_B4_Moon (2024-06-06 08:10:53)

RGClark

Member

From: Philadelphia, PA

Registered: 2006-07-05

Posts: 765

Website

Re: SpaceX COULD have done a manned lunar mission this year…

My suggestion was to use an expendable 3-stage architecture for the Starship vehicle. I suggested a "mini-Starship" for the 3rd stage, but it would work just as well to use the already existing Falcon 9's 100 ton 2nd stage for the purpose.

Note, since the Starship stages are expendable they would have much reduced dry mass, which increases the payload mass. I estimated with the Falcon 9 upper stage being used as a 3rd stage for the Starship, you could get single launch missions to the Moon and Mars NOW.

  Bob Clark

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Old Space rule of acquisition (with a nod to Star Trek - the Next Generation):

      “Anything worth doing is worth doing for a billion dollars.”