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Elon Musk Proposes City-to-City Travel By Rocket, Right Here on Earth (theverge.com)
SpaceX CEO Elon Musk unveiled revised plans to travel to the Moon and Mars at a space industry conference today, but he ended his talk with a pretty incredible promise: using that same interplanetary rocket system for long-distance travel on Earth. From a report: Musk showed a demonstration of the idea onstage, claiming that it will allow passengers to take "most long-distance trips" in just 30 minutes, and go "anywhere on Earth in under an hour" for around the same price as an economy airline ticket. Musk proposed using SpaceX's forthcoming mega-rocket (codenamed Big Fucking Rocket or BFR for short) to lift a massive spaceship into orbit around the Earth. The ship would then settle down on floating landing pads near major cities. Both the new rocket and spaceship are currently theoretical, though Musk did say that he hopes to begin construction on the rocket in the next six to nine months. In SpaceX's video that illustrates the idea, passengers take a large boat from a dock in New York City to a floating launchpad out in the water. There, they board the same rocket that Musk wants to use to send humans to Mars by 2024. But instead of heading off to another planet once they leave the Earth's atmosphere, the ship separates and breaks off toward another city -- Shanghai. Just 39 minutes and some 7,000 miles later, the ship reenters the atmosphere and touches down on another floating pad, much like the way SpaceX lands its Falcon 9 rockets at sea. Other routes proposed in the video include Hong Kong to Singapore in 22 minutes, London to Dubai or New York in 29 minutes, and Los Angeles to Toronto in 24 minutes.
Nothing but the best for the best people.
There is no way that this craft could be made safe enough for people to trust it. First accident, and no one wants to use it anymore.
There is also no way the launch cost and infrastructure required could be made affordable for city to city travel. Even a Concorde turned out to be unaffordable over the long term, and that was quite a bit simpler than this scheme.
HBI's Law: Frequency of calling others Nazis is directly correlated with the likelihood of the accuser being Communist.
Well this is one way to test anti missile tech
The point stands though that this is incredibly wasteful
love is just extroverted narcissism
I have been wondering one related thing: It seems that the Falcon 9 is built just around the maximum size they can manage to move by road.
Now that the rocket has become reusable, could they work around the transport issue by launching the empty rocket from the manufacturing plant and having it land right at the launch pad?
If this is actually viable it could be huge -- build wherever it's most comfortable to build, launch wherever it's most comfortable to launch. I imagine satellites are far easier to ship than the entire rocket, so this might even work to change the launch site to avoid bad weather.
So does keeping servers powered on 24x7 to host a web site for making "Beowulf Cluster" and "In Soviet Russia" jokes, but you don't see me not complaining.
So does keeping servers powered on 24x7
That's a damn lie! You take that back. Slashdot doesn't run 24x7 and you know it!
NK already has them, but they only sell one-way tickets.
Table-ized A.I.
The point stands though that this is incredibly wasteful
Elon said it would cost the same as an economy class ticket ... which means it would have to consume about the same amount of fuel per person as a conventional aircraft flight. Otherwise the cost couldn't be so low.
He is not "proposing" this idea--he's suggesting he can implement it.
The notion of suborbital/ballistic transport has been downright common for decades. The question isn't whether you could launch such a thing, or how long it would take, but rather the cost of propelling such a thing (and the willingness of anyplace to have an incoming object like this).
hawk
Elon has been saying a lot of things recently, doesn't mean it'll all come true.
Not necessarily. Unfortunately a lot of people advocating environmentalism don't have a clue about opportunity cost. It's incorrect to compare this to a zero base state - if the travel didn't happen at all. The correct comparison is to what would happen if this rocket travel weren't available. i.e. what happens right now? People fly between these locations. So the correct comparison is the monetary and pollution cost of a plane vs. rocket.
I haven't done the math, but I can see where Musk is going with this. The vast majority of the energy used by a plane on these long flights is overcoming friction with the air. A rocket eliminates that frictional energy loss by traveling above the air. In other words, the energy cost to fly on long flights is pretty close to proportional to the distance flown. While the energy cost to achieve a sub-orbital trajectory is very close to fixed (a fraction of escape velocity, with a slight increase in velocity translating into a very large change in distance traveled). So there's a certain distance beyond which the rocket will require less energy than a plane. If you can get the price of the technology down enough, a rocket between destinations greater than that distance will be both cheaper and less polluting than flying. The trip being quicker is just gravy.
Probably less than you think. An airliner flying 20,000 km uses about 400 kg of fuel per passenger. The payload fraction of the launcher can run as high as 6.5% (Space Shuttle, taking the whole vehicle as payload). The unfueled weight of airliner is about 400 kg/passenger, let us assume that as the payload; and the fuel + oxidizer weight is usually 90% of the weight of booster, and the fraction of that F+O weight that is actually kerosene is 1/3.56. So the RP-1 (kerosene) weight per passenger would be something like (400/0.065)*0.9/3.56 = 1550 kg, or about 4 times what a regular airliner. Now, currently about 20% of airline costs are fuel, labor costs are larger. So if they can save big on labor costs (you are "spam in can", no flight crew at all) then maybe they can hold the extra cost to 40% or so of the whole service cost. I don't see it competing with economy fares though.
Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
So does keeping servers powered on 24x7
That's a damn lie! You take that back. Slashdot doesn't run 24x7 and you know it!
It does, but neither the 24 hours or 7 days are contiguous.
It's incorrect to compare this to a zero base state - if the travel didn't happen at all. The correct comparison is to what would happen if this rocket travel weren't available. i.e. what happens right now? People fly between these locations.
Nope. Jevons paradox kicks in. If you can get between London and New York in 25 minutes for no more cost than an airline economy ticket, more people would be doing it than now, negating any savings in fuel consumption. Like aircraft are more efficient than ocean liners in terms of fuel per passenger-mile, but far more people travel by aircraft now than by ship in the 1930's and the total fuel consumed is greater.
Costs of space rockets compared with aircraft is not just about fuel. Rockets structures are more minimal than aircraft so are very highly stressed (to save weight). The amount of inspection, looking for fatigue cracks etc, that re-usable people-carrying rockets would have to undergo will be very expensive.
The BFR hold 240 tons of methane and 860 tons of oxygen. A 747 uses 10 tons of fuel and hour and carries 524 passengers. You can do your own math.
love is just extroverted narcissism
The point stands though that this is incredibly wasteful
The idea is to eventually create the methane fuel via the Sabatier process which converts carbon dioxide and water into methane. This is a necessary capability to refuel on Mars. Using solar energy to power the fuel manufacturing process would essentially make this vehicle solar powered.
Most noxious emissions from combustion are due to:
Once out of the earth's atmosphere, aerodynamic drag goes away. Which also might save some energy.
Please watch the entire talk. It's very informative.
One of our competitors trademarked the term "hypothesis". From now on, we will call them "boneheaded ideas".
The kinds of flights you'd use this on are around 20 hours. So the amount of 747 fuel use is similar to what the BFR holds (200 or so tons; the oxygen isn't fuel and the 747 needs to use that much as well, although it will cost something for the BFR to liquify it).
Presumably if the BFR can put itself into orbit with that much fuel, it can use quite a bit less to do a suborbital hop. The log in the rocket equation kicks in here, in favour of the suborbital BFR.
The BFR is supposed to take 100 people, and at least life support supplies on a multi-month trip to Mars. I wouldn't be surprised if you could pack 1000 people in airline seats into that space for an hour flight. Also, fuel is less than 20% of the cost of operating an airline. You realize quite a bit of savings by being able to use your aircraft to do 15+ flights per day instead of one.
The back of the napkin analysis suggests the idea, at least from a fuel point of view, isn't immediately infeasible.