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#1651 2022-07-09 17:58:39

Void
Member
Registered: 2011-12-29
Posts: 5,087

Re: Starship is Go...

I think this is worth a look: https://www.youtube.com/watch?v=E7MQb9Y4FAE
Quote:

Elon Musk Explains SpaceX's Raptor Engine!
180,651 viewsJul 9, 2022


Everyday Astronaut
1.29M subscribers
Today we’re getting up close and personal with SpaceX’s Raptor 2 engine with Elon Musk. We get into all sorts of details on this engine including how exactly it’s been upgraded and simplified compared to Raptor 1.

This video has a ton of fun details on some fairly technical stuff, so be sure and watch my "Why don’t rocket engines melt" video - https://youtu.be/he_BL6Q5u1Y - so you know what we’re talking about with some of the cooling techniques as well as my video on engine cycles - https://youtu.be/Owji-ukVt9M - so you understand how the Raptor’s full flow staged combustion cycle works and why it’s advantageous!

00:00 - Intro
00:50 - Conversation Starts
02:00 - Raptor 1 vs Raptor 2
03:50 - Thrust and Chamber Pressure
05:30 - Iteration Philosophy
06:30 - Melting Engines and Cooling
09:30 - Torch Igniters and Starting
13:00 - Full Flow Advantages
15:30 - Swirl Injectors
16:40 - Thrust Vector Control
20:30 - Simplifications
24:50 - Removing Throat Film Cooling
25:35 - Boost Pumps and Impellers
30:35 - Inline Powerhead Discussion
32:15 - Fluorine, Dual Cooling and Aerospikes
35:00 - Chamber Pressure and Impulse
40:00 - Outro

--------------------------

Louis! Come back!

Done


Done.

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#1652 2022-07-15 07:20:17

Void
Member
Registered: 2011-12-29
Posts: 5,087

Re: Starship is Go...

Elon Musk's Genius Solution to Launch Starship from the sea...No More FAA, "GREAT SPACEX"

https://www.bing.com/videos/search?q=+E … &FORM=VIRE

This is interesting of course, as the sea launch facilities may be in a more favorable location, and also might not be entangled in as much red tape.  And then insurance and lawsuits may be less of a concern.

OTEC, an energy manufacturing platform(s), are placed in a special slot in the weather between North and South Hemispheres, (Approximately), where Hurricane problems are much less.  So, Starship might do similar.

In the Pacific, I think this runs roughly from ~Panama, to a bit north of Papua New Guinea.  Somewhat south of the Hawaiian Islands.

I believe the ultimately SpaceX wants to produce its own Methane and Oxygen from so called "Green Energy".  I don't like that term, actually,

But I suppose tankers could deliver it to the platform, from locations in the Pacific.  Australia is likely great for Solar Energy, so, perhaps from there.

But I am not thinking that at first, they would do it that way.

So, I am thinking of propellants to orbit for this as you have the other benefits of the platform concept, and also the Equatorial spin.  The platforms could probably go on to the actual Equator, except for during the storm seasons.

After Breakfast, I intend to make some further comments on "Index» Terraformation» Worlds, and World Engine type terraform stuff."
It will involve the concept of orbital propellant depots, and launching 1000 Starships almost at once, periodically to Mars.

http://newmars.com/forums/viewtopic.php?id=10144&p=15  It will likely be post #374.

Done.

Last edited by Void (2022-07-15 08:59:13)


Done.

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#1653 2022-07-15 11:37:30

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,952
Website

Re: Starship is Go...

The news reports say an engine exploded in the B7 static test.  Did not really look like that to me,  not violent enough.  Looked more like engine exhaust lighting off an exploding cloud of methane air from a methane leak. 

But I've seen nothing.

GW


GW Johnson
McGregor,  Texas

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

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#1654 2022-07-16 14:19:57

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 26,803

Re: Starship is Go...

From the short clips not, all engines ignited and after a bit just before there was something that exited from the group that was running prior to the next group which was on the outside ring to flash ignite before going out.

https://www.spaceflightinsider.com/miss … gine-test/

https://techcrunch.com/2022/07/12/space … one-wrong/

SpaceX Tests Super Heavy Booster 7, Results in Explosion and Pad Fire video

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#1655 2022-07-17 07:20:15

RGClark
Member
From: Philadelphia, PA
Registered: 2006-07-05
Posts: 558
Website

Re: Starship is Go...

I’m not sanguine about using the 33 engines on the Superheavy for regular passenger flights. I think better would be developing using the 9-engine Starship for that purpose. The Superheavy could be used for delivering to orbit cargo or the large components of beyond LEO flights, i.e., Moon or Mars.

To this end SpaceX should develop a smaller 3rd stage to go atop the Starship, a mini-Starship if you will. I speculated about this before. Since it is comparable in size to the earlier Starhopper test stage, I called this stage, modified to be space-worthy, “Starhopper”. This would allow ca. 100 tons expendable payload for the TSTO Starship/Starhopper. And an expendable 3-stage Superheavy/Starship/Starhopper could do either lunar or Mars missions in a single flight.

  Bob Clark

Last edited by RGClark (2022-09-04 22:06:58)


Nanotechnology now can produce the space elevator and private orbital launchers. It now also makes possible the long desired 'flying cars'. This crowdfunding campaign is to prove it:
Nanotech: from air to space.
https://www.indiegogo.com/projects/nano … 13319568#/

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#1656 2022-07-17 08:42:02

Void
Member
Registered: 2011-12-29
Posts: 5,087

Re: Starship is Go...

RGClark,

I find your thinking interesting, and you have stimulated my thinking, but I have a "Kids" table where I can comment, that way I don't as much interfere with professional thinking.

Index» Interplanetary transportation» Alternate BFR (Big Falcon Rocket), perhaps Post #480.

I will just put my comments there, and no response is expected.

Done.

Last edited by Void (2022-07-17 08:42:54)


Done.

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#1657 2022-07-17 16:30:29

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 26,803

Re: Starship is Go...

Falcon 9 can lift up to 22,800 kilograms in weight (50,300 lbs) whereas the Falcon Heavy rocket can lift a payload of 64000 kilograms or 141,000 lbs. Falcon Heavy is expected to take 4 times more mass to LEO than Falcon 9 (53 instead of 13 tons).

Falcon 9 has a mass of 505,806 kg while the Falcon Heavy weighs 1.421 million kg. The first stage is

That said we are using a disposable second stage, but starship is a fully recoverable that. Since the first stage is the main difference.

https://en.wikipedia.org/wiki/Falcon_9
https://en.wikipedia.org/wiki/Falcon_Heavy

Sure with fuel change and engines we are not comparing Apples to Apples but more like oranges.

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#1658 2022-07-26 09:23:30

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,952
Website

Re: Starship is Go...

Before this development effort is over,  I bet Superheavy has more than 33 engines.  Probably nearer 36 or 37. 

33 is not that different from 27,  which is what they have flown successfully a few times on the Falcon-Heavy.  But,  multiple 10's of engines is PRECISELY the reliability problem that the Russians never solved with their giant N-1 moon rocket decades ago.  So there is reason to worry.

It's been a couple of years now,  since I did a ballpark mission analysis of Starship/Superheavy to LEO.  I was using Raptor-1 data that I had reverse-engineered,  to match projected performance claims at the full design chamber pressure.  In terms of Isp at full pressure,  Raptor-2 is little different,  but has higher thrust because the throat diameter is slightly larger. 

Spacex was never able to reach full chamber pressure with Raptor-1,  so the thrusts and Isp's all fell a bit short.  But with the new turbopump design,  they have the high-pressure flow rate capability to reach full pressure,  even with the larger throat,  and they say they have reached it.

What that says,  is that my mission analysis 2 years ago is probably pretty close to what they might achieve with Starship/Superheavy-Raptor-2 today.  Close enough to be fairly representative.  I found 170 m.tons payload to LEO.  With booster flyback and everything.  Hand calculations,  not a computer trajectory code.

The trouble I identified 2 years ago was insufficient thrust for the launch weight,  at the 29 engines they were taking about back then.  I got adequate thrust with 37+ Raptor-1's.  Raptor-2 has higher thrust,  so that launch thrust/weight is less of an issue today with 33 Raptor-2's.

The inert masses I see being bandied about today for Superheavy are too small. I used 180-200 tons 2 years ago,  assuming landing legs.  They have deleted the legs to catch it instead (we'll see if that really works -- I have my doubts).  But deleting the legs will only save a couple of tons,  not dozens.

I see the same trouble with the inert masses being bandied about for Starship,  too.  Musk's comments make it clear they are striving for about 100 tons,  but they have never gotten to that value.  All the prototypes so far have been nearer 120 tons (I heard Musk say so at one of his events).  And that's for no cargo decks and no pressurized crew structures. 

By the time this design is finished,  it will be closer to 130 tons,  in my opinion.  And by the time they fit it with legs adequate for the soft dirts on the moon and Mars,  it'll be closer to 140 tons.  Those will have to have a wide stance,  they will have to fold out some very large pad surfaces,  and the ones on the belly side will have to have heat shield tiles.  Such legs will be totally unlike any we saw on the Starship prototypes so far.

GW

Last edited by GW Johnson (2022-07-26 09:26:36)


GW Johnson
McGregor,  Texas

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

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#1659 2022-07-26 11:05:13

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 12,063

Re: Starship is Go...

For GW Johnson ... thanks for your review of SpaceX developments (and your projections) in Post #1658

As I read your comments about wide landing legs and pads for a Moon lander, it crossed my mind that those could be added ** after ** a Moon lander vehicle is in LEO.  The legs and pads could be carried up in a separate freight shipment.  Once fitted, they would be (could be) permanent, since there is no need to retract them after liftoff from the Moon.

Update ... after posting, I realized there is the issue of slowing the rate of travel as the vessel approaches Earth.

Question ... could permanent landing legs and pads help to slow a vehicle returning from the Moon?

Specialized heat management coatings would be needed.  Is such a concept practical?

(th)

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#1660 2022-07-26 12:55:19

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,952
Website

Re: Starship is Go...

Tom:

Coming back from the moon you hit atmosphere at about 10.9 km/s,  which is fast enough that radiative heating from the plasma sheath is starting dominate over convective heating,  and the plasma sheath is getting fairly opaque to visible and infrared light,  as well as radio.  Under those conditions,  refractories like the ceramic shuttle tiles and blankets no longer work,  being radiatively cooled to space.  Your only remaining choice is ablatives.   You hit peak heating and deceleration not simultaneously,  but down nearer 5 km/s.

SpaceX's tiles on Starship are NOT ceramic refractories,  they are slow ablatives.  They are SpaceX's variant of NASA's old PICA material.  The SpaceX variant is PICA-X,  and it is easier and cheaper to make than NASA's original PICA.  "PICA" is an acronym for Phenolic-Impregnated Carbon Ablator.  And that's my point:  it is an ablator. Just a slow one.  Like carbon-carbon composite,  but nowhere near as expensive.

Coming back from the moon and hitting the atmosphere at about 10.9 km/s,  at a grazing tangential strike such that the entry angle was 1 to 2 degrees below local horizontal,  Apollo experienced a peak deceleration rate of 10 to 11 gees.  No two vehicle designs are the same,  but it would be safe to posit 6+ gees for just about any shape and mass coming back from the moon.  So,  the airloads on exposed structures are quite high,  which means local pressures are quite high.  Ballpark,  a guess of 5000 lb per sq. ft at peak deceleration is not a bad guess. Which is another reason you could not possibly use a low density ceramic refractory approach.  The pressure would crush and pulverize the tiles,  as they melt.

Extended structures could provide drag for deceleration,  yes,  but many shapes and masses will already have too much drag,  and so experience too many peak deceleration gees.  That problem roughly scales with dimension,  so twice as big makes it twice as bad.  It's a volume to surface ratio thing.  That's how ballistic coefficient scales with size.

The other problem with extended structures is shock wave impingement heating.  If the shock wave shed by one structure strikes against an adjacent structure,  the aeroheating rate at the impingement point is greatly magnified.  This was demonstrated in the X-15 program to be about an order of magnitude increase in heating rate locally,  at only Mach 6+ (2 km/s).  Temperature is unchanged,  but the heating rate is amplified.  It nearly cut the tail off the X-15 that suffered this. The material then quickly soaks out to the driving temperature,  no matter how it might be cooled.  At 11 km/s this is ballpark 11,000 K.  At 8 km/s it is ballpark 8000 K.  At 4 km/s it is ballpark 4000 K.  There are simply no materials that can take this abuse. In the X-15's case,  2 km/s was ballpark 2000 K,  and that was too much for its Inconel X-750 skin,  ceramic paint coating on the X-15A-2 notwithstanding. 

I really doubt there would be much practicality to attempting to use landing legs as a decelerator when coming back from the moon.  These issues get worse the larger your vehicle gets.

GW


GW Johnson
McGregor,  Texas

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

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#1661 2022-07-26 19:41:02

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 26,803

Re: Starship is Go...

Engine arrangement articles

Super heavy installed 29 in a night Russian N1 configurationn1-base-1024x665.jpg

20 engine outer ring with 9 inner with 3 central installed1622474895_Elon-Musk-Super-Heavy-the-first-stage-of-Starship-will-770x515.jpg

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#1662 2022-09-03 09:35:42

Void
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Registered: 2011-12-29
Posts: 5,087

Re: Starship is Go...

I found this from Marcus House today: https://www.bing.com/videos/search?q=Ma … %26ghpl%3D

It contains speculation on a disposable Starship, which I find interesting.

You would leave out the Heat Shield, the Landing Flaps, and the propellant and tanks for landing.  That is a significant reduction in mass I think.

Such a thing could be compared with the Falcon 9 & 2nd Stage.

This might more resemble a Lunar Starship,

If functional, I anticipate that it may be more effective than Falcon 9 & 2nd stage, financially.  If that is true, then SpaceX would still have the edge on competitors, who may produce the equivalent of Falcon 9.  That would be an important edge to have.  It also might allow the completion of Starlink, which is also financially important for SpaceX.

I am tempted to add more speculations on its further use in orbit, but I will stop with only the speculations Marcus House has done.

Done.

Last edited by Void (2022-09-03 10:18:38)


Done.

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#1663 2022-09-03 17:07:38

Void
Member
Registered: 2011-12-29
Posts: 5,087

Re: Starship is Go...

Following up on the last post, "The Angry Astronaut", has explained that the Orion space capsule is actually a very good item.

I have been wondering if SpaceX might make a version of Starship that lands nowhere.  Of course, I am not a strong thinker on Rockets, but I will give this some further talk.

I am sure that there will be many types of Starships that go to the Moon.

One I would be speculating on here would not land at all and would be able to Aerocapture to the Earth.

I you had a lander like the Alpaca then that could do the landings.  If you also had an Orion capsule with you, then the Starship would not need to Aerobrake in just one pass, so perhaps the heat shield could be of a lesser nature in what it would need to endure.

I am thinking that having a 3-component mission to the Moon, 1) Orbital Starship, 2) Orion Capsule, 3) Lander, then I would think that you would get by with less filling from a propellant depot.

This might fit well for a Lunar outpost, where it has already been established to make many parts of hardware and propellants on the Moon.  Perhaps you would only use this to transfer a handful of people, and bring back samples for science, maybe even Jewlery?

Well of course there will be more inventions and imagined configurations to be discovered over time.

Done.

Last edited by Void (2022-09-03 17:18:42)


Done.

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#1664 2022-09-04 12:07:06

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,952
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Re: Starship is Go...

Orion is Apollo on steroids.  It is rather heavy because it carries life support for at least 4 occupants for at least 2 weeks,  more actually.  If you need that,  you need Orion.  If not,  something far lighter would be the better choice. 

Dragon supposedly can carry 8 for a few days.  Unoccupied,  it is good for 6 months,  then can be activated and used.  I don't know about Starliner,  but it's probably similar to Dragon in that respect.  Both are much lighter than Orion.  And then there's Dreamliner.  Probably same basic class of life support,  but I guess a bit heavier.

Now,  even with a long-duration vehicle like Orion,  space is limited.  The crew simply needs somewhere else to go.  We have known that to be a serious issue since Gemini 7.  NASA's solution to that quandary was to house them in a space station,  and just use the vehicle for transport to and from the moon.  I've seen nothing yet that is credible for housing crews on the moon for long durations,  so until there is something credible,  lunar missions will be short. 

Actually,  that issue may be part of why NASA funded SpaceX to do a lunar version of its Starship as the lander for Artemis.  For a small crew,  such would be quite spacious inside. 

Just food for thought.

GW


GW Johnson
McGregor,  Texas

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

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#1665 2022-09-04 17:27:09

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,343
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Re: Starship is Go...

Orion is too heavy. It was designed to be launched on Ares I, which was a single 5-segment SRB with a liquid fuel upper stage. It was tested unmanned with a boiler plate capsule; that test was called Ares I-X. It produced so much vibration that crew would not be able to see their instruments. Orion was deliberately made heavy in an attempt to dampen the vibrations of the big SRB, but it wasn't enough. And a spacecraft is not supposed to be heavy, it's supposed to be light. Orion can carry 6 astronauts to ISS or 4 astronauts to Lunar orbit and back. Starliner is also a scaled-up Apollo capsule, but it can carry 7 to ISS. Even though Starliner (formerly known as CST-100) can carry 1 more astronaut, it's smaller and lighter. It was originally Boeing's bid for Crew Exploration Vehicle (CEV) to carry astronauts to Lunar orbit and back. It would need a larger service module to do so, and again life support for that duration would occupy space in the capsule, reducing crew to 4. But it could do the job. Dragon was the bid from SpaceX for CEV, also originally designed to carry 4 astronauts to Lunar orbit and back. Dragon was designed from first principles, a new design. It's lightest of the three. Ironically, Dragon is the only capsule to use PICA for the heat shield, specifically the SpaceX version called PICA-X. So Dragon is the only one with a heat shield rated to return from Mars.

Dragon can carry 7 astronauts to ISS. That is 4 astronauts in the middle row, and 3 astronauts in the lower row. The upper portion of the spacecraft is equipment. The lower portion of the capsule has RCS thrusters, propellant tanks, oxygen tanks, and parachutes, so the pressure shell is actually narrower lower down.
34adsw5ly7i41.png?width=640&crop=smart&auto=webp&s=47fb2a5e5421436d2df54578bbe7be5cfeb3b821
800px-SpaceX_Dragon_v2_%28Crew%29_interior_%2816763231836%29.jpg?20150322083337
index.php?action=dlattach;topic=29182.0;attach=419438;image c70426da9dd500be30bbbc176c850342.jpg EeqggVZWAAAb7b2?format=png&name=small
The last image is from Twitter, but the source is "SpaceX overview of environment and life support systems". This diagram shows the toilet is on the ceiling.

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#1666 2022-09-04 17:39:28

kbd512
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Registered: 2015-01-02
Posts: 6,241

Re: Starship is Go...

Reduce the crew of each Dragon capsule to 2 astronauts and launch 2 capsules per mission.  4 Falcon Heavy launches are still cheaper than 1 SLS launch.  If you're fixated on spending a billion dollars per mission, then launch 10 Falcon Heavy rockets.  2 for crew, 8 for landers, return propellant, cargo, etc.  Alternatively, wait for Starship to come online and then you can launch at least several dozen times for the same cost.

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#1667 2022-09-04 17:56:35

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,343
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Re: Starship is Go...

kbd512,
I posted an alternative Lunar mission years ago.
- launch a new Lunar Module into Lunar orbit with one launch of Falcon Heavy. The LM will be reusable and one stage. It uses onboard propellant for Lunar Orbit Insertion (LOI), so arrives in orbit with propellant tanks empty. No crew, but capable of carrying 4 crew.
- launch Dragon with 4 crew. One launch of Falcon Heavy. This will require both the Falcon upper stage, and a new stage called a crasher stage. RobS explained the term "crasher" to me. The trunk of Dragon will be filled with propellant tanks and engines for Trans-Earth Injection (TEI).
- side boosters of Falcon Heavy will be recovered on drone ships, but central core stage will have to be expended.
- Trans-Lunar Injection (TLI) will be done by Falcon upper stage.
- Crasher stage has 3 jobs: LOI, refuel LM, and de-orbit LM.
- Dragon will dock with LM the same as Apollo CSM docked with Apollo LM. Once docked, the crasher stage will have to detach and move around to the back of the LM. It will attach to the LM and transfer LOX and LCH4, as well as helium pressurant and O2 for life support. Astronauts will insert a new LiOH canister into the LM by hand, from inside Dragon.

This means 2 launches of Falcon Heavy for the first mission. Each subsequent mission only requires 1 launch of Falcon Heavy. Because the LM will be reused, left parked in Lunar orbit between missions.

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#1668 2022-10-14 12:10:04

Void
Member
Registered: 2011-12-29
Posts: 5,087

Re: Starship is Go...

I also wish Louis would return.

But until then, I will wake this topic up a bit: https://www.bing.com/videos/search?q=Ut … &FORM=VIRE

I think that the "Stretched Starship" will be good for Earth landings, as they are going to try to catch it on the chopsticks.

For the Moon landing presumably on the tail, the Moon lacking an atmosphere, it should be possible to have a very broad-based landing gear attached to the Starships so, that even the Stretched version might land safely.

For Mars though on a tail landing, I think it will be hard to bring landing gear through the atmosphere and have a large, based leg system to land on, so perhaps the smaller version will make sense.

Of course, that is just my thinking, which is "For what it is worth", .02$ perhaps.

Done.

Last edited by Void (2022-10-14 12:13:46)


Done.

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#1669 2022-10-14 20:06:59

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 26,803

Re: Starship is Go...

The claw is to catch the first stage BFR booster.

AS prelude space x is slated to get a working refueled starship to go around the moon before Nasa will call it a useable ship and a bonus is Dennis Tito and another that will be onboard that first trip around the moon.

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