SpaceX should withdraw Starship as an Artemis lunar lander.

GW Johnson · 2023-09-10 21:30:39

I looked up the thrust of the original Atlas. It was in the 400,000 lb class, total for two booster engines and one sustainer engine, plus two small vernier engines, all simultaneous at liftoff.

The thrust of a sea level Raptor is in the 400,000 lb class or a bit higher (perhaps 500,000 lb for Raptor 2), depending upon exactly which version. Raptor 3 is higher still, but not ready to fly yet. So the Starship flying alone from Boca Chica was liftoff thrust somewhere around factor 3 to possibly 4 times the original Atlas: 1.2 to 1.5 million lb, or close to the original Saturn 1. I'm not sure how it survived being launched at Boca Chica without a flame diverter and water deluge, but it did.

The Superheavy uses 33 of those same engines, which puts it in the 13.2-16.5 million lb class if all are burning. Saturn 5 was initially 7.5 million lb, growing to 8.5 million lb, by the end of Apollo. So Superheavy would rate at twice the thrust of a Saturn-5. That's roughly 10 times the thrust of a Starship launched on 3 engines.

That first Starship/Superheavy launch seemed to have at least 3 engines not running at liftoff. That reduces the total thrust by about 10%, so it's still 9 or 10 times more than a Starship on 3 engines. Later in its flight, it had yet more engines out, and at least 3 plumes shooting out more sideways than aft. It's in the video. Anyone care to guess why it tumbled? (Maybe too much sideways thrust at one end, far from the cg?)

Pad damage and thrown debris risk without a diverter and deluge increase greatly as thrust level increases. SpaceX was already in unknown territory launching Starship at 1.2-1.5 million lb thrust levels without a diverter and deluge. Increasing that force by a factor of 10 made the risk much, much worse: as we saw in their video with the chunks rising up right alongside the vehicle at liftoff. Anyone care to guess why it suffered so many dysfunctional engines? (Odds favor concrete chunks busting chunks out of engine bells.)

Landing on Mars with only a smidge of propellant left over: inert ~ 120 ton, payload ~ 100 ton, and call it 10 ton leftover propellant. That's 230 metric tons mass, or 230 tons-force of weight here on Earth. On Mars at 0.38 gee, that's 87.4 tons-force of weight, or about 193,000 lb, around 1/3 to 1/2 the thrust of a single sea level Raptor. You need about 2-gee capability to make a safe thrusted landing, so that's nearly full thrust on one Raptor to land, or half thrust on only two of them. I base this on the sea level engine, because you need the thrust vector control of the gimballing, and the smaller sea level engines were projected to have it, while the larger-bell vacuum engines did not, because there was insufficient room to move those bells around. So, you are looking at about 400,000 lb thrust required to land on Mars. The moon would be about half that.

Those are the numbers you need, to be debating whether thrown debris is a problem landing on Mars or the moon. Regolith will not explode when hit by flame, but it will be flung radially outward, and more or less horizontally. It's moving quite fast, too. We already saw that while landing Apollo LM's on the moon. It's right there in the old movie camera footage.

Combined with the low thrust levels on Mars and moon, having rocks fly up and damage engines seems at least fairly unlikely for landings or takeoffs, although anything else nearby is quite a high-probability impact target for the flung rocks and dirt.

I'd be a whale of a lot more worried about landing legs sinking into soft dirt, even with loose rocks in it. Landing, you need to double the weight to guess about the right transient touchdown force. I'd also be far more worried about locally-large slopes on uneven ground exceeding a topple-over limit for a tall, narrow vehicle, that I estimated some time ago at only 5-6 degrees out of plumb.

In my opinion, the diverter and deluge is of more concern for Earth launches, especially of Superheavy as we already saw. If they ever fly Starship alone again, I'd recommend they add it for that contingency, simply based on the decades of experience by others. The force levels launching Superheavy are just very much higher. That's simply a huge pad damage and flung debris risk, as we have seen. And as I have already pointed out, for the last several decades, nothing bigger than the original Atlas was launched without a diverter and deluge. Smaller, yes. Larger, no.

GW

Last edited by GW Johnson (2023-09-10 21:52:55)

kbd512 · 2023-09-11 08:58:55

1. The 6 Raptor engines in Starship, which will be used to takeoff from Mars to come home, generate 3,100,000lbf. Maybe we only need to use 3 of the 6 engines on the moon or Mars, so 1,770,000lbf (more than Atlas V at liftoff, which uses a water deluge system).

2. This is the same level of thrust as 2 F-1 engines used by the Saturn V produced 3,000,000lbf.

3. One Space Shuttle Solid Rocket Booster is 2,650,000lbf (liftoff).

4. Atlas V liftoff thrust is 1,619,200lbf (liftoff).

5. Gravity on Mars is just over 1/3 that of Earth, and gravity on the moon is 1/6th Earth gravity, so debris will be thrown much further. We won't have a flame diverter trench, water deluge system, or even a CO2 deluge system.

6. Elon Musk / SpaceX, decided to test whether or not they could get away without using a flame diverter, because no such system will exist on Mars or the moon. The giant colonization rocket / upper stage needs a viable landing system.

7. The test clearly damaged the pad, but we still don't know if it damaged the rocket. Indicators point to a hydraulic system failure which is no longer in use.

8. We could use some sort of tractor rocket system mounted in the nose of Starship, but the weight and complexity of such a system would detract from its usefulness as both an upper stage and a lander. What we need is a rocket that can survive both the heat generated from its own thrust, as well as any debris it happens to kick up.

9. In this context, SpaceX's "no deluge system" launch makes perfect sense. If the rocket can survive the event without appreciable damage, then we don't need a launch pad to ensure that we can take off from the surface of the moon or Mars. There are still good reasons for using a water deluge system on Earth, but Starship's first test flight approximates the reality of taking off from a planetary surface without the benefit of Earth-based launch infrastructure.

10. The viability of lunar and Mars takeoffs need to be properly evaluated, knowing that Earth-based pad amenities will not be available. This is a technical task that requires an aerospace engineer looking dispassionately at the subject to arrive at a valid vehicle protective scheme that doesn't substantially increase weight or complexity.

GW Johnson · 2023-09-12 08:52:37

Do the math. Starship masses are ~120 metric ton inert, around 100 ton payload (but probably less leaving Mars), and 1200 tons propellant for a full load. That's 1420 metric tons at ignition. The Earth weight would be 1420 metric tons-force = ~3,131,000 lb, but the Mars weight at 0.38 gee would be 539.6 m.tons-force = 1,190,000 lb. On the moon at 0.165 gee, the weight is 234.3 m.tons-force = 517,000 lb.

For takeoff and good ascent kinematics (not dawdling around burning propellant without gaining much speed), the rule-of-thumb says you need a thrust/weight ratio of 1.5-ish. So on Mars you need a takeoff thrust near 1,785,000 lb. Raptor 3 is supposed to have about 590,000 lb thrust at sea level, a few % higher in vacuum. 3 of those would launch you quite handily on Mars, even fully loaded.

On the moon, you would need about 775,500 lb of thrust at 1.5 factor. That's two Raptor-3's at 67% power, launching quite handily fully loaded. The rule of thumb says "1.5 or higher", so two Raptor-3's at full power would be a fully loaded takeoff thrust/weight of 2.28, even better.

However, if used as a NASA lunar lander, Starship will not be taking off fully loaded with propellant, and it likely will not be carrying 100-ton-class cargoes. Try 1/3 propellant left and 25 ton cargo. Inert 120 + payload 25 + propellant 400 = 545 metric tons mass at takeoff ignition. Lunar weight is 89.9 m.ton-force = 198,300 lb. One Raptor-3 at full power is supposed to be 590,000 lb. That's a takeoff thrust/weight of 2.98, which is more than enough.

The old Atlas B-G models had ignition thrust levels in the 400,000 to 500,000 lb class, and every one of those was launched with diverter and deluge. Smaller rockets were launched without it, larger rockets always had it. Which is where the old rule of thumb comes from, regarding diverter and deluge.

SpaceX got away with launching Starship-only flight tests from Boca Chica without a diverter and deluge, at 3 Raptor-1 / -2 or some mix of them, which were around 380,000 to 400,000 lb thrust at that time. That's near 1.1 to 1.2 million lb thrust at liftoff, in violation of the old criterion. They may or may not have suffered engine damages from thrown debris; there was one flight where the engine burned itself up from a mix too rich in oxygen, spouting green flames. I never did hear a final explanation of what went wrong, but one cannot ignore leaked methane from a damaged bell as a possible cause. That's just a possibility. But it is a real one.

Excusing the lack of a diverter and deluge for the Superheavy launch as testing launch conditions on Mars or the moon is just that: a cover-the-ass excuse. For one thing, Superheavy has 10 times the thrust of the upper stage Starship. For another, Superheavy will not be launched from Mars or the moon. That's actually rather lame.

They were making changes to that Superheavy/Starship right up to the launch. They were also working on a diverter/deluge assembly for that pad, although that wasn't widely publicized. I really do believe that Musk over-ruled Shotwell and her engineers, and forced them to launch without standing down to install the diverter/deluge, because he wanted to fly as soon as possible, and he did not care that without the diverter, anyone with any common sense knew that debris would be flung much further than was covered by their launch license.

And THAT is what got him into trouble! That and demonstrating that the required demolition system didn't work right.

They already had another one on the pad, but the FAA grounded them, until they install a list of 63 "fixes", and Musk is really fuming about that. He sees the FAA as only an impediment to be gotten around if possible. He seems incapable of understanding the regulation for what it really is: protection for SpaceX's neighbors from the consequences (intended or not) of what SpaceX does.

I hope SpaceX succeeds with this thing, I really do. They truly do make NASA and old space look incompetent. But Musk is going to have to belly-up to the bar and do this "right", meaning within their launch licenses. Because if he keeps on doing it the way he has up to now, some members of the public are going to be hurt or killed. Precisely because space is hard, and disasters will always happen.

GW

Last edited by GW Johnson (2023-09-12 09:12:43)

Void · 2023-09-12 09:45:16

This prompts some ideas in my mind.

Send a Starship prototype to drill a hole, and burn all of at least one of it's propellants. If you then have a rover that could roll in you could examine the hole. If the Starship had legs perhaps it could hop sideways and try to land. If it topples, then it is scrap metal to help build a base. If you did not intend to land it perhaps it would not have landing legs at all.

This would be a first step trial of landing education for the Starship.

There would be a concern for polluting orbits with rocks, but perhaps it could be tolerated once.

The two versions of how a Starship could land are 1) Small upper body side engines. 2) Raptors of the future being able to throttle down enough. So, this first landing/crash might help to learn which is better to try for.

And now, I am thinking that if Starship can drift sideways while landing it may not make a deep crater, but a ditch.

For Mars this could be useful as it may be that the end of the ditch is shallow enough that sufficient footing can be available. Upon contact though you would need some kind of side thruster to stop toppling in the direction of side travel.

Done.

Last edited by Void (2023-09-12 09:51:07)

Void · 2023-09-12 10:16:55

Continuing with the previous post perhaps skids lubricated with a gas could be the landing gear. Cold gas thrust under the skids. But you would really want the anti-topple thruster(s) on the sides.

https://www.space.com/7891-cosmic-winte … ating.html
Quote:

Cosmic Winter Olympics: Moon Skiing and Mars Skating
By Charles Q. Choi published February 12, 2010

Perhaps this could be used for Mars somehow. You could have a topple arrest thruster on the leeward side of the ship.

How you would protect the skids though atmospheric entry though would be some trouble.

Now can you land on a descending slope like as in ski jumping? Tricky stuff, but it all is. You could distribute an impact over an extended period of time.

Done

Last edited by Void (2023-09-12 10:22:05)

tahanson43206 · 2023-09-12 15:04:54

For Void re #55

I like your suggestion of setting up slow-down system on the slope of a mountain such as Mount Olympus...

On Earth, water in a trough was used to slow down the rocket sleds used for experiments by (I think) the US Air Force .... Colonel Stapp, if memory serves.

Mars has little water, and if has any it wouldn't be used for a slow-down trough.

However, Mars has LOTS of sand ... If you were to start a topic about slow down on Mars using sand, I would be glad to see it.

However, if you create a new topic about a serious topic, please do not spoil it with an off-topic rant about other human beings. This has happened twice, so I am on the alert for it happening again.

This topic is (supposedly) about Starship not being a good landing vehicle for the Moon.

Your post is on topic, because you've proposed a possible solution to the landing problem.

That said, I'd like to see if your idea might have legs on it's own.

(th)

Void · 2023-09-12 15:28:16

Oh thanks! I will observe the stipulations reasonably well.

A Lubricant for skids could be compressed gas or even rocket exhaust applied to the runners. But yes in low gravity worlds at an incline sand or dust may help.

I won't mention that the Ancient Aliens used it in the Andes, because you would not like that.

Done.

GW Johnson · 2023-09-13 16:40:27

nReturning to the original topic per title, you have some issues with SpaceX's Starship as a lunar lander. Offsetting that are its enormous cargo capacity when operating fully-fueled.

Issue #1: it is tall and narrow, with its center of gravity at about half the elevation of its nose. If the min dimension of the polygon made by its landing leg foot pads is not comparable to that center-of-gravity height, there is a serious risk of falling over during landing. Nothing we ever before landed on the moon or Mars had a center of gravity height taller than the min dimension of the landing leg polygon. That ought to scare the hell out of everybody, and rightly so!

Issue #2: SpaceX has as of yet no landing leg designs that can take the weight on each leg without sinking into soft dirt, an issue that not only stops takeoff by "staking-down" the ship, but also risks falling over, because those legs will inevitably sink in unevenly. And the moon's regolith, and about 90+% of the surface of Mars, is little different from soft, fine, dry sand. Have you ever tried to walk on a sand dune? Then you understand the risk.

Issue #3: thrown debris damage to the ship or any stuff nearby, from the jet blast of the engines. What we saw with the Apollo LM at rather small thrust levels was stuff flung out radially but more-or-less along the ground. Starship will be a much higher thrust level, but unlike concrete, regolith does not explode violently into chunks when exposed to hot flame. This is still an unknown, but the odds would seem to favor there being more risk for objects nearby than for the ship itself. The old rule of thumb here on Earth for launches was use a deluge/diverter assembly for thrusts exceeding about 400,000 lb, so the concrete pad would explode into chunks. Those tend to get thrown straight up toward the bottom of the vehicle by the explosion action. They can hit and damage or destroy engine bells.

Mitigation for issue #3: nose mounted tractor engines farther from the surface, giving the plumes time to spread dramatically in vacuum before they strike the surface. But, on the other hand, that could be a heating risk for the sides of the ship, though. Plumes in vacuum DO NOT behave like plumes in the atmosphere here on Earth! They spread dramatically, through slightly more than 90 degrees at the bell exit lip. The 6-7 mbar atmosphere on Mars is essentially vacuum, for fluid dynamic purposes. Earth standard sea level pressure is 1013 mbar.

There, that's the physics and the numbers that we know so far. Now debate the issue again.

GW

Last edited by GW Johnson (2023-09-13 16:45:26)

RobertDyck · 2023-09-13 17:30:01

In post #35 (page 2), I added a link to another discussion thread. This is an old thread in which I proposed a lunar lander that SpaceX could build. Several principles:
1) Start small, don't go for the big thing immediately. Once you get the small one to work, use lessons learned to build the big one.
2) Reusable
3) Use existing SpaceX launch vehicle (Falcon Heavy)
4) Use principles that Starship will require such as liquid methane / LOX propellant, on-orbit propellant transfer, on-orbit crew transfer.

Since everyone ignored me, I'll give some details. That proposal would use SpaceX Dragon to transport crew to lunar orbit. The trunk would have to be filled with propellant tanks and engines, you could think of it as a service module. The Dragon trunk would only have enough propellant to send the capsule & trunk out of lunar orbit, into a trans-Earth trajectory. That's called Trans-Earth Injection or TEI. All crew would descend to the lunar surface, leaving the Dragon in lunar orbit unattended, operated solely by computer. Modern computers can do that, 1960s computers, not so much.

To start: launch the lunar module on SpaceX Falcon Heavy. The Falcon upper stage will push it into Trans-Lunar Trajectory; that's called Trans-Lunar Injection or TLI. The lunar module itself will use onboard engines for Lunar Orbit Insertion (LOI). The Apollo Lunar Module (LM pronounced LEM) had 2 stages: descend and ascent. This new lunar module will have only one. The lunar module will enter lunar orbit unattended, and the LOI manoeuvre will leave propellant tanks depleted.

Next launch crew in a Dragon on Falcon Heavy. This will require both the Falcon upper stage, and a new stage on top of that. The Dragon with it's modified trunk will be on top of the new stage. We'll call the new stage a "crasher stage". When I worked out launch mass based on my rough calculations, I estimate the side boosters of Falcon Heavy will be able to be recovered via drone ship, however the central core stage will have to be expended. That's necessary for launch mass involved. The Dragon will not loiter in Earth orbit, but head directly into trans-lunar trajectory. The Falcon upper stage will execute the TLI burn.

The new crasher stage will have 3 jobs. Upon approach to the Moon, it will enter Lunar orbit. So LOI burn will be it's first job. Then the Dragon/trunk with crasher stage will rendezvous and dock with the lunar module. Dock the same way that Apollo CSM docked with the LM. However, once docked the crasher stage will detach from the trunk, move around and attach to the back side of the lunar module. Once attached, the crasher stage will execute it's second job: refuelling. The crasher stage will transfer propellant to the lunar module, both LCH4 and LOX. If helium is required as pressurant, that will be transferred too. The crasher stage will also transfer oxygen for breathing. While that is happening, astronauts will transfer by hand lithium hydroxide canisters from Dragon to the lunar module. Also transfer any special instruments required for that mission. If the surface stay will last more than a few hours, food will also be transferred from Dragon to the lunar module.

Then crew enter the lunar module, seal hatches and detach. Leave Dragon/trunk in orbit while the lunar module descends to the surface. Once a safe distance, the crasher stage executes its third and final job: de-orbit burn. Slow out of lunar orbit, 90% of the work required to go from lunar orbit to landing on the surface. Once the lunar module is descending to the surface at a safe speed, the crasher stage detaches and crashes into the surface of the Moon. That's where the name comes from. The final touch-down is done with on-board engines on the lunar module. However, most of the propellant of the lunar module is still in the tanks when it lands. That same engine used for touchdown will be used for ascent.

The crasher stage will use LCH4/LOX, and so will the lunar module. The trunk will too. Whether RCS thrusters use LCH4/LOX or MMH/N2O4 is a detail I leave to engineers. Remember, the Apollo Service Module used Aerozine-50/LOX for its main engine, but MMH/N2O4 for thruster quads.

When the lunar module lifts off, the only thing left will be foot prints and land pad prints. Well, there will also be science instruments, and any garbage. If they stay more than a day, garbage left on the lunar surface will include bags of human feces. Yes, Apollo astronauts had to go in a bag; this lunar module will require the same.

Once in lunar orbit, the lunar module will rendezvous and dock with Dragon. Transfer any lunar samples to Dragon. Also transfer the spent lithium hydroxide canister to Dragon. Leave the lunar module clean, ready for the next mission. Then separate, and Dragon/trunk will depart back for Earth (TEI). This will leave the lunar module in lunar orbit waiting for the next mission.

This requires one launch of Falcon Heavy to deliver the lunar module. One launch of Falcon Heavy for Dragon with crew. The second and subsequent missions only require a single launch of Falcon Heavy.

SLS block 2 could launch a Mars Direct habitat directly to the Moon. Yes, the Moon. This would form a permanent lunar base. This was part of Robert Zubrin's proposal for Mars Direct in 1990. Using a Mars Direct hab for a Moon base is not my idea, and not new. What is new is the SpaceX lunar module.

Also, Dragon was originally proposed for NASA's Crew Exploration Vehicle (CEV). Orion won that contract, but Dragon was the competitor from SpaceX. So modifying Dragon for lunar orbit would be easy, what it was originally designed for.

Question: if trunk is filled with propellant tanks and engines, could the launch escape system drag trunk along, or would the Dragon capsule have to escape without the trunk? Right now trunk is designed to carry unpressurized cargo. Could the launch escape system operate with the additional mass of that cargo? If so, could it operate with propellant tanks and engines?

SpaceNut · 2023-09-13 17:58:49

It was about the plan of 2 cargo and a lander to get 4 men to the moon quickly rather than what is now getting close to a decade which was on the home page.

https://newmars.com/2018/03/moon-direct … our-years/

RobertDyck · 2023-09-13 18:24:15

Yea, Robert Zubrin's article was from March 2018, my post was May 2016. Robert Zubrin's Mars Direct was June 1990. Robert Zubrin's newer article, the one you linked, uses nothing but Falcon Heavy. One reason I suggest using SLS to launch the Mars Direct habitat is that Old Space contractors will lobby Congress to use SLS for something. Yes, $2 billion per launch is a lot, but those who supported SLS will want to see it used for something.

Besides, the Moon base should be a test/demonstration of a Mars habitat. A full-size Mars Direct hab is too big for Falcon Heavy. Using a Mars Direct hab for the Moon base means testing Mars hardware before actually going to Mars. Mars Direct could be launched on 2 Starship launches: one for the ERV, one for the Hab. I could mention my modification of Mars Direct, the one I presented in 2002. The difference is really just a reusable habitat for Earth return, something the size of a single deck of Mars Direct hab. That additional hab would be left in Mars orbit, and ideally park in Earth orbit so could be used again. That would give a lot more living space than a capsule. But whether my modification or original Mars Direct, it means fewer launches of Starship. It also means testing small equipment before sending a full-size Starship to the surface of Mars and back.

And GW keeps raising the issue of high to landing leg spread. If landing legs have foot pads too small, they could sink into the dirt. And if they're too close together, the rocket could fall on its side after landing on uneven unprepared ground. That's why the Apollo LM had a broad stance. Mars Direct hab and ERV would have an equally broad stance.

RobertDyck · 2023-09-13 18:36:03

Here's a slide from old Mars Direct. It shows lunar modification of the hab and ERV. I argue landing the equivalent of an Apollo CSM on the surface of the Moon and expecting to launch again is not reasonable. It works for Mars because of ISPP, but the Moon does not have a CO2 atmosphere. That's why I proposed an Apollo architecture for the ERV for the Moon. Also note this image is so old that it shows the hab with one deck. Experience with ISS has taught us that life support equipment must be accessible for constant maintenance. And other experiences showed the rover must be enclosed during landing so rocks thrown up from rocket exhaust does not damage the rover. These two changes turn the equipment underside of the hab into a lower deck. Besides, moving the airlock to the lower deck has obvious advantages. Anyway, the point is that using Mars Direct for the Moon has always been part of it.

Void · 2023-09-13 21:01:02

I choose to reenter the conversation.

And yes, I will stay rigidly on topic since that appears to be a thing so much required.

I am not an expert, but what little I know, I believe I have read.

Recent modifications of Starship indicate a possibility to lift 220 tons of cargo.

From what I have read, and viewed, SpaceX intends to try landing several Starships, which I interpret as at least 2 successful, before attempting to land crew.

Landing gear is not likely to be a huge problem. They should have plenty of cargo lift to bring along landing gear. They even could bring the landing gear up in a separate starship launch.

As for the engine plumes, I have seen the notion that either side engines would be used that from what I can tell would run of gas not liquid, or they think they may be able to get the raptors to throttle down enough. Nothing in this matter is well defined yet. I think that the Lunar Starship will be well insulated thermally, so the use of side landing thrusters might be a very brief event relatively so maybe not too bad. If it increases boil off, then that actually could feed the side engines, if I understand their nature.

As far as I can see, I would like a special crew oriented new vehicle for the Moon other than Starship. I am hoping that some variation of Terran-R might fit the bill eventually. But for a time to get big bunches of cargo onto the Moon Starship might be a really good device. Particularly if it does not need to take off again. There seems to be hints that the landing legs will be self-leveling.

But I agree that planning for a future Moon vehicle, particularly for crew is a very good idea, Robert.

Done.

Last edited by Void (2023-09-13 21:13:15)

RobertDyck · 2023-09-14 08:37:20

Sorry if my long rant was not understood. If anyone here claims SpaceX should withdraw Starship as a lunar lander, then what is your alternative? Do you think Starship is too big, that a major failure would result in catastrophic destruction? That's why the Boca Chica launch site is on the Gulf coast surrounded by miles of swamp. Do you think landing a vehicle that tall and narrow will result in tipping over? Valid concern, however, what's the alternative? I gave specific alternatives. If you can't provide alternatives, then stop complaining.

Elon wants Starship to be everything. One ship that does everything. He tried that with Falcon 9. Turned out strapping 3 Falcon 9 core stages together was more complicated. The centre stage had to endure the stress of the side boosters. That required modification, a custom stage. But he got it to work. Next he's going to discover landing on the Moon is not as easy as landing on Earth. And Mars is different again. However, with persistence and enough money, he'll get it to work.

Again, to those who want SpaceX to withdraw, what's your alternative?

Void · 2023-09-14 08:40:09

I think I agree that Starship is fabulous and in some form can be very useful on the Moon. And I do not criticize the current Lunar Starship.

We do not know what the scale of establishment of object manipulations will be on the Moon. But at some point, if most resources become Insitu from the Moon, then the need for moving huge mass to the Moon will be reduced. We do not know what sort of population numbers for the Moon will be like. We do not know how long humans can stay healthy on the Moon. So, I am attracted to the idea of Dr. Robert Zubrin for a Mini-Starship. I think that Terran-R although not to have a reusable 2nd stage for now, could have a variant which could resemble a Mini-Lunar Starship.

That could be more useful for small trips and to ferry people to and from a Lunar Space Station(s).

At the other end, Dream Chaser may be sufficient for bringing people up and down, LEO.

Stage '0' may suffer congestion as there may be limits on how many places are optimal for the full stack.

Passenger Service with Starship is not to involve Super Heavy. So, depending on congestion and the number of people traveling to and from LEO, Super Heavy stacks may be reserved more often for other uses like building space stations. Yes, there will be attempts to send crewed missions to Mars, but those will at first involve only a small amount of people.

I think we are going to wait at least 10 years before Starship can be ready to ship masses of people to Mars.

Dream Chaser will be able to bring people down to airports supposedly.

But we will see. I think a combination of Lunar Starship and Mini-Lunar Starship would work nicely.

I know you may have been talking towards other members Robert, so I will finish.

Done.

Last edited by Void (2023-09-14 08:57:38)

GW Johnson · 2023-09-15 14:00:13

Today's local TV noon news carried the story that SpaceX may get to fly its Superheavy again as soon as October's end. They have to show compliance with FAA's 63-item fix list, and the reporters quoted Musk as saying they were complying with everything. The report said something about having to update or replace their environmental impact statement.

Bear in mind that this is not an EPA-type impact statement. This has to do with the proximity of outsiders, the strength and range of blast waves, the range of thrown debris, fires, that sort of thing. Entirely unsurprising, in view of what happened the first launch.

GW

Void · 2023-09-23 08:53:41

I guess I will do this here, rather than start a new topic.

It is very hard to see what is really going on socially in regard to permissions for Starship.

I am a little ambivalent in notions towards it. I think a little patience is not necessarily a bad thing. The SpaceX model of development is try-fail-learn-try. But that is a very big rocket. Just a little more prudence may be a good ingredient to add.

I am looking at what I feel may be a rather myopic practice of environmentalism. By focusing on one small location and not thinking about the big picture, the planet may be doomed. (Probably not but injured).

One possible "Green" energy can be space-based energy collectors. Now if there are some special very endangered creatures near the launch site, then that is a concern. But if I am to believe the Doomers, the whole planet is at risk. Doom.

Starship and things like Starship, therefore, are potentially quite "Green", for the whole planet. Because we know that the poor of the world will burn the last Carbon, rather than to suffer, and have their families suffer.

We can't actually beat them up to stop them from doing that. We can run concentration camps to get rid of them all. Not only would it be immoral, but they would also be quite willing to fight back, I am sure. And I very likely would join that side.

So, what is needed is energy to replace the Carbon, or some of it anyway.

Space Based power is not a guarantee, it is a potential.

Environmentalists should consider this. Also, environmentalists should not assist the money siphon looters either. The looters always want to make a quick buck. Destroying one technological advance after another does not bother them, as the way they make money is by getting government money to build a new one. When that is built, then of course you don't actually want success, success is being able to do the whole thing again and to divert the gold coins into the anointed blessed one's pockets.

So, please think about what you are really doing. You are hurting the common people, and the planet by being fetish level environmentalists. Be practical environmentalists, please. We need you to do that instead.

Done.

Last edited by Void (2023-09-23 09:05:41)

GW Johnson · 2023-09-25 08:28:01

The delays getting Gateway started have NASA in the position of having an SLS/Orion launch scheduled, but looking for a useful mission to do. Not what you want for a rocket and capsule that costs over $4 billion per launch.

The real reason for having Gateway at all is because Block 1 SLS/Orion can reach the halo orbit, but cannot reach low lunar orbit. It's ballyhooed as "the best way to go to lunar surface", but the truth is the dV from Gateway to the surface is over 50% larger than the dV from low lunar orbit.

The problem they solve with Gateway is reaching the lunar poles. The halo orbit is so extremely elongated that you can do a 90-degee plane change for a trivial dV at its apoapsis. The cost for that approach is is periapsis speed: very nearly lunar escape. That is the velocity you have to kill to land.

To do low lunar orbit in a polar direction, the dV to enter lunar orbit from the transfer orbit is much higher. Not even Apollo-Saturn-5 could do it. Not even the block 2 SLS/Orion can do it. Block 1 cannot even get to and from low lunar equatorial.

The higher dV to land (and return) from the Gateway halo orbit drives the lander to something far bigger than the Apollo LM, even with only a small crew and no cargo. THAT is why they bought a Starship variant as a lander option, even though it hasn't successfully flown yet. And it won't fly again unless and until Musk can behave himself and stay within the requirements of his launch licenses from the FAA. And rightly so. Given Musk's past behavior, some would say fat chance of that. The entire SpaceX company is at risk: they have bet their future on Starship/Superheavy, with the Falcons and Dragons considered to be a dead end.

With neither Starship nor Blue Origin's lander design having flown, NASA still has no lander for any Artemis missions. It takes time to fly a spacecraft enough to risk using it for a mission, certainly any manned missions. It takes a few years to get that done. So talk of a 2024 or 2025 landing on the moon is just utter BS.

Sorry, THAT is where we are. As I see it.

GW

RGClark · 2023-09-28 08:28:51

RobertDyck wrote:

Sorry if my long rant was not understood. If anyone here claims SpaceX should withdraw Starship as a lunar lander, then what is your alternative? Do you think Starship is too big, that a major failure would result in catastrophic destruction? That's why the Boca Chica launch site is on the Gulf coast surrounded by miles of swamp. Do you think landing a vehicle that tall and narrow will result in tipping over? Valid concern, however, what's the alternative? I gave specific alternatives. If you can't provide alternatives, then stop complaining.
Elon wants Starship to be everything. One ship that does everything. He tried that with Falcon 9. Turned out strapping 3 Falcon 9 core stages together was more complicated. The centre stage had to endure the stress of the side boosters. That required modification, a custom stage. But he got it to work. Next he's going to discover landing on the Moon is not as easy as landing on Earth. And Mars is different again. However, with persistence and enough money, he'll get it to work.
Again, to those who want SpaceX to withdraw, what's your alternative?

My main objection to the Starship HLS is I really don’t like the 8 to 16 refueling flights needed for a single mission. In my mind, a Moon rocket should be A Moon rocket(singular).

I don’t remember seeing this when it was first announced but Boeing has proposed a single launch architecture for Artemis:

Boeing aims for Moon landing in 'fewer steps'
Published
6 November 2019
https://www.bbc.com/news/science-environment-50322402#

No $3 billion Starship or $4 billion lunar Gateway required. Of course being Old Space, Boeing would find a way to charge NASA a billion dollars for the lander anyway, no mater how much smaller it was than the Starship lander(see my sig file.)

Robert Clark

Last edited by RGClark (2023-09-28 08:35:02)

kbd512 · 2023-09-28 09:17:53

RGClark,

Boeing's proposal more is more of the same exceedingly expensive non-reusable hardware intended to be another reprise of the unsustainably expensive Apollo missions. It does nothing to advance the state-of-the-art, nor does it achieve anything from a scientific understanding that will be useful for long term human habitation of space or colonization of other planets.

Refueling your ship, even if you have to do it 8 times to completely fill its tanks, is the least absurd proposal I've seen, if cost and general utility are at all important. SpaceX has already demonstrated the launch cadence to make that happen. Eventually we'll require on-orbit refueling to send people and cargo to other planets with any regularity. If we develop this technology now, then it doesn't need to be developed later. They're advancing the art of aerospace engineering, drastically improving our capabilities to land serious tonnage on other planets, and returning them home, all using the same basic launch vehicle design with 3 variants- crewed, cargo, and tanker.

150t of payload to the moon is enough to do lots of useful long-term science and exploration missions. It's a Space Shuttle that can go to other planets with 5X more payload than the Space Shuttle, land on those "other planets", which the orbiter was never designed to do, and then return to Earth. Why settle for reduced capability that can never do what we want it to?

The Boeing proposal requires 2 SLS launches at $2B each, 2 new rocket stages for their lunar lander, and a new aerospace vehicle design. It took Lockheed-Martin and Boeing more than 10 years to develop new vehicles. As of 2023, the first crewed flight has yet to occur. The Apollo Program lasted from about 1965 to 1975, from start to finish.

If Boeing said "we're going to spend $3B to deliver a working lunar lander in 2 to 3 years", I'd be onboard with that, but Boeing's ability to accurately estimate cost and timeline is nonexistent. This is essentially the same as delivering a B-2 stealth bomber. We're spending a known quantity of money to deliver a known quantity result. That is not what Lockheed-Martin and Boeing actually do.

Void · 2023-09-28 11:12:39

I support the notions of kdb512.

It appears that Starships performance is possibly going to become 220 tons to orbit, possibly. This then would reduce the number of propellant deliveries required to have an outward expedition, perhaps to the Moon.

It appears that they are going to have a "Stretched" Starship with 9 engines but still have the current version with 6 engines.

I don't know if it would be sensible to have a "Shortie". That might have one sea level engine and two vacuum engines. (I am completely pulling that out of my "Dark Side"). Such a ship might have landing gear with cargo storage in the landing gear. That might be a good adaptation for a ship not doing aerobraking. Cargo could be loaded while in microgravity. (Again, my BS). In such a delivery, perhaps the landing gear with cargo would be left on the surface and the Starship itself, only would launch up to orbit again. The materials of the landing legs would be used then to also build up infrastructure on the Moon. So, the legs would be cargo also. So, the landing gear can be very large, to avoid topple, and the major cargo can be on the landing legs to avoid topple, and when you leave you leave the landing legs and cargo behind. (All are my speculations).

Without that consider that Starship might refuel a Terran-R derived Lunar lander, or someone else's, maybe Stoke Space. https://www.stokespace.com/

I think kdb512 is correct that the cargo capacity for Starship to start up a Lunar base is fantastic. Maybe later on a crew exchange vehicle of more modest proportions can appear.

But for now, a Lunar lander based on Starship, is the closest thing in reasonable reach.

Done.

Last edited by Void (2023-09-28 11:25:47)

RobertDyck · 2023-09-28 15:36:32

Aries launch vehicle that was proposed as part of Mars Direct would have had a core stage diameter of 8.4 metres. That was exactly the same as Space Shuttle ET because it was supposed to be a modified ET, made at the same factory with the same tools. Mars Direct habitat had the same diameter to match launch vehicle. Starship has 9 metre diameter, so Starship could definitely launch a Mars Direct hab. Lift mass for Starship is sufficient for the hab with a fully fuelled TLI stage in one launch, and Starship is still recoverable.

So don't talk about requirements to build a lunar base. It only takes one launch.

kbd512 · 2023-09-28 16:52:32

Void,

These lunar mission with Starship (as a lander) are "a full dress rehearsal for Mars" - NASA's words, not mine. The Lunar Orbital Gateway is supposed to function as the deep space transport (a real survivable purpose-built interplanetary ship, not a rocket-powered lander). Orion functions as a deep space capable lifeboat. Starship has to land the many tons of consumables required to support 4 to 6 astronauts living on the surface of Mars for 2 years. Nothing Lockheed-Martin or Boeing are working on can do that.

If we handed Boeing all the money upfront, 10 years from now they'd still be messing around and asking for more money. NASA has given them multiple opportunities. Starliner is still MIA and SLS is the most expensive rocket ever built, with the most protracted development cycle of any western launch vehicle I'm aware of. Absolutely every piece of the SLS was rebuilt using new technology, from the engine controllers to the alloy that the external tank is made from, which makes a mockery of the entire idea that the vehicle was to have been built using "flight proven" hardware. SLS and STS share a common lineage, but that's about it. The pad, pad infrastructure, high bay, and crawler-transporter had to be rebuilt as well. The advanced boosters and disposable RS-25s still haven't seen a test fire. This is well past the point of ridiculous. NASA is setting money on fire to please their politicians.

We don't have to worry about SpaceX screwing around. Their founder has staked the future of his company on making Starship work, and there's no reason to think he's going to stop. Even if Elon Musk wasn't there, I don't think SpaceX would stop at this point. Money has already changed hands, and customers have been promised cheap Starship flights in the near future. That's where we're at, as I see it.

Void · 2023-09-28 17:59:45

I think you have it right kdb512. As for my part I want somebody to do something, and SpaceX looks like the most doing somebody on the stage.

I am also pro New Glen, and many others, I want to have them show me their hardware. More is more, and also better.

I will be happy for any types of Starship that SpaceX produces. The more the better.

Done

RGClark · 2023-10-01 13:42:20

kbd512 wrote:

RGClark,
…
The Boeing proposal requires 2 SLS launches at $2B each, 2 new rocket stages for their lunar lander, and a new aerospace vehicle design. It took Lockheed-Martin and Boeing more than 10 years to develop new vehicles. As of 2023, the first crewed flight has yet to occur. The Apollo Program lasted from about 1965 to 1975, from start to finish.
If Boeing said "we're going to spend $3B to deliver a working lunar lander in 2 to 3 years", I'd be onboard with that, but Boeing's ability to accurately estimate cost and timeline is nonexistent. This is essentially the same as delivering a B-2 stealth bomber. We're spending a known quantity of money to deliver a known quantity result. That is not what Lockheed-Martin and Boeing actually do.

Yes. I took it be a single launch proposal because it said the lunar lander would be launched on a single launch of the SLS. But the Orion and service module would be on a separate launch.

Robert Clark

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#51 2023-09-10 21:30:39

Re: SpaceX should withdraw Starship as an Artemis lunar lander.

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