It's important to not simply look at the total cost figure vs. the likely final results when comparing projects, but also what technologies you'll be developing to achieve said results - because, apart from things like pouring concrete and such, that's where the money goes. For example, there's a lot of people here who hate ITER and see it as a waste of money. But regardless of whether or not tokamak fusion eventually becomes economically viable, the work on superconducting magnets that's been spawned because of ITER is going to be of immense value. In particular, while the ITER design isn't going to use them because it's too far along (DEMO might), new high temperature superconducting tapes have made magnets that are much more powerful and energy efficient - and at the same time likely cheaper in bulk production, and cheaper to operate - a reality. Which obviously has huge implications everywhere from medicine to spaceflight. The size (and thus cost) of many technologies corresponds directly with the strength of the economically-achievable magnetic field.
When a project is expensive, it's good to ask why it's expensive. Is it expensive because you're pouring a lot of concrete / buying a lot of some raw material / doing research that only pertains to the given project, or because you have a lot of scientists' salaries going toward developing enabling technologies that also have significant applications elsewhere? And if so, how valuable are those technologies in addition to the main project?
It's not an easy assessment to make, but an important one.
Hmm, I replied to this, but I can no longer find my reply. That statement was based on a propellant loading timeline posted at NASA Spaceflight; if the timeline was incorrect then that would indeed change the picture, and suggest for example a common bulkhead failure (although that would raise the question of why). Alternatively combustables on the outside (a leak, for example) could ignite with liquified air / LOX coming off of the outside of the LOX tank (unlike boiling point LOX, superchilled LOX can liquefy air and/or just the oxygen fraction on the rocket's skin). But in that case I'd expect the explosion to begin further down the stage.
It's trickier than that. They were loading LOX. There was no RP1 in the upper stage yet. So why did the LOX explode?
I've read a fair bit on LOX handling, and while it's tamer than, say, HTP, there are some risks in handling it. The biggest one is contamination - which has taken down craft in the past. Most notably, the X-1A and X-1D were taken down by a contamination from a chemical used in the manufacture of their gaskets. Most organics are incompatible with LOX and become contact sensitive, including - wait for it - tending to be set off by pressure changes.
Another issue is the tank itself. LOX is compatible with most aluminum alloys, hence aluminum is frequently used for LOX tankage. However, there are some caveats. One, it must be well cleaned in a proscribed manner, due to the aforementioned contamination issues. Furthermore, it must have an intact oxide layer. If the oxide layer is damaged (bending, stretching, shearing, overaggressive cleaning) or never formed, it must be exposed to atmospheric air and allowed to reform; it begins reforming immediately but takes about three days to reach maximum thickness (slowing with time). Bare aluminum is still not hypergolic, but it is impact sensitive with LOX. It can also be set off by the same phenomenon that damages the tank - for example, heavy warping, which can create localized hot spots.
Contamination is generally considered more of a concern, however (particularly since SpaceX uses aluminum-lithium, which is more resistant to impact/pressure-induced explosion with LOX than non-lithium alloys). That said, regardless of what causes the initial burn, if temperatures are high enough, the aluminum will burn, and it burns very aggressively. Indeed, it was the addition of aluminum powder that revolutionized solid rocket propellants (powdered to make it easier to ignite and burn completely, as well as to blend), giving them a major simultaneous improvement in ISP, thrust, propellant density, and burn quality. Aluminum has such a high affinity for oxygen that it also burns in CO2 and water, stripping the oxygen from them. The general way firefighters put out large aluminum fires is.... they don't.
All of that said, these sort of problems are rare. Which makes one wonder about the unusual factor in SpaceX's case: densified/superchilled propellants. SpaceX is the only major launcher to use them, and the behavior of superchilled LOX isn't anywhere near as well studied as that of LOX at its boiling point. It changes what may liquify or freeze in contact with it, it changes the flexibility or fracture properties of physical components on contact with it, it has a higher viscosity, etc. Things that freeze into it could melt/boil as the LOX warms up as well. So it obviously draws the question, is this problem a result of the use of superchilled LOX, some unanticipated effect in the production / storage / delivery system that led to problems within the tank, or an unexpected reaction within the tank itself?
Will anyone read the actual tweets? This summary is one of the worst I've seen on Slashdot in a long time. Musk asked Twitter for pictures and videos, not to "find the cause of the explosion". They're trying to figure out whether a particular sound came from the rocket or elsewhere. The summary makes it sound like - as you put it - they're inviting arm char scientists to solve the issue for them.
It would have been nice if the summary had mentioned what specifically he asked for, rather than including everything but what he asked for. They make it sound like he asked Twitter to solve the problem. What he actually asked twitter for was any photos or videos of the event that anyone may have:
Please email any recordings of the event to report@spacex.com.
If you have audio, photos or videos of our anomaly last week, please send to report@spacex.com. Material may be useful for investigation
The connection with the "bang" is precisely what he wrote immediately after the first tweet:
Particularly trying to understand the quieter bang sound a few seconds before the fireball goes off. May come from rocket or something else.
If they have more videos, they can triangulate the location of the sound and determine whether it came from the rocket or elsewhere.
Musk did Not just go on Twitter and say "Well, we're baffled - go on, Twitter, figure out why it exploded for us!" like the summary makes it sound.
To move everything down a dimension: picture a balloon that started as an infinitesimally small point and expanded from there. You're a dot on the surface. There are other dots, all drifting around in random directions. The balloon keeps inflating. You may still get closer to certain ones because of your relative motion, but overall everything is moving further apart.
Which dot on the surface is "the centre"? None of them. Every direction you look you see other dots. They're's no particular structural bias - they're anisotropic. They all see the same pattern.
We are of course, not a 2d surface inflated in 3 space, where the radial dimension represents inflation - and, within certain constraints and nonlinear scaling relative to the other dimensions, time. We can be correspondinly be seen as a 3d surface inflated in 4 space (or higher).
First off, there was no fire. Secondly, what the kind of rescue service doesn't have a class C fire extinguisher? What do they do if a car crashes into a power pole?
Regardles, my reaction to this article is "Slow News Day". Basically:
"Man Dies In Car Crash. Details at 11."
Or...
"Car with high voltage battery pack crashes." Because clearly that's never happened before. And crashed cars full of gasoline are totally safe environments for rescuers.
Seriously, do they not train rescue workers? If so then why don't they train them to respond to electric and hybrid vehicle crashes so that they know what's safe and what's not? It's their job, they should know what the heck they're doing.
Rescue workers are supposed to assume that every vehicle is a hybrid or electric until proven otherwise. Badging and identifying details can be damaged in a crash, and many vehicles come in similar electric/or hybrid and gasoline versions. It's not just about high voltages. There are many things that disconnect the HV system, and one of them is crash sensors. But a problem with hybrids or EVs is that the vehicle may still be "running", but without the noise of a running gasoline engine. Hence immobilizing the vehicle - both turning it off, and clipping or removing the 12V system - is one of the first steps. A vehicle that is still energized could, for example, unexpectedly deploy an undeployed airbag.
All high voltage components are brightly marked. Again, by default a vehicle will disable its battery pack in a crash. Nonetheless, you never cut a bright-colored cable. The concept of having to avoid cutting certain areas should be nothing new to a rescuer, because it's also dangerous to cut other parts of a vehicle, such as airbags (side curtain airbags in particular are vulnerable to being cut) or the fuel tank. A rescue worker is supposed to have an idea of where things are. And speaking of "where things are", if they know where the HV pack is, they can throw the switch. All HV packs have a switch to shut them off for maintenance.
Right. Because "Transportation" equals "Telepathy" and "Perpetual Motion". Got it.
If you're a big fan of arguing about things that you don't even know the basics about, go ahead. But you're only going to make yourself look like an idiot.
Don't get me wrong, I do support the eventual expansion of the human species into space. I think it's an important goal to have on the horizon. What I don't support is the concept that it must be done "soon", at the sort of prices that today's missions cost. And I strongly oppose attempts to justify the cost with "science". ISS, for example, at $150B is the most expensive structure ever made. Yes, it absolutely has returned useful data. But $150B worth of data? I'd like to see someone argue that with a straight face.
The same applies with asteroid missions, Lunar missions, Mars missions, and yes, even my personal topic of interest, Venus. I support the eventual Landis-style colonization of Venus. But I don't support HAVOC. Namely because in the first several stages of HAVOC, humans are basically just an extremely expensive cargo. Yes, I know they would argue that having humans along can increase the scientific output, that they can repair things, all of the standard arguments that manned spaceflight promote. That's all well and good, but not when you're talking about needing to pay for SLS launches and engineer massive, failure-cannot-be-an-option structures to do so. And I find trying to cloak that in the guise of science to be facetious.
I prefer the concept of keeping the idea of eventual manned settlement on the horizon while keeping the focus on science. This means advancing the state of the art at the same time as exploring.
For example, concerning Venus I would like to see a probe use a ballute entry system rather than an aeroshell. Ballutes have high TRL as an in-atmospheric deceleration system but low TRL for entry. But the benefits of significantly reduced mass and gentler deceleration promised by ballutes is very significant - not only for Venus, but for all bodies with an atmosphere. Hence, if a probe can simultaneously conduct its mission and advance the state of the art for future missions, it's doing double duty - and I find that to be worth taking on some risk.
Likewise, with the ISS: it's now a massive sunk cost; we're not getting that money back. If we can keep it operating with reduced operating cost, then that might be justifiable. Hence I support, for example, the concept of testing VASIMR on ISS - namely, since a VASIMR reboost system would not only reduce the required frequency of resupply trips, but also increase VASIMR's TRL to make it more usable for outer solar system exploration.
In short, I support a program of simultaneous exploration and the advancement/testing of technology that makes both exploration - and eventually, manned settlement - more accessible. But until manned missions don't require tens to hundreds of billions of dollars, until they're actually long-term sustainable, I find it to be just bread-and-circuses.
I said nothing about it being "a done deal". I said that if you want to argue against a topic, you should at least know what it is before you do so. The design document can be read in an hour, is publicly available, and easy to find. I find it absurd that every bloody time that people on Slashdot want to argue against Hyperloop, they've A) never read the document, B) have posts packed with misconceptions about the very basics of even what Hyperloop is, and C) raise arguments almost entirely already addressed in the document.
This says absolutely nothing about whether it will ever be built. But for crying out loud, if you want to make an engineering argument against a project, at least read the project's bloody design document first.
The large amount of observation of Earth's magnetosphere is complimented by observation of Jupiter's, in the sense that the sum is greater than the sum of the parts.
Cluster answered many important questions, but brought up new ones and left others unanswered. Some of those could only be answered by going much further than Earth's magnetosphere, and that data can make the analysis and conclusions from Cluster all the more better
Yeah, just go ahead and drop me a line when we get another 3000 papers out of Juno.
There is the is problem when you half-ass a mission and people complain about, "Why didn't you just use attach an XYZ to it, and get a huge marginal science to marginal cost gain." It is sort of like the complaints here about the lack of a better camera that wouldn't have added that much more science to the mission, but when made by scientists actually involved in the decision processes, there is an actual problem. When trying to maximize science for a given budget, there are important targets where something resembling a maximization is only really achieved with a go big or go home attitude.
All missions have to make tradeoffs. New Horizons is a great example. They couldn't even include a magnetometer on it, that's how constrained they were. The amount of data they could have gathered could have been vastly expanded with a few hundred million more in budget. Does that do anything to change the immensity of the discoveries they were able to make on the budget that they were with?
I'll repeat: the fact that you can get even better value out of a mission by giving it even more money does nothing to change how much value you could get out of it at a given budget figure. If Mission X is already a significantly better buy than Mission Y, and you can make Mission X even better by increasing its budget, that doesn't change the fact that Mission Y is a poor use of money.
Space agencies have a huge bias towards spending money that can support manned space programs for a variety of reasons.
Except that we're not talking about, as alternative to Juno, anything at all having to do with manned space missions. Your attempt to ascribe my arguments as being somehow equivalent to a bias toward manned space programs hence comes across as yet another attempt by you to label me as just some moron who wants a "National Monster Truck Administration".
Especially so when it seems you had limited to no knowledge of what the project was even about, and don't actually talk about it until this post some time later.
I'm sorry, I didn't realize that I was supposed to open this conversation by writing a book on Juno to prove my worth to you. My humble apologies.
There is a huge difference between having differing priorities vs. trying to insist a project has minimal science value to the point better images would have been consoling.
Again: wake me up when Juno is the source of ~3000 publications on plasma dynamics. Yes, I do think that Juno was a big waste of money. So freaking sue me.
And don't act like you've never been, or at least will be, in this situation, since I know how you feel (like me) about manned exploration. Because manned space exploration has its backers, including in the scientific community. Don't tell me that you don't look at the vast sums spent on manned space exploration compared to their minimal (per dollar) returns on science and find that situation extremely frustrating. Now, tell me, how would you feel if you were talking with a backer of manned space exploration and they treated you like a moron because you didn't see the same value in the manned space program as they did? Because that's precisely what you're doing with me concerning Juno.
Without the extended mission NH still provided vastly more compelling science than Juno will in its entire mission. Seriously, "better quantifying Jupiter's already fairly quantified plasma environment", or "finding that something that we thought was a dead iceball has its mantle actively convecting on its surface, active photochemistry in its atmosphere, precipitation and glaciation of multiple substance, evidence of possible surface liquids in its past, cryovolcanoes, terrains like the "snakeskin" that we have hardly even begun to understand, mountains the size of the rockies (some smaller ones of which actively drift among the convection cells), significantly reduced atmosphere loss to space than we thought (want to talk plasma interactions?), and perhaps most importantly, that there appears to be more heat inside Pluto than we had previously given it credit for and signs that it may still have a deep liquid water layer (Hammond, Barr and Parmentier, 2016), implying a tremendous liquid water inventory in the Kuiper belt and in the universe in general. How can you even compare that sort of thing to Juno? For 2/3rds the budget. Heck, even what we learned about Charon alone would have been worth the budget.
And seriously, you're going to argue that Juno, with only 37 orbits, is going to provide more revelations about plasma dynamics in space than a cluster of four better instrumented satellites operating for 15 years that's been the source of nearly 3000 publications? Can you claim that with a straight face?
The fact that a flagship may provide even better capabilities for Titan and Enceladus does nothing to diminish what is possible with a New Frontiers budget. There is little doubt that we can, on a New Frontiers budget, conduct *at a minimum* an Enceladus plume flyby and analysis. Sampling another world's ocean, an ocean that appears to be heated by serpentinization, and if so not only involves direct water/rock contact but additionally the presence of hydrogen gas. Likewise, there is little doubt that we can get a probe and aeroshell to Titan and a solid suite of scientific instruments. Yes, we could make a larger, more capable, more mobile exploration vehicle on a Flagship budget. But the fact that better options do exist does not change that there are huge unanswered questions about Titan that we could answer on a New Frontiers budget. To pick some random ones: where the heck has the surface and acetylene and ethylene gone? Is the data suggestive that hydrogen is also disappearing near the surface correct? What's the basic chemical composition of any of Titan's seas? How complex does the atmospheric chemistry get? What's up with the unusual shoreline hydrology we're observing, such as disappearing islands? Are theories that the atmosphere is replenished by methane springs in the lake basins correct? Is there young cryovolcanism that could give a sense of what's contained in Titans subsurface seas? No, a New Horizons budget can't answer everything, but it can sure bloody help.
despite the limited PR and manned mission support they provide.
"Manned mission support"? What on Earth are you talking about? Are you envisioning a manned mission to Enceladus, Titan, or the Kuiper Belt any time soon? Or was that another jab similar to your previous "National Monster Truck administration" one?
Again, to back up: I'm sorry that I don't find a probe designed to give us better details of a different planet's plasma environment (which we've already had a number of probes taking measurements from - yes, there are gaps in our knowledge, but it's hardly undiscovered ground); multiple instruments studying aurorae (seriously? Of all of the things to dedicate the mass budget to...); and getting a deeper temperature / mass distribution profile of a planet that has zero possibility for life, near-zero possibility for interesting chemistry (at least at depths we'll ever be able to sample), and whose actual int
The Cluster mission cost about $700 M (2016 USD) originally close to the original Juno budget of $700M... but the suffered launch failure and was important enough that they spent another $350 M to rebuild and relaunch
So we're going to combine Cluster and Cluster II to try to find something even close in terms of budget, are we? Which together represent a total of 8 separate satellites built in the largest orbital plasma science mission conducted to date, taught us far more about plasma interactions than Juno ever will, and which even with a launch failure (something that was no fault of their own, unlike Juno's nearly 60% budget overrun) was $100m cheaper than Juno.
Yes, I think Juno's funds could have done far more good elsewhere.
You didn't just bring up "pretty pictures"
Apparently you don't know what the phrase "at least" means. Apparently in your world, "at least" means "the primary purpose and all that one cares about", rather than "a consolation prize for an overbudget, underwhelming mission". I'd been trying to generate some excitement for myself by telling myself - to repeat - that at least there would be some nice pictures out of it. And if there was a mission that you were underwhelmed with, I don't doubt in the least that you would do the same. And if even that turned out to be underwhelming, I don't doubt that you'd take that as an opportunity to snipe at the mission itself. And I furthermore don't doubt that if someone responded to your disinterest in the mission as if you're a nitwit that wants a National Monster Truck administration, you'd be a bit ticked off about it as well.
Do you know what $1,1B could do toward advancing our understanding of them?
Do you?
Yes, and the fact that you have to ask means that I need to turn this back around and ask, do you? Every last thing I mentioned has active mission proposals for it at New Frontiers or Discovery budgets (with the exception of the Uranus and Neptune orbiters, but see below), many of them multiple proposals.
Some of those prospects had proposals that would have cost more.
Let me go down the list. Given that Juno was a largely-inflated New Frontiers budget, anything New Frontiers or cheaper can be expected to be a cheaper mission
* Titan & Enceceladus - Ocean Worlds (New Frontiers)
* KBOs - Just did one at a New Frontiers budget, remarkably successful
* Trojan Asteroid Tour and Rendezvous - (New Frontiers)
* Psyche - Not even close (Discovery proposal)
* Venus In-Situ Explorer (among many others, including some at Discovery budgets) - New Frontiers
* Uranus and Neptune orbiter budgets could actually surpass Juno... but then again, given Juno's price inflation, that's not much difference. Contrarily, there have been proposals to use new Uranus and Neptune flybys en route to studying KBOs on New Horizons budgets, getting a large combined scientific return on a low budget.
Yes, studying these bodies can be done on budgets well cheaper than Juno, and address far more interesting scientific questions.
Others that proposed to cost less are still in consideration by NASA
Red herring. Don't pretend that you don't know that due to budget constraints most will get put off indefinitely or outright cancelled, and their proponents will likely spend decades trying proposal after proposal to try to make it happen. If Juno's funds hadn't been spent on Juno, they would have been spent on something else. The money doesn't just disappear if you don't select Juno.
If anything, what killed some of those is the insistence on manned missions to Mars and the need
Question: How do you prevent nutjobs from shooting at all those miles of exposed vacuum tubing? Answer: Sudden decompression is covered in the document
Question: How do you handle the explosive decompression if there's an accident of any sort? Answer: Sudden decompression is covered in the document
Question: What happens when there's an earthquake? Answer: Earthquakes are covered in the document
Question: Are there really enough people who want to go from LA to San Fran or back to make this economically feasible? Answer: Passenger traffic is covered in the document
Why is is that debates about Hyperloop always involve the naysaying side having never read the details of the very thing that they're arguing against?
Question: Do airplanes work? Answer: Yes! Question: How high can airplanes fly? Answer: The jet record is over 37 kilometers, around 4mb air pressure (4x Hyperloop). Question: Was it lift that limited it, or a lack of oxygen for the engines? Answer: Not even a contest - oxygen! Question: Was it in ground effect? Answer: Not even close! Question: Can ground effect increase lift by literally orders of magnitude as you reduce the distance to the lifting surface? Answer: Yes! Question: How far are Hyperloop's air bearings from the skin? Answer: 0,5 to 1,3mm Question: Is that the only source of lift? Answer: No! They also shunt in air from the big compressors on the front of each pod - 0,2kg/s at 9,4 kPa - the compressors using 276 kW to take in 99Pa air at 292K at 0,49kg/s to compress to 2,1 kPa at 857K, cooled in an intercooler with onboard water (0.14kg/s) to 300K, with 0.29kg/s shunted to the nozzle expander, leaving 0.2kg/s into the second stage compressor 11kPa 557K via 52kW of compressor power, into the second stage intercooler to 400K, and out via the air bearings. Question: Is all of this stuff and much more in the Hyperloop Alpha document for all of this? Answer: Yes! Question: Did the person you're responding to bother to read the document before going off on the concept? Answer: No! Question: Why would a person think that was a reasonable thing to do?... Sorry, I've got no answer to the last one.
Your analogies are total BS, and i do know what I'm talking about.
Until you've actually read the proposal, which thusfar you have demonstrably not read, then you don't know one iota about the subject, and I'm not going to read another word you write. For the simple reason that I'm not going to waste my time arguing with a person about a subject that they can't be bothered to learn even the most fundamental aspects of..
Let me know when you've actually read it in its entirity, then get back here and we can talk.
We've learned a lot about fundamental plasma physics and space weather from simple satellites in high Earth orbit
And how many of them cost $1,1B?
more exciting or make prettier pictures,
I'm not talking about "pretty pictures" either. You consider "the internal structure and weather of Jupiter" as pretty high up there on the priority list. How does that even compare to other things we could be spending our money on? Let me just toss a couple examples out there.
* Finding out whether the solar system's subsurface oceans could be harbouring life as we know it. Some of said bodies which spray their contents straight out into space.
* Finding out whether bodies such as Titan could be harbouring life *not* as we know it
* Unraveling the steps that led up to life as we know it, and where we should look for life beyond our solar system.
* Finding out *anything* about the diverse range of large KBOs, the most numerous large bodies in the solar system, a class that we know is diverse, and of which we've seen precisely one - a mission that blew away all of our expectations as to what such a body would be like in terms of diversity and geological activity.
* Vising a Jupiter trojan, bodies that again we know next to nothing about
* Visiting the exposed core of a protoplanet (aka, 10 Psyche)
* Stopping the long-term ignoring of Earth's hellish twin Venus, the easiest planet in the solar system to get to and yet one that we know embarrassingly little about.
* Actually getting an orbiter to each of our two ice giants for the first time ever, for crying out loud.
Really, Juno takes priority over these sorts of things? Do you know what $1,1B could do toward advancing our understanding of them?
But hey, thanks for assuming that all I care about is "pretty pictures". I really hate that whole "because you're not excited about the particular aspects that I'm excited about, that means that you're some sort of moron who just wants to oggle at pretty pictures" attitude.
You said a few other things, but I had trouble hearing you because your horse was too damn high.
I will only comment on Hyperloop Alpha. The new "Hyperloops" in the competition have nothing in common with it, and I'm not going to bother with them.
Let's just say this works and I'm sure it will, as the engineering of vacuum tubes has been known for nearly a century
Hyperloop is not a vactrain.
(for those of you older folks, this is just an evolution of the system we used before ATMs when you deposited your check at your drive-up bank into a vacuum tube system to the bank teller).
No, those are pneumatic tubes, which are neither nor vactubes nor Hyperloop.
Don't you think you should at least know what you're talking about before you start criticizing something?
The infrastructure alone will cost $100B. I get that number because I anticipate that building a sealed tube is going to be a lot more expensive than high speed rail tracks
1) Explain why rail tracks are the best analogy for building a Hyperloop tube, as opposed to, you know, actual long tubes. 2) Explain why Hyperloop should cost anywhere near that much when actual pipeline costs, per unit cross section, are well in line with Hyperloop.
There are of course, differences, but they fall on both sides. For example, comparing to oil pipeline, Hyperloop requires much greater straightness, high wall smoothness, and accelerator segments. An oil pipeline deals with a higher pressure differential, deals with much more challenging environmental/permitting issues, higher power pumps and has thermal management challenges not faced by Hyperloop. I could keep going on both sides, of course.
, and the cost of the high speed rail project in California is now estimated at $68.4B.
Rail isn't a pipeline.
If you want to go into some of the reasons for the differences in cost:
1) HSR does more. Hyperloop is a straight shot between two cities. HSR has stops. These stops involve going through towns. This is very expensive. It also means more stations. These too cost money. HSR is also higher capacity (although Hyperloop is in turn higher capacity than LA/SF air traffic, and significantly cheaper per ticket than both rail and air)
2) HSR is hurt by its path. A large portion of HSR's costs are permitting and right of way. Hyperloop minimizes these by using public right of way with elevation, on a premise of government buy-in to the concept (although other options not considered in the Alpha document are possible, such as rail right-of-ways). HSR's need to serve specific cities for political purposes limits where it can go.
3) HSR is limited by its weight. The cost of elevating a structure is directly proportional to its peak loadings. HSR's peak loadings are an order of magnitude higher than Hyperloop's.
The steel alone will be very hard to come by,
Not in the very least. They budget several times the billet price, on the high end of the tonnage price for delivered tube segments. It's really not that much steel - subtract the inner cross section from the outer cross section and multiply the length if you don't believe me.
because while rail steel and ribar is made in tremendous volume,
The word is "rebar". Rebar is irrelevant to this conversation. There is no single type of "rail steel", particularly when one is discussing HSR.
this requires plate steel that is then rolled by a steel fab
That is not how pipelines are made. Pipelines are made of extruded tubular steel segments, the same as "ribar" and "rail steel".
Then there's the regional politics to deal with. Building a Hyperloop from LA to San Fran will run through the cities or counties of at least 6 and as many as 9 municipalities depending on the route you choose.
I don't know what you refer to when you say "Elon suggested", but the Hyperloop Alpha document argued strongly against maglev, for cost reasons and because air bearings can be even more efficient.
It also argued strongly against a hard vacuum, and for a battery-powered compressor to prevent the accumulation of a high pressure area ahead of the vehicle. All of the competitors use either hard vacuum or do nothing to prevent pressure buildup.
What's being discussed now is nothing like what was being discussed then. I liked the original idea. I'm not a fan of this new stuff.
Because it's hard to know what one means when they talk about "Hyperloop" anymore. The original Hyperloop Alpha document spelled out a very explicit concept. Then they held the student Hyperloop pod competition and the winners were absolutely nothing like what was laid out in Hyperloop Alpha.
It comes across to me that the main point of this competition is more to drive student interest in engineering rather than to build a viable transportation alternative. Hyperloop Transportation Technologies and Hyperloop One seem more focused on the latter.
Good to know I'm not the only person underwhelmed by Juno.
I tried to get myself excited about this one, but I just can't. The target is way down on my list of "unsolved things in the solar system to investigate", and the mission profile uninteresting. I was telling myself, well, at least you're going to get a bunch of pretty pictures out of it. Well, honestly, these aren't that great, and this was the closest pass. The quality is underwhelming, and at least to my eye the poles look basically like the rest of the planet, just with more upwelling-driven storms and less banding effects.
Of all of the ways NASA could have spent $1,1 billion...
Well, maybe there will at least be some interesting papers that come out of it. Onward to OSIRIS-REx, another billion-plus dollar mission that I find myself trying to be excited for in its own right rather than thinking about the other ways that money could have been allocated. But at least we get a sample return out of that. Which is not just useful in its own right but also helps advance our experience with robotic sample returns, which is pretty limited (Luna, Stardust, and Hayabusa... and the Luna tech is obsolete). That said, the sample return results from Hayabusa were pretty underwhelming. Basically, "Hey, the sample return from this LL chondrite is just like LL chondrites on Earth". Now, Stardust had some interesting work come from it... but I just have a nagging feeling that we're spending a billion dollars to get a "Hey, the sample return from this carbonaceous asteroid is just like carbonaceous chondrites on Earth" moment.
1) A rocket is not "a mostly empty tube". A rocket is a heck of a lot more than just engines bolted onto tanks. 2) Only the Atlas V has Russian rockets, the Delta series use Rocketdyne engines. 3) None of this changes the fact that these are SpaceX's domestic competition, and they're not made by NASA. NASA hasn't been running commercial launches since the Space Shuttle, and even then they were a small fraction of commercial launches.
Slashdot Mirror
It's important to not simply look at the total cost figure vs. the likely final results when comparing projects, but also what technologies you'll be developing to achieve said results - because, apart from things like pouring concrete and such, that's where the money goes. For example, there's a lot of people here who hate ITER and see it as a waste of money. But regardless of whether or not tokamak fusion eventually becomes economically viable, the work on superconducting magnets that's been spawned because of ITER is going to be of immense value. In particular, while the ITER design isn't going to use them because it's too far along (DEMO might), new high temperature superconducting tapes have made magnets that are much more powerful and energy efficient - and at the same time likely cheaper in bulk production, and cheaper to operate - a reality. Which obviously has huge implications everywhere from medicine to spaceflight. The size (and thus cost) of many technologies corresponds directly with the strength of the economically-achievable magnetic field.
When a project is expensive, it's good to ask why it's expensive. Is it expensive because you're pouring a lot of concrete / buying a lot of some raw material / doing research that only pertains to the given project, or because you have a lot of scientists' salaries going toward developing enabling technologies that also have significant applications elsewhere? And if so, how valuable are those technologies in addition to the main project?
It's not an easy assessment to make, but an important one.
Hmm, I replied to this, but I can no longer find my reply. That statement was based on a propellant loading timeline posted at NASA Spaceflight; if the timeline was incorrect then that would indeed change the picture, and suggest for example a common bulkhead failure (although that would raise the question of why). Alternatively combustables on the outside (a leak, for example) could ignite with liquified air / LOX coming off of the outside of the LOX tank (unlike boiling point LOX, superchilled LOX can liquefy air and/or just the oxygen fraction on the rocket's skin). But in that case I'd expect the explosion to begin further down the stage.
It's trickier than that. They were loading LOX. There was no RP1 in the upper stage yet. So why did the LOX explode?
I've read a fair bit on LOX handling, and while it's tamer than, say, HTP, there are some risks in handling it. The biggest one is contamination - which has taken down craft in the past. Most notably, the X-1A and X-1D were taken down by a contamination from a chemical used in the manufacture of their gaskets. Most organics are incompatible with LOX and become contact sensitive, including - wait for it - tending to be set off by pressure changes.
Another issue is the tank itself. LOX is compatible with most aluminum alloys, hence aluminum is frequently used for LOX tankage. However, there are some caveats. One, it must be well cleaned in a proscribed manner, due to the aforementioned contamination issues. Furthermore, it must have an intact oxide layer. If the oxide layer is damaged (bending, stretching, shearing, overaggressive cleaning) or never formed, it must be exposed to atmospheric air and allowed to reform; it begins reforming immediately but takes about three days to reach maximum thickness (slowing with time). Bare aluminum is still not hypergolic, but it is impact sensitive with LOX. It can also be set off by the same phenomenon that damages the tank - for example, heavy warping, which can create localized hot spots.
Contamination is generally considered more of a concern, however (particularly since SpaceX uses aluminum-lithium, which is more resistant to impact/pressure-induced explosion with LOX than non-lithium alloys). That said, regardless of what causes the initial burn, if temperatures are high enough, the aluminum will burn, and it burns very aggressively. Indeed, it was the addition of aluminum powder that revolutionized solid rocket propellants (powdered to make it easier to ignite and burn completely, as well as to blend), giving them a major simultaneous improvement in ISP, thrust, propellant density, and burn quality. Aluminum has such a high affinity for oxygen that it also burns in CO2 and water, stripping the oxygen from them. The general way firefighters put out large aluminum fires is.... they don't.
All of that said, these sort of problems are rare. Which makes one wonder about the unusual factor in SpaceX's case: densified/superchilled propellants. SpaceX is the only major launcher to use them, and the behavior of superchilled LOX isn't anywhere near as well studied as that of LOX at its boiling point. It changes what may liquify or freeze in contact with it, it changes the flexibility or fracture properties of physical components on contact with it, it has a higher viscosity, etc. Things that freeze into it could melt/boil as the LOX warms up as well. So it obviously draws the question, is this problem a result of the use of superchilled LOX, some unanticipated effect in the production / storage / delivery system that led to problems within the tank, or an unexpected reaction within the tank itself?
Will anyone read the actual tweets? This summary is one of the worst I've seen on Slashdot in a long time. Musk asked Twitter for pictures and videos, not to "find the cause of the explosion". They're trying to figure out whether a particular sound came from the rocket or elsewhere. The summary makes it sound like - as you put it - they're inviting arm char scientists to solve the issue for them.
It would have been nice if the summary had mentioned what specifically he asked for, rather than including everything but what he asked for. They make it sound like he asked Twitter to solve the problem. What he actually asked twitter for was any photos or videos of the event that anyone may have:
The connection with the "bang" is precisely what he wrote immediately after the first tweet:
If they have more videos, they can triangulate the location of the sound and determine whether it came from the rocket or elsewhere.
Musk did Not just go on Twitter and say "Well, we're baffled - go on, Twitter, figure out why it exploded for us!" like the summary makes it sound.
** Isotropic, not anisotropic.
What do you mean "centre of the universe"?
To move everything down a dimension: picture a balloon that started as an infinitesimally small point and expanded from there. You're a dot on the surface. There are other dots, all drifting around in random directions. The balloon keeps inflating. You may still get closer to certain ones because of your relative motion, but overall everything is moving further apart.
Which dot on the surface is "the centre"? None of them. Every direction you look you see other dots. They're's no particular structural bias - they're anisotropic. They all see the same pattern.
We are of course, not a 2d surface inflated in 3 space, where the radial dimension represents inflation - and, within certain constraints and nonlinear scaling relative to the other dimensions, time. We can be correspondinly be seen as a 3d surface inflated in 4 space (or higher).
First off, there was no fire. Secondly, what the kind of rescue service doesn't have a class C fire extinguisher? What do they do if a car crashes into a power pole?
Regardles, my reaction to this article is "Slow News Day". Basically:
"Man Dies In Car Crash. Details at 11."
Or...
"Car with high voltage battery pack crashes." Because clearly that's never happened before. And crashed cars full of gasoline are totally safe environments for rescuers.
Seriously, do they not train rescue workers? If so then why don't they train them to respond to electric and hybrid vehicle crashes so that they know what's safe and what's not? It's their job, they should know what the heck they're doing.
Rescue workers are supposed to assume that every vehicle is a hybrid or electric until proven otherwise. Badging and identifying details can be damaged in a crash, and many vehicles come in similar electric/or hybrid and gasoline versions. It's not just about high voltages. There are many things that disconnect the HV system, and one of them is crash sensors. But a problem with hybrids or EVs is that the vehicle may still be "running", but without the noise of a running gasoline engine. Hence immobilizing the vehicle - both turning it off, and clipping or removing the 12V system - is one of the first steps. A vehicle that is still energized could, for example, unexpectedly deploy an undeployed airbag.
All high voltage components are brightly marked. Again, by default a vehicle will disable its battery pack in a crash. Nonetheless, you never cut a bright-colored cable. The concept of having to avoid cutting certain areas should be nothing new to a rescuer, because it's also dangerous to cut other parts of a vehicle, such as airbags (side curtain airbags in particular are vulnerable to being cut) or the fuel tank. A rescue worker is supposed to have an idea of where things are. And speaking of "where things are", if they know where the HV pack is, they can throw the switch. All HV packs have a switch to shut them off for maintenance.
Right. Because "Transportation" equals "Telepathy" and "Perpetual Motion". Got it.
If you're a big fan of arguing about things that you don't even know the basics about, go ahead. But you're only going to make yourself look like an idiot.
I'll add, concerning manned exploration:
Don't get me wrong, I do support the eventual expansion of the human species into space. I think it's an important goal to have on the horizon. What I don't support is the concept that it must be done "soon", at the sort of prices that today's missions cost. And I strongly oppose attempts to justify the cost with "science". ISS, for example, at $150B is the most expensive structure ever made. Yes, it absolutely has returned useful data. But $150B worth of data? I'd like to see someone argue that with a straight face.
The same applies with asteroid missions, Lunar missions, Mars missions, and yes, even my personal topic of interest, Venus. I support the eventual Landis-style colonization of Venus. But I don't support HAVOC. Namely because in the first several stages of HAVOC, humans are basically just an extremely expensive cargo. Yes, I know they would argue that having humans along can increase the scientific output, that they can repair things, all of the standard arguments that manned spaceflight promote. That's all well and good, but not when you're talking about needing to pay for SLS launches and engineer massive, failure-cannot-be-an-option structures to do so. And I find trying to cloak that in the guise of science to be facetious.
I prefer the concept of keeping the idea of eventual manned settlement on the horizon while keeping the focus on science. This means advancing the state of the art at the same time as exploring.
For example, concerning Venus I would like to see a probe use a ballute entry system rather than an aeroshell. Ballutes have high TRL as an in-atmospheric deceleration system but low TRL for entry. But the benefits of significantly reduced mass and gentler deceleration promised by ballutes is very significant - not only for Venus, but for all bodies with an atmosphere. Hence, if a probe can simultaneously conduct its mission and advance the state of the art for future missions, it's doing double duty - and I find that to be worth taking on some risk.
Likewise, with the ISS: it's now a massive sunk cost; we're not getting that money back. If we can keep it operating with reduced operating cost, then that might be justifiable. Hence I support, for example, the concept of testing VASIMR on ISS - namely, since a VASIMR reboost system would not only reduce the required frequency of resupply trips, but also increase VASIMR's TRL to make it more usable for outer solar system exploration.
In short, I support a program of simultaneous exploration and the advancement/testing of technology that makes both exploration - and eventually, manned settlement - more accessible. But until manned missions don't require tens to hundreds of billions of dollars, until they're actually long-term sustainable, I find it to be just bread-and-circuses.
Just wanted to be clear about that.
I said nothing about it being "a done deal". I said that if you want to argue against a topic, you should at least know what it is before you do so. The design document can be read in an hour, is publicly available, and easy to find. I find it absurd that every bloody time that people on Slashdot want to argue against Hyperloop, they've A) never read the document, B) have posts packed with misconceptions about the very basics of even what Hyperloop is, and C) raise arguments almost entirely already addressed in the document.
This says absolutely nothing about whether it will ever be built. But for crying out loud, if you want to make an engineering argument against a project, at least read the project's bloody design document first.
Yeah, just go ahead and drop me a line when we get another 3000 papers out of Juno.
All missions have to make tradeoffs. New Horizons is a great example. They couldn't even include a magnetometer on it, that's how constrained they were. The amount of data they could have gathered could have been vastly expanded with a few hundred million more in budget. Does that do anything to change the immensity of the discoveries they were able to make on the budget that they were with?
I'll repeat: the fact that you can get even better value out of a mission by giving it even more money does nothing to change how much value you could get out of it at a given budget figure. If Mission X is already a significantly better buy than Mission Y, and you can make Mission X even better by increasing its budget, that doesn't change the fact that Mission Y is a poor use of money.
Except that we're not talking about, as alternative to Juno, anything at all having to do with manned space missions. Your attempt to ascribe my arguments as being somehow equivalent to a bias toward manned space programs hence comes across as yet another attempt by you to label me as just some moron who wants a "National Monster Truck Administration".
I'm sorry, I didn't realize that I was supposed to open this conversation by writing a book on Juno to prove my worth to you. My humble apologies.
Again: wake me up when Juno is the source of ~3000 publications on plasma dynamics. Yes, I do think that Juno was a big waste of money. So freaking sue me.
And don't act like you've never been, or at least will be, in this situation, since I know how you feel (like me) about manned exploration. Because manned space exploration has its backers, including in the scientific community. Don't tell me that you don't look at the vast sums spent on manned space exploration compared to their minimal (per dollar) returns on science and find that situation extremely frustrating. Now, tell me, how would you feel if you were talking with a backer of manned space exploration and they treated you like a moron because you didn't see the same value in the manned space program as they did? Because that's precisely what you're doing with me concerning Juno.
Without the extended mission NH still provided vastly more compelling science than Juno will in its entire mission. Seriously, "better quantifying Jupiter's already fairly quantified plasma environment", or "finding that something that we thought was a dead iceball has its mantle actively convecting on its surface, active photochemistry in its atmosphere, precipitation and glaciation of multiple substance, evidence of possible surface liquids in its past, cryovolcanoes, terrains like the "snakeskin" that we have hardly even begun to understand, mountains the size of the rockies (some smaller ones of which actively drift among the convection cells), significantly reduced atmosphere loss to space than we thought (want to talk plasma interactions?), and perhaps most importantly, that there appears to be more heat inside Pluto than we had previously given it credit for and signs that it may still have a deep liquid water layer (Hammond, Barr and Parmentier, 2016), implying a tremendous liquid water inventory in the Kuiper belt and in the universe in general. How can you even compare that sort of thing to Juno? For 2/3rds the budget. Heck, even what we learned about Charon alone would have been worth the budget.
And seriously, you're going to argue that Juno, with only 37 orbits, is going to provide more revelations about plasma dynamics in space than a cluster of four better instrumented satellites operating for 15 years that's been the source of nearly 3000 publications? Can you claim that with a straight face?
The fact that a flagship may provide even better capabilities for Titan and Enceladus does nothing to diminish what is possible with a New Frontiers budget. There is little doubt that we can, on a New Frontiers budget, conduct *at a minimum* an Enceladus plume flyby and analysis. Sampling another world's ocean, an ocean that appears to be heated by serpentinization, and if so not only involves direct water/rock contact but additionally the presence of hydrogen gas. Likewise, there is little doubt that we can get a probe and aeroshell to Titan and a solid suite of scientific instruments. Yes, we could make a larger, more capable, more mobile exploration vehicle on a Flagship budget. But the fact that better options do exist does not change that there are huge unanswered questions about Titan that we could answer on a New Frontiers budget. To pick some random ones: where the heck has the surface and acetylene and ethylene gone? Is the data suggestive that hydrogen is also disappearing near the surface correct? What's the basic chemical composition of any of Titan's seas? How complex does the atmospheric chemistry get? What's up with the unusual shoreline hydrology we're observing, such as disappearing islands? Are theories that the atmosphere is replenished by methane springs in the lake basins correct? Is there young cryovolcanism that could give a sense of what's contained in Titans subsurface seas? No, a New Horizons budget can't answer everything, but it can sure bloody help.
"Manned mission support"? What on Earth are you talking about? Are you envisioning a manned mission to Enceladus, Titan, or the Kuiper Belt any time soon? Or was that another jab similar to your previous "National Monster Truck administration" one?
Again, to back up: I'm sorry that I don't find a probe designed to give us better details of a different planet's plasma environment (which we've already had a number of probes taking measurements from - yes, there are gaps in our knowledge, but it's hardly undiscovered ground); multiple instruments studying aurorae (seriously? Of all of the things to dedicate the mass budget to...); and getting a deeper temperature / mass distribution profile of a planet that has zero possibility for life, near-zero possibility for interesting chemistry (at least at depths we'll ever be able to sample), and whose actual int
So we're going to combine Cluster and Cluster II to try to find something even close in terms of budget, are we? Which together represent a total of 8 separate satellites built in the largest orbital plasma science mission conducted to date, taught us far more about plasma interactions than Juno ever will, and which even with a launch failure (something that was no fault of their own, unlike Juno's nearly 60% budget overrun) was $100m cheaper than Juno.
Yes, I think Juno's funds could have done far more good elsewhere.
Apparently you don't know what the phrase "at least" means. Apparently in your world, "at least" means "the primary purpose and all that one cares about", rather than "a consolation prize for an overbudget, underwhelming mission". I'd been trying to generate some excitement for myself by telling myself - to repeat - that at least there would be some nice pictures out of it. And if there was a mission that you were underwhelmed with, I don't doubt in the least that you would do the same. And if even that turned out to be underwhelming, I don't doubt that you'd take that as an opportunity to snipe at the mission itself. And I furthermore don't doubt that if someone responded to your disinterest in the mission as if you're a nitwit that wants a National Monster Truck administration, you'd be a bit ticked off about it as well.
Yes, and the fact that you have to ask means that I need to turn this back around and ask, do you? Every last thing I mentioned has active mission proposals for it at New Frontiers or Discovery budgets (with the exception of the Uranus and Neptune orbiters, but see below), many of them multiple proposals.
Let me go down the list. Given that Juno was a largely-inflated New Frontiers budget, anything New Frontiers or cheaper can be expected to be a cheaper mission
* Titan & Enceceladus - Ocean Worlds (New Frontiers)
* KBOs - Just did one at a New Frontiers budget, remarkably successful
* Trojan Asteroid Tour and Rendezvous - (New Frontiers)
* Psyche - Not even close (Discovery proposal)
* Venus In-Situ Explorer (among many others, including some at Discovery budgets) - New Frontiers
* Uranus and Neptune orbiter budgets could actually surpass Juno... but then again, given Juno's price inflation, that's not much difference. Contrarily, there have been proposals to use new Uranus and Neptune flybys en route to studying KBOs on New Horizons budgets, getting a large combined scientific return on a low budget.
Yes, studying these bodies can be done on budgets well cheaper than Juno, and address far more interesting scientific questions.
Red herring. Don't pretend that you don't know that due to budget constraints most will get put off indefinitely or outright cancelled, and their proponents will likely spend decades trying proposal after proposal to try to make it happen. If Juno's funds hadn't been spent on Juno, they would have been spent on something else. The money doesn't just disappear if you don't select Juno.
Question: How do you prevent nutjobs from shooting at all those miles of exposed vacuum tubing?
Answer: Sudden decompression is covered in the document
Question: How do you handle the explosive decompression if there's an accident of any sort?
Answer: Sudden decompression is covered in the document
Question: What happens when there's an earthquake?
Answer: Earthquakes are covered in the document
Question: Are there really enough people who want to go from LA to San Fran or back to make this economically feasible?
Answer: Passenger traffic is covered in the document
Why is is that debates about Hyperloop always involve the naysaying side having never read the details of the very thing that they're arguing against?
Question: Do airplanes work? ... Sorry, I've got no answer to the last one.
Answer: Yes!
Question: How high can airplanes fly?
Answer: The jet record is over 37 kilometers, around 4mb air pressure (4x Hyperloop).
Question: Was it lift that limited it, or a lack of oxygen for the engines?
Answer: Not even a contest - oxygen!
Question: Was it in ground effect?
Answer: Not even close!
Question: Can ground effect increase lift by literally orders of magnitude as you reduce the distance to the lifting surface?
Answer: Yes!
Question: How far are Hyperloop's air bearings from the skin?
Answer: 0,5 to 1,3mm
Question: Is that the only source of lift?
Answer: No! They also shunt in air from the big compressors on the front of each pod - 0,2kg/s at 9,4 kPa - the compressors using 276 kW to take in 99Pa air at 292K at 0,49kg/s to compress to 2,1 kPa at 857K, cooled in an intercooler with onboard water (0.14kg/s) to 300K, with 0.29kg/s shunted to the nozzle expander, leaving 0.2kg/s into the second stage compressor 11kPa 557K via 52kW of compressor power, into the second stage intercooler to 400K, and out via the air bearings.
Question: Is all of this stuff and much more in the Hyperloop Alpha document for all of this?
Answer: Yes!
Question: Did the person you're responding to bother to read the document before going off on the concept?
Answer: No!
Question: Why would a person think that was a reasonable thing to do?
Until you've actually read the proposal, which thusfar you have demonstrably not read, then you don't know one iota about the subject, and I'm not going to read another word you write. For the simple reason that I'm not going to waste my time arguing with a person about a subject that they can't be bothered to learn even the most fundamental aspects of..
Let me know when you've actually read it in its entirity, then get back here and we can talk.
It's not a high vacuum. What is hard about this for you to understand?
And how many of them cost $1,1B?
I'm not talking about "pretty pictures" either. You consider "the internal structure and weather of Jupiter" as pretty high up there on the priority list. How does that even compare to other things we could be spending our money on? Let me just toss a couple examples out there.
* Finding out whether the solar system's subsurface oceans could be harbouring life as we know it. Some of said bodies which spray their contents straight out into space.
* Finding out whether bodies such as Titan could be harbouring life *not* as we know it
* Unraveling the steps that led up to life as we know it, and where we should look for life beyond our solar system.
* Finding out *anything* about the diverse range of large KBOs, the most numerous large bodies in the solar system, a class that we know is diverse, and of which we've seen precisely one - a mission that blew away all of our expectations as to what such a body would be like in terms of diversity and geological activity.
* Vising a Jupiter trojan, bodies that again we know next to nothing about
* Visiting the exposed core of a protoplanet (aka, 10 Psyche)
* Stopping the long-term ignoring of Earth's hellish twin Venus, the easiest planet in the solar system to get to and yet one that we know embarrassingly little about.
* Actually getting an orbiter to each of our two ice giants for the first time ever, for crying out loud.
Really, Juno takes priority over these sorts of things? Do you know what $1,1B could do toward advancing our understanding of them?
But hey, thanks for assuming that all I care about is "pretty pictures". I really hate that whole "because you're not excited about the particular aspects that I'm excited about, that means that you're some sort of moron who just wants to oggle at pretty pictures" attitude.
You said a few other things, but I had trouble hearing you because your horse was too damn high.
I will only comment on Hyperloop Alpha. The new "Hyperloops" in the competition have nothing in common with it, and I'm not going to bother with them.
Hyperloop is not a vactrain.
No, those are pneumatic tubes, which are neither nor vactubes nor Hyperloop.
Don't you think you should at least know what you're talking about before you start criticizing something?
1) Explain why rail tracks are the best analogy for building a Hyperloop tube, as opposed to, you know, actual long tubes.
2) Explain why Hyperloop should cost anywhere near that much when actual pipeline costs, per unit cross section, are well in line with Hyperloop.
There are of course, differences, but they fall on both sides. For example, comparing to oil pipeline, Hyperloop requires much greater straightness, high wall smoothness, and accelerator segments. An oil pipeline deals with a higher pressure differential, deals with much more challenging environmental/permitting issues, higher power pumps and has thermal management challenges not faced by Hyperloop. I could keep going on both sides, of course.
Rail isn't a pipeline.
If you want to go into some of the reasons for the differences in cost:
1) HSR does more. Hyperloop is a straight shot between two cities. HSR has stops. These stops involve going through towns. This is very expensive. It also means more stations. These too cost money. HSR is also higher capacity (although Hyperloop is in turn higher capacity than LA/SF air traffic, and significantly cheaper per ticket than both rail and air)
2) HSR is hurt by its path. A large portion of HSR's costs are permitting and right of way. Hyperloop minimizes these by using public right of way with elevation, on a premise of government buy-in to the concept (although other options not considered in the Alpha document are possible, such as rail right-of-ways). HSR's need to serve specific cities for political purposes limits where it can go.
3) HSR is limited by its weight. The cost of elevating a structure is directly proportional to its peak loadings. HSR's peak loadings are an order of magnitude higher than Hyperloop's.
Not in the very least. They budget several times the billet price, on the high end of the tonnage price for delivered tube segments. It's really not that much steel - subtract the inner cross section from the outer cross section and multiply the length if you don't believe me.
The word is "rebar". Rebar is irrelevant to this conversation. There is no single type of "rail steel", particularly when one is discussing HSR.
That is not how pipelines are made. Pipelines are made of extruded tubular steel segments, the same as "ribar" and "rail steel".
What do yo
The concept that Hyperloop Alpha was a vactrain is one of those persistent ideas that just refuses to die.
I don't know what you refer to when you say "Elon suggested", but the Hyperloop Alpha document argued strongly against maglev, for cost reasons and because air bearings can be even more efficient.
It also argued strongly against a hard vacuum, and for a battery-powered compressor to prevent the accumulation of a high pressure area ahead of the vehicle. All of the competitors use either hard vacuum or do nothing to prevent pressure buildup.
What's being discussed now is nothing like what was being discussed then. I liked the original idea. I'm not a fan of this new stuff.
Because it's hard to know what one means when they talk about "Hyperloop" anymore. The original Hyperloop Alpha document spelled out a very explicit concept. Then they held the student Hyperloop pod competition and the winners were absolutely nothing like what was laid out in Hyperloop Alpha.
It comes across to me that the main point of this competition is more to drive student interest in engineering rather than to build a viable transportation alternative. Hyperloop Transportation Technologies and Hyperloop One seem more focused on the latter.
Good to know I'm not the only person underwhelmed by Juno.
I tried to get myself excited about this one, but I just can't. The target is way down on my list of "unsolved things in the solar system to investigate", and the mission profile uninteresting. I was telling myself, well, at least you're going to get a bunch of pretty pictures out of it. Well, honestly, these aren't that great, and this was the closest pass. The quality is underwhelming, and at least to my eye the poles look basically like the rest of the planet, just with more upwelling-driven storms and less banding effects.
Of all of the ways NASA could have spent $1,1 billion...
Well, maybe there will at least be some interesting papers that come out of it. Onward to OSIRIS-REx, another billion-plus dollar mission that I find myself trying to be excited for in its own right rather than thinking about the other ways that money could have been allocated. But at least we get a sample return out of that. Which is not just useful in its own right but also helps advance our experience with robotic sample returns, which is pretty limited (Luna, Stardust, and Hayabusa... and the Luna tech is obsolete). That said, the sample return results from Hayabusa were pretty underwhelming. Basically, "Hey, the sample return from this LL chondrite is just like LL chondrites on Earth". Now, Stardust had some interesting work come from it... but I just have a nagging feeling that we're spending a billion dollars to get a "Hey, the sample return from this carbonaceous asteroid is just like carbonaceous chondrites on Earth" moment.
1) A rocket is not "a mostly empty tube". A rocket is a heck of a lot more than just engines bolted onto tanks.
2) Only the Atlas V has Russian rockets, the Delta series use Rocketdyne engines.
3) None of this changes the fact that these are SpaceX's domestic competition, and they're not made by NASA. NASA hasn't been running commercial launches since the Space Shuttle, and even then they were a small fraction of commercial launches.