totm nov 2023 SpaceX Discussion Thread

[Exploro]

35 minutes ago, YNM said:

Regarding BFR Earth-to-Earth concept...

 

So, how do we differ a BFR from an ICBM, again ?

My guess is that as a BFR-based passenger transport would operate within controlled air space through part of it's flight there would have to be some means provided for ATC to track and identify it. It's not a stretch to imagine such a craft being equipped with something like ADS-B (or an equivalent system). Ballistic missiles obviously would not.

[tater]

P2P is more useful to the military than it will be for travel. Redefines "rapid response."

[regex]

39 minutes ago, tater said:

P2P is more useful to the military than it will be for travel. Redefines "rapid response."

ICBTC? I'm skeptical but it makes /some/ sense against non-state actors.

[mikegarrison]

 

2 hours ago, tater said:

I said do the math. Fuel cost plus amortized vehicle cost/flight is the marginal cost, right? If you can put 1500 people on it (most tanks gone), or 800 and no booster, then you're in the ballpark of long haul tickets (at cost). Charge 1st class prices for the window seats (literally 10X coach), and you're likely OK. They could charge more, as well, since a 40 minute flight time is still worth something. It's worth a lot. If you only can take a week off, and your international vacation has a couple days each way wrecked with air travel, the opportunity cost of the lost days is huge. Most high-price travel is business, as well, and you're not jet lagged, etc, worth extra.

You are not "doing math". You are making up numbers to fit your desired answer.

Edited September 30, 2017 by mikegarrison

[tater]

23 minutes ago, mikegarrison said:

 

You are not "doing math". You are making up numbers to fit your desired answer.

The pressurized volume was given. The max seats in an A380 are given (850-soemthing). Economy-plus coach fares for long haul flights are known. We know that almost no propellant is needed in the US for a ballistic trajectory (because orbital mechanics).

We can then solve for what the marginal cost would have to be for that to be the case. We were also told that marginal cost is below the cost of Falcon 1. Clearly spacex has done that math.

As we have both said, that math doesn't matter if there is no way they'd pass regulatory hurdles, but that doesn't invalidate the fact that they might in fact be able to charge those rates theoretically.

27 minutes ago, regex said:

ICBTC? I'm skeptical but it makes /some/ sense against non-state actors.

That was the idea Douglas (Phil Bono) was pushing in the 1960s. 

Edited September 30, 2017 by tater

[YNM]

2 hours ago, magnemoe said:

ICBM is smaller than an falcon 9
If this is an issue you would also raise warnings with all sort of rockets even tactical ones 
You can also predict the trajectory of an ballistic missile after 5 minutes of flight. 

It is an issue for some bits of the world. I'm not going to specify, but please think farther.

 

1 hour ago, Exploro said:

My guess is that as a BFR-based passenger transport would operate within controlled air space through part of it's flight there would have to be some means provided for ATC to track and identify it. It's not a stretch to imagine such a craft being equipped with something like ADS-B (or an equivalent system). Ballistic missiles obviously would not.

Well, that's one framework. I was just throwing a wrench anyway, don't take it as I'm being opposed, I'm just unsure how everyone would react.

[Grand Ship Builder]

Did ITS get a name change or something? What was called ITS is now being called BFR. Or are they interchangeable?

[tater]

Was BFR, then ITS, but they never liked that, and kept using BFR.

[Grand Ship Builder]

27 minutes ago, tater said:

Was BFR, then ITS, but they never liked that, and kept using BFR.

ITS would be a better name for the original craft, instead of replacing it with BFR. Also makes BFR and ITS distinguishable. Maybe they'll use MCT some other day.

[Mitchz95]

Elon said he wanted to name the first ship Heart of Gold, so... HOG?

No, probably not...

[Grand Ship Builder]

Just now, Mitchz95 said:

Elon said he wanted to name the first ship Heart of Gold, so... HOG?

No, probably not...

A name just like OCISLY and JRTI.

[Exploro]

1 hour ago, YNM said:

Well, that's one framework. I was just throwing a wrench anyway, don't take it as I'm being opposed, I'm just unsure how everyone would react.

Not to worry YNM. I didn't interpret your question as statement of opposition.

[tater]

Those are ship names, not class names. Ocisly and jrti are General Contact Units (GCU).

[Northstar1989]

17 hours ago, Jaff said:

So what happens to the dragon capsules and the certification F9/FH has/should achieve? 

 

Perhaos i I was hopeful FH would be a success where they think it won’t be but it seems really stupid to put all your eggs in 1 basket. 

 

Hes got got people lining up to get a satalite or something on top of a F9, I don’t think people will be so keen on a new rocket just because of its size. 

One word: Money.

In case you didn't follow any of the discussion of that here, on numerous other web forums, or YouTube, the general consensus among intelligent space nerds about Falcon 9 upper stage reusability is that it would be impractical (you'd have too little useful payload), and that it would cost BILLIONS of dollars to develop and perfect with the Falcon Heavy.

The BFR has an entirely different style of upper stsge reusability than the Falcon Heavy would, so there really would be no overlap between that and BFR's reusability.

Elon Musk (or more likely, one of his brightest engineers) had the insight to realize that once you perfect 100% stage reusability, the cost of building the rocket really doesn't add that much to your launch cost compared to the costs of things like ground operations.

By discontinuing the Falcon 9 and Falcon Heavy, SpaceX is able to focus its product line- eventually no longer needing to maintain part inventories for the Falcon 9 or Falcon Heavy.  More importantly, SpaceX is able to skip over most of the expense of perfecting Falcon Heavy upper stage reusability entirely- saving BILLIONS of dollars in R&D and test launches.

For a marginal cost of BILLIONS of dollars the only thing the Falcon Heavy provides is *slightly* lower launch costs than a fully-reusable BFR, since with 100% reusability the costs of building the rocket no longer become that significant (since it can be re-used again and again) compared to costs like ground control and launchpad construction.

Put a different way and using made-up numbers: if your cost to LEO is $10,000/kg with a gigantic rocket launching small satellites then it makes sense to spend $2 Billion to reduce launch costs by 20% to build a rocket that is more appropriately sized to small payloads.  But if your launch costs are only $500/kg with the 100% reusable gigantic rocket and you're going to have to build up an extensive operational history for it before you entrust it with human crews anyways, then it makes no sense to spend an additional $2 Billion to reduce launch costs by a further 20% to $400/kg by perfecting 100% reusability for the smaller rocket as well...

 

If SpaceX ever acquires major competitors in the field that perfect both launch and upper stsge reusability as well, then they will be forced to revive the Falcon Heavy and perfect 100% reusability for it if they want to remain competitive.  But barring that, a 100% reusable rocket, even a giant freaking rocket that's way too big for most of the payloads it launches is still MUCH cheaper than a smaller, expendable rocket.

 

It's like Elon Musk said at the IAC presentation- it's cheaper to charter a reusable 747 than it is to purchase a single-prop Cessna and throw it away after the slight.  A reusable Cessna would be cheaper- but SpaceX is taking advantage of the fact that it has no serious commercial competitors for upper stsge reusability to leapfrog ahead to going to Mars sooner ratger than later...

It's about putting the big picture ahead of the details.  Is the BEE cheaper than a reusable Falcon Heavy?  ABSOLUTELY.  But, it's better for the company and better for humanity to have the capability of re-visiting the Moon, placing GIGANTIC payloads in orbit (including new space stations and REALLY BIG space telescopes), and traveling to Mars 10 or 20 years sooner rather than having a 10 or 20% cheaper launch system for sending small satellites to LEO when the reusable NET will already be DRASTICALLY cheaper with its 100% reusability than anything we have today...

 

The BFR also gets around the problems of mass-growth in developing upper stsge reusability.  If it turns out they're only going to be able to get 1/6th the payload-fraction they originally planned with 100% reusability, the BFR still has a perfectly commercially viable LEO payload-capacity of 25 tons to LEO.  If the Falcon Heavy ends up losing thos much of its payload-fraction in order to achieve rapid 100% reusability, it becomes *worthless* as a commercial launch vehicle in 100% reusability configuration.

So, due to a weird sort of logic of bigger being better because you can lose more payload-fraction to achieve rapid 100% reusability and accomplish a wider variety of missions with it, going straight to the BFR is actually a SAFER investment of capital in developing upper stage reusability. I knew the brilliance of the plan the moment I saw it- and can't believe I didn't realize its inherent advantages myself before Musk told the world about his plan...

[Northstar1989]

18 hours ago, mikegarrison said:

There is another issue here, which is scale. In his talk, he mentioned that it's cheaper to charter a 747 across the ocean than it is to buy something like a Q400. This is true. But it's cheaper to fly a Q400 on a feeder route than it would be to fly a 747 that is nearly empty.

His payload cost to orbit for his big f***ing rocket is cheap -- if it flies full. So he needs a big growth market in mass-to-orbit for this to pay off.

No, Mike, you're wrong.  I'm sorry but you really missed the point here.

Musk's point implicitly relied on the knowledge that THERE ARE NO 100% reuse rockets currently in existence yet.  Not Falcon 9, not Falcon Heavy (which hadn't yet even flown) NOTHING can recover both its launch and upper stages yet.

So, the most apt comparison *really is* between buying a small plane, flying it once, and throwing it away vs. an excessively large for the cargo  but reusable, 747.  It's cheaper to charter a 747 for one day than it is to buy a small plane you will destroy- even if your cargo is only 1 passenger.

There ARE no "feeder routes" to orbit.  You either make it to orbit with your cargo or you don't.  There is no halfway point where you drop off your cargo and wait for anothet small rocket to carry it the rest of the way to orbit

There was also another hidden logic to Musk's comparison that he didn't really get very explicit about so as not to scare his shareholders- it's possible that it might not be possible to reuse a small rocket with a useful sized payload *AT ALL.*

It might just turn out that upper stage reusability requires so much mass that the only way to accomplish it even for, say, a 15 ton payload, is with a big honking rocket like the BFR.  It might turn out that the payload-fraction that is possible with cheap 100% reusability and today's technology is so small that even a Falcon Heavy can only carry a couple tons to orbit.

In that case, this spells doom for Falcon Heavy 100% reusability, but still leaves the door open for re-using the entire BFR.   Even if it requires launching the fuel tanker for the BFR 30 times to LEO instead of a half-dozen times (and probably using a fuel-depot as an intermediate stsging-point for the BFR,  to reduce the docking-hazard to the valuable crew and Mars cargo), it's still possible for the BFR to accomplish everything Elon Musk envisioned for it including going to Mars on such a tiny payload-fraction.  On the other hand, a completely reusable Falcon Heavy configuration with only a 0.3% payload-fraction becomes next to worthless...

 

Edited September 30, 2017 by Northstar1989

[Northstar1989]

16 hours ago, KSK said:

I can't tell a lie - this makes me uneasy. Awesome if it works but will it work? It seems like a very large leap into the unknown to bet the company on.

More importantly - will it work on time? I'm a big SpaceX fan but... well Elon time. Have they properly accounted for it?

Even Elon seemed doubtful they would make the 2022 launch-date.  He said it was aspirational.

I would expect they DON'T make their 2022 launch date for the first cargo (with humans by 2024).  In fact I don't expect any humans of Mars until 2032.  But I'll only be 43 then and I'll probably live to see it.  Heck, I might even be a surgeon with a wife and family to bring to Mars with me as one of the early colonists by then (though I'd probably wait another 5-6 years for the colony to be more on its feet before leaving) and not be too old for interplanetary travel.

By contrast, with Musk's plans to perfect Falcon Heavy reusability first, it's probably not by until at least *2052* that the first human colonists would set foot on Mars, and I'd be an old man by then, and so would Elon.  I don't blame him for wanting to leapfrog ahead of all that extra Research and Development- ESPECIALLY when a big-picture analysis shows there's more benefit to be gained and more money to be made by going for a 100% reusable BFR first and skipping the 100% reusable Falcon Heavy, so long as SpaceX doesn't suddenly face any competitors that can develop a smaller, low-cost 100% reusable launch system in the next 20 years...

Before the collapse of Escape Dynamics due to lack of financing (which was working towards a 100% reusable microwave-thermal spaceplane), and revelations that SKYLON probably don't be ready as soon, or as cheaply as initially anticipated (it should STILL, as a 100% reusable HTHL spaceplane be able to beat conventional launchers like the Delta 4 and Ariane 5 on a cost-basis: but it's unlikely to be able to beat the BFR's 100% reusable cost for undersized payloads, despite its much smaller vehicle size than the BFR...  It turns out spaceplanes are expensive and difficult to build, even innovative ones with SABRE engines...) I would have said this was a risky move for SpaceX.

But now it doesn't look like SpaceX has any realistic competitors for the position of cheapest traditional launch service to LEO or GTO, except eventually Blue Origin- and their company motto is basically "slow and steady wins the race".  A 100% reusable BFR will DEFINITELY bear only partially-reusable Falcon 9 launches on a cost-basis...

This is a case of "I don't have to outrun the bear, I just have to outrun YOU!"  SpaceX doesn't really have any competitors that can come anywhere CLOSE to the Falcon 9 on a cost basis, so the BFR doesn't really have to live up to its promise of being drastically cheaper than the Falcon 9 due to full reusability, it doesn't even have to be as affordable as tge CURRENT Falcon 9- it just has to be a marginally cheaper way to launch small commercial satellites than anything produced by their competitors.

If SpaceX can do that, they can build up a massive launch history for the BFR launching small satellites- and then assuming they can avoid or fix any major issues, it should be a no-brainer to talk NASA into partnering with them to send astronauts to the Moon (and after that, Mars) on a proven launch vehicle with hundreds of successful launches under its belt while Orion/SLS is probably still dicking around in Low Lunar Orbit at best...

Edited September 30, 2017 by Northstar1989

[Northstar1989]

16 hours ago, sevenperforce said:

I have some concern about the cargo version. What about servicing smaller launches and GTO stuff? Are we going to see an orbital tug? It's a huge waste to put a BFR into orbit just to send up a 6-tonne GTO comsat.

A huge waste, how?

Sure they expend a lot of fuel- but it's also a huge waste to build an upper stage for every launch, only to burn it up in tbe upper atmosphere after using it.  The BFR has enough payload-capacity that it can afford to slash it's payload-fraction by 80 or 90% in the pursuit of reusability and still have enough capacity to put usefup payloads in Low Earth Orbit...

If you mean a waste accelerating a (mostly empty) BFR from LEO all the way to GTO, yeah you're probably right.  Maybe SpaceX can be convinced to build a reusable space-tug to move payloads from LEO to GEO and return to LEO for refueling, but I doubt it... (Musk has his eye on the prize- Mars, and the cargo BFR is probably perfectly capable of hauling payloads from LEO to GTO or GEO after a few tanker-launches if necessary...)

[tater]

No reason not to give GEO stuff an upper stage inside the cargo bay (like PAM on Shuttle, or the never used Centaur version).

The vehicle size/cost doesn't matter, all that matters is the real cost of a launch (amortized vehicle, operations, plus propellant). If such a launch costs less than an expendable F9 (already a bargain), then they can charge the same price, and not lose money. If it costs a lot less, then they make a decent amount. If they can co-manifest, gravy.

This, like BO's model for NG, is predicated on durable reusability. Rockets that are used almost like aircraft, and can fly enough times to make the pro rata cost of their construction not a big deal. The old ITS version had the fabrication costs of the tanker at 130M$. 200M$ for the spaceship, and 230M for the booster. These should all be somewhat cheaper due to reduced size. The tanker was judged to be good for 100 flights.

So the cargo version (tanker) should be on the order of ~100M$ to fabricate, and the cost per launch of this would be 1M$. The booster is good for 1000 launches, so the per launch cost is under 200k$. Operations for tanker/booster are 0.7M$/launch. So the total vehicle costs and operations would be on the order of 2 million. What's the total cost of the propellants? A couple million? Less?

That makes the cost of this thing quite cheap.

A Falcon 9 stage 2 alone might cost more than a launch of BFS, actually.

Edited September 30, 2017 by tater

[Northstar1989]

On 9/29/2017 at 2:25 PM, mikegarrison said:

Musk got big cheers for his moonbase slide, but what would we do on a moonbase? It's got too much gravity to do zero-G manufacturing, but probably too little gravity to keep people healthy. There is basically nothing there that we really need. Everything on the moon is already on the Earth.

If we ever have large-scale orbital industry, then the moon could be a cheaper place to get raw materials from. But that's a long. long way away.

You'd build a science outpost.  That's the main thing you'd get from the Moon (besides maybe Helium-3)- scientific data.

With 150 metric tons of mass-budget (and possibly multiple such landings to a single site) you could launch a lot of equipment for excavating an underground base for radiation and micrometeorite protection.  You could also build a LOT of surface solar arrays (redundancy for micrometeorite strikes), underground battery-banks (2 weeks of night!), and underground greenhouses to grow food (the radiation of the lunar surface could actually kill or severely harm your plants, not to mention the occasional micrometeorite, and 4 week long day/night cycle: which would kill any Earth plant all by itself...)

In short, when you start talking about 150 tons per landing, you can start thinking about a small permanent scientific outpost capable of growing it's own food, recycling it's own waste, with respectable long-term crew quarters, and doing lots of scientific research on the Moon itself requiring heavy equipment...

Edited October 1, 2017 by Northstar1989

[mikegarrison]

1 hour ago, Northstar1989 said:

No, Mike, you're wrong.  I'm sorry but you really missed the point here.

Musk's point implicitly relied on the knowledge that THERE ARE NO 100% reuse rockets currently in existence yet.  Not Falcon 9, not Falcon Heavy (which hadn't yet even flown) NOTHING can recover both its launch and upper stages yet.

So, the most apt comparison *really is* between buying a small plane, flying it once, and throwing it away vs. an excessively large for the cargo  but reusable, 747.  It's cheaper to charter a 747 for one day than it is to buy a small plane you will destroy- even if your cargo is only 1 passenger.

There ARE no "feeder routes" to orbit.  You either make it to orbit with your cargo or you don't.  There is no halfway point where you drop off your cargo and wait for anothet small rocket to carry it the rest of the way to orbit

There was also another hidden logic to Musk's comparison that he didn't really get very explicit about so as not to scare his shareholders- it's possible that it might not be possible to reuse a small rocket with a useful sized payload *AT ALL.*

It might just turn out that upper stage reusability requires so much mass that the only way to accomplish it even for, say, a 15 ton payload, is with a big honking rocket like the BFR.  It might turn out that the payload-fraction that is possible with cheap 100% reusability and today's technology is so small that even a Falcon Heavy can only carry a couple tons to orbit.

In that case, this spells doom for Falcon Heavy 100% reusability, but still leaves the door open for re-using the entire BFR.   Even if it requires launching the fuel tanker for the BFR 30 times to LEO instead of a half-dozen times (and probably using a fuel-depot as an intermediate stsging-point for the BFR,  to reduce the docking-hazard to the valuable crew and Mars cargo), it's still possible for the BFR to accomplish everything Elon Musk envisioned for it including going to Mars on such a tiny payload-fraction.  On the other hand, a completely reusable Falcon Heavy configuration with only a 0.3% payload-fraction becomes next to worthless...

 

You know the last time this argument was used? With the Space Shuttle.

Let me put it more plainly. This rocket is NOT the cheapest way to launch a cubesat. No matter whether it is reuseable or not. It might well be the cheapest way to launch 10,000 cubesats, sure.

Even more important, though, is how many times it will be reused. If there is only enough demand for it to be used 10 times a year, they are going to have a lot of trouble amortizing the capital costs. Airplanes are flown most of the hours of every day, and yet the capital costs are still a big fraction of the total operating costs. These rockets are going to be hideously expensive if they are just sitting on the ground waiting for cargo that never materializes.

8 minutes ago, Northstar1989 said:

You'd build a science outpost.  That's the main thing you'd get from the Moon (besides maybe Helium-3)- scientific data.

With 150 metric tons of mass-budget (and possibly multiple such landings to a single site) you could launch a lot of equipment for excavating an underground base for radiation and micrometeorite protection.  You could also build a LOT of surface solar arrays (redundancy for micrometeorite strikes), underground battery-banks (2 weeks of night!), and underground greenhouses to grow food (the radiation of the lunar surface could actually kill or severely harm your plants, not to mention the occasional mucrometeorite, and 4 week long day/night cycle: which would kill any Earth plant all by itself...)

In short, when you start talking about 150 tons per landing, you can start thinking about a small permanent scientific outpost capable of growing it's own food, recycling it's own waste, with respectable long-term crew quarters, and doing lots of scientific research on the Moon itself requiring heavy equipment...

What kind of scientific research could be done better on the Moon than on the Earth?

[Northstar1989]

9 hours ago, mikegarrison said:

A 777 across the Pacific is hella expensive per person if there is only one passenger on board. But it's pretty reasonable with an 80% load factor.

A 777 charter flight across the ocean is still a LOT cheaper than BUYING a new smaller plane and then destroying it after you reach your destination (a Cessna don't do, by the way- you need to compare two planes with similar ranges...)  That's the comparison here: gigantic and reusable vs. small and expendable.  Turns out that reusability still beats expendability, even with a very low load-factor.

Edited September 30, 2017 by Northstar1989

[tater]

Using the stuff they posted last year about ITS, the cost per launch is ~2M$, plus propellant cost (unless they included that in their operations costs).

For really small stuff, outfits like Vector would still presumably be cheaper (once they fly), but if the cost/kg is lower, then there is less reason for customers to go to tiny sats.

@mikegarrison is right about launch frequency, however, up to a point. If they just build one, then fly it 30 times a year, then that's probably OK, but if the goal is to build more, particularly wanting to iterate the design after experience, then the fabrication costs really demand more flights. Presumably the notion of sending cargo models to Mars is predicated on expending the prototype vessel at the very least. Use it, offset the coast, then send it off.

[kerbiloid]

1.
How many launchpads/landing zones will be built for the Big F. Hopper?

If 1..2, then you have to spend several hours getting to the nearest one,
then jump from one continent to another,
then several hours more to get from the LZ to your destination.
Instead of just sitting several hours in a regular plane from the nearest airport.

If many - how often would fly a hopper from any of them?
So, you have to wait several weeks to save several hours? Very fast way, indeed.

2.
How many Big F. Hoppers would be built?

If 1..2 - they are unique original product, very expensive.

[Nibb31]

49 minutes ago, kerbiloid said:

1.
How many launchpads/landing zones will be built for the Big F. Hopper?

The P2P plan is not practical in any sense. Not gonna happen. Not worth discussing at this stage. Can we please get over it ?

[Rakaydos]

9 hours ago, RedKraken said:

Just watched Scott Manly's reaction to iac 2017 : https://www.youtube.com/watch?v=wEokBZkZWxo

He makes a good point with the engines for a moon landing.

170t thrust engines are way too big (for an 85t+cargo craft on the moon) and can't throttle deep enough.

They will be moon landing on something 10 times smaller.... maybe a pair of 17t thrusters?

 

The engins dont HAVE to throttle as deeply at the moon, because the rocket (refueled in eliptical orbit) is still going to have half it's fuel when landing on the moon, lowering it's TWR.