"Once you get to Earth orbit, you're halfway to anywhere in the solar system."
- Robert Heinlein, science fiction author
While counterintuitive, Heinlein's statement is mostly true. Rockets routinely break the gravity bonds of Earth and coast to their destinations across unimaginably vast distances through the near-frictionless vacuum of space – using less energy than it took to launch the rocket into Low Earth Orbit.
Understanding space physics can humble the brightest of minds. Most Earthlings go about their daily lives secure in the knowledge that solar flares, asteroid impacts, and Hohmann transfer orbits all happen “out there,” not “down here.” Our culture tends to leave space physics to the spacemen, writing off thousands of space-inspired spinoffs as “inevitable advances”. Ignorance is bliss.
Soon, that attitude may change. A new consortium called ET3 (Evacuated Tube Transport Technologies) intends to revolutionize the transportation industry on Earth by leveraging the properties of space physics behind Heinlein’s quote: the lack of friction, air resistance, and heat conductivity in a near vacuum environment.
Physics textbooks devote whole chapters to the relationships between forces like friction, air resistance, heat, and kinetic energy – on Earth. These forces both help and hinder most popular forms of transportation. Moving vehicles usually require a dense fuel to create energy for acceleration and maintaining a steady velocity, fighting friction and air resistance while dissipating heat. Suddenly removing a force like friction from a body in motion usually leads to a messy situation (think fender-benders on icy Colorado highways).
Look Ma, no friction!
Yet the ET3 consortium hopes to do just that: someday remove friction – and air resistance - from up to 90% of all Earthly transportation, thereby reducing the cost of transport by a factor of 10. Your Denver Space Industry Examiner met ET3 CEO Daryl Oster at a recent DaVinci Institute event, where Oster presented the basic concepts behind ET3 and its ambitious goals.
By the way, the “Space Travel On Earth” title for this article came from Daryl’s business card. To find out why this is such a great slogan for ET3, keep reading!
Oster’s consortium envisions that nearly all cargo and passengers will travel through vacuum-sealed tubes connecting nations, cities, and popular local destinations. Consortium affiliates will build the tubes above the surface or underground, whatever is economically, legally, and logistically feasible for the particular location and traffic patterns. While a single tube provides a one-way, one-speed link, multiple tubes would enable travel in different directions and speeds.
Using electromagnetism, canisters in a tube can accelerate quickly. With current or near-future technology, tubes could zip a 400lb canister and its 800 lbs of cargo or human passengers to a local destination at about 350 mph. International travel could reach speeds ten times faster.
Imagine passengers grabbing a canister at a local distribution center – perhaps a Wal-Mart store, a sports stadium, a parking garage, or a bus station. Since each canister is small, light, and cheap, advanced scheduling would not be required (contrary to bus or train transportation). Just pass through a security checkpoint, hop on a tube, sit back, and enjoy the ride in your own personal carriage. The system would operate like a network of taxis – without the high fares and white-knuckle lane-changing.
As it travels through the tubes, a canister expends very little energy and produces minimal heat or waste of any kind. That’s the space part. The key to waste-free transport is to remove all air resistance (vacuum) and friction (contact between the canisters and tube walls). Each canister is, in effect, a small, pressurized, personal space vehicle, coasting to its destination much like a spacecraft travels through open space to another planet - all within a sealed tube. Is that not the coolest concept ever?
Superconductive rails eliminate friction from the system much like the “maglev” surface railways already operating in China, Japan, and South Korea. However, maglev railways must expend energy during the trip to compensate for air resistance. Other maglev complications include bad weather, debris on the track, and inconvenient scheduling options.
Yet maglev research and demonstration projects continually push ET3 and related technologies forward. University researchers have jumped onto the bandwagon as well. This cool video illustrates some basic concepts – in a simple table-top environment.
Air pumps placed at strategic intervals would create and maintain the near-vacuum inside a sealed ET3 tube. Adequate air pumping technology already exists, as does the material technology for building walls capable of holding a near vacuum for long periods of time. Round tubes actually gain structural strength from an internal vacuum, as opposed to a typical pipeline prone to bursting because the liquid or gas pressure inside exceeds the outside air pressure.
As with maglev demonstration projects, the construction cost is a difficult issue to overcome. A ten mile demonstration stretch of ET3 tube could be built – perhaps at a theme park in the US - for around $10 million. Component costs should drop substantially once mass production kicks in. When comparing the initial construction costs and maintenance concerns to comparable train or highway systems, ET3 should prove quite economical – eventually – but getting there could be a bumpy ride (no pun intended).
At about this point, some astute readers might be asking, “OK… why not abandon the vacuum stuff and increase the air pressure behind the canister, shooting it forward like a air gun?” Answer: this may work well for one canister… but each tube will carry many, many canisters at the same time. In fact, assuming a 350 mph canister velocity and adequate safety margins (discussed below), a local tube could easily replace the equivalent vehicle mass of a 40 lane superhighway. If that doesn’t pique your interest in the concept, it really should… especially when you consider how dangerous a 40-lane superhighway would be.
Safety: a major selling point or an Achilles Heel?
So now we’re putting many canisters within the same tube. What happens if they collide? How do we manage all these cargo pods or human-laden vehicles all going to different destinations?
Currently, the brief answer is: self-switched network management. ET3 envisions a system where canisters in a tube network operate like self-routing packets on a data network – with some important differences and restrictions.
As with packets in a data network, all canisters in a tube must move at the same speed and maintain adequate physical separation. These two requirements eliminate most of the concern with canisters colliding with each other within a tube. Even at high speeds like 350 mph, distances can be controlled down to several inches, so two canisters should never collide with each other once they’re in the same tube – under normal conditions.
But the network consists of multiple tubes and speeds. When a canister of lawnmower parts leaves the factory in St Louis destined for a Wal-Mart distribution center in Denver, the initial velocity of the canister is zero. It must accelerate – then merge into a local tube – then perhaps switch tubes, accelerate again, etc, depending upon the location of the factory, its neighborhood volume, time-of-day commuter traffic, special events like a St Louis Cardinals World Series game, etc. Eventually, the canister would merge into a higher speed regional tube that zips it to the Denver area where it must reach the Wal-Mart distribution center through a similar deceleration and routing process.
Due to these complications and others, the ET3 consortium suggests that each tube should strive to allocate only one-third its maximum capacity. This conservative strategy frees plenty of bandwidth for mild surges in volume without posing much of a safety risk. On and off ramps facilitate the acceleration and deceleration phases. All such ramps must be planned carefully - and redundantly – so they don’t become choke points.
The biggest problem with this approach is that it won’t work all the time. In a self-routing data network, servers and routers sometimes experience severe overload. Imagine the tube traffic congestion around the St Louis Cardinals World Series game mentioned above. Self-routing packets could easily find themselves unable to reach their destination, but they must end up somewhere. Physical canisters can’t be “dropped” from the network like routers drop data packets when buffers overflow. Perhaps red-and-white clad baseball fans would be rerouted across the Mississippi River to East St Louis or miles westward to Forest Park?
Fortunately, these and other network problems have potentially simple solutions. Besides the packet-loss problem, our data network analogy breaks down in other, beneficial ways when applying it to networks of bulky canisters traveling hundreds of miles. Even when moving at the fast physical speed of 350 mph, loaded canisters appear stationary to the centralized network of light-speed computers controlling them. Canisters in a centralized network could avoid congested areas if each canister files a “flight plan” (like a private pilot would file with the FAA). A centralized network could easily predict overload conditions anywhere along the route or at the destination, preventing a canister from entering the network until its entire route was reserved. Compared to a data network, there just aren’t that many packets, and they’re moving sooooo sloooooowly…
According to Oster, "... another way to reduce congestion and ensure reserve capacity at peak demand times could employ demand pricing, or an auction system." Network priority can be given to passengers who pay more or agree to listen to advertising along the route - both potentially lucrative options for the people running and maintaining the network. Conversely, rates can drop during off-peak hours, especially for low priority cargo transport.
The discussion above is a taste of the numerous questions surrounding the concept of tube transport. No doubt, the ET3 consortium will develop even better strategies as they demonstrate and implement this promising technology.
Around the world for $7
Rather than lugging along a bulky engine, wheels, struts, and fuel tank, each ET3 container carries a small reservoir of (non-toxic) liquid nitrogen. About $7 worth of liquid nitrogen would enable a seven hour journey, enough to travel around the world at the higher speeds of 4,000 mph envisioned for international tube transport. At these higher speeds, passengers could travel from New York to Beijing in about two hours.
These numbers may be quite conservative. In reality, Oster is confident the system could operate even more efficiently. "In a vacuum, heat gain is much less, so we anticipate cooling costs less than 10 cents per hour. Energy cost for 4,000 mph trips will be about $2.50 per stop."
System operation requires very little electricity. Most of the energy that accelerates a tube canister can be reclaimed upon braking. Air pumps for maintaining the vacuum, routing and switching equipment, life support, and control systems also require minimal energy expenditure. Backups (batteries?) must guard against full power outages, maintaining enough electrical power to cleanly shut down the system in case of catastrophic failure.
All things considered, total energy costs could feasibly drop below 1% of the operational cost for an average automobile or jet airplane.
With a concept this simple, what could possibly go wrong?
Besides the routing and power issues discussed above, planners envision many other potential failures. No method of transportation is perfect, and in the aggregate, ET3 believes their transportation network would be far safer than any other form of transportation ever attempted. Let’s speculate briefly about other things that could go wrong, keeping in mind that accidents will happen – and do happen thousands of times on city streets and freeways around the world every day.
Since each ET3 container doesn’t carry flammable fuel, a worst-case high-speed crash would bear little resemblance to a crash of a powered vehicle today. Kinetic energy would kill the occupants, for sure (hitting anything at 350 mph would be a Bad Day), but explosions and major secondary damage seem unlikely.
The threat of terrorism takes several forms. A bomb on a container could destroy a tube and perhaps some surrounding infrastructure. The situation is worse for international travel, such as the New York to Beijing route mentioned above. Repairing a damaged or destroyed tube somewhere underground in Alaska will be more difficult than repairing a surface tube in Kansas.
Passengers could create other emergencies, like somehow puncturing the pressure seals or hardened walls of a container. Any major drop in a container’s internal air pressure must trigger an alert and immediately flood the local tube with outside air (difficult in some underground or underwater stretches, but possible). Such an event would shut down the whole tube for a brief time, until containers could be cleared out and rerouted, but are unlikely to cause any loss of life.
Oster puts the various train-like risks into a proper perspective. "Trains are about 1/10th the risk of flying, and flying is about 1/15th the risk of driving in a car. Driving in a car is an acceptable risk for most of us, yet car wrecks are the leading cause of accidental death for Americans under about the age of 70."
When will we see ET3? And why should I get involved?
The ET3 Consortium actively seeks partners to help research and develop the concept. Monitor their website for the latest status and for opportunities to participate.
Among the obvious reasons for getting involved on the ground floor of a revolutionary project like this (i.e. making truckloads of money)… consider the impact of a system like ET3 on the psyche of the American public. Tube transport through a vacuum is so obviously “space technology” that not even the most hardened anti-space critics can deny the contribution and legacy of space technology research. This one project can potentially do more to brighten the funding outlook for space exploration (public and private) than any other effort ever attempted – in space or on Earth.
And if that isn’t a great reason for space advocates to rally behind ET3 and work to implement it, I don’t know what else ever could be.