To clarify for people, this isn't NASA endorsing the idea in as much as NASA just hands out small amounts of money to different ideas in many different science or engineering related spaces.
The fact of the matter is that this concept, if it works, will only launch as much payload into orbit as an Electron rocket (a very small launch vehicle), and would require payloads specially designed for the g-forces which would make them heavier. This launch concept has exchanged fuel mass for heat shield mass to allow it to survive after it leaves the spin system.
Now, one actual use case for this type of technology is if they were to build it on the moon, especially for launching things like mined resources off the surface. The launch forces would be lower as the speed requirements are lower and it would allow launching material with little to no fuel consumption as long as there is electrical power (of which there is near infinite amounts of because of the semi-constant sunlight).
Not contesting but just adding a bit of context, NASA doesn't really just 'hand out' money for the research they conduct. There's a pretty extensive process of running panels and collecting feedback from subject matter experts to select the winning bid for most (not all, of course) of these awards/grants:
What about using it to cheaply send fuel from earth up into LEO? that is, take a fuel tank with some minimal set of RCS, compute and radio for remote control / locator beacon, and some fuel transfer / docking arrangement, and wrap it all in a disposable fairing for launch.
You'd still need to send spacecraft and larger cargo up the old fashioned way, but this would allow you to neatly work around the "your only fuel is what you carry to orbit with you" problem (as long as you carry enough fuel to rendezvous with one of the fuel pods to begin with).
> What about using it to cheaply send fuel from earth up into LEO?
Just to clarify for you here, but this can't actually launch anything directly into LEO. It needs a rocket of some sort, or something in space to "catch" it and complete the orbit. This is why what they're launching in their slingshot isn't a payload, but a small rocket with plentiful heat shielding that will contain the payload to be released. That small rocket still needs to be built every time so it doesn't actually reduce costs that much until there is something in space to "catch" the payloads. Which I am skeptical of the ability to do for Earth orbit given the much larger speed differentials of catching things in LEO.
Also on the cost thing, you have the cost issue inverted and you're trying to solve the wrong problem. The most expensive part of space travel is the whole "throwing away the vehicle after one use" aspect, not the cost of the fuel. SpinLaunch makes the vehicle itself cheaper, but it's still throwing it away.
Aye, I've been thinking these systems could be useful for hoisting dumb mass such as water in particular. Water's good for human consumption, hygiene, conversion to fuel (or ejection mass for electric motors?) and even as radiation shielding.
As here on Earth, it's probably one of the most valuable 'heavy things' we need up there. it's just bloody expensive to get up there. At least until we can start lassoing asteroids... .
This can be done with conventional rockets too, where the payload is fuel to be used by other craft.
I assume there are some reasons this isn't done, like the rocket equation persisting outside of Earth's atmosphere and gravity well, ie. you still have to accelerate the fuel mass if you intend on taking it with you, but taking it from launch obviates the needed complexity to rendezvous with an orbital gas station.
This made me wonder if it's possible to create a terrestrial spaceport which walls out the atmosphere to provide an area for low friction launches and landings. That's probably even more materially impossible than a space elevator would be, though.
A structure to "wall out" the atmosphere would be pretty heavy, and if it existed putting launcher on top would be easier.
https://en.m.wikipedia.org/wiki/Space_fountain of around 20km of height, is rather close to this idea.
Might even make sense in-orbit, for sending probes, further out, giving them initial boost. Wouldn't need to be so powerful either. Just small initial boost could do wonders.
Problem (for both lunar or in orbit idea) is getting the heavy motors off earth.
> (of which there is near infinite amounts of because of the semi-constant sunlight)
Unless you want to launch on the night side of the moon, then you have to wait up to 14 days. But yeah the moon with its lower atmosphere makes a lot of sense.
One wonders how practical this would be given the huge G forces involved, especially so for large complex satellites.
However, electronics have been subjected to such high G forces as far back as WWII but on a much smaller scale when the proximity fuze was introduced towards the end of the War (one of its first uses was at the Battle of the Bulge, Patton waxed lyrically about its high effectiveness): https://en.wikipedia.org/wiki/Proximity_fuze
When I first heard about VT Fuzes years ago I didn't really believe it because it didn't use solid state devices, transistors etc. but rather a 'ruggedized' vacuum tube (this was several years before the transistor was invented in 1947). At the time I couldn't see how glass vacuum tubes could withstand ≈20,000Gs when fired out of a gun barrel but somehow they did.
Therefore, I'd imagine that upgrading to solid state devices would allow an even higher scaling in the G department (i.e.: relative to the VT Fuze), so it seems highly possible (perhaps the SpinLaunch idea actually originated from VT type Fuzes, I'd not be surprised).
I see this as being far more useful to send large quantities of fuel into orbit, and then use that fuel to accelerate to reach the outer planets.
Electronics and such are pretty light, the regular rockets we have are fine for that. This is more for raw material, for example the structural components of a space station.
Maybe it could provide a nice assist to Elon’s batshit insane plan to launch a Starship every four hours for years in order to put a Mars colony worth of supplies into LEO.
Thanks for that video reference. I was aware of much of the history from past interest but I'd not seen that video previously nor had I seen all of that film footage in other WWII docos.
The more I read about US research developments during WWII the more I appreciate the tremendous effectiveness of the US's OSRD (Office of Scientific Research and Development)—the instigation of the Manhattan Project, the huge enhancement of RADAR by the MIT Rad Lab (https://en.wikipedia.org/wiki/MIT_Radiation_Laboratory), the proximity fuze and much other work (as here: https://www.loc.gov/rr/scitech/trs/trsosrd.html), owes a huge amount of success to its science administrator, Vannevar Bush. Whilst Bush is still known amongst technical cognoscenti, it seems to me he ought to be much better known amongst the broader public. Not only was he a top rate scientist and engineer but also a first-rate administrator who got things done. It's very rare that we get someone with such a wide understanding of physical phenomena and engineering expertise in addition to having excellent administrative skills and experience.
It seems to me historians ought to promote Bush up amongst the ranks of the key players who were responsible for the US/Allied victory in WWII. Of course, Bush had much help from other important notables such as Alfred Loomis, Fredrick Terman (father of Silicon Valley and author of one of my textbooks), Henry Stimson, (War Secretary) and many, many others. Nevertheless, there was something unique about this group of individuals which is pretty rare, just about everything they touched worked well and was on time to help the war effort (shame that team isn't around today).
We continue to see many documentaries about military action during the War but they almost never mention anything about the enormous 'backroom' effort made by many, many people and of the remarkable amount of coordination that was necessary between them—unfortunately, they are now mostly forgotten to history. We need to give much more credit to those who made this huge contribution to the War effort—those who not only developed reliable and effective prototypes of new weapons but also who ensured that these weapons were put into production quickly and manufactured in sufficient quantity to effect a successful outcome of the War. Seems to me that the broader historical record ought to be changed and updated to reflect these forgotten facts.
Back to proximity fuzes. I'm still amazed these devices worked as well as they did. To understand why I'm still trying to find out more about their design details. For instance, on the web there are any number of cutaway drawings of the Mark 53 VT fuze together with lots of general descriptions of its operation but I've not found a fully detailed drawing of its circuit (engineering drawings, etc.). Nor have I come across a detailed description of its theory of operation (only general outlines). Nor have I ever seen its detailed specifications.
From various reports of its development, many thousands of test firings were done so where are these test results now (it's hard to believe that they no longer exist)? For instance, what was the sensitivity of the device, that is, what is the nominal distance from an aircraft (of given size) for its thyratron to trigger? There has to be a nomogram of aircraft sizes (or types) versus trigger distances, as this information would have been a vital conclusion from the testing procedures (not to mention also being key operational parameters).
Similarly, there seems to be no detailed description of the dry battery (aka its energizer) which provides the 'delayed-start' power to the device (some published circuits show that it supplies 100 Volts needed to operate the vacuum tubes and this voltage is what we would expect for battery-powered tubes)—but there's nothing about the battery's chemistry or its actual physical construction). To achieve 100 Volts EMF, multiple cells would have had to be involved (joined in series), however this poses a problem and it's never explained. The breaking of a single ampule of electrolyte to start the battery needs more detailed explanation. After breaking, the ampule would have flooded the whole (single) battery compartment which contained the dry battery cells. However, individual cells can never reach more than a few volts each let alone 100 Volts using standard chemistry—electrode potentials forbid such high voltages: https://en.wikipedia.org/wiki/Standard_electrode_potential_(.... So with only one single battery compartment why didn't the electrolyte short out cells as the voltage tried to rise above the nominal voltage potential for a single-cell? (Clearly, the fact that the fuze worked meant that the battery also worked and supplied the high 100V, so some important information is still missing.)
Perhaps this information is readily available and it's just that I've somehow missed it. I can't see any reason for why parts of this information would be still classified after all these decades. Moreover, such info could no longer be classed as a security risk for the simple reason that there is no way that you could get the specialized components for, say, to manufacture a clandestine device (the ruggedized tubes alone were very special and are no longer made).
If anyone knows where this additional info can be found then I think many of us would be interested in seeing it.
__
FYI, here's an aside comment on the strength of normal commercial glass vacuum tubes and vacuum tube glass.
Years ago, I worked in a TV station and there was always ongoing banter and rivalry between the electronic staff (engineers and technicians) and the electrical staff (electricians). Electronics staff looked down on the electricians and considered them clowns, likewise they considered electronics people as overpaid professional wankers (the rivalry didn't descend into animosity, rather it was more like behavior seen between competing football teams). What exacerbated this rivalry was that the electricians had their own building some 20/30 meters from the main building, it not only housed their complete operations but also the station's emergency power source (an ex-WWII submarine diesel engine and a 3-ɸ alternator). In essence, as a group, the electricians were isolated from the rest of the staff which put them slightly apart.
Anyway, some of the more adventurous of the electronics staff (including yours truly) were always up to mischief and one of our inventions was our infamous Valve Gun (Tube Gun for you US-ers). Initially, its invention had nothing to do with the electricians but later we found it a devastatingly effective 'weapon' to use against them. It consisted of a CO2 fire extinguisher with a conical discharge nozzle, two lengths of plastic electrical conduit about 2m in length. One conduit had an internal diameter just sufficient to snugly (but not tightly) fit 7-pin vacuum tubes (6AU6, etc.), similarly the other was for 9-pin tubes (12AT7, etc.). To operate, place a vacuum tube into the conduit at the near (extinguisher) end with base/pins first, couple the conduit into the extinguisher's nozzle until it is a tight fit, aim and then pull the trigger. Not far from us was an old disused quarry that we used as a test firing range, tubes would leave the gun with such velocity that there was no way anyone could ever see them exit the conduit. They'd then immediately disappear many hundreds of meters off into the distance to eventually land somewhere at the bottom of the quarry.
The electricians' building's entrance was through a green wooden door that faced the electronics department and OB garage exit on the main building. Much to our amazement, tubes fired from the garage at the electrician's door would embed themselves in the wood up to the full length of their pins but they would rarely break (after this tortuous ordeal their glass envelopes remained intact and their getter deposits were still a shiny silvery colour which meant their vacuums were still OK). Their internal electrodes, however, would often collapse downward towards the tube's base (to the glass seal area where the pins exit). Surprisingly, the collapse of the internal structure was often limited to only the support wiring that connected the pins in the glass base to the electrodes, that is, top and bottom mica separators, cathode, grids and anode structures often remained intact without any noticeable damage or obvious physical distortion.
This turned out to be more than just stupid antics on our part in that we all were amazed at the G forces that these glass tubes could take before their glass envelopes would break. Unfortunately, we had no simple way of measuring the exit velocity of the tubes but I'd confidently say it was such that if one of those tubes hit one in a vulnerable part of one's body then one could easily have been killed. At that time I was unaware of the history of VT fuzes. If I'd known about them back then, then I'd have taken more interest in the tubes' exit velocity. (In hindsight, we had access to 931A photomultipliers and oscilloscopes, so with a little effort we could have timed the tubes' velocity over a known distance). Perhaps in some minor way our 'gun-tube' experiments add a modicum of weight to the accuracy of the VT fuze story (even if at the time we were oblivious of the fact).
Oh, the electricians: they were only day workers, so we carried out our nefarious work on evening shifts. Suffice to say, they were not amused when they'd arrive in the morning to find a dozen or two vacuum tubes embedded in their front door. They couldn't retaliate either, whilst they could have easily built the gun only we had carefully guarded access to the tube ammo. Incidentally, removing the tubes from the door turned out to be very difficult. They were embedded in the wood so very tightly that they could not be removed by just pulling on them by hand. To remove them we forced screwdrivers under their bases and this was difficult (there being no space between the glass and the door surface). When glass envelopes were broken it mainly happened at this time.
Human bodies are a tiny fraction of the mass footprint of a space mission, and especially a deep space mission. Imagine the cost savings of spinlaunching the pieces of a vessel and supplies into orbit and then being able to launch an astronaut on a rocket the size of a telephone pole.
Like many others I was very skeptical of SpinLaunch's claims. Even with their successful demo launch you wondered if you'd be able to build a viable payload (especially one with a rocket motor, not just solid state electronics).
Though if NASA have chosen to enter into a contract them that gives a big credibility boost. It'll be very interesting to see how it goes.
I think their basic idea is sound, it'll probably eventually function. My concerns are if it'll be worth it, since there's a trade-off being made between fuel mass and heat shield mass, and at least based on Scott Manley's summary video this week, the rocket with the heat shield is close to the same mass as the Electron rocket. In which case I'm not sure the complexity of SpinLaunch is worth it.
NASA can probably trade the tech, if it even barely works, for budget from the Pentagon. This is a ballistic launch system without the tell of a rocket burn.
I haven't seen Scott Manley's video; but if the mass cost of a heatshield is so significant that's a problem.
However, there's a benefit in this case: heat shield probably scales with area (often something like mass^(2/3)), making it progressively less significant compared to fuel mass (which is roughly a constant fraction, i.e. it scales like mass^(1)). I think a high altitude launch site could make a significant difference as well (although that creates other logistic inconveniences). Atmospheric pressure approximately halves every 5km, and air resistance is roughly proportional to pressure.
Building and SpinLaunching at above 10k feet (3km) seems like a no-brainer. It reduces heating and weight while increasing terminal altitude substantially... like 2x.
It would be more efficient, if they could use a whip effect to (match impedance) capture much more of the rotational energy they put into the spin, more like a trebuchet.
It cannot be a coincidence that spinlaunch’s first stage (the spin) is designed to release at a speed equal to trans-earth injection from the lunar surface, and with a total mass equal to what a starship can deliver to the lunar surface. They’re playing the long game.
Very interesting. Maybe you're right! One of the complexities of SpinLaunch is that the centrifuge needs to be inside a vacuum chamber, which just completely disappears if you're launching from the moon.
What's currently worth mining on the moon and sending back to earth? Most resources are great for building more things on the moon, but valuable enough to send back.
Helium-3 is the obvious one, but that is also betting on fusion reactors becoming viable in the near future.
Some "rare earth" minerals might also be economically viable.
Rare, but industrially useful metals (cobalt, lithium, etc.) should be present in localized concentrations of high-grade ore on the lunar surface, along with platinum-group metals. We didn't use to think so, but our understanding of regolith and impact dynamics has come pretty far in the last few years and we now expect that a lot of the small impact craters on the moon asteroid cores that survived and are either dispersed in the crater floor, or for metallic impactors buried a few 10's of meters underground. So basically everything you would go to the asteroid belt to get, you can find on the lunar surface, far more accessible to humans in the decades to come.
But beyond that, the moon will no doubt export large amounts of volatiles from the permanently shadowed craters in the poles, and structural building materials for construction in Earth orbit or elsewhere in cis-lunar space, or the fueling of expeditions to the rest of the solar system. You'd just have to tilt the spin launcher to a different angle and adjust the throw velocity to send payloads on other trajectories through cis-lunar space.
The economics of all of this totally collapses when you can launch 150 tons of whatever fully reusable to earth orbit.
What's cheaper, mining infrastructure on moon, with a launch system on the moon to transport it back to Earth?
Considering you need potentially 100 launches from the moon to match one Starship launch. And the capital cost for the moonining and launch is absurdly high. And the only way we will ever even be able to build such a system will require a Starship type vehicle anyway.
That doesn’t affect the economics (and environmental impact) of mining the moon vs the earth for industrially useful metals.
The actual cost for Starship is unlikely to be the crazy low numbers space nerds like us are hoping for. No space launch system (including Falcon) has ever reached its theoretical minimum cost. It will be transformative, but not too cheap to meter.
By that logic building a mining base on the moon would also be far more expensive. You see how this makes no sense?
We will never build an industrial base on the moon unless we have a full reusable launch system and if we have such a system mining things on earth is just far, far, far, far, far, far cheaper.
The only reason you would mine on the moon is to build things ON THE MOON.
It's quite possible that the expense can be made comparable. Many resources available in the solar system exist in non-oxidized forms that just aren't available on Earth. Mining already reduced, pure metal nuggets is a huge reduction in energy costs and eliminates the need for refining steps with hugely toxic side products. Also have you seen how we mine many resources on Earth? Going to the moon (or near-Earth asteroids) and sifting out nuggets a few meters under the powdery surface regolith is way easier to do than drilling 2 miles underground for increasingly harder to find deposits.
The actual energetic cost of going from the moon to an Earth-capture orbit is only about 1 kwh/kg. Or about $150 per metric ton. Obviously real costs will be higher than physical limits, but you still might want to check your intuitions about just how costly mining the Moon really could be.
Ultimately we need to move our heavy industry off-earth to save our planet's biosphere. In a hundred years when there is a vibrant interplanetary economy, its possible we could eliminate toxic heavy industry on Earth entirely.
The cost from the moon to earth orbit isn't really the issue.
The problem is that to do mining you need a huge industrial base. Mining starts with prospecting. Then you need to develop the resource. You need to refine the resource at least a little. Then you need to mine that resources. Then you need to transport those resources to wherever your cheap launch option is. And then you need to launch it.
Building up such an industrial base on moon is incredibly difficult and would for sure require a massive Starship like rocket at the very minimum.
> Ultimately we need to move our heavy industry off-earth to save our planet's biosphere. In a hundred years when there is a vibrant interplanetary economy, its possible we could eliminate toxic heavy industry on Earth entirely.
Ok, in 100 years, but predicting that far ahead is pretty much useless. My point is that for any foreseeable future launching resource from earth is far more practical.
And from a money perspective it might never make sense, specially from the moon.
If its about the environment, then maybe but then you might capture asteroids instead.
Water, Oxygen, Hydrogen, possibly aluminium. Not to send back to Earth, but into Earth orbit to use as consumables and fuel. And these bulk materials aren’t going to be bothered by G forces.
> Though if NASA have chosen to enter into a contract them that gives a big credibility boost. It'll be very interesting to see how it goes.
NASA also funded experiments into the microwave engine thing [1], and that turned out to be bunk [2].
The point is, these are just tests. They give them a fair shake and see what happens. I highly suspect there are simply too many problems with flinging stuff into space for it to be practical.
Plus the soul of NASA is innovating material and techniques for doing what can't yet be done -- even attempting the plainly impossible is likely to give engineers a fair shot at inventing something novel just trying to make it work.
Launch conditions are already very harsh. Rockets vibrate a lot.
I have no doubt that useful payloads could be designed to withstand the spinning as well as later rocket thrusts. (source: a couple of years on a satellite design project in university)
One other detail I've learned is that the G load increase is incremental, not all at once. Which apparently is very significant according to the company.
OK, so my knowledge of physics is lacking, but wouldn't the decrease of non-centrifugal G-load also be a bit slow as it takes the atmosphere some time to slow down the speed of the projectile?
The radial load/unloading is (approximately) instantaneous at the moment of release and does not vary in proportion to wind resistance.
Edit: this is, btw- fixable. Like other commenters mentioned, a trebuchet/sling like release mechanism would slow that radial unloading and reduce stress on the spinning arm too. It’s a lot more complicated to achieve though (as if this prototype/trial weren’t complicated enough!)
During spin-up the lateral force on the projectile increases slowly until it reaches maximum. When it's released, this load disappears almost instantaneously and the object is effectively in free-fall ... effectively 0g.
Then it hits the atmosphere and is subjected to significant drag, but that onset is reasonably slow (by some metric) compared with the release mentioned above, but it's along a different axis. What's more, the projectile has spin along its long axis ... I don't know how that's imparted.
Yeah, there are some huge forces that change rapidly in lots of directions.
"Busted" videos like this are low quality armchair analysis aimed at giving giving the viewer a sense of intellectual superiority. Saying "this solution breaks the laws of physics" can be valid if analysis is done correctly, saying "this problem is hard, and they haven't already solved every single piece of it so their whole business is stupid" is not valid.
I agree with you that the video could be more detailed on some of the technical analysis. However it raises enough technical arguments, to justify any approach to SpinLaunch to be done in private and with a very skeptical attitude.
Only thing NASA seems to have contracted the company for is for a technology demonstrator, of throwing a small rocket at Mach 2.
The article describes it like they are throwing satellites into orbit. In reality even the far fetched plan, is to throw a small rocket into high altitude to save money on the first stage. Then the rocket is what will put the satellite in orbit.
I can't find a single reference to this agreement (yet) in any NASA official site. Not saying it's not real, just that I can't find an official NASA reference yet. It's not yet listed here under the current available ongoing agreements:
Here's the thing: If you built something like Quicklaunch instead (https://en.wikipedia.org/wiki/Quicklaunch), your g forces would already be an order of magnitude lower. So the question is, why not do that instead?
They could have lowered the g forces by having a longer arm, they essentially picked the g forces as acceptable and then designed the system around that constraint.
As to why not use a gun, barrel damage is probably a deal killer for Quicklaunch and other such designs. Quickly spinning something in a vacuum and letting go should allow for launches roughly as fast as you can pull vacuum. Supporting something like a Starlink constellation seems possible with their design which could be incredibly profitable.
Starlinks are pizzabox-shaped. That's a terrible shape to launch unless you have a stack of them, and this won't be able to launch a stack of them.
As for barrel wear...it's possible that that would be higher than for a normal gun, but I'm pretty sure that the rather famous author of that design took that into consideration. (It doesn't seem like SpinLaunch's design is immune to firing wear either, considering the sudden rush of air into a space with hypersonic machinery in motion.)
You can have a door close behind the projectile to limit the amount of air that gets into the main chamber. I suspect spin launch to include that simply to reduce the amount of vacuum pumping needed. The idea showed up on one of the early space gun designs for similar reasons.
Starlink’s shape is optimized for it’s launch system, while I doubt spaceX is going to use a competitor anytime soon they would seriously consider sufficient cost savings.
You can reach somewhat higher accelerations by making the center of the rotor thicker than the periphery, but you start getting into ridiculous ratios pretty quickly.
I don't think Quicklaunch would have to suffer significant barrel damage, maybe some fouling that can be cleaned off. The pressures and temperatures required are pretty low, and the required chemistries are pretty tame; it's just the velocities that are high.
The g forces are from rotation not how fast you spin up. To take it to the extreme an arm that’s slightly longer than the radius of the earth for sometime moving at Mach 22ish hits ~1g, because that’s orbit. Hitting Mach 22 or even Mach 10 on an arm that’s 500m means vastly higher g-forces.
And how long is the arm supposed to be in the intended orbital system? Because if you want a 500m arm, you literally have a millions-of-cubic-meters-sized vacuum chamber -- and not only that, you have a vacuum chamber with a highly disadvantageous shape (a flat disc). That sounds like a mildly insane design to me.
Submerging the gun barrel in the ocean presents huge engineering and maintenance challenges. It's not impossible but building anything underwater is extremely expensive. And then you have to deal with currents, corrosion, storms, leaks. People who aren't experienced in marine engineering tend to drastically underestimate the costs.
One thing I was thinking about some time ago was that if you wanted such infrastructure while still being able to adjust azimuth and elevation, perhaps an artificial lake would work? At the very least you avoid salt water this way. Of course at that point you can't pick and choose your launch site after the fact, but that's not a regression compared to stationary launch pads anyway.
Just watched this video. His argument for why Spinlaunch won't work is basically:
1) in the video of their first test chamber (12m diameter) there's some dirt and rust, therefore they don't know anything about vacuums
2) in their first ever test fire of a projectile leaving their 33m chamber, the projectile is wobbling, therefore they don't know anything
3) in a mock up video they made of a future launch system the headquarters is close to the launcher, which might explode if there's a misfire, therefore they don't know anything
4) the founder has an uninspiring resume when you look online
'Add these up and there's no chance they'll succeed. What they've done isn't as impressive as 50+ year old gunships.'
Give me a break. Their rate of progress is exceptional. They've already overcome so many challenges. These are weak arguments. Doesn't mean they'll be successful. But these arguments are weak. Some quick counter-arguments
1-) the 12m test chamber was a demo chamber. they were constantly spinning it up and letting people go inside. doing tours. stress testing new materials and arms. blowing stuff up. if anything the fact that it was so reliable even with the imperfections is a positive
2-) when someone is learning to throw a football there's tons of wobble. spinlaunch needs to figure out a perfect spiral. these videos were from their first couple attempts ever out of a chamber. what they're showing is very hard. this team has shown an ability to innovate and improve. those were images of their first few attempts to "throw the football"
3-) give the team some credit. these videos are designed for the general public. what they built already has an incredible amount of kinetic energy. they stress tested many tethers (past their limits) before going to this scale. when you're picking on things as small as "they're going to kill themselves by sitting right next to the system" you clearly don't have much left to nitpick
4-) jonathan is an absolute genius. just because he has a spartan online bio and unorthodox background doesn't mean he's not an absolute force of nature. thunderf00t is a very smart dude. but i'd bet anything that in a debate -- on basically any topic -- jonathan would absolutely decimate thunderf00t
The last video I watched of his was a debunking of flat earthers that was so bad it almost gave the flat earthers some credibility. Many of his 'debunkings' consisted of 'no, because science that's why' where the flat earthers had actually raised interesting questions where the answers provide a great jumping off point to explore things in more depth.
Taking ten years to come up with some simple experiments to debunk someone who is reasonably frequently publicly wrong and then labouring the point and being really condescending isn't a sign of someone being especially smart (although it's hardly stupidity either).
Its the typical build credibilty with debunking total nonsense and then use that to generate views on videos where he is suposidly depunking a lot more viable stuff.
Combine that with serving on the Anti-Musl wave and you have surefire way to be reddit famous.
Smart people make mistakes all the time. He has correctly debunked a lot of scams, it is easy to get jaded and carried away. Since he isn't an investor and doesn't have the inside scoop it is plain to see how his nitpicking, based on the publicly available information, potentially led him to a wrong conclusion.
SpinLaunch is a rather out there. I've actually had this idea and I'm sure many others have as well. I happen to think it can work but I was still skeptical when I first heard of them. You can only infer so much from the outside.
Thanks for the additional info blackholesRhot and for throwing money into this, the sort of bets we should be making. Godspeed. :)
The only thing that’s valid (and I didn’t really understand if the video maker understood it bc he wastes so much time on the wobble) is that if you spin sth up to, say, 200 /s, then your rocket will spin, with its full length, at 200 /s. I don’t know how they want to address that.
I clearly see their rocket rotate around its center of gravity, with the same angular velocity as the arm it's sitting on, while the center of gravity is moving on a circular path.
So, again, how is it not spinning? Where does the angular momentum go?
No, the better question is where it came from. The launcher spins the payload like a bucket on a rope. So upon exiting the launcher it isn't spinning. But by setting the guide vanes at a slight angle the payload can be made to spin to give it more stability (since this is essentially unpowered flight for the first bit) and it can be de-spun in the same way.
The launcher does not spin the payload around the long axis.
I can tell you exactly where it came from, it's being spun up in that launcher thing, obviously, that's the whole point of spin launch. You can see it for yourself in the video. Is the pointy end of the rocket always facing in the same direction, e.g. upwards? No, it's changing its orientation continuously, it's always facing 90 degrees from the arm of the launcher, which, you guessed it, spins.
It is indeed exactly like a bucket. And the bucket changes its orientation throughout you spinning it, that's the whole thing, that's why the water stays inside. The top side of the bucket is always facing you. For that to happen, it has to rotate around its COG with the same rate it's rotating around.
A different example: the moon is tidally locked to the earth (like the bucket to you, or the rocket to the spin launcher) - very obviously, it needs to spin around its axis to achieve that, and it does so at exactly the same rate as it is rotating around the earth.
SpinLaunch's website claims: "To date, we’ve conducted tests over 6x the speed of sound."
However, that doesn't seem possible because the centrifuge is not in a decent vacuum (as Thunderf00t points out in his second video) due to the whooshing sound of the centrifuge 'blade', and the speed can be estimated as just less than the speed of sound. If they have the ability to do hypersonic tests already, why would they not show it in their promotional video?
The fact that they intentionally blurred the data on the screens during the demo is also odd.
---
Regarding your final point, it's much easier to pretend to be a genius than to actually be one; Elon Musk is a master at it. Additionally, debating skill is a very misleading measure of intelligence.
I really hope NASA is making better use of taxpayer dollars than paying their decision-makers to watch clickbait trash on Youtube. How any serious person could take this sort of thing seriously is beyond me.
I have years ago stopped watching his videos. He has long ago discredited himself and should not be promoted.
He should improve his video making skill beyond 2003 and stop making insulting people a core part of his message.
I have no interested in addressing his arguments, whatever they are on SpinLaunch. And I don't want to defend SpinLaunch anyway as it is terrible idea.
I think you are taking him too seriously and being maybe being a bit harsh. He is a mix of John Oliver and Johnathan Colbert with a bit of more precise shades of Veritasium.
He is primarily producing entertainment, and there is no harm in that. But he does it with a correct scientific background and some humorist tones not everybody appreciates. It's not a purely scientific channel, sometimes he get's some things wrongs, mostly on his opinions about the economics of projects.
The only thing I found too many, easily dismissing in this thread, is that when he makes one these busted videos he is also daring to make a statement and they are not random ramblings.
For example his first video of SpinLaunch, if you ignore the tone is a much better analysis than the one from Scott Manley, even if Scott Manley is a much better source for anything else related to Space.
Can you point me one of those egregious errors he made? Because I looked at this whole thread out of curiosity, and every single commentator criticizing him, did not provide a single concrete example.
It's a new genre...Scientific Entertainment ( bit still scientific) Not sure everything in this short life of ours, needs to be taken so seriously:-)
His fans believe any video by him is the god given be all and and all statement on any topic.
He employs a large number dishonest lines of arguments. Drawing large conclusions for limited unrepresentative data. Not actually fairly representing the things he is arguing about. What he does is build narratives to lead viewers to the conclusion he want them to reach.
> Can you point me one of those egregious errors he made? Because I looked at this whole thread out of curiosity, and every single commentator criticizing him, did not provide a single concrete example.
I have not one of his videos in a long time. I remember watching his videos on Falcon 0 and struck by him clearly have no understanding of the issues with his driving goal seeming to be to gather all possible evidence and building a 'Busted' narrative while ignoring any evidence that points into another direction.
In general, looking at his videos he seems to have made a career out of calling Musk an idiot. To be fair their are a lot of low equally low quality channels that made a career out of calling Musk a genius but those are equally stupid.
He even attacks some of those channels in his own videos, but its very telling that those are the kinds of channels he interacts with. Because that the level he is playing at.
> It's a new genre...Scientific Entertainment ( bit still scientific) Not sure everything in this short life of ours, needs to be taken so seriously:-)
You don't have to be serious but I very much get the vibe that he thinks he is very serious and his fans think he is very serious as well. A also think he is deeply unfunny and his videos are pure cringe to watch. Somehow he is a genius who knows everything about everything and yet his videos production quality is worse then a 8 year old on Instagram.
His channel is the kind of channel that is designed around making online interactions worse for any topic, not better.
This is the kind of video that I find actually helpful:
As Kerbal Space Program has taught me, it’s all very well reaching ballistic apogee but you need to apply thrust again at apogee to circularize orbit (raise your perigee to the same altitude as you are right now.) Otherwise you’ll just come straight back down again.
How can this device fling a functioning rocket motor into space?
Rockets already have to withstand some pretty extreme structural challenges. The spinning would certainly involve a bit of a different challenge but not necessarily out of scale for things they already have to survive.
I think launch angle can be adjusted, it's just straight up for the photo. Eg, see the rendering further down the page on the grassy hill which shoots at an oblique angle.
Your periapsis — the lowest part of your orbit — is always the place you return to. Throwing harder or at a different angle just determines how high you get when at your highest point, before coming all the way back down again.
This isn't the case at all. The trap your reasoning falls into is assuming that for some reason an object must be in an orbit after being thrown. Obviously, an orbit comes back to it's original position at some point. In many cases atmospheric drag converts what would be an orbit into burning up in the atmospheric or smashing into the ocean somewhere.
But if you throw something hard enough from the Earth's surface, it absolutely does not have to return to that position. You would just need to throw it hard enough that it was at escape velocity. Due to air friction, the actual speed you would need to throw the object would be flat out absurd if on Earth at sea level. But on a body like the moon with no atmosphere it isn't that bad at all. The bonus to this is the direction doesn't matter at all really. Anything other than straight down is fine.
Now, where this does become problematic is when the velocity you would need to achieve is higher than the speed of light. At that point you're basically on a neutron star or some supermassive planet.
> Now, where this does become problematic is when the velocity you would need to achieve is higher than the speed of light.
Isn’t this sort of a definition of a black hole? My non-physicist intuition tells me a neutron star can’t have an escape velocity higher than the speed of light, otherwise the light wouldn’t escape
We're not talking about escape velocity though. (And if we're going to nitpick, even on an escape trajectory, the launch point is still on the hyperbola.)
If NASA had plans for a moon base, and also had plans to send things back from there, this might become an interesting launch capability - no atmosphere and lower escape velocity provides more flexibility. Run it with stored solar power and it’s self contained and needs no expendable supplies
The interesting thing about this technology, is that it's a way to bypass the rocket equation - in theory at least. There are a lot of practical objections, not the least of which is the fact that they've had to add so much heat shielding that it cancels out the gains of not needing to take so much propellant. But maybe they can work around that at some point.
The practical problems make me skeptical, but the potential advantages make me hopeful. To all the skeptics out there : remember that people were also skeptical when SpaceX said they wanted to land their rockets, yet here we are.
“People who say it cannot be done, should not interrupt those who are doing it.” - George Bernard Shaw
It "bypasses" it by reducing the amount of fuel needed at the start, which (via the rocket equation) means substantially less fuel that needs to be carried.
Those kind of speeds are common at altitude, in the upper atmosphere.
The drag and resulting heat production at sea level would not be as easy to deal with if you were zipping along at Mach 25 right after launch. Even supersonic aircraft don't run full speed (for a whole host of reasons) at sea level.
The Sprint missile could hit mach 10 from sea level in 5 seconds. But I think by the time it got that fast it would already have considerable altitude.
Yeah, Spinlaunch is going to dump a lot of energy into the lower atmosphere, shed its glowing white hot shell, and then need get enough deltaV to put up a payload.
Anyway, the earliest patent I could find was a steam centripetal launcher in 1918. It never went anywhere and it has been followed by a number of improbable reinventions that all faded away.
NASA and the US Army tried again in 1982 and thought they could put a 60g projectile down range at 3 km/s. Mach 8. Guns and rockets could perform as well or better with simpler systems and the idea was shelved.
I hadn't read much about that missile before now, but apparently it got so hot it required an ablative coating just to survive it's very short intercept mission.
He...encourages caution. It's one thing to call a technology "debunked", another to say it's very difficult or that it has a low probability of success.
Thunderf00t is not a credible source, even if he's right sometimes, it's in the "a broken clock is right twice a day" sense. So these aren't good videos.
He is a scientist with published papers, and he seems to have a decent understanding of physics.
Obviously scientists are not perfect, but you seem to imply that most of his videos are incorrect. I can't see any evidence to support that, but I'm happy to be contradicted.
Its a collosally impractical idea for many reasons, but I'll give the simplest one
Whatever rotating mechanism (call it flywheel) they have needs to be charged up with rotational energy to launch. The amount of energy remaining in it after the projectile gets launched is the fraction M/(M+m) where M is the flywheel mass and m is the mass of the projectile.
Now you see the problem (if you have any physics instinct)
If you dont want a sudden shift in the center of rotation (going off balance) then you need the flywheel mass to be high. But the higher the flywheel mass, the more amount of energy left "wasted" as it spins to a halt in the de-evacuated atmosphere.
Bearings can handle some amount of jerking and some amount of imbalance in most applications.
But here there is massive centrifugal pull of the imbalanced flywheel, the instantaneous jerk as the rotational center shifts after launch, shock wave of the instantaneous rushing in of air into the vacuum (speed of sound), the massive heating up of the whole structure, the precession that may be induced by turbulence etc.
This will most likely destroy the whole shebang in seconds, if not make it completely unusable a second time.
Slingshots work only because the sling has negligible mass compared to the stones that are launched.
This comic book idea dreamed by by some non-engineer is just going to eat up investor money and lots of precision machined equipment
Perhaps NASA is backing this because they think there’s a good chance that at some point the launch facility will experience a RUD and they really want to be there to watch.
Coolest part of this company is the founder is a (i think high school) drop out who read some physics books and thought "this should work." Have spent some time with Jonathan on MajikBus.co and I appreciate the way his mind works.
I guess that's not too bad, but still wonder how difficult it is to reliably achieve a precise launch angle?
Or are sensors so fast these days that this is easy? Maybe this is just a misplaced instinct from my subconscious fear of stuff hitting me in the head when kids inevitably start playing with centripetal motion using heavy objects.
At 12 m diameter it would be 82000 gees, eight times the acceleration they're targeting; their render is of a roughly 100-meter-diameter chamber. At 82000 gees rotor integrity becomes probably unmanageable with existing materials. At 100 meters we're talking 420 rpm, 22 radians per second.
I don't think the launch angle needs to be precise; if it's off by 10 degrees (175 milliradians) they lose 1.6% of their altitude to cosine error. That would be an error of plus or minus 8 milliseconds, which seems about two orders of magnitude on the easy side of achievable.
Well, a low orbit is 18,000 miles per hour. This system wants to use 5000 miles per hour in their test of tech. That still leaves 13,000 miles per hour delta V, plus atmospheric drag will slow it until the rocket fires. Might be good to build this in Bhutan or another place with flat land over 12,000 feet high = far lower drag to launch. This is a test at 5000 = next 10,000 - how far can the strength of materials go when spinning at these rates?
And if they can do both, spin at 10,000 mph+ as well as launch from Bhutan/Hawaii/Chile - it is worth exploring.
If they can get this working reliably on Earth then I would imagine it would work incredibly well in space. Could do (cargo) launches from the Moon to Earth with just energy from solar panels without any propellant. Probably would be the optimal way to put a ton of satellites in orbit of the Sun too for something like a Dyson Sphere.
Conservation of (angular) momentum would mean that you'll need at least some amount of propellant to compensate. The rotational inertia that's present during/after spinup can pose challenges for aiming as well.
I have to admit I know nothing of launching stuff into space. Whilst that's interesting my first thought on watching their video was comparing it to a railgun. No payload just a solid projectile at high speed. I don't know the viability of that but it seems like a logic other usecase.
Rather than a spin system with all that g force, i would have thought it more useful if an electric rail gun was used along a very long track in a helium filled tube that swept up a at a modest rate at the end to get the angle.
I've thought this through and I think the Gerald Bull supergun HARP/Project Babylon approach is more cost-effective.
8000km/hour is 2200m/s. Reaching 2200m/s at only 10000 gees takes 23 milliseconds, which is only 25 meters if you're traveling in a straight line. So you might be able to do this with, say, a 2-meter-diameter by 25-meter-long supergun, with a total volume of 79 cubic meters, which you might want to dig into the ground to reduce the risk of explosion. Accelerating a 200 kg launch vehicle at 10000 gees takes 20 meganewtons; over a 2-meter-diameter area that's about 6 megapascals of gas pressure, which is only 900 psi, eminently achievable with a light gas like hydrogen (the SHARP gun reached 3km/s). Then it's just a matter of timing the gas release through different ports as the launch vehicle moves through the barrel, a problem that's enormously easier now than in the 01960s with HARP or in 01918 when the Germans solved it for the Paris Gun.
The vehicle itself doesn't have to be 2 meters in diameter, and shouldn't be; an APDS-like approach with a lightweight sabot that fragments upon exit from the barrel gives your launch vehicle better power to penetrate the atmosphere.
Contrast that with a centrifugal launcher like the SpinLaunch design. For the centripetal acceleration to be only 10000 gees at 2200 m/s, the radius of the spinning arm needs to be 49 meters, which means its diameter is 98 meters, four times the length of the supergun. It's a building the size of a city block! But turned up on its side, vertically, so it's 40 stories tall. Its total cross-sectional area is 7700 square meters. You probably have to evacuate the interior so air resistance doesn't melt your rotor, since its outer edge is spinning at Mach 6.7. (This is the "300-foot diameter steel vacuum chamber" mentioned in the article). Even if you can make it only 100 mm thick over most of its area, it's 770 cubic meters, about an order of magnitude more volume than the supergun, and that entire huge area has to be leakproof, which makes it expensive (though admittedly it only has to withstand one atmosphere of pressure, not 60 like the supergun barrel).
From appearances their test launch facility is only about 7 stories tall, so only about 20 m, and they say they're only doing launches at about 450 m/s, which would work out to about 2000 gees by the same math. But it also looks like it's about 3 m thick, 30 times more volume (per unit area) than I described above: 20000 cubic meters at full scale.
The usual problem with centrifugal weapon systems doesn't apply here, though: you don't need to aim your launch vehicle precisely at a target to milliradian precision, you just need to hit the exit port instead of the solid launch-chamber wall. (The enormously larger radius also means you're spinning at many fewer radians per second.) And the free breaking length of carbon fiber is 400 km at one gee, and thus 40 m at 10,000 gees, and the outer part of the rotor can be thinner than the inner part, which is also under proportionally lower acceleration, and there are another half dozen materials with free breaking lengths over 150 km, so a 49 m rotor that spins at this speed is straightforwardly achievable. So I think the SpinLaunch approach will work if they spend enough money on it. I'm not a SneerClubber, I'm not here to sneer.
(Realistically the most likely way for centrifugal space launch to happen is that NASA will cut their funding before they can do their first launch, and ten years later China will build a working centrifugal launcher, because building new things is not really a thing people do in the US anymore.)
But if you're willing to evacuate 20000 cubic meters to launch your vehicle at 2200 m/s, you could drill your supergun barrel down through 6 km of rock, dropping the necessary acceleration to only 42 gees. That would enormously simplify the design of the launch vehicle, though it still wouldn't allow crewed spaceflight.
These definitely seem like they would be really good as like a return system from mars to earth… like factories ok mars could use this to probably launch materials back to earth
With these sorts of technologies I wonder if it just makes more sense to lay whatever needs to be paid to build a space elevator or equivalent and be done with it.
What makes you think the problem is money and not materials science? We have no substance suitable for the cable. The closest we've come is various nanofilaments that we can perhaps produce in centimeters, not kilometers.
I recall excitement that https://en.m.wikipedia.org/wiki/Colossal_carbon_tube were just the ticket. But since there has been zilch published on them in the last 14 years, I'm guessing the original work couldn't be reproduced.
I agree that the problem is materials science. My point is how much money is actually being allocated towards that vs sending stuff in space, to what end?
I don’t follow material science stuff super closely but as far as I’m aware the investment is orders of magnitude less than propulsion and other tech.
Then again these things just take time unfortunately
10,000Gs is probably too much for electronics, but fine for raw steel. Probably useful to have a low cost way of shooting a lot of working material into space.
The problem with this is if you toss a chunk of raw steel, no matter how fast or at what angle, it will always simply fall back down [1]. The minimum payload for this system absolutely requires a (extremely robust) rocket engine and propellant and avionics to circularize the orbit at apogee. That's the only way to achieve orbit. That puts a disappointingly high floor on the cost per launch and launch rate.
[1] Technically, escape velocity is also a possibility. But it's not a useful one, as the payload is still lost.
That only holds true assuming a 2-body (earth and rocket) system - add in forces from the sun or from the moon and you can actually achieve orbit with only a single surface level impulse, although it does require some pretty precise aim.
It would be super cool to use the moon to circularize the orbit. But the orbit you'd get wouldn't be super useful, probably. I wonder about stability as well. And the practicality of achieving the velocity to reach that high, and aiming that precisely. It would be really cool to see some analysis of that.
Another out-there idea would be to shoot things at a space station that had a giant catcher's mitt or something. Would it be possible to design a decelerator that would work? And to hit it precisely with a dumb projectile from the ground?
A third possibility would be to recover and reuse the rocket engines en masse. Not sure how it could be done in a way that was cost effective though.
> But the company says it'll be appropriate for smaller launch vehicles weighing up to about 440 lb (200 kg)
In this particular configuration, the rotational kinetic energy for a 200kg load would be massive and the current materials would not be able to withstand it and another issue would be the release timing through the opening, as seen on the video the margin of error would be so narrow that is likely not possible with the current technology. I hope I am proven wrong in my armchair assessment though.
I agree the entire thing sounds completely impractical and even if it can be made to work reliably, the number of suitable payloads would seem to be tiny. Maybe you could launch a 200kg billet of solid aluminum or titanium or other raw materials that could be used in space for manufacturing of components for a space station or Mars transport vehicle?
>In this particular configuration, the rotational kinetic energy for a 200kg load would be massive and the current materials would not be able to withstand it
Got any numbers or facts to back this assertion up?
I haven't investigated the mechanics behind spin launch, so I'm eager to see something concrete.
Just for giggles, that works out to ~17.42 kilowatt-hours per kilogram of mass, just for the pure kinetic energy. Then you have inefficiencies like electricty-to-kinetic-energy conversion losses and atmospheric drag to contend with.
It's honestly a smaller number than I expected it to be. So I suspect that those inefficiencies add up pretty fast.
It would still need a rocket to prevent the waste from coming back around and striking the launch site. To not have it come back, it'd need to be shot out at Earth escape velocity (there's also the option of shooting it out fast enough for the Moon to offer an assist to put things into orbit).
Although of course that fast of a throw from within the atmosphere is probably not practical.
The fact of the matter is that this concept, if it works, will only launch as much payload into orbit as an Electron rocket (a very small launch vehicle), and would require payloads specially designed for the g-forces which would make them heavier. This launch concept has exchanged fuel mass for heat shield mass to allow it to survive after it leaves the spin system.
Now, one actual use case for this type of technology is if they were to build it on the moon, especially for launching things like mined resources off the surface. The launch forces would be lower as the speed requirements are lower and it would allow launching material with little to no fuel consumption as long as there is electrical power (of which there is near infinite amounts of because of the semi-constant sunlight).