380s for ISP for the Raptor vacuum engine seems durn good, considering the tradeoffs between hydrogen and methane.
The most efficient engines we've flown, the RL-10 [0] (used on the Delta IV and Atlas rockets as part of the Centaur Upper Stage) and the RS-25 [1], (the Space Shuttle Main Engine) get around 450-460s for their specific impulse. These engines use liquid hydrogen and liquid oxygen. The issue with liquid hydrogen is twofold: it is not very dense, and to keep it from boiling away in liquid form, it needs to be really cold. So you need huge, insulated tanks to store it. Hydrogen is everywhere, but it's kind of a pain to use as rocket fuel.
Merlin Vacuum [2], which is currently used on the Falcon vehicles gets 311s. The RD-0110 [3], used on the Soyuz gets 326s. These use RP-1, which is highly refined kerosene. It's super easy to work with. On earth. Where we have 200 years of infrastructure in place to support using hydrocarbons. It takes that infrastructure to refine it into a form that rocket engines can use without gunking up the works with unburnt carbon and other particulate crap.
Raptor uses methane, which is kind of like a jack of all trades between density, efficiency, ease of processing, storage, and ease of use in engines. This is basically how SpaceX seems to operate: rather than optimizing a single part of the system (like trying to get the most efficient engine), they try to optimize from a systems level. I don't really know much more than that, because there hasn't really been a lot of stuff for civilians to read on methane engines. This is kind of the cutting edge of the second golden age of space exploration. This freaking rules, what a time to be alive.
> This is basically how SpaceX seems to operate: rather than optimizing a single part of the system (like trying to get the most efficient engine), they try to optimize from a systems level.
They're optimizing for "real" reusability, as in eventually aiming for airline-like turnarounds. None of the earlier engines you noted were reusable except the RS-25, and given how long it took to turn the Shuttle around one could argue it doesn't really count as "reusable" in sense SpaceX is aiming for.
Aiming for reusability and ease of maintenance leads to different optimization paths, in particular we should expect that any one component is going to be less powerful, it'll need to account for wear & tear, not use once and crash it into the ocean.
But raw performance on a single trip doesn't matter much if you can just deliver the same payload in two trips to orbit instead.
> and given how long it took to turn the Shuttle around one could argue it doesn't really count as "reusable" in sense SpaceX is aiming for.
Not just the time but the cost, if you take the figure of how much the space shuttle program cost, and divide it by total number of flights (including the two lethal ones), it cost somewhere between $900 million to $1.1bn every time the thing launched. It was very far from the early 1970s dream of an economically reusable spacecraft.
Indeed, the space shuttle was so expensive it burned up much of the rest of NASAs budget-- keeping that disastrous, failed program running is why NASA doesn't have manned spaceflight capability at the moment.
Well, from an outsider perspective, the SLS/Orion program is pure pork. Nobody holding the purse strings cares whether the thing ever flies. Heck, probably they even prefer if it never flies (always just a few years and tens of billions in the future); a failed launch is potentially politically catastrophic.
If you throw away the rocket, sure, you're doubling the cost if you have to do trips.
If the rocket is reusable, then the vehicle cost gets amortized over the total number of trips, and the per-trip cost gets closer to just the cost of fuel (hopefully at least an order of magnitude less than a new vehicle+fuel on each flight).
You missed one of the most important parts about methane as well: The Sabatier Reaction [1]
Hydrogen + CO2 => Methane + Water
This is an extremely important reaction. Mars, for instance, has effectively unlimited Hydrogen and CO2 which also means effectively unlimited Methane and Water. How just absurdly convenient is that?
But it also plays a major role in things like life support. We breathe out CO2. On Earth where we have an enormous atmosphere this doesn't matter. But in closed systems, such as the ISS or what will be the habitation regions on Mars, this is a major issue that needs to be dealt with or we'd kill ourselves with our own exhaust.
NASA, on the ISS, used to deal with life support by producing oxygen from imported water, and discarding the produced hydrogen. They'd then collect exhaled CO2 from the air using CO2 scrubbers and also discard that. That was a pretty inefficient system that required large amounts of imported water to sustain. Now they use the Sabatier Reaction to convert the exhaled CO2 into water and methane. Only the methane is discarded. And as a result of this, instead of needing to import large amounts of water, now all they need to import is a small amount of hydrogen to keep the reaction running.
On Mars this will result in a really cool system. What will be an increasingly large scale life support system will be literally creating rocket fuel as a byproduct. Of course methane is also a controlled and efficient gas, so it can also be safely used for things like cooking dinner.
Here's a Wired article about the raptor engine - it's "a full-flow staged combustion engine, only the third engine in history to employ this technique ... The previous two attempts at such an engine, one in the Soviet Union in the 1960s and another in the US in the early 2000s, never made it beyond testing."
And if you want to get a lot more detail on what makes a "full flow staged combustion engine" so special, this article from Everyday Astronaut goes into some amazing detail on this and many other engines.
I think they might be suggesting that Scott may have specific exemption from Apple's PR policy (summary: "say nothing to anyone") to be allowed an independent public voice - particularly on a technical/engineering topic. Apple is not, so far as we know, currently developing orbital-class rocketry, but there's genuine potential for product topic overlap in Project Titan vs Tesla and perhaps more besides.
I would not be at all surprised if there's a List Of Things Apple PR Hereby Politely Requests That Scott Doesn't Mention.
When I was at AWS I was similarly forbidden from mentioning anything to do with video games to just about anybody, despite not having anything to do with video games myself, and many other topics besides the obvious (e.g. "don't disclose EC2/S3 capacity numbers"[1], "don't reveal how Glacier works"[2]), and in fact there was a whole programme of PR training and tiered permission to speak at conferences or to the press/analysts that boiled down, mostly, to knowing what you could and couldn't say, and how diplomatically you parried questions on the latter.
Either that or Terry Pratchett's law of rewritten rules applies.
[1] no-one would believe me anyway
[2] it's a massively redundant array of vinyl records
He started out (or at least found fame) doing Kerbal Space Program tutorials and play throughs, that's how I first came across him. He's also a pro DJ with an awe inspiring music collection and knowledge of music, though I'm not sure how much of that he still does. Oh, and he's also a fully qualified Astrophysicist and has worked in the field.
Nope, same guy. Scott Manley has a degree in astrophysics (I think) and worked as an astronomer for a while, then got a job coding at Apple. He's a smart guy
I'm no rocket scientist, so bear that in mind, but something has been bugging me about the flight paths for this vehicle [0]. It has to make some very large, specific orientation changes several times during descent, using the heat shield on one side of the vehicle, and then only rotating to upright orientation in the lower atmosphere, after quite a lot of falling sideways. The orientation maneuvers seem much more complicated than their current booster re-entry flight paths [1]. and even more complex than the space shuttle [2].
This appears to me to make each flight much more complicated to pull off, introducing more points for it to fail without contingencies, and it makes me nervous. But, again, I am an just an unenlightened observer from an unrelated field. I don't even play Kerbal Space Program! I'm sure they've weighed a million different options and their risks, and have arrived at this one after a lot of thinking, but it has been bugging me. The stainless steel construction certainly looks beautiful out there in Texas.
It’s actually similar to the shuttle, In a couple of ways simpler, and a couple of ways more complex. The shuttles body was also designed to both generate lift and be a blunt body - with a transition of mode between them. The blunt body allowed it to survive reentry while the lifting body allowed it to glide. However that glide was way more complex then NASA generally talked about. The shuttle pulled some aggressive s-turns to bleed off energy during the re-entry.
This approach is more or less the same as what the starship is doing here, except instead of using a glider trajectory for the controlled landing they instead use retropropulsive landing. This is needed because what SpaceX is landing here is a second stage, not a first stage. Way more heat, way more power.
A lot of the complexity is hidden in the second video. It's the exact same deal, it just doesn't look like it. In particular those innocuous 'waffle irons' on the side play an incredibly important role. You miss the scale in the video thanks to how big everything is. Those fins are each 4' x 5' large. And each of them can independently yaw/pitch/roll. And of course the exact angle that the rocket is at when it fires its boostback (as well as when it's coming down), exactly how long the boostback is fired, and a large number of other variables all need to be lined up exactly perfectly. Otherwise you end up literally thousands of miles from your destination, run out of fuel, or otherwise condemn your mission in a surprisingly large number of innovative ways.
The big difference you're seeing compensated for is that Mars atmosphere is less than 1% dense as Earth. So to slow yourself down you need a much larger exposed surface area. Do that exact maneuver on Earth and you'd get an 'unplanned rapid disassembly' during reentry thanks to the thicker atmosphere. That danger and complexity is also something that's hidden.
I cannot recommend Kerbal enough for anybody even vaguely interested in space. Just absurdly fun and does really help you get a feel for all of these issues.
> Do that exact maneuver on Earth and you'd get an 'unplanned rapid disassembly' during reentry thanks to the thicker atmosphere
That is the planned Earth re-entry maneuver. Belly first almost all the way down, using the heat shield on one side, then flipping and completely re-orienting near the ground so that the vehicle is pointed upwards, and then the final burn to land upright.
But it does make sense that this path has arisen from a secondary capability: to land on planets or moons with less atmosphere. It still doesn't make me less nervous about their ability to pulli it off reliably. Here's hoping.
Learning how to reliably control the damn thing on descent is certainly their greatest hurdle. Refueling in orbit being the second biggest. I expect things to go boom at least a few times before they learn to land properly. Saying people Wil go to orbit within a year is most likely not to happen.
Methane was chosen to a large extent because you could make it fairly easily on Mars which is necessary if you want to fly people there and then get them back again.
> This is basically how SpaceX seems to operate: rather than optimizing a single part of the system (like trying to get the most efficient engine), they try to optimize from a systems level.
A system of local optimums is an inefficient system. Sort of the self-identified takeaway of the book _The Goal_, and I haven't stopped thinking about this statement since I read it.
Musk thinks like a software engineer. Create simple, reusable, components that can scale efficiently. I’m taking some liberties in saying this, but the gist remains the same. Musk keeps it simple and focused.
Agreed! Only a software engineer would risk a product launch delay because of an uber-bikeshedded pet feature (Model X doors) or wait until the last minute to ship and then construct a makeshift “factory” in a parking lot and make staff go through a death march, QA be damned.
I haven't used or wanted a roof rack in 30 years (extra mass and drag at the highest location? No thanks), but the Model X has a lot of storage space, including the frunk so it's a non-issue.
The falcon doors also provide a surprising benefit: cover in the rain. And they are very practical with small children.
Musk was chief designer for Falcon 1, their first rocket. Musk is very much involved in detailed technical decisions.
Musk is very much responsible for why the team works the way it does. He specifically focused on hiring people who experiment and try out things a lot. He did not want just pure theoretical guys.
He doesn't do most of the work but he's very involved. Here's an interview Mueller gave that describes some things Elon did with the Merlin engine, search for "face-shutoff."
> And, uh, I’ve seen that hurt us before, I’ve seen that fail, but I’ve also seen— where nobody thought it would work— it was the right decision. It was the harder way to do it, but in the end, it was the right thing. One of the things that we did with the Merlin 1D was; he kept complaining— I talked earlier about how expensive the engine was. [inaudible] [I said,] “[the] only way is to get rid of all these valves. Because that’s what’s really driving the complexity and cost.” And how can you do that? And I said, “Well, on smaller engines, we’d go face-shutoff, but nobody’s done it on a really large engine. It’ll be really difficult.” And he said, “We need to do face-shutoff. Explain how that works?” So I drew it up, did some, you know, sketches, and said “here’s what we’d do,” and he said “That’s what we need to do.” And I advised him against it; I said it’s going to be too hard to do, and it’s not going to save that much. But he made the decision that we were going to do face-shutoff.
So, he knew about a problem, he heard someone mention a possible solution, and he insisted they use that solution.
Mueller begs to differ "And now we have the lowest-cost, most reliable engines in the world. And it was basically because of that decision, to go to do that. So that’s one of the examples of Elon just really pushing— he always says we need to push to the limits of physics."
There won't be much literature because Raptor is essentially the first production methane engine. Everyone in the past seems to have decided to optimize strongly for either Isp, bulk density, or storability, and methane is the best at nothing.
Right, because in the past we were building first stages which had to be optimised for operations in the lower atmosphere, and upper stages which had to be optimised for vacuum. Hence the Saturn V had an RP-1 powered first stage and Hydrolox second stage.
But the raptors on the second stage have to operate efficiently in a vacuuum, but also work well and sea level for the landing. So even taking Mars out of the equation (which we really shouldn't, but just for sake of argument), it's requirements are quite different to anything we've built before.
SpaceX has a good design philosophy. They use cheap, reliable, and sturdy components, take the hit on payload fraction, and just make really big rockets to make sure _total_ payload is adequate. I'm reminded of the old quip apocryphally attributed to Stalin: "quantity has a quality all its own"
You can raise the Isp of any vacuum engine by using a bigger nozzle. The RD-58MF is a small engine and there's room for a relatively huge nozzle. That's not true for big engines.
For example, Merlin vacuum has a 1:165 expansion ratio. The RD-58MF has a 1:500 ratio. The Wikipedia article for the RD-58 family shows the increase in Isp from various expansion ratios.
Right. There is however an argument that the smaller total impulse a stage does (RD-58 is used for upper stages, where the stage mass is closer to the stage payload), the smaller the relative mass of fuel+engine of that stage is, and so the fixed mass of the bigger nozzle added to the stage costs more, in Tsiolkovsky equation, that the mass for the bigger stage. Going further, we can argue that for larger stages it's beneficial to spend some mass on nozzle, because that mass is used for larger impulse provided by the stage.
Interesting that using http://rocketworkbench.sourceforge.net/equil.phtml I couldn't get declared Isp (380) for methane-LOX for reasonable nozzle expansion ratios. Maybe the model is too approximate...
I am so amazed by the genius of making it out of steel. It's just so completely counter intuitive but has accelerated their progress so much.
If they told you the stats of the material, better strength at cryo tempertures meaning mass reduction, higher melting point meaning minimal heat shielding and great thermal conductivity it would be easy to imagine it was some new super composite. Then your head explodes when they tell you it's 2% the cost of what they were using before and it's so easy to work with they don't even need a factory they can just weld it in a field.
Imo Elon is starting to get into contention for greatest engineer of all time.
Didn't the Russians use a lot of steel in their Space Age era rockets? It always seemed to me like we went too high tech too quickly and the Soviets were practical to a fault, and the truth should be something in between.
I find it odd that Russia hasn't fought back and tried to do a reusable program of it's own. Putin talks big talk about wanting to develop high tech industries so why just give up on space?
His nuclear cruise missile program is so lame by comparison.
Russia needs an oil price of at least $74/barrel to balance the budget, which means they've been in a lot of economic pain for the last 5 years. Roscosmos was seen as a cash cow, requiring minimal investment to make reliable $ income off their mature launch business. As a result they were starved of investment and are a pale shadow of their former selves.
Building a dynamic, innovative organisation capable of developing a re-usable architecture would be very expensive, and unless they can not just equal but handily beat SpaceX, there's just no money in it. Their current launch systems already meet their military needs, so there's no political support from that quarter either.
I'm out of date. The Moscow Time says $49, but you're quite right in that Russia has done a lot in the last few years to bring their budget under control.
Their war chest is not looking too healthy though, the hit to oil prices in the last 5 years depleted a lot of their reserves. Thanks for the correction.
From memory the MiG-25 interceptor had quite a lot of steel in it for thermal reasons. Titanium was too difficult to work with for them at that time (or something).
Depends how you define "design". Most engineers I know are not involved in the bog-standard design, but rather when the decisions get outside the comfort zone of the designers (either engineers or engineering techs themselves). From all accounts ("Switching to stainless steel is one of the best design decisions I've ever made"[1], comments from Tom Mueller about Elon leading the design team on Raptor[2]), Musk is performing the role of a head engineer.
Many jurisdictions would still have an issue with him using the title engineer. (edit: it's recently been determined to infringe on first amendment rights [3]. Still applies in Canada)
Meta-engineer? Engineering executive? At least he's trying to advance humanity instead of squandering it all on yachts like almost all the rest of the world's billionaires.
Lets be honest, he's kinda transcended all definitions, and that is necessary to be the kind of full picture problem solver that he is... Gain all the information about the problem areas in all contexts from your experts, while having executive authority to execute radical solutions.
I think visionary is the best descriptor and there aren't too many of those folks alive at a given time that are properly placed to execute, and even fewer who actually DO execute.
I was as entranced with the possibility of a permanent extraterrestrial base while watching the presentation last night as I was when I saw the boosters land tandem style in 2018.
What an amazing thing to see happen, the people Elon has brought together have done amazing things on the shoulders of already incredible work.
If he didn't design it himself, the people he hired and gave overall direction to did. And they are doing way better than anyone else, which means he must have done a better job of hiring and directing than anyone else.
I have read that when he gets interested in a technical area, he reads a ton of books at a remarkably fast pace, remembers everything he reads, next analyses everything at a fundamental level, and finally comes up with a radically better plan than anyone else has before. I guess you could call that engineering capabilities.
I had three peers in my entire engineering classes like that. Two became PhDs, one has changed fields and applied himself rapidly.
I wasn't like them, but that ability to understand on a fundamental level, not forget, and then very quickly tackle more and more complex problems so fast was like a superpower. It took me much much longer, without the detailed understanding.
he's intimately involved in every aspect of the design of the vehicles. For example, he's personally responsible for the change to steel construction and had to convince the rest of the team to switch from composites.
I know there are 1000 of them 100x smarter than me at all of this, but I have my doubts that the specs for "cold rolled" stainless will hold up after tens of re-entries, as it is effectively being tempered over and over.
From the sounds of it steel structure can basically handle much greater temperatures routinely and also even more in rare situations that might mean retiring the ship afterward but not losing everything. In his presentation Elon says that aluminum alloy or carbon fiber structure is basically done for at 300 to 400 Celsius, well that's the temperature at which stainless steel can just begin to get conditioned by heat, it doesn't structurally 'melt' until over 1000 Celsius.
Although its a curious topic, I would have no doubt that whatever temperature cycling they design parts of the structure to go through in their "rapidly reusable" regime, the effects of "heat fatigue" or whatever to call it will have been rigorously assessed .
Steel won't melt at 300-400 Celsius but "handling" those temperatures for 10 minutes will change the properties of the material, possibly by a lot, so you don't need "melting" for structural collapse (Twin Towers style).
As the GP says, if you put cold rolled steel, which has an elastic yield strength of >1500 MPa, at 300-400 Celsius, then it is only a matter of time (30-120 min) till the elastic yield strength sinks to 500 MPa or less.
So either this is a single use device, or the steel isn't reaching temperatures over 250 Celsius, or the steel isn't cold rolled but is a low strength steel instead (although that would have other problems).
Re-entry will take something on the order of 10m or less. Even the space shuttle only took 30 minutes while flying like a plane. There will be no circumstances where the ship is going to be subjected to that amount of heat for 30-120 minutes.
> or the steel isn't reaching temperatures over 250 Celsius
That might be the case. The space shuttle had an aluminum structure that would fail at 175C, and now we have 40 years of technology advancements for the heat shield.
Also I notice Cr-Steel's elastic yield strength at 400C is about 87% of its strength at room temp and I don't think it does alter significantly over these timescales at that temperature.
It will be interesting to see how high it can be routinely cycled without losing its temper, but it seems to certainly provide much more overhead for safety margins as well as routine operation.
As of the last time I heard, SpaceX was planning to use an extremely aggressive active cooling system: cold fuel would be bled through many holes in the hull, in a process similar to sweating. The hull may never get above room temperature.
No, the "sweating methane" cooling is no longer happening (per the presentation/q&a last night). Instead they're using ceramic insulating heat shield tiles - similar to the shuttle, but different materials, very different attachment mechanism, and a regular shape (tiles will all be hexagonal)
As I understand it, 300-series stainless is not heat treatable, so this should not be a problem. (304 stainless is routinely used in exhaust systems where they are heated up to glowing red temperatures every time. If the starship tank gets anywhere near that hot on entry I think there are worse problems given that on the other side of the tank is cryogenic propellants.
Stronger is not a specific enough term with metal, but tempering is the opposite of what you described, which is hardening.
Steel becomes harder and more brittle if quenched (hardening), and softer and less brittle if cooled slowly (tempering).
Cold Rolling steel is done to avoid the heat cycle which would otherwise result in tempering, which is why its specific stats don't strike me as particularly relevant past the first launch.
Heat cycles also have the effect of warping steel.
Uh what? This is exactly the inverse of what happens. Quenching leads to stronger, more flexible steel. Slow cooling leads to harder, but more brittle steel. The reason is grain structure - slow cooling allows larger grains, which don't allow the movement of dislocations as freely, but the loss of flexibility costs in ultimate tensile strength.
Please cite your correction or delete it if you find you are in error. I have provided my 2 sources which are in addition to my peer and personal experience in blacksmithing.
I don't know about his general claim, but a detail within his comment is right.
Smaller grain size leading to stronger material -- this is a result of more grain boundaries as the scale of the grain goes down. Hall-Petch strengthening.[0] A secondary effect is that with smaller grains oriented in random directions the metal is more resistant in general from stresses in all directions; whereas with larger grains you tend to get weakness in a particular direction (along the slip planes.)
This is common knowledge, at least it's basic material physics that I learned in college.
Actually I said strong is too ambiguous of a term to use. For instance, do you want it "strong" enough to not bend under x force at y temperature, or do you want it "strong" enough to bend rather than shear at z force?
It is more practical to discuss the hardness and ductility at specific temperatures, as well as its ability to keep its carbon content under those temperature conditions.
But I think the word GP was looking for was annealing. Annealed metal bends quite easily (that's the analogy in 'simulated annealing' in optimization theory). For instance the wire bonsai practitioners use is traditionally made of annealed copper. Copper is already pretty ductile but once annealed it's positively floppy. Bending it work-hardens it, causing it to stiffen back up. Eventually one learns that if you bend it just so, it will stay where you wanted it to stay.
You do not want your space craft reconfiguring itself.
Tempering is the correct terminology. Annealing is a slow and controlled heating, gradually reducing the heat over time.
from Wikipedia:
"Tempering [...] is done by heating the metal to some temperature below the critical point for a certain period of time, then allowing it to cool in still air."
The benefits of standing up to high temperatures are important for reusable rockets that need to land (the heating happens on the way down, not on the way up). If you're not going to land, aluminum-lithium like Falcon 9 is better.
You're only heating your structure that much when you're landing an entire spacecraft. If you just have a capsule going down its usually easier to have an ablative heat shield.
Also, it's a lot easier to foresee the weight of a design than its cost so most space programs use it as a proxy for cost. So generally the space industry would optimize for minimizing weight and not even try to think about how the materials used would affect cost.
Steel was used before for the early Atlas rocket models. But the skin was too thin and collapsed on its own weight. You can see YouTube videos of this.
Those were balloon construction, which is a bit different. They were designed to be kept rigid by the internal pressure of the propellant. Actually the Centaur[0] is still built this way, using stainless steel.
Not your parent commenter, but SpaceXs innovations start with pulling most design and fabrication in-house, rather than NASA relying on (multiple levels of) defense contractors redesigning ICBMs. ICBMs are single-use only and cost is no object when you're fighting WW3. Similarly, cost was no object for launching military spy satellites, so there was no reason to reduce the launch cost of a $1B recon satellite.
Here, specifically, with regard to steel rockets? SpaceX stopped optimizing for weight and used thick steel. SpaceX optimized for cost and practicality. Brute force rocket engineering, rather than "the best performance numbers on paper" which is where a lot of rocket designs seemed to get lost in the weeds of some component that ends up being a massive maintenance mess but gives you "the best performance".
The steel tanks that collapsed in the sixtys? They were so thin they needed pressurization at all times or they would collapse. SpaceX realized that was a design and maintenance risk, and just built thick tanks.
I totally understand why they've gone for that design but the welded together steel plates really make me think of the sort of thing Wallace and Gromit would build.
I am totally with you on this - I just can't get over how utterly rudimentary and basic this thing looks! I can't wait to see it fly!
I am so used to seeing space stuff done in clean rooms, and things taking years and years to come to fruition (e.g. hearing about and seeing NASA or ESA probes etc getting made) that to see what is essentially a bunch of guys in a field just welding something together blows my mind.
I mean, is it just the outside that looks like that and inside it is ultra-exotic materials and tanks? Of course the engines are sophisticated machinery, but what about the insides? Are we just seeing the outer shell and it's all unobtanium nano-tube composite on the inside?
I suspect most of the structure that gets really hot or cold is steel. To save weight, they are probably also letting more of the rocket get colder/hotter than normal, thanks to the wider temperature range of steel.
Once the temperatures get reasonable, it might be aluminum or or carbon fiber. The passenger/cargo/avionics section are probably the only areas where this would be true, so a bulk of the rocket will be steel.
Steel can tolerate a lot more deflection before it bends, and much more stress before it cracks. And while I would never expect a space craft mechanic to employ this technique, any bike mechanic will happily offer to bend steel back into shape for you, but bent aluminum or carbon fiber is scrap. Bending it back will fracture it, if it hasn't already.
When Canondale hit the big time, they had one model year where they made the dropouts out of solid aluminum and in the next model year the derailleur hanger was bolted on. It's the easiest part to bend and there's no repairing it. Bad enough for road bikes, spectacularly dumb for mountain bikes.
I recall quite a while back, when titanium started first showing up outside of aerospace, that someone had created a titanium-titanium composite by layering plate titanium with titanium cloth and welding it together somehow. Was supposed to be stronger. Wonder if there's a steel equivalent possible.
I think the military was looking at a similar material to replace depleted uranium with something non-radioactive (depleted uranium still experiences alpha particle decay, which is fine if you don't aspirate or ingest it, but a shell can pulverize on impact with a target. Also it's still a heavy metal even if you don't take rads from it).
> I think the military was looking at a similar material to replace depleted uranium with something non-radioactive
I thought the point of depleted uranium projectiles was simply the density of uranium, giving them large impact energy for a given volume. If that's the case, titanium (4.5 g/cm^3) will not even be as good as steel (8 g/cm^3), let alone uranium (19 g/cm^3).
Yea it's pretty wild. Although I am certain this is just for a prototype. I think the actual ones that will be sent to the Moon & Mars will be done in a clean room.
Is the surface of these less smooth than surface of normal rockets/planes, or is it simply the effect of mirror like surface making bumpiness easier to see?
We work with multiple tens of ton of SS steel per month, and I would have never thought this heavy thing could fly with all the stress of the sky. I hope it fly good.
he addressed in presentation, from what i remember it had a lot to do with cost. Like $130k/ton with carbon vs $3k/ton with steel. He mentioned a few other factors. Also it allowed them to build outside, not sure if t that is true in production.
As he said in the presentation, it was because at cryogenic temperatures (which is the important part when you're building a liquid oxygen / methane tank) 301 stainless is actually _stronger_ than Al / carbon fiber. It also handles heat much better, which allows you to have a much thinner heatshield.
Both characteristics combine to give a lighter rocket than one built out of Al / carbon fiber.
the material isn't the question, it's why they had to weld it together in a patchwork quilt. Elon talked about the next version would simply have rolled coils with a single seam weld (although the cylinders would have to be welded together too), which would be better structurally and cosmetically, and likely lower cost of production. Sounds like they just didn't have the rolling machines to do the job, or perhaps there was an availability issue with the specific alloy.
It will reduce the length of the welds (for the hull) quite a bit.
The number of rings is roughly 35 for Starship, with about ten vertical seams each.
For easier thinking, line the vertical seams up and you see that this gives 50m length per vertical seam from bottom to top of Starship. So there are a total of 500m for that.
35 rings with ~28m circumference add up to about 1km of seams between them.
Now if they can use rolls twice as wide and only a single vertical weld each, then that's 500m between the rings and 50m for a single vertical seam. 550m of welds there instead of 1.5m before. This should speed things up quite a lot and reduce the cost of labour.
The way I understood the presenation, they plan to use a single piece of steal, bent at an angle and rolled around (think one of those Pillsbury roll cans) with a single weld seem, in a giant helix.
>Raptor production is the real bottleneck, though.
They are shooting for one per day, no? Based on the differences identified in the three hanging under the Boca Chica vehicle now, it’s still in development.
You basically need to do that as the steel rolls off the press, though, which is why they didn't do that for Mk I. They'll need to cold roll the steel onsite.
He also talked about how stainless steel has a high melting point (which means their re-entry heat shield doesn't need to be as thick) and gets stronger rather than weaker at very low temperatures.
What I loved the most was the optimistic outlook, the forward looking focus and the implicit belief that any problem will be solved and we'll advance.
This is exceedingly rare in a pessimistic world drowning in the voice of Luddites and backwards-looking preservationists.
Like always, technology solving real world problems versus politicians (professional or amateurs) creating (and never really solving) self-serving perpetual issues.
I suspect that having a sense of urgency and limited resources contributed to this phenomenal pace of development, it's in stark contrast to the glacial pace of the SLS project (Boeing/Nasa) which is much better funded.
NASA was never a space exploration agency; in its heyday, it was a combination thinly veiled demonstration of military capacity and thinly veiled military projects agency, but most of both of those functions were superfluous by the last decade or so of the Cold War.
Elon Musk said 5% of SpaceX was working on Starship and that the hardware for crew would be ready this year (in interview to CNN after the QA he said October for in flight abort and November for DM-2).
Almost certainly the top minds at spacex are focussed on starship, and the 5% number might only be kinda-true because starship is being built with a lot of contractors.
Well when you tell a customer you will have all hands on deck and then are out back playing with your go-kart then expect your billion dollar customer will say something.
I imagine all the necessary hands are already on deck for Crew Dragon.
Starship wasn’t built by the Falcon or Crew Dragon manufacturing teams, and the vast majority of the design and engineering currently happening for Starship has long been completed for Crew Dragon.
Let’s also remember that NASA is hardly the only company that pays SpaceX, they have other income sources and what they do with that income is ultimately their choice. Unless they are using NASA money to build Starship there should be no problem.
"Musk said in 2018 that SpaceX was “all hands on deck for Crew Dragon,” and it would be making trips to the ISS by December 2018.
After that, he said, “most of our engineering resources will be dedicated to BFR, and I think that will make things go quite quickly,” he said. BFR was the earlier name for Starship."
"All hands on deck" is not some subjective term, it is naval and means get everyone on deck now to repel boarders.
Except there is nothing they can do now. There are a ton of safety reviews which depend on NASA, and only a small amount of people at SpaceX are required to keep the NASA team more than filled with work.
Elon responded saying he would do whatever it took to go faster, but there was nothing he could do.
I think people are missing an important point when talking about Falcon Heavy. Yes it was delayed, but the Falcon Heavy that was eventually launched, was WAY, WAY better then the one announced in 2011.
The payload of the 2011 version was almost reached by the Falcon 9 itself. That was one of the major reasons for the delay, not design and production issues. The Falcon Heavy profited from all the advancments on Falcon 9 and it made no sense to actually build a Falcon Heavy before Block 4.
In fact the first costumers for Falcon Heavy flew on Falcon 9 instead.
FH was 5 years+ behind schedule before it was built and launched. Starship already has multiple constructions going on, with multiple prototypes to test and multiple full-size vehicles planned quickly.
In 2011, FH was supposed to have "arrival at launch site" by 2H 2012. It first launched in 2018 (after arriving at launch site in 2018 not 2012). The same level of delay would mean the first Starship does not reach orbit until ~2025. That seems crazy pessimistic and would be a dramatic departure from the otherwise normal delays faced by SpaceX.
I think it's extremely unlikely that Starship would face FH-level delays. That would cancel the Starlink constellation, cede the space-internet game to others, hand the torch to BO or others working on large projects, and absolutely destroy morale at SpaceX.
FH got delayed because they kept improving the F9, so they didn't need the FH for many of the original target payloads. Some of the delay was due to technical issues, but changes to the F9 were significant over that time period. Starship has no dependencies on the Falcon stack.
Another company would have rushed it out "on schedule" and have been stuck with the results forever. Delaying something until you need-need it can be a very good strategy ensuring the best possible final results at go-time if that avenue is available to you.
The thing with the F9H is, that there was no real need for it for years, it almost got cancelled entirely. The F9 was improved to a point where it could do most missions which initially were thought to require a F9H. So the development of the F9H was done at a lower speed than if the business had depended on it. But as there seem to be some contracts requiring the F9H, they made it eventually. How often it will fly though, entirely depends on how quickly the Starship progresses.
The center core of the Falcon Heavy has been described by Musk as effectively an entirely new rocket, due to the million pound lateral forces holding the three rockets together. It's not just three Falcon 9 strapped together.
There is a quote somewhere (by Elon?) saying that FH is not "just" 3 F9s strapped together. A significant source of the slowdown for FH was the desire to not launch it without full reusability of all 3 stages and not to launch it without significant improvements (block 5 etc).
Starship has none of those potential delays and has already solved most of the hard problems (as evidenced by the Hopper hopping already). Starship has all of the learnings and experience that FH and F9 didn't have.
There will be delays, sure. But we won't be waiting 5+ years again for a single launch. Those days are over, and SpaceX is proving it.
> Keeping that in mind, having 5 year delay on brand new design, using totally different materials, new engine, etc isn't far fetched.
The first full size Starship prototype is already built though (within ~2 years of initial announcement? Not behind schedule basically at all, so far?). IIRC for FH it was a ~5 year delay before SpaceX even starting construction on the first parts. The difference with Starship is staggering. The pace is dramatically faster, the risks are reduced up-front, and the tests are planned on a much shorter timeframe.
We would frequently go 6 months to a year and hear no news at all about FH. There is news, updates and progress available to the public on an hourly or daily basis about the Starship progress. Night and day.
Hopper shows that engine works outside of test lab. That's great, but it's far far away from showing that they solved most of the hard problems.
Experience from FH and F9 is useful, but it's a totally different type of spacecraft, with different use-cases, different materials, engines, cooling, etc. There's TONS of new stuff that they have to research, experiment, fail, try again, etc, until it's doing even 50% of what Elon promised.
Perhaps I'm misunderstanding something. I thought Hopper was not about Raptor tests but about VTOL as well. The FH had to wait while F9 got down the vertical landing science and engineering (though a lot of tests, explosions, delays).
StarHopper seems like it can use those learnings, and that was tested recently. The engine was already functioning on a test stand and mated to Hopper for static fires; the Hopper hop itself is testing the engine, sure, but also the complex math of doing a vertical landing with a gimballing engine, etc.
The general space industry considered reusabable spacecraft that land vertically to be pretty much impossible until F9 and FH did it. But Hopper just does that casually, you don't bat an eye, you don't even comment that Hopper was testing a new rocket dynamics/physics for the math that (almost) only SpaceX has figured out.
I just don't see the pessimism here. I've been watching SpaceX for 12+ years and I don't see any of the same issues plaguing them today as did in the past.
New issues, but not the same ones. The new issues have dramatically smaller turnaround time to resolve.
> The general space industry considered reusabable spacecraft that land vertically to be pretty much impossible until F9 and FH did it. But Hopper just does that casually, you don't bat an eye, you don't even comment that Hopper was testing a new rocket dynamics/physics for the math that (almost) only SpaceX has figured out.
VTVL isn't new. To do it you need ability to throttle engine and do trust vectoring - once you have that, it's "fairly" simple math and physics.
SpaceX is first company that commercialized it, and huge props for that. No one cracked economy of it before (and it's not 100% sure that spacex did - no one saw their financials).
> New issues, but not the same ones. The new issues have dramatically smaller turnaround time to resolve.
We'll see, but I'm extremely sceptic about it. With F9/FH SpaceX did amazing but incremental improvements to current rocket technology. Starship has tons of uncharted territories.
So that quote by the CNES director of launchers praising SpaceX for pioneering supersonic retropropulsion... he's confused and SpaceX didn't do anything new?
I'm not sure I would call starship VTOL maybe vertical takeoff acrobatic landing? I'm sure falcon helped a lot, especially with control surface actuation resilliency, but I think they still have a lot to learn about this amazing new maneuver.
They are building 4 partially functional prototypes to mess up and learn stuff fast.
The FH released did not have the payload capacity they originally intended. The mid-launch fuel bussing was critical to that, and abandoned. Instead they managed to squeeze out more thrust from the engines and make up some of the difference.
Not entirely sure about that. Have no skin in the game but from what I can tell Starship is just a bigger version of the Falcon 9 second stage. FH on the other hand required a lot of engineering investment to figure out how to bolt three F9s together and how to make the software work between all three.
I'm certain it will be a long time until it can get to Mars, but LEO within the next 2-3 years is probably realistic.
> Starship is just a bigger version of the Falcon 9 second stage
Starship is designed to land from interplanetary speeds (not just LEO orbital speeds), can re-fuel in orbit, and has the world'd most advanced rocket engines. The jump from F9 -> Starship is substantially larger than the jump from F9 -> FH.
> Starship is just a bigger version of the Falcon 9 second stage
No way, that's where most of the differences are. The Falcon 9 second stage is a classic expendable stage but Starship is a brand new design which aims to be fully reusable.
> from what I can tell Starship is just a bigger version of the Falcon 9 second stage
I know I'm piling on here with this quote but I just don't understand why you'd say this if you'd done the least amount of research. They are about as different as two rockets can be—do you think Starship is "just a bigger version" because it's an upper stage? Because it's built by the same company? Its design and (theoretical, until it flies) capabilities are radically different and expanded relative to F9 stage 2.
To me the SLS is like Brexit: obscenely wasteful and short-sighted, seemingly inevitable, but somehow I still don't believe it will ever leave the ground.
The Artemis thing is like a joke for real, though. After the last 30 years of bullshit we've seen from the US government's manned space exploration efforts I think I'll be living in a SpaceX-manufactured igloo on Titan before Richard Shelby and his obstructionist, pork-slinging ilk manage to put footprints on the moon.
The SLS is pure politics. You're welcome to ignore that, if you like, but that decision means you won't have a good understanding of why the rocket "exists", or why it's designed the way it is, or what the prospects are for its future.
NASA is still waiting for SpaceX to complete the Crew Dragon spacecraft that will fly astronauts to and from the International Space Station. The space agency has picked SpaceX (and another company, Boeing) to provide commercial crew flights to the station.
While SpaceX did launch an unpiloted Crew Dragon test flight to the space station this year, a subsequent abort system test failed, leading to the destruction of the vehicle. SpaceX aims to resume abort system tests later this year ahead of the first crewed test flight.
NASA Administrator Jim Bridenstine, it seems, is not happy with the years-long delays of Crew Dragon, as well as Boeing's Starliner spacecraft, especially after seeing SpaceX build Starship Mk1 this year ahead of its own test flight.
"I am looking forward to the SpaceX announcement tomorrow," Bridenstine wrote on Twitter Friday. "In the meantime, Commercial Crew is years behind schedule. NASA expects to see the same level of enthusiasm focused on the investments of the taxpayer. It's time to deliver."
I would love to know what the "Day-in-the-life" of a welder working on those ships would be. Did they train specifically for aerospace welding? How did they land that specific gig. Must be so inspiring to wake up and work on that.
And as I saw someone else say, the welds on a water tower also have to be good under pressure, otherwise the water tower bursts and dumps all its water.
I'd love to know the hiring process. There must be many people applying for these positions and I doubt that whiteboard welding is a thing. Or is it? :)
There is definitely tests for welding jobs. And then their welds are regularly tested to maintain certifications.
The tales I heard from my father were X-ray scans of their finished, grinded, polished welds and they had to be perfect. Not a hair-sized infraction would be permitted.
I can't imagine anything but xray for the entire ship, every mm of weld. Given the forces involved, it seems like a completely new level of perfect is required.
My dad did this kind of work in the oil industry for 30+ years as a pipe fitter. His specialty was stainless and they had to be x-ray perfect welds. He recently retired but was always very proud of his work. It took me a long time to understand why.
I wish he could have gotten into the space industry vs oil refineries. The latter is much harder on a person.
Ahaha absolutely. He's as square and as prudent as it gets. I mean to an extreme. My siblings have always laughed at him for it [outside of the workplace and in everyday matters where he carries those habits on].
It's hard on people regardless. And the oil industry is not known for being prudent in looking after their workers' health.
They got real pissed when he filed a workers compensation claim for a hearing aid before he retired. Thankfully he had support from his union.
And the number of stories he's told me where he was nearly killed...
Yeah, having learnt the (very) basics of welding recently it has become very clear to me how much of a skill/art it actually is. Even at the basic level it is a combination of a lot of senses; sight, hearing, touch. And there are multiple movements which need to happen both simultaneously and smoothly, and be adjusted based on the aforementioned senses.
I used to wander around the reactor auxiliary building at the nuclear plant I worked at and take pictures of the piping welds. They were works of art. The skill was obvious.
I imagine for the Mk1/2 they are using in house teams but for the hopper they contracted out the construction to a company that builds water towers (Caldwell Tanks). I mean - it makes sense, it's really just a water tank with an extra bulkhead that SpaceX just so happens to want to attach a rocket engine to...
For real. I wonder how much innovation really exists because the engineers have read golden age sci-fi 25-40 years ago as kids. Could be also that human aspirations are predictable, but I do believe this link should not be ignored. Musk himself acknowledges it some by naming Space X barges after sentient spaceships from Iain M Banks "Culture" series. Or maybe not Musk himself, but whoever named the barges.
For me the biggest "wow" (and there were a lot of those) was the capacity comparison:
Currently the entire world has a launch capacity of 200-300 tons into LEO per year.
With just ten starship/booster combos, that will change to a max capacity of over a million tons into LEO per year.
A factor of over a thousand. The entire current capacity (including the Falcons) at less than 0.1% of the new capacity, a mere footnote. Not even a footnote, really. And apparently they're cheap(er) to build as well. Complete game changer. And game over for everybody else in the launch business.
I'm surprised to hear Musk tone. He's not that friendly usually. Maybe it's because Tesla is a different business and its struggle got to him. Maybe it's because his inner child dreamt of this ship for decades..
I think it's been a good week for him. The Starship of course, but on the Tesla front they are coming up on the end of a quarter with record deliveries, shipping Smart Summon which might let them finally add the FSD revenue to the Tesla reports, etc.
On uBlock Origin you'll want to enable all of the additional filter lists (except the regions/languages section). Doing so blocks the redirect automatically.
That was a very dense an informative presentation last night, but I think the main take away is that rapid reusability is a game changer. In fact, game-changer is probably an understatement, basically every intuition and rule-of-thumb we have about space launches and travel will have to be rethought. And this will be true even of SpaceX falls well short of meeting their stated targets (2020 orbit, 150t capability, multiple refights per day, etc.
Musk stated (I think he just did some mental napkin math at one point) that if they meet their goals, the world's launch capacity will be expanded by two orders of magnitude. How often does any new development in any field bring about two orders of extra capacity? How does this incredible capacity change how you use this thing?
First consider prices. A launch would cost fuel + support operations + amortized cost of rocket. The last two will tend towards zero as they can be increasingly automated and will be a small fixed cost. IIRC, fuel costs roughly $60-100 per kilo to LEO, a 100kg person with 100kg of supplies and life-support equipment can reasonably expect to get to LEO for $20000 in fuel costs. Ok, so you need to "rent" the rocket (you want to stay there at least a few days), pay operations, SpaceX margin, R&D etc. Even then, imagine weekend LEO launches for $50,000 in the late 2020s. That's astounding. Given millenials' propensity for "experiences", they're going to have hoards of people buying this.
But what about risk? They've been trying to launch Crew Dragon for many years and still haven't. Well, with expandable rockets, you have to establish a safety record, it takes multiple flights, it's extremely expensive, you need a new rocket for each one. With fully reusable rockets, you can literally establish a safety record for an individual rocket within a matter of weeks, not years. Even launching once every three days (ie, far from their daily targets), it would take only a year to do more launches than Falcon or Arienne 5 have made in decades. Also, people are far more willing to take risks than organizations like NASA. Consider a thought experiment: SpaceX does 100 launches of Starship and establishes a safety record of 99% (1 blew up). They then start selling tickets, will people still buy, fully signing away any liability? Yes, you'll still have hoards of people lining up for a chance.
Finally, this is going to change science as well. Today, sending a 1 ton rover to the surface of Mars is a Really Big Deal. Hence, probes are made very carefully, very expensively and very very slowly. Not just design and build (it takes a decade), but operations as well (Curiosity traveled only 20km in the last 8 years). Everything is essentially super-low bandwidth. But once you know you can get a cheap ride to Mars (of anywhere else) any time, you don't have to go to such extremes. You can easily send more rovers, more radio relays, they can travel further, experiment more, take more risks and if you lose one, it's just not a big deal anymore!
SpaceX is completely changing the opportunities of getting to space. The reduction in price has been nuts.
According to NASA the space shuttle was ~$450 million per launch, or $16,364 per kg to LEO. The Delta 4 Heavy is $12,156 per kg. For some launches it's even higher- the Air Force paid $15,109 per kg for four launches.
The Falcon 9 is $62 million, or $2,719 per kg to LEO. The Falcon Heavy is $2,351 per kg when expendable or $1,411 when reused.
The BFR is supposed to have 2.5x the payload for 8% of the cost: $46 per kilogram. Even fully expendable it's $2,233 per kg. That's INSANE. It's space elevator money:
> For a space elevator, the cost varies according to the design. Bradley C. Edwards received funding from NIAC from 2001 to 2003 to write a paper, describing a space elevator design. In it he stated that: "The first space elevator would reduce lift costs immediately to $100 per pound" ($220/kg).[1]
If the BFR actually becomes reality it turns a journey to orbit into an airplane ride. A $10,000 airplane ride that will shake your fillings loose, but make no mistake: that completely changes everything about space. It makes putting satellites in orbit around Jupiter as hard as visiting the north pole. Fucking TV hosts will be able to go for a quick jaunt around the moon.
If the BFR happens, we'll have a mars base just because it would be so cheap it's a no-brainer. Building a new ISS would be about as hard as building a new Sealab.
And though Musk isn't a fan, this could even make solar power satellites economical. The monolithic designs from the 1970s would be absurdly expensive, but modern designs like SPS-Alpha get economies of scale by using lots of small identical parts that self-assemble in orbit. According to the book The Case for Space Solar Power, a 2GW satellite would deliver electricity at 15 cents/kWh at pre-SpaceX launch costs. I plugged BFR's $50/kg into its cost breakdown and got 4 cents/kWh, which is pretty good for zero-carbon baseload. Ground solar is cheaper by itself, but probably not after including storage.
The basic idea is geosynchronous orbit, microwave power transmission with a phased array device that requires a reference signal from the target location, and a wire mesh collector several miles wide. Over 24 hours, a solar panel in geosynch collects 5.4 times as much light as one on Earth. At the time the book was written, the power transmission had been tested over a couple dozen miles, and was 40% efficient.
Longer-term, if we collect fuel from the moon to go from LEO to GEO, we could make it even cheaper.
Geostationary orbit is further away than the most distant part of the Earth. If you have a way to transmit power efficiently over that distance, it’s still going to be cheaper to put the panels on the ground in Nevada, the Sahara, Saudi Arabia, the Gobi, and Australia, and transmit the power from there. (Microwave towers, LEO satellite relays, superconducting wire, whatever).
It’s likely to be really hard to make it efficient to transmit the power, because either it will be microwaves or it will be lasers; lasers can be blocked by clouds, microwaves need an huge antenna at each end (the numbers I’ve seen say that the one on the ground has to be big enough that people will ask why you’re not just using building a PV solar array on the ground instead of the antenna). If the antenna isn’t big enough, transmission losses from beamed power is proportional to distance squared, whereas resistance loss in wires is only proportional to distance (P = I²R, R = distance * some_design_specific_number Ω/m).
And that’s without the geopolitical implications of anyone worrying if the enormous directed microwave/laser source could be weaponised. Just saying “trust us” isn’t going to be good enough.
Why not PV on the ground: because wire antenna is a lot cheaper.
Why people don't have to trust us: because the technology isn't physically capable of maintaining even that low energy density at the target, without the reference signal from the ground.
Why put the PV in space instead of on the ground: because there's 5.4X as much energy available and it's 24/7.
I'm not aware of any real engineering studies for things like transmitting power via LEO satellite relays from the Sahara. Personally I don't find it plausible, but if you can provide such a study I'm willing to change my mind.
> Why people don't have to trust us: because the technology isn't physically capable of maintaining even that low energy density at the target, without the reference signal from the ground.
From what I see that’s a design choice not a fundamental aspect of reality, but even if it isn’t: what stops a hostile actor creating their own guide signal, either to direct the power towards an vulnerable location, or to directed away from the receiver, causing wide-scale power outages in the process?
> I'm not aware of any real engineering studies for things like transmitting power via LEO satellite relays from the Sahara. Personally I don't find it plausible, but if you can provide such a study I'm willing to change my mind.
This is because beamed power in general is a bad idea compared to simple wires, however the Sahara is a lot closer than Geostationary orbit and therefore any technology that works for Geostationary orbit will also work for the Sahara, and at guaranteed lower cost regardless of the technology.
Sure, it's the physical design of the device. But that's a consequence of making something cheap from lots of small identical parts that self-assemble. You could make something that didn't require the reference signal, but it'd cost significantly more. And you could always allow inspections if people are really concerned.
Changing the beam target would require a repointing of the satellite in addition to the new guide signal. If you somehow do that militarily, it's still a pretty weak weapon; it'd slightly increase people's body temperature and they'd have to evacuate unless the guide transmitter could be found quickly. It probably wouldn't be hard since it's sending a signal that can be detected 36,000 miles away.
I'd like to see a real engineering cost estimate of transmitting power from one side of the planet to the other, by wires or any other method. I really doubt it can be done for four cents/kWh. And it would certainly introduce a possibility for hostiles to cause wide-scale power outages.
> Changing the beam target would require a repointing of the satellite in addition to the new guide signal.
I can believe either-or, not both. If a guide signal is important, antenna orientation isn’t; if orientation is important, guide signals are not.
> I'd like to see a real engineering cost estimate of transmitting power from one side of the planet to the other, by wires or any other method. I really doubt it can be done for four cents/kWh. And it would certainly introduce a possibility for hostiles to cause wide-scale power outages.
Do I have to? Geostationary is 36,000 km, pole-to-pole is 20,000 km over the surface. All I am claiming here is that any tech you use would also be able to solve my alternative more easily.
The guide signal is what you need for a tight, coherent beam. Direction is up to the satellite, which can choose which of multiple receivers to target.
The advantage of transmitting power from space instead of the other side of the planet is that there's a straight line with no planet in the way. To go around the planet you need relay stations or wires. Plus there's the 5.4X more energy collected by each square meter of panel. So yes, some supporting evidence would be nice. Maybe even take a quick look at the NASA report I provided, too.
> The advantage of transmitting power from space instead of the other side of the planet is that there's a straight line with no planet in the way. To go around the planet you need relay stations or wires.
Which is why I said 20,000 km not 12,000 km. Even if the circuit approximates the Earth as a square and goes up 6,000 km, turns 90 degrees at one relay, goes 12,000 km, makes another 90 turn at a second relay, and then 6,000 km down, that’s still a shorter path (though I’d expect the important distance in that instance to be 12,000 km not 24,000 km because it’s related to the inverse square law between any two antennas not over the whole distance).
> Maybe even take a quick look at the NASA report I provided, too.
I did. Now that I no longer at work I have time for a more detailed (though still brief) look at the contents rather than just skim read.
• That research was an attempt to turn a TRL-1/2 into a TRL-3.
• It is suggesting that — with further work — it could deliver electricity rate of 9 cents per kilowatt hour, whereas the Lazard 2017 price estimate for utility-scale ground mounted PV electricity was about half that (4.3-5.3) and the record (unless it’s been beaten since) is 2.4 cents/kWh.
• What I have read about the Retro Directive Phased Array is that it is it an assistant for good actors, not that it is a safety mechanism. By analogy, it seems that saying it makes this system “safe” is like claiming the passive aerodynamic stability of a 747 will prevent it crashing into a building — not the claim made by the inventor.
RDPA looks to me like a nice improvement to a traditional phased array antenna. Phased arrays can be re-aimed dynamically without physical rotation — which is, I think, why it’s being used in this design.
• The link itself suggests using its own wireless power transmission tech as a substitute for wires (page 50)
• Their own estimate for an initial full-scale (1 GW) is “far term (20-30 years)” (page 65) whereas their “mid- to far-term” market opportunities are the $0.5-$3.0 per kWh range (page 51)
$0.5/kWh is worse than combining batteries (~$0.18/kWh) with 5.4 times as much ground-based PV.
• The construction costs for the 2 GW plant “With aggressive tech advances“ are estimated at $16 per Watt (page 83), compared to current ground mounted costs of $0.103-$0.278 per Watt according to PV EnergyTrend on October 31 last year.
• Check out that risk-impact matrix for the 2 GW “mature” design on page 95
• The ground receiver is estimated to cost $10/m^2 on page 79; Unfortunately page 70 says “Determination of the actual power received will require additional, more detailed analysis“, which makes me wonder what the claimed costs per kilowatt hour even refer to. (Transmission? But there are estimates of beamed power efficiency…)
I’ve not seen estimates for the size of the ground station in that document, I’m going to have to handwave this one and say that the ground station is a 10 km diameter circle (because that’s the value that I’ve seen in other analyses of space-based solar power), which gives 2 GW / (π (5000m^2)) ≈ 25 W/m^2, which is both a bit higher than I’d be comfortable with and simultaneously so low that at $10/m^2 = 2.5 W/$ = $0.4/W, even the ground station alone is significantly more expensive than PV ($0.13/W).
So bear in mind the study was done before SpaceX did much. The $0.09/kWh and $16/watt on page 83 assume $500/kg launch cost. I wouldn't suggest SPS except in a scenario where SpaceX achieves the goals that Musk laid out Saturday night: $50/kg launch and total launch capacity thousands of times higher than the world has now, within the next several years. That kind of capability drastically advances the possible schedule, and drops the cost quite a bit too.
Meanwhile, the comparable cost from solar is the total required for dispatchable power 24/7, not just the cost of PV alone.
Also bear in mind that it involves technology which hasn’t been sufficiently developed yet, technology which would make ground-based solar power cheaper (robotic assembly, beamed power), and that even with the relevant technology the ground station (whose costs are necessarily not impacted by lower launch costs) is more expensive on its own then an equivalent ground PV system including the cost of a battery for nighttime power.
Not really. Even at the intended target, it's diffuse enough not to raise body temperature much. Birds could fly through without harm. Under the antenna, there'd be very little microwaves leaking through. Aim anywhere without a homing signal and you lose the coherent beam, making it much more diffuse.
iirc, Novar Conrols/Novar Electronics out of Barberton Ohio (at the time) was testing the phased arrays using bees and their hives and what ever else got in the area. Oh, yeah, and apparently some of the engineers and the boss.
(I used to work in a lab there next to some of the equipment and one day I asked my good friend about it - he had been there for decades.)
How can you get more power from an orders of magnitude less powerful beam than from an orders of magnitude more powerful beam (sunlight) over an equal surface area? And if you can’t, why do it? This blows my mind.
Disclaimer: I do not know the specifics, but I guess neither do you. The gist of it is probably that more energy gets transmitted per surface unit, but in a way that's less dangerous than sunlight.
Firstly, you have 24/365 production, always at peak power. All things equal, you need a lot less capacity for equivalent power generation.
Then, I am fairly certain that the amount of power that can be collected depends a lot on antenna size, just like standard wireless transmission: the antenna needs to be "tuned". And a few hundred meters of steel cable would likely absorb a lot more energy than an 80 L water bag.
And finally (but related), microwaves are likely a lot less dangerous than UV: it isn't ionizing, because individual photons cary a lot less energy. That also means that they penetrate more "cooking" (increasing temperature) more deeply the objects in its path. Instead of getting your skin burnt from the energy, you feel slightly warmed up (and would likely be able to dissipate the small extra heat in the atmosphere). A sizeable portion of this energy would likely end up in the ground, if no antenna is present to collect it.
This technology is interesting, as it offers a lot of new possibilities: it's easy to relocate, for instance. We might also be able to split the beam to power multiple places simultaneously, reducing grid losses (and load balancing at the satellite).
I think this illustrates what someone who actually understands the engineering being in charge of a company can really do to revolutionize a field.
If a non-engineer is in charge of a space company, they'll look at the popular science articles and assume that single launch is the only way to do things. They'll also assume that we just need to get the material science right to be able to do space elevators. They'll assume that the only way to get into space is to get bigger and bigger space budgets. That will increase shareholder profits after all.
When you have an actual engineer running the company, they can question all those assumptions. They can take everything apart and put it back together again in different ways and question the assumptions of the "thought leaders" in the space.
In a way, this outside "thought leadership" by research institutes has hindered science by leading researchers given grants to carefully conserve and develop their pet solution to a problem that they are an authority on. If their idea falls out of favor, then they will lose their grant money. It's the extreme version of the innovator's dilemma. An entrepreneurial engineer just wants to get the job done. If they can't deliver a great product, they'll lose their revenue stream. If they can leapfrog the competition by capitalizing on their innovator's dilemma, then they'll move to true greatness.
I love how we've suddenly decided that all the solid engineering done in the space industry, for decades, was done by fools reading pop science. But now a "real engineer" is showing us the way.
For the first few decades after WWII, the rocket and space industry was run by brilliant engineers. After Apollo it got taken over by mba's and political types, and basically stagnated. That is why you have SLS which is actually inferior to Saturn V.
But then Musk took over and once again a brilliant, innovative engineer was in charge, and so we are back to making real progress in space travel.
By the way, I am not talking about the space probe designers. They have been brilliant, and have produce an astounding series of scientific advances. But the rocket industry has stagnated.
You didn’t even read his argument. He isn’t talking about the golden years of NASA when real engineers like Werner von Braun made shit happen. It is about the time after.
Sure there are lots of brilliant engineers in the years after but these guys were not making top level decisions.
You can see that in all industries. MBA guys have kicked out engineers as leaders. I have seen the same while working in software engineering. Business thinking dominate over engineer thinking. You end up with these really short sighted decisions and there is an inflated fear of trying anything new.
Look at the SLS disaster: stuck on coupling together a whole bunch of old tech to the point that it creates its own complexity.
$50 a kilogram makes it almost cheap enough that immigration to the moon would be practical. Certainly if a large enough group wanted to band together and pay for the launching of their own infrastructure and passenger rides, they could do it. Forget "just" the start of a new Space Race. This would be the opening of the space version of the Oregon Trail!
I've seen some say this will put the trad space companies, Lockheed, Boeing, Airbus, etc out of business.
It's going to hand them the biggest bonanza they have ever seen. All that launch capacity Starship brings online will have to be used to launch stuff, and these guys are going to be building the stuff. They're not just rocket manufacturers, but have huge satellite manufacturing arms. If I had the money, I'd be investing in space technology stocks like crazy right now.
I'm a huge fan of spacex, but Elon is, as always, "optimistic".
> Musk stated (I think he just did some mental napkin math at one point) that if they meet their goals, the world's launch capacity will be expanded by two orders of magnitude. How often does any new development in any field bring about two orders of extra capacity? How does this incredible capacity change how you use this thing?
With napkin math is't easy. Adding one zero here, one zero there, and you can easily show that you're increasing world's capacity by two orders of magnitude. Elon is known for big over-simplification in his vision statements.
> A launch would cost fuel + support operations + amortized cost of rocket. The last two will tend towards zero as they can be increasingly automated and will be a small fixed cost.
That's just day-dreaming, that support will tend towards zero. Even if it's design for rapid reuse, and they deliver on it, support is a almost always biggest cost of running any complicated machinery.
"the world's launch capacity will be expanded by two orders of magnitude"
How will so many more launches impact the space junk problem?
From what I understand, there's already a catastrophe waiting to happen if some space junk collides with a satellite and causes a chain reaction of more space junk destroying more satellites, etc... until there's an impenetrable debris field around the earth.
Will having that many more launches and the potential accidents therefrom significantly increase the odds of such a catastrophe?
In an interview Musk said there is this strange rule that no matter what you make the schedule, it takes twice as long, so what makes the most sense is to just set it unreasonably short, and then it will take longer, but be as fast as possible.
Some statements are so absolute that they cannot possibly be correct.
> "The best part is no part."
Simple design is better because less moving parts means less complexity.
> "The best process is no process."
No single process is a panacea for all situations, so strictly adhering to a process will eventually cripple you. The best process is the ability to quickly change your process when it is necessary.
I’d be interested to learn if advances in digital computing/controlling potentially solve most of the problems that were seemingly unsolvable in the Soviet era N1 rocket failures.
I’m assuming the inability to control and harmonise 30 rocket engines on the N1 first stage for pitch/yaw contributed significantly to the N1 failures and cancellation.
Will digital computing/control advances control for that and the 42 rocket engines on the SpaceX starships 1st stage?
Or are there other major engineering problems(such as aeronautical/mechanical) to solve as well?
Falcon Heavy managed 27 rocket engines just fine, so the N1 problems has been solved. In fact I don’t think multiple rocket engines ever was a problem with the N1. Its problems were quite different.
SpaceX is able to shut down failing engines quickly, as has been demonstrated so multiple engines don’t present added risk.
Vibrations from multiple engines is something they are able to model much easier with computer simulations today.
I'm slightly reminded of Sea Dragon[1]. That is, using fairly standard steal construction has the possibility to decrease costs even if it increases the net weight of the vehicle simply because it's so much easier to work with and cheaper than minimum weight high tech alloys. Also, because both are quite big though Elon's ship isn't as huge as Sea Dragon was proposed as being.
I just want to point out that SpaceX has not yet successfully put a human in LEO. The moon seems well beyond their technical capabilites at the moment and Mars seems like a fools dream at this point in time.
> I just want to point out that SpaceX has not yet successfully put a human in LEO.
Does this preclude them from doing so in the future? They certainly will within the next year or so (crew dragon).
The moon has been out of reach of humans for 47-ish years mostly because we haven't had the orbital capacity to get there. Humanity has not had a super-heavy-lift launcher since the Saturn V (excluding the Shuttle and Energia, as they're mostly launching inert structural mass, rather than the fuel necessary to get elsewhere and back).
Certainly it's challenging, and their timelines are incredibly optimistic, but I've been watching SpaceX for about a decade, and they generally do the things they claim they will (on delayed timelines).
> Does this preclude them from doing so in the future?
Certainly it doesn't preclude them from doing so, but a healthy dose of skepticism never hurts. Talking about the moon and mars when they have not yet successfully put someone in LEO is a little bit like putting the wagon before the horse.
I don't understand the point you're trying to make. All I am saying is that I think they should first demonstrate LEO capability if they want to be taken seriously about putting 100 people on the moon or mars.
Getting anything, including humans, to LEO is the hard part though. Once they have brought crew to the ISS and have demonstrated a spaceship flying to the moon, landing and returning to earth they will have solved most of the challenges of bringing humans to the moon. And they make good progress on both fronts.
I disagree. Going to LEO vs going to the moon vs going to Mars each pose a unique set of challenges. Manned flights to the moon for instance is many times harder to achieve than putting someone in LEO. U.S, China and Russia have all achieved manned flights to LEO for decades whereas only the U.S was successfully able to put someone on the moon.
>only the U.S was successfully able to put someone on the moon
But is that because it's hard to put people on the moon or because only one country tried? (Sure, the USSR tried too, but they stopped trying before succeeding to put a large enough rocket into LEO).
There is a very unique challenge in landing on the moon, and most moon landings still fail. But that can be perfected with unmanned landings, and Space X has the unique advantage of having plenty of experience with powered landings, and not requiring a separate lander.
As you say yourself, the USSR did try and failed. The N1 failed in all four launch attempts, including destroying the launch complex. They even orbited two prototypes of their lander design. I think that counts as trying.
Then I think you'd be very reckless with your life, given the failure that happened with crew dragon this year that resulted in the vehicle blowing up.
It is going to be interesting to see what happens to SLS once SS/SH starts flying. I am guessing there is going to be big public campaign for NASA to cancel SLS and go with the SpaceX craft.
Yeah, I've been wondering about this too. In my opinion, it's been apparent for some time now that newer commercial launch providers are going to render SLS obsolete too early in its lifecycle for it to be worth the ongoing costs of continuing to develop it.
You might even argue that it's already obsolete, as despite it still potentially being the most capable rocket for some subset of missions, the per-launch costs are so high it might arguably be better to re-architect those missions to use multiple launches of a cheaper vehicle rather than launch on SLS. (You can launch 10 reusable Falcon Heavys for the cost of a single SLS launch.)
NASA/Congress has been stubbornly continuing to develop SLS despite that, but how much longer will they be able to hold out? Surely they won't be able to justify continued spending on SLS once there's another operational rocket that's both more capable in every respect, and a couple orders of magnitude cheaper to operate?
So at what point will they finally give up? Are they going to wait until after Starship hops? Until after it reaches orbit? Until after it achieves in-orbit refueling? Until after it lands on the Moon? Until after it lands on the moon, with crew? When?
Cranes are far and away the lightest way to move something up and down. Wires are incredibly strong for their weight; five times stronger than normal mild steel. Thats due to the stress exerted when they are made affecting the crystal structure.
Not only that, but tensile stress is the strongest mode in general. Structures holding up mass have to resist buckling from all directions. Tensile structures can use every bit of mass budget to hold force going precisely down.
Not only that, but you dont need all of rhe structure to hold a crane up, since its just sticking out the side of the rocket.
Not only that, but you dont even need a motor since you just need to slow things down a bit as they descend.
Cranes aren't especially heavy. You would need a boom to extend 2x the maximum dimension of the cargo hatch, so probably 8 feet, out past the exterior skin, plus some dyneema or steel cable, plus a winch motor of some sort. Not 100 lbs but probably less than 1000.
Pop open a hatch, crank out your jib crane [1], use a long steel cable to lower loads down. Pay attention to weight distribution inside starship to ensure it doesn't tip over.
If you've followed the progress of Starship closely over the last months (and its progress has been stunning), you didn't hear much new stuff at the presentation.
We heard there will be Starship Mk 1 through 4 before we see manned flights. I wonder what their test payloads are going to be when they go for orbit.
Eventually the shell will be a single large roll of steel that is unrolled, bent into a tube with a seam going hotdog that is welded. It will be very strong, lighter than the current patchwork, and extremely beautiful. More similar to the renderings. Can’t wait.
Definitely not hotdog (assuming that's from stem to stern). Musk wasn't totally clear when describing it, but he said mk3 would be in three months. The circumference of starship is 28.26 meters. For a single weld the entire length of the ship, the roll itself would need to be that wide.
The largest rolling mills in the world are ~4 meters wide[1]. They require backup rollers[2], ie rollers that push down the rollers that push down the rollers that push down the metal. Bending deflection increases with width^2. A 28 meter wide rolling mill does not exist AFAIK and cannot be built in three months.
Wow what an incredibly substantive comment. I remember pretty clearly he said that there would be a single seam weld. Maybe I’m remembering wrong. Or maybe they’ll seam weld multiple rolls into a really wide roll and the only weld required to turn the final roll into the shell is that final hotdog weld.
I think when Elon said "there will be a single seam weld" (which I also remember), he meant this in comparison to the current welds.
It's been 12 hours and I only skimmed the video, so I might be misremembering what he said. My understanding was this: Mk1 is welded from plates so at each layer of the stack you have n-1 welds holding the n plates together. My understanding of his comment was that the steel coils will wrap around the major axis of the rocket but instead of each layer containing n-1 welds to join n plates, there will just be one weld in each layer to join the beginning and end of that coil. That would still leave you with welds joining the different layers of coils but only one "seam" weld along the rocket's major axis.
There are a lot of problems with a spiral. Thin sheets of steel, even hot rolled, are very affected by the rolling process. There's also the weld line going up in a spiral. That will cause uneven heat diffusion and expansion, which is a recipe for disaster given that the skin will be cold enough to liquify helium on one side and boiling hot on the other. Then red hot during reentry. Straight lines don't have the same problems.
The "single piece" method he is talking about is that the individual _rings_ will be made of a single piece with a single weld, and the rings are then stacked. You can see it already in the Starship under construction in Florida. (Look at the unstacked rings.)
Spiral tube are a bad choice for a rocket. Because rolled steel has the grains largely aligned with the direction of rolling, it is stiffer and has less thermal expansion in one axis than the other. Large forces and temperature changes therefore cause a twisting motion, which can put weird strains on the internal components.
Pillsbury rolls come to mind. The tube is under pressure from the leavening agent, and you apply torsion on the tub until the can ruptures along the spiral seam.
The most efficient engines we've flown, the RL-10 [0] (used on the Delta IV and Atlas rockets as part of the Centaur Upper Stage) and the RS-25 [1], (the Space Shuttle Main Engine) get around 450-460s for their specific impulse. These engines use liquid hydrogen and liquid oxygen. The issue with liquid hydrogen is twofold: it is not very dense, and to keep it from boiling away in liquid form, it needs to be really cold. So you need huge, insulated tanks to store it. Hydrogen is everywhere, but it's kind of a pain to use as rocket fuel.
Merlin Vacuum [2], which is currently used on the Falcon vehicles gets 311s. The RD-0110 [3], used on the Soyuz gets 326s. These use RP-1, which is highly refined kerosene. It's super easy to work with. On earth. Where we have 200 years of infrastructure in place to support using hydrocarbons. It takes that infrastructure to refine it into a form that rocket engines can use without gunking up the works with unburnt carbon and other particulate crap.
Raptor uses methane, which is kind of like a jack of all trades between density, efficiency, ease of processing, storage, and ease of use in engines. This is basically how SpaceX seems to operate: rather than optimizing a single part of the system (like trying to get the most efficient engine), they try to optimize from a systems level. I don't really know much more than that, because there hasn't really been a lot of stuff for civilians to read on methane engines. This is kind of the cutting edge of the second golden age of space exploration. This freaking rules, what a time to be alive.
[0] https://en.wikipedia.org/wiki/RL10
[1] https://en.wikipedia.org/wiki/RS-25
[2] https://en.wikipedia.org/wiki/Merlin_(rocket_engine_family)
[3] https://en.wikipedia.org/wiki/RD-0110