We’re familiar with rockets, those controlled explosions that carry cargo and fragile humans to space. But are there some non-rocket ways we could get to space?
Want to go space? Get a rocket. Nothing else ever invented can release the tremendous amounts of energy in a controlled way to get you to orbit.
It all comes down to velocity. Right now, you’re standing still on the Earth. If you jump up, you’ll come right back down where you started. But if you had a sideways velocity of 10 meters/second and you jumped up, you’d land downrange a few meters… painfully. And if you were moving 7,800 meters per second sideways – and you were a few hundred kilometers up – you’d just orbit the Earth.
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Gaining that kind of velocity takes rockets. These magical science thundertubes are incredibly expensive, inefficient and single-use. Imagine if you had to buy a new car for each commute. Just blasting a single kilogram to orbit typically costs about $10,000. When you buy a trip to space, only a few hundred k goes to the gas. Those millions of dollars mostly go into the cost of the rocket that you’re going to kick to the curb once you’re done with it.
SpaceX is one of the most innovative rocket companies out there. They’re figuring ways to reuse as much of the rocket as they can, slashing those pesky launch costs, which ruin what should otherwise be a routine trip to the Moon. Maybe in the future, rockets could be used hundreds or even thousands of times, like your car, or commercial airliners.
Is that the best we could do? Can’t we just ditch the rockets altogether? To get from the ground to orbit, you need to gain 7,800 meters per second of velocity. A rocket gives you that velocity through constant acceleration, but could you deliver that kind of velocity in a single kick?
How about a huge gun and just shoot things into orbit? You need to instantly impart enormous velocity to the vehicle. This creates thousands of times the force of gravity on the passengers. Anyone on board gets turned into a fine red coating distributed evenly throughout the cabin interior. You can only get away with this a few times before your guinea pig passengers get wise.
“Steward, there’s bone chips in my champagne!”
If you extend the length of the barrel of the gun over many kilometers, you can smooth out the force of acceleration that humans can actually withstand. This is the idea Startram proposed. They’re looking to build a track up the side of a mountain, and use electromagnetism to push a sled up to orbital velocity.
This might sound far fetched, but many countries are using with maglev technology with trains and breaking speed records around the world. The Japanese recently pushed a maglev train to 603 kilometers per hour. This first version of Startram would cost $20 billion, and the tremendous forces would only work for any cargo being delivered in a non-living state, despite how it started out.
Even more expensive is the version with a 1500-kilometer track, able to spread the acceleration over a longer period and allow humans to fly into space, arriving safely in their original “non-paste” configuration.
There are a couple teeny technical hurdles. Such as a track 20 kilometers in altitude where projectiles exit the muzzle and venting atmosphere to prevent the shockwave that would tear the whole structure apart.
If it can be made to work, we could decrease launch costs down to $50/kilogram. Meaning a trip to the International Space Station could cost $5,000.
Another idea would be, unsurprisingly, lasers. I know it sounds like I’m making this up. Lasers can fix every future problem. They could track and blast launch vehicles with a special coating that vaporizes into gas when it’s heated. This would generate thrust like a rocket, but the vehicle would have to carry a fraction of the mass of traditional fuel.
You don’t even need to hit the rocket itself to create thrust. A laser could superheat air right behind the launch vehicle to create a tiny shockwave and generate thrust. This technology has been demonstrated with the Lightcraft prototype.
What about balloons? It’s possible to launch balloons now that could get to such a high altitude that they’re above 90% of the Earth’s atmosphere. This significantly reduces the amount of atmospheric drag that rockets would need to complete the journey to space.
The space colonization pioneer Gerard K. O’Neill envisioned a balloon-based spaceport floating at the edge of space. Astronauts would depart from the spaceport, and require less thrust to reach orbit.
We’ve also talked about the idea of a space elevator. Stretching a cable from the Earth up to geostationary orbit, and carry payloads up that way. There are enormous hurdles to developing technology like that. There might not even be materials strong enough in the Universe to support the forces.
But a complete space elevator might not be necessary. It could be possible to use tethers rotating at the edge of space, which transfer momentum to spacecraft, raising them step by step to a higher velocity and eventually into orbit. These tethers lose velocity with each assist, but they could have some other propulsion system, like an ion drive, to restore their orbital velocity.
Future methods of accessing space will be a combination of some or all of these ideas together with traditional and reusable rockets. Balloons and air launch systems to decrease the rocket’s drag, electromagnetic acceleration to reduce the amount of fuel needed, and ground-based lasers to provide power and additional thrust and pew-pew noises. Perhaps with a series of tethers carrying payloads into higher and higher orbits.
It’s nice to know that engineers are working on new and better ways to access space. Rockets have made space exploration possible, but there are a range of technologies we can use to bring down the launch costs and open up whole new vistas of space exploration and colonization. I can’t wait to see what happens next.
What alternative methods of getting to space are you most excited about? Let us know your thoughts in the comments below.
10 Replies to “Do We Really Need Rockets to Go to Space?”
Some of those alternatives would already be practical for launching small unmanned payloads (which are the most important kind). We could “easily” build a cannon (or laser, maglev ramp, etc.) powerful enough to launch a cubesat, for instance. (especially a very sturdy one). I doubt though that, in the near future, we’ll be able to build a cannon large enough to launch humans or big stuff like ISS construction components.
Seems to me, a system big enough (and safe enough) to launch humans would cost a trillion dollars, take 40 yrs to develop, might blow itself up, and would be obsolete before it was completed. Seems like you’d have to launch a real lot of stuff to get the costs *down* to $10,000/kg!
Balloons look particularly good to me as cheap, low tech launching platforms for small stuff.
In the not too near future I imagine using something like balloons or scram jets to carry rockets just high enough to reach something like an orbital tether that could lift them the rest of the way to low orbit. Being able to refuel or re-ship in low orbit would be great – therefore we need asteroidal ice mining & refineries in space.
I’m replying to myself to say, as for large scale, reusable, ground based launch systems: If it costs “only” $50 billion, with negligible fuel, financing and overhead costs, then you’d have to launch 5 million kg (5,000 tons) OF PAYLOAD to get the cost down to $10k/kg. I’m pretty sure (based on wild guessing) that’s more payload than all previous space flight combined. And all that would save zero dollars.
To get down to $1000/kg (making tourist flights to orbit cost a mere ~$250k, based on wild guesses), you’d need to launch ten times that, or 50 million kg. That’s about 200,000 space tourists paying $250k apiece. (Just for the ride up.)
You’d need 2 million tourists to pay $25k each to get it down to $100/kg. That’s a lot of launches. If spread out over a 20 year lifespan of the launcher, it’s almost 300 people a day. How big is a launch vehicle? If it hold 10 passengers, that’s 30 launches every day for 20 years. Hard to believe a launcher could work that hard for that long.
So I think: Balloons & smaller scale ideas have got to be cheaper, easier to fund, less financially vulnerable to obsolescence, etc.
* Space Elevators & Orbital Tethers
These are very unstable structures. You have to make the ropes as thin as you sensibly can, and even then they have to double in thickness several times just to support themselves. Add a bit of margin for error, and they double in thickness ten or twenty times. If anything goes wrong, and a rope snaps then half the structure flies out into space and the other half wraps itself most of the way around the world. It is a fun idea, but too brittle.
* Atmosphere skipping aircraft
More promising, but still tricky. The up side is you can load hydrogen, and take the oxygen (16 times heavier) from the atmosphere. The down side is the oxygen is mixed 1:4 with nitrogen, and the lot isn’t at rest. The Concorde’s Olympus jets had a standing shock wave to compress and accelerate the air on the way in, and get most of that energy back on the way out. A Scramjet uses a whole set of stacked shockwaves to do the same thing. You can get to about Mach 8, which is handy but not escape velocity, but no-one has got a scramjet flying for more than 15 seconds before they destroy themselves. We might be able to fix this, but we haven’t done yet.
* Rockets are a tough act to beat.
Yes, you have to take your oxygen with you. And you have to throw away the tube then the rocket is used, and go onto the littler rocket on top. And you have to push your way through the atmosphere, but, by the time you have got up any serious velocity, you are through most of the atmosphere anyway. And you can use the same motor for in the atmosphere and out of it, so you don’t have to bring on a second one.
See above. The rocket does not really spend a lot of its time pushing against the atmosphere. The height of the launchpad doesn’t make that much difference: you could launch from Kilimanjaro instead of Florida, but that just means a lot more work taking rocket bits up a mountain. Rocketoons are almost the same.
* Project Orion / Medusa (lots of atom-bombs)
You could leave the earth with this. But you might want to come back after you have launched a few.
That might do it. Leaving your power supply behind, rather than taking it with you is a great idea. Can you convert your energy into enough focussed light, or does the losses in conversion end up eating up the gains? The numbers do not look great.
I wish there was a good way of hopping into space. But I don’t see anything close.
I kind of like the idea of a rail gun/solid rocket combination to get to orbit. The track can be cut into a valley and curved up a mountain. It could start in the Rockies and across the Great Plains and up the Smokies. It could generate enough thrust to equal the first stage of a rocket ship. Then once at the proper height, the solid rocket boosters could finish the orbital insertion. The rail gun would be limited to how ever much energy you wish to pump into it. The solid rocket boosters would be limited to how much weight you wish to get to orbit. It’s a variable system which could even safely launch human cargo into orbit. It literally could be our only way to permanently colonize space. And best yet, we already possess all the technology. Just have to run the numbers.
What’s the estimated cost of a thousand mile rail gun? I bet the environmental impact report would cost a $billion. I remember failing to get the supercollider built in Texas. It cost $2 billion to not even build it. A thousand mile launcher would be 20 times longer. It’d be a hard sell.
The good news is, I don’t think we’ll need a megastructure for space colonization. Not one on Earth, at least. I think the best idea is, build stuff in space, out of stuff from space, for use in space. You could start (relatively) small, with ice mining & processing, and gradually scale up, paying as you go. Colonization would be (must be?) an unintended by-product of industrialization. And it would be profitable, instead of costing trillions. (Make profit by selling metals to Earthlings, among other opportunities. Sending stuff down is much cheaper than sending it up.)
My guess is, there won’t be a permanent colony until virtually all the infrastructure is already in place (put there for entirely other purposes) to make it possible.
Cuz honestly, as far as I can see, earthly taxpayers are never going to foot the bill for a permanent space colony. And probably they’d be right to refuse!
And, importantly, a colony launched from earth by NASA, for instance, without massive space-based infrastructure (raw materials, refining, manufacturing etc.), would be dependent on Earth (and earth politicians) for almost everything. The first time the taxpayers balked, or the next time the banking system crashed, the whole experiment would come to a sad end. It’s better my way! Lol.
The balloon prelaunch would be feasible if you use hydrogen instead of helium for lift, then draw down the hydrogen at the apex of the flight, add oxygen from on-board tanks to a small rocket engine for a final boost. The empty shell can then be used as a solar sail.
see http://www.h2liftship.com for more information
To get launch costs below $10 kilogram for LEO we need something radically different from conventional technologies and conventional thinking. Try:
The rational is briefly explained in “Beyond Einstein: non-local physics” by Brian Fraser (2015)
Traditional chemical rocket technology is mature and reliable and perfect for space launches! If they are reusable they only cost the fuel, which is 1-2% of the cost of the rocket. Even Skylon if it works technically, cannot compete with that. Rockets can run on natural gas (methane) which is available at practically infinite quantities and is now at record low prices.
There’s not even a problem to solve here, except for making the launchers reusable. The shuttle was reusable and now SpaceX, Blue Origin, ULA and Airbus (and who did I forget ) are seriously working on developing reusable launchers. It is about to happen, one way or another. Like any air travel, a space launch will only cost the fuel, and some overhead which also will be cut back as routine is gained. There’ll be a Ryan Air to space.
The “space elevator” would be horrible! Anyone who has waited for an elevator, or for a loo to become unoccupied, knows why. One at a time, at a distinct place and set time. It is a logistical nightmare. And it is on a geographically fixed place. One could build a space elevator on Phobos with today’s materials. But one could much easier escape its orbit with a trampoline. (Space tethers have other good uses, though, in microgravity).
One idea for propulsion that has me intrigued is the use of Entanglement.
1. Entangle a set of atoms
2. Take the counterparts of the entangled set to orbit around Mercury with some solar panels that impart energy into the entangled set of atoms.
3. Consume the energy where ever you want to (where the other set of entangled atoms reside)….since the energy state is instantaneously shared with the entangled set.
This is useful for not only propulsion systems, but really any transport of energy you need “anywhere”. A spaceship powered by energy from our star, but not required to have a conventional powerplant that produces energy (but merely consumes it) would reduce weight dramatically, and allows the system to run like some kind of uber-sterling engine that is fed from the outside.
Sure…keeping the entangled atoms….well, entangled for an infinite amount of time is something people are working on (well, at least longer durations), but if the author gets to make “pew pew” sounds in space with lasers, I get to dream a little too.
It is fun to think that I could turn on my light-switch on my spaceship in interstellar space from an immediate transfer of energy from Mercury. BTW, I selected Mercury simply because it’s efficiency would be higher than solar panels on earth. But in actuality, you could impart the energy to an entangled set of atoms from a hydro-electric dam…to your spaceship.
Also, I’m a big fan of the VASMRI propulsion system. However, you need to be in the vacuum of space, and this article is really about getting off the earth….and in that regard, a SCRAM/Rocket combo gets my vote for reuse/practicality and safety.
Good article and I enjoyed it.
I don’t think you can change the state of the atoms after they have become entangled.
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