Elon Musk's ideas are in the news right now, rockets with first stages that fly back to a soft landing under auto pilot. But you might be surprised to learn how many other ideas there are under active development, for low cost ways to get into orbit.

The British Skylon would fly directly into space from a reinforced airport, taking off like a plane, without need to discard anything (single stage to orbit). Then JP Aerospace plan airships to float up to 200,000 feet followed by transfer to a lighter than gossamer skinned, "orbital airship" that never lands, but can accelerate gradually through the near vacuum of the troposphere and above, to orbital velocities.

Other projects remain ideas, but worked out in some detail, and may be practical if funds become available. This includes, many ideas for single stage to orbit - tethers to pluck an airplane traveling at Mach 12 out of the atmosphere and boost it up to LEO at Mach 25 - lightweight craft propelled into space on a laser beam -  space guns to fire materials such as water and fuel into orbit - super fast trains that accelerate to orbital speeds along Maglev tracks - and many more ideas.

Then you have the future dream of a space elevator made of exotic materials, which would let you go up in a lift to orbit from the Earth's equator - and more practical versions of this space elevator which could be built with present day technology on the Moon and on asteroids.

I thought it would be fun to look at some of these projects, first, and then I'll ask what our world will be like if we can fly into orbit as easily as we can cross an ocean in a plane. We have tens of thousands of planes in the air every day, and millions of flights a year. 

Here is the FlightRadar map showing many - though not all - of the flights currently in the air just now. It relies on technology not yet fitted to all planes, and they also rely on amateurs to record and relay the data - for details, see their FAQ. ( another live map with commentary from the Guardian newspaper - and more live maps) For comparison, you can go here to find out how many people are in space right now.

What if we had a million spaceflights a year?

That world may not be too far away, perhaps a couple of decades into the future, if any of these ideas pan out. Or it might be that none of them work and it's fifty years from now. Still many of those alive today may live to see this world - what will it be like?

There would be countless benefits from space to help the Earth - almost unlimited energy, no more dirty mining, minerals and rare elements in abundance. But also many challenges also. How can we make a safe transition to a world where every country and many private individuals have the ability to fly at speeds of satellites or faster - to anywhere in the world? Also interstellar travel of space probes at least might not be so very far away - at slow speeds, but perhaps with surprising implications for the future of humanity.

First though, let's look at some of the ways it might become easy to go into orbit.


First, let's look at SpaceX because they are in the news, and are closest to actually achieving low cost flights to orbit, even interplanetary flight - though they probably have a fair way to go to reduce costs to match an airplane flight over an ocean.

Their innovative idea is to re-use the first stage boosters for the rocket. These are expensive and complex engines that are just thrown away and destroyed with most rocket flights. It's like building an airplane for a single flight, to do that and it's no wonder spaceflight is so expensive. Even with SpaceShuttle, the boosters were discarded after each flight.

Their spacecraft will have that capability also, to land like a helicopter.

They have made lots of progress on this, here is a recent video of one of their spacecraft taking off, and then landing again, just like the rocket ships in science fiction

Their plan is to land the boosters like this also, see this video explains the concept:

They are in the process of testing this as well in a series of tests - the most recent one landed the booster in the ocean, here is an artist's impression

News story about it on SpaceflightNow

The way SpaceX are going, perhaps in a few years rocket flights like this will be routine, hugely reducing the cost of going into space.


This is a UK project, called Skylon, a jet that can fly directly to orbit. It would launch from an ordinary runway - like an airplane - the runway needs to be strengthened but is otherwise normal. And it doesn't need booster rockets at all, it carries all its fuel on board.

Artist's concept of it taking off into orbit

It burns a mixture of hydrogen and oxygen, but in the early stages it gets the oxygen from the atmosphere. It does that by a remarkable system that cools down the incoming air by 140C in a hundredth of a second, so can take in the air and still use lightweight materials.

 has a massive reduction of fuel needs because it is air breathing in the early stages of its flight.

This is under active development right now, they are working slowly but steadily towards their goals. So one day it might happen.


This is the classical "rocket" of science fiction and it's been explored many times.

This is a 1970s idea for a single stage to orbit vehicle, which would land like the SpaceX booster after delivering its payload to orbit. Nothing is discarded. This shows the return:

And this is the vehicle itself. It makes  sense to return base first because that part of the spacecraft is already designed to withstand high temperatures.

There were earlier ideas also, in the 1960s, and earlier. Here is the 1960s Douglas SASSTO artist's impression.

One of the most developed ideas to date is the Delta Clipper. This was able to take off, and then land again, just like the SpaceX rocket, but this is back in 1995.This is the Delta Clipper. This was able to take off, and then land again, just like the SpaceX rocket, but this is back in 1995.

It was only intended as a proof of principle, and wasn't capable of gong into orbit at this stage. So we can’t compare it directly with the SpaceX rockets. But they did have the plan for the future that eventually it could become a fully automated, reusable, single stage to orbit space shuttle for unmanned cargoes - and it could also take humans. As with the Russian Buran version of the space shuttle - they wouldn't need to pilot it as it was fully automated.

It started as a Strategic Defense Initiative project, in collaboration with McDonnell Douglas, the McDonnell Douglas DC-X and it flew three times successfully in 1993. NASA took the project on after funding ran out in 1995, rebuilding it as the DC-XA. They did the first test flight in 1996, and it flew three times successfully, the third one to a height of 3,140 meters on the 8th June, each time landing vertically. The last attempt on 7th July failed however. A landing strut failed to extend and the whole vehicle tipped over as it landed and blew up:

It was beyond repair, and they would have had to build a new one to continue the tests. That’s when NASA chose to cancel the project. McDonnell Douglas DC-X

Their eventual aim was more ambitious than the Falcon 9 and simpler - instead of returning each stage separately - then refurbishing them and then putting the rocket together again for the next launch, they were exploring the idea of a single stage to orbit vehicle, which would land like the SpaceX booster after delivering its payload to orbit. Nothing is discarded, no need to put the rocket back together again from re-used stages. The whole spaceship returns to Earth.

However they didn’t get that far in those tests, because the project was canceled after only seven flights total (only four of the rebuilt DX-A),

This is not a new idea. It goes back to the 1970s, but the delta clipper is the closest anyone has come to date to actually make it, except perhaps for the Blue Origin “New Shepherd”.

This also is similar to what Blue Origin are working on at present. They were first to achieve a successful vertical landing in modern times, since the Delta Clipper. SpaceX did several attempts but they crashed, and Blue Origin achieved a successful vertical landing before SpaceX.

They went much higher than the Delta Clipper, to the edge of space, over 100 km. This is their first test flight:

It’s a single rocket and a separated crew capsule that parachutes down separately after the suborbital flight. This is just a test flight, no crew on board.

Again - it’s just a sub orbital flight so far.

Still it is fully reusable. So far, the Falcon 9 is only partly re-usable and needs a rebuild after each flight. Also - so far only the first stages of the Falcon 9 are re-usable.

As for re-usable stages like SpaceX - then ESA also looked into that for their Ariane rocket - and so that’s not a new idea either - but they decided they didn’t have enough launches a year to make it worthwhile.

There’s a lot of upfront cost involved in setting up the capabilities to re-use the stages - and the main reason SpaceX can contemplate that is because they have so many more launches a year than the likes of ESA.

What SpaceX achieved is more difficult in some ways than what Blue Origin and Delta clipper did, see Why you shouldn't compare Blue Origin's rocket landing to SpaceX

There have been many many other ideas for single stage  vehicles to orbit and low cost ways to get into orbit or for sub-orbital flight. Most of these are no longer under active development. 

For a huge list of many other single stage to orbit spacecraft, with images, see Space Vehicles at Spacefutures.com. Also, see the Wikipedia article on Reusable launch systems.


This is a neat idea, but so far has only been tried in small scale demos, to raise models a hundred feet or so on laser beams


Just mentioning it for completeness, it might, who knows, become the standard way to get into space some time in the future, but is a long way from achieving that potential right now.

A related idea is a mixed laser or microwave system supplying energy, and fuel on the rocket. See Laser Propulsion Could Beam Rockets into Space, and Jordin Kare's talks to the Space Show.


A balloon filled with hydrogen or helium could rise almost indefinitely - if the skin is light enough, even close to the boundaries of low Earth orbit. This is a very low cost method because no fuel needs to be expended to do the lifting itself.

JP Aerospace plan to make airships that would rise to orbital platforms at 200,000 feet - so that's 60 km, in the mesosphere - above the stratosphere, near vacuum conditions.

They have the current altitude record for an airship for an unmanned but manoeuvrable airship of 95,085 feet, or 29 km

JP Aerospace Airship Flies to the Edge of Space, Smashing the Existing World Altitude Record

The maximum height achieved with any ground launched balloon so far is 56 km with a NASA experiment Bu60-1 

This is the highest flying balloon ever at 56 km, on the edge of space
ISAS | BALLOONS:Research on Balloons to Float Over 50km Altitude / Special Feature

JP Aerospace plan to build airships that set off at a level higher than the highest flying balloon ever - huge airships made of such light materials that they couldn't be inflated at ground level.

These would be truly orbital airships - slowly accelerating to Mach 20 and greater.

When they set off from their base station at 200,000 feet (60 kms), they would be just floating. It's almost a vacuum inside the ship, yet still, because it is filled with hydrogen or helium, contained by the skin, then the lighter atoms of hydrogen or helium will float on the denser almost vacuum of oxygen / nitrogen outside it.

LEO starts at around 160 km Low Earth orbit

They would accelerate to orbit slowly over several days, by using ion thrusters. First they use a combination of lift and velocity - and eventually travel at orbital velocity at levels too high to get noticeable lift.

This idea of Mach 20+ airships accelerating to reach orbital velocity may seem absurd at first, it did to me when I first read it. But the more you think about it, the more it begins to make sense.

We launched several balloons to LEO in the Echo program, so there is no problem with balloons once they reach LEO. The problem is the transition between high altitude and LEO. For that, we want to find out about suborbital balloon flights. Those are rare.

An early experiment sent one of these balloons into a sub orbital hop which it survived for most of the hop and disintegrated eventually. When it did explode, this was mainly because they made a mistake and left too much gas in it. 

That isn't much by way of experimental data, as this seems to be the only example of a suborbital balloon flight to date. Also that's with a small balloon not the huge kilometer scale airships of JP Aerospace.

Still, what data there is, is reasonably promising that the high speeds of the balloons won't be a problem so long as they are well above most of the atmosphere in close to LEO vacuum conditions by the time they approach orbital velocities. At any rate, JP Aerospace don't consider this to be their main challenge.

You can hear John Powell, the man himself talk about it in a recent Spaceshow talk, and decide for yourself. They have a very interesting philosophy also, it's a company that does its development in the slow lane. They've been working towards this for decades and finance their development by the discoveries they make along the way. 

Find out more here: Guest: John Powell. Topics: Updates on JP Aerospace and the Airship To Orbit program.


This is a short speculative section for discussion.

JP Aerospace are working within the limits of present day materials and technology. But what could the future bring for orbital airships?

We do have extraordinarily light materials we can create in small pieces and might eventually be make into large sheets. 

Especially if you could make a balloon out of graphite sheets, for instance - and if you could make it impervious to helium so it can contain the gas - who knows how high a balloon could float with future materials just under its natural bouyancy? See for instance, Atom-thick carbon sheets set new strength record

Maybe airships made of strong materials such as this could fly all the way to orbit from the ground?


There are various ideas for ways to, basically, drive most of the way to orbital speed on a Maglev track. 

A Maglev train is a natural for acceleration to super fast speeds of kilometers per second - as it has no on board fuel, gets all its energy from the track so no need to accelerate the fuel. And also as there is no physical contact with the track, friction can be almost zero.

First, there's the idea of some researchers for a long MagLev track which accelerates a spaceship inside an evacuated track up the side of a mountain, continuously until it reaches orbital velocities when it leaves the tube. They think this could cost $20 billion to build and it would cost about $50 per kilogram to get cargo into orbit, and the project would take about ten years to complete. For details see Maglev track could launch spacecraft into orbit

That's for cargo.

You could send passengers too, but would need a longer railway line, and slower accelerations, would take longer to build and cost more.

Maglev track could launch spacecraft into orbit.
This track is magnetically elevated

Then more exotic, is the idea of a kind of "moving walkway" Maglev track, that elevates into the sky under centrifugal force". There are many ideas like this, but this is one of the simplest and most practical of them. 

The loop continually moves around like a moving walk way from one end station to the other and back again. The loop is elevated away from the Earth by the centrifugal effect of the moving walkway. This centrifugal effect raises the centre portion of the track to about 80 km. Then, much as before, the vehicles accelerate along the track until they reach orbital velocity, and release themselves from the track to launch into orbit, See Launch Loop (wikipedia)


A surprising thing about these dynamic structures held up purely by kinetic energy of rapidly moving liquid or particles - there is so much energy in the system, and so little loss, that if you stop supplying energy, they lose it only gradually. It's rather like energy stored in a flywheel or a gyroscope. Stop supplying energy and the flywheel keeps spinning, it doesn't just stop instantly. They deserve close attention, and are not as way out and crazy as you might think when you first encounter them.

For other ideas like this, see the Dynamic Structures section in Wikipedia


This is the idea of an elevator, just a cable that goes from the Earth's surface all the way up to geostationary orbit and beyond. 

The physics is sound but materials are not yet strong enough to build it. Steel, titanium etc can support 20 to 30 of kilometers of its own weight in an untapered cable (can go up higher if the cable starts very wide and tapers).

For a tether able to go all the way from geostationary to the surface - well it doesn't need to support it's weight under full gravity all the way, but it still turns out, you need a material able to support thousands of kilometers of its own weight of cable. 

For that you need carbon nanofibres, which are just strong enough - but with no safety margin, and in any case can only be used to make tiny, microscopic even, sections - certainly can't yet be made into a long cable.

See the wikipedia entry: Space elevator -cable

You can reduce the required strength of the material with a tapered space elevator - but that also increases its total mass.

For details, looking at various materials that have been made so far, and to see how close or far we are from having the materials needed, at various tapers, see

The Spaceward Foundation - When

The details are pretty well worked out, ready for some future time if we have a strong enough material. We might have this in a few decades. You'd need a counterweight to keep the cable stretched and the cable would go beyond geostationary orbit. 

It would then be very easy to go into space. The gravity goes down slowly as you go up the cable, is zero at geostationary - and then you get the centrifugal effect pushing you away from the Earth after that. Spacecraft could accelerate along the track away from the Earth just under the centrifugal force and build up speed in that way - assisted if needs be by MagLev driving along the track.

However, you don't even need to do that with a space elevator. Just by releasing payloads at various points beyond geostationary, they have the delta v needed to go to various places - either the moon, or elsewhere in the solar system. Indeed if you just release a spaceship from the end of the tether and it has enough delta v to go to Jupiter without need to use any rocket fuel at all to do it Space elevator - launching into deep space

That's for the future of course, as we don't have the materials yet to build it.


But you can do a space tether from the Moon with existing materials. because of the lower gravity. 

The best way is to do it from the center of the near side of the Moon going up through the L1 position towards the Earth. You could build that out of kevlar for instance, though the authors take as their reference material a similar stronger material called M5 fiber

Here is the paper about the lunar elevator design Lunar space elevators for cis-lunar space development.

It is something you could, at least according to the author of the paper, do within the budget of a return of humans to the Moon, and could launch tens of thousands of tons of material from the lunar surface which you could then use e.g. to build settlements in space or whatever, Might be a better way of doing that than the rail guns of the Stanford Torus design.

The  LiftPort Group have plans to actually create this lunar elevator. They did a successful Kickstarter project as an early phase of their project. Space Elevator Science - Climb to the Sky - A Tethered Tower. Here is their page about it Lunar Elevator | LiftPort Group

LiftPort plans to build space elevator on the Moon by 2020


You can also use elevators for launching materials from rapidly spinning asteroid. Asteroids normally do spin, and if your asteroid rotates quickly enough, you can attach a space tether to it. Then you can use that to launch  materials to the Earth, or anywhere else in the solar system you need it.


You can also use a similar system for diverting asteroids. If it's projected to hit the Earth, and spinning, as most do, you could attach a tether to it, and by mining the asteroid and sending the material away from it in calculated trajectories (hopefully do something useful with the material at the same time) you could divert its course.

Another idea involves a permanently attached counter weight to change its centre of gravity and so its orbit. It is a minor effect in this case, but someone looked into it and found it could make a difference for light weight comets and asteroids. See news article - and then the paper:  Asteroid Diversion Using Long Tether and Ballast


This is perhaps a bit of a digression from the main theme, but while we are on the topic can't resist mentioning it as it is such a fun idea.

Tethers can also be used as a way for spacecraft to do a slingshot type change of course - but instead of using gravity as you do for huge planets - instead it just throws out a grappling hook, as it were, on the end of a long tether as it approaches. This then diverts its course around the asteroid, and then when it reaches its desired course change, it releases the tether.

This is an old 1986 paper describing the idea: Tethers and asteroids for artificial gravity assist in the solar system


You also have the idea of a Rotovator, - this is a tether that's not permanently connected to the ground, but instead - e.g. for the Moon - you have it spinning around a center of gravity in orbit - and once every orbit it touches ground - and you arrange it so that it is spinning against the orbital velocity in such a way as to exactly balance out, so that it's stationary relative to the ground when it touches the ground. So then you can put materials into it at that point and is an easy way to transfer those materials into orbit. 

This animation of a rotating wheel with a point on the circumference traced, shows how the rotovator is able to achieve zero horizontal velocity as it approaches the ground. It's similar to the principle of a wheel in transport - though a car moves at great speed, the portion of the wheel that touches the ground, momentarily, doesn't move at all.

You can have similar ones like that in Earth orbit, but of course not touching the ground, and you can have shorter ones - so the lower tip is simply rotating at a rather slower orbital delta v so easier to get to from the ground, gets rid of the need to accelerate once you get into orbit, or not so much.

And one idea takes that a bit further, and has the tip actually extend down into the atmosphere. Although with existing materials it couldn't be stationary at the Earth surface, it would be able to snatch a rocket or extremely fast aircraft in a suborbital trajectory --, and fling it into high orbits. 

Normally, you need about Mach 20-25 to go into low Earth orbit (depending on how high), by comparison, Virgin Galactic would go at about Mach 3, and the unmanned HTV2 Falcon Hypersonic Technology Vehicle 2 at Mach 17, and the North American X-15 at Mach 5.4 approx. (using Miles Per Hour to Mach Numberconverter) - those two are Rocket-powered aircraft.

The launch assist tether reduces that to Mach 12 or less See Launch Assist Tethers

This requires constant input of energy as the tether would slowly de-orbit - loses delta v every time it does one of these gravitational assists. But it can get the energy back again by using solar power and then sending electric current along the tether to accelerate it back into orbit using the Earth's magnetic field for a motor.

This was fully worked out in a plan called the Hypersonic Airplane Space Tether Orbital Launch (HASTOL) System

T hen finally, remarkably, you can have a complete transportation system combining a rotovator in lunar orbit, and a gravity assist tether bolo in LEO - and then because the Moon is higher in the gravity well, if you arrange things carefully, then simply by dumping lots of lunar dirt into the tether system continually at the lunar end - that can power up the whole system, giving all the energy you need to send materials from Earth to the Moon - and simultaneously transferring lunar materials to LEO or to the Earth itself. See the cislunar tether transport system architecture

There are many other ways of using space tethers. I got most of this from Wikipedia, then of course, following up the links to check what the original links say. For more information, see for instance Space elevator, and Momentum exchange tether, also Non-rocket spacelaunch


We have a billion airplane flights a year at present. What would the world be like if we had a billion similarly priced flights into space every year? 

Then, what if we can get into space as easily as we can sail a boat across the ocean right now?

If any of these ideas come to fruition, that might be the reality, say 50 or even 25 years from now. After all 25 years ago (the 1990s) hardly anyone had a mobile phone, the internet was in its infancy, didn't have GPS, or skype or facebook etc, we were still in the cold war and hardly anyone had heard of global warming.


There would be many benefits for sure. Easy to construct solar power satellites to beam clean uninterruptable energy back to Earth. That could mean an end to global warming issues, and low cost electricity for everyone. That would benefit the poor people most of all.

Then, in same world, we'd have low cost materials mined in space, moving all the "dirty" mining technology away from Earth into space where, if we are careful, it can do no harm, in the vastness of space. 

And fast transport on the Earth - could go from Europe to the US with only 12 minutes travel time (though surely with overhead in the airports, and launch and take off).

There would be countless benefits like that. 


This might be the first and most immediate benefit from space industry for the Earth.

Either the satellites are light weight and sent from Earth - or costs to launch from Earth have gone right down - or they are constructed in space. There have been many ideas like this, back to the Stanford Torus design and earlier.

The big advantage over Earth based solar power is that solar power in space is uninterrupted, while solar power on the Earth is interrupted by night, and clouds, and by the long winter nights in the higher lattitudes.

We do get plenty of solar power on the Earth - and now we also have methods of long range transmission. It might be, that solar power and other renewables gets cheap enough, and storage capacity increases enough, so that we don't need to think in terms of solar power satellites to solve our energy problems.

But solar power from space could be a significant part of the mix for a clean energy source in the future.

There are various ways to make it safe to beam energy from space. One of these is to use many low energy beams, designed in such a way that they can only focus on a ground station if it gives them a beacon to aim at - and make sure that even when focused like that, energies are so low it is eye safe. With these designs, you could walk right through the collection area and look up at the solar satellites and still not damage your eyes. See for instance Space Based Solar Power (SBSP), at Airbus.


Mining in space might be easier than you would think. Yes, of course, it's pretty hard to get the mining gear to the asteroids in the first place. But once you've done that- and you only have to do that once, or rarely - getting space materials from space back to Earth could be easier than you'd expect.

First - since you only have freight to transport, it's like shipping oil or ore, there is no hurry. You can use solar sails and gravity assist and trajectories that involve multiple flybys of the Earth, Moon, Venus or Mars also if it helps, depending on the original orbit. It might take years to return your cargo, but if it costs much less per ton to do it that way, you would probably do it.

There are many NEOs that come close enough to Earth to make return of materials relatively easy and they would make attractive first targets. You can also use the mini space tether idea to use natural rotation of the asteroid to propel the materials into space - in that case then they might use hardly any fuel at all to get back to the vicinity of the Earth.

That gets it back to the Earth Moon syste. To return materials to Earth, you have to target the Earth's atmosphere and to hit it slowly enough so that the materials you mine don't burn up in the atmosphere. You might do aerobraking first to reduce speed, and then over a period of time, skimming the atmosphere, lower the orbit to make the landing gentler.

When you are ready, then actually landing the materials on Earth is relatively easy. To make sure there is no risk of damage to Earth, if the parachute or aeroshell fails to deploy, make sure you send the materials in small amounts, small enough to burn up in the atmosphere in its entirety without the aeroshell - and equip each one with an aeroshell and parachute.

Conventional aeroshells are likely to be too complex  to create on-site at least at the early stages of development, and too heavy and so too costly to export from Earth. But there's an alternative here, the ballute, an inflatable balloon that works like an aeroshell

See the New Scientist article Inflatable cushions to act as spacecraft heat shields, and this article Profitably Exploiting Near-Earth Object Resources

Space mining would probably start with mining of water from asteroids, for use in LEO and other spacecraft missions, as suggested for instance in this article Asteroid Usage by Planetary Resources, an asteroid mining company - because of the high cost of supply of materials to orbit, making it far easier for the mining to turn a profit and pay for itself. But later, funded by the sale of water to space agencies, it could then move on to mining metals and other resources useful for Earth itself.


This is a natural thought as a way to dispose of high level nuclear waste, if you can get safely to orbit. With low cost transfer of materials to space, if you could do it safely as well, you could send any extremely hazardous waste into space. 

You could fire it into the sun. The numbers though don't add up, it's really hard to hit the sun from the Earth as you have to counter nearly all of the Earth's orbital velocity one way or another - by rocket launch or by flybys. 

You could, more cheaply, send it into interstellar system, out of the solar system. once you have ways to send material with escape velocity more easily. See Shooting for The Sun

Nowadays these issues are not so acute since we have programs to burn long lived nuclear waste in reactors and the possibility of turning the shorter lived waste into synthetic rock, and such like ideas being explored.

Still, sending hazardous wastes into space and into the vastness of interstellar space has its attractions once spaceflight is far lower cost especially if you can send non living cargoes into space for dollars per ton. Perhaps have reprocessing facilities in space. 

It's the close proximity of Earth life that makes the wastes hazardous on Earth. In space, with no living creatures to be harmed by them, then it's not the same issue. You need to make sure they won't get back to Earth or anywhere else that will be hazardous for life.

Perhaps they even be useful in space for various things.

One might well have mixed feelings about mining the asteroids or sending wastes into space or doing industrial operations with hazardous biproducts in space. 

Space is vast and the asteroids numerous almost beyond imagining. Yet - some feel unsure if we should exploit it at all.

Still, we might well do, and the benefits for the Earth could be huge. If you have thoughts about this, do say in the comments!


Our rockets or planes might not only thrust during lift off. They may have powered flight throughout the entire orbit by then if we have, e.g. easy portable fusion power. 

If you can do that, then you are not limited to the 90 minute plus orbits of normal satellites.

If you travel fast enough to have a 1 g force outwards away from the Earth, comfortable for humans used to full g, then you can go round the entire Earth in 60 minutes. Increase that to 3.45 g outwards artificial gravity, which many will be able to tolerate for a while, and you can get around to the far side of the Earth in 20 minutes.

By then, the ordinary everyday "planes" may also be able to travel as far as other planets and the outer solar system, with journey times of weeks or days - if you can do continuous thrusting at one g, you can get to various places in the solar system very quickly.


So, there could be many benefits. But, there would be issues as well. What kind of a world would it be where just about every single country and many large companies have the capabilities to launch intercontinental ballistic missiles?

Your ordinary "plane" 25-50 years into the future is likely to be as fast as present day ICBMs, or most likely faster if they have this capability to accelerate throughout the flight.

How can such a world be a safe place to live in? Well I think it's pretty clear it wouldn't be if you were to suddenly give that technology to all the countries on the Earth right away. But we have technology now that would be just as hazardous to world peace if we magically sent it back 50 years to the 1960s.


Can we make the transition to such powerful transport methods safely? If so how?

And what happens about property rights in space. Would we end up having nations trying to carve up territories in space? Could we have wars in space? Those would probably be fatal for all concerned in such fragile communities. Any space station or space colony, say on the Moon, has to contain ten tons of air pressure per square meter, and the spacecraft themselves are traveling at immense speeds, any station would be hugely vulnerable to an adversary who wants to destroy it.

If we ever did have an all out war in space, using fast spacecraft with advanced technology, probably there would be almost nothing left a short while after the war started.

And what would happen in the inevitable conflicts of interest between the various groups of people in space?

These could include:

  • Scientists who want to study the solar system in its pristine state
  • Exobiologists who want to keep many places like Mars, Europa, possibly even areas of the Moon, uncontaminated with Earth life
  • Engineers who want to use the materials to build things
  • Miners who want to extract materials from space to sell, or use on Earth or to make solar satellites etc
  • People who just want to go everywhere as tourists and potentially contaminate sites of special scientific interest with Earth life
  • People who just take things of scientific value away as souvenirs
  • And many others with various agendas for space, bound to conflict from time to time


Well there is some reason for optimism. We have already got technology that, back in the early C20 would seem just as bewildering and impossible to imagine how we could handle it safely. But somehow we have, with some major hiccups but with many internationally accepted rules and guidelines that make present day society work,

So, I think we'll manage it, hopefully. And it's probably no more possible to have an accurate idea of how it will happen as it would be for someone 50 years ago to imagine how the world would work today. 

But it can't do any harm to think over the consequences in advance. I think we have an excellent start on this with the Outer Space Treaty which helps to protect nations and promote peaceful uses of space. Also I think it helps that there is nowhere in space that is, in its natural state, anything like as habitable as the Earth. And the OST already protects habitats that you make yourself. So we could build on that to have laws in space that work, without need to designate territories in the solar system to assign to particular nations or entities. Rather we could use a functional type of ownership in space.

Legal Property Rights under the Outer Space Treaty

Here the relevant article is

Article VIII

    "... Ownership of objects launched into outer space, including objects landed or constructed on a celestial body, and of their component parts, is not affected by their presence in outer space or on a celestial body or by their return to the Earth..." . (Outer Space Treaty)

This has been interpreted as meaning that if you construct a habitat on the Moon or use materials from an asteroid to construct a habitat in space, that you own the habitat though not the Moon or asteroid.

If understood this way, it could be a basis for laws of functional ownership within the context of the Outer Space Treaty. See the article at spacefuture.com by Wayne White: Real property rights in outer space. This is a matter of a fair bit of discussion but it does seem at least possible that one could develop reasonable laws of ownership within the context of the Outer Space Treaty.

Assuming that we do make it into space, peacefully, without destroying our civilization, then there are many other questions and issues to think about.

I've already written many articles about issues we need to keep aware of to do with contamination of other planets in our solar system, and some of the things that could go wrong. See especially, No Escape From Problems in Space Colonies - Earth is Des Res - Even After Nuclear War or Asteroid Impact - Let's Plan For Exploration and Discovery of Space with no End Date - NOT Escape from Earth - Opinion Piece, then also "Ten Reasons Not To Live On Mars, Great Place To Explore" - On The Space Show (where I talk a bit about the legal situation for instance, the section above is taken straight from that article) and many other articles under http://science20.com/robertinventor.

This time, let's look further into the future, what about interstellar exploration?


Why stop at the solar system? Many have wondered if we will travel into interstellar space some day.

One estimate is 44 years to get there with the Orion probe. Project Orion (nuclear propulsion)

There's also this intriguing idea, which I found from that article: Use of Mini-Mag Orion and superconducting coils for near-term interstellar transportation

It's  about an idea to send a stream of mini solar sails - each one is just a pellet in a Mylar sheath - as a way of refueling an interstellar spaceship in flight, throughout its early acceleration phase from Earth. The solar sails are accelerated close to Earth, so you don't have the spreading problems you get if you try to transfer laser power all the way to a distant interstellar spacecraft. This lets you transfer energy from Earth all the way to the interstellar spaceship at high efficiency throughout the long acceleration phase.

You could just use the momentum of the solar sails for acceleration, as in this earlier concept by Jordin Kare Sailbeam (slides) - Paper (to get an idea of how it works see the Figure 1: SailBeam Concept in the paper). Jordin Kare thinks there's a chance you could manage 0.1c or faster with this method.

But the authors' idea in  Use of Mini-Mag Orion and superconducting coils for near-term interstellar transportation is that it's more efficient to send fuel for the spaceship rather than just send a stream of solar sails for momentum exchange.

Then the deceleration phase can be simpler. The spacecraft generates a magnetic field which acts as a brake against the solar wind of the destination star. In this idea, it uses a superconducting coil to generate the magnetic field

So the deceleration here uses a Magnetic sail

A similar idea to the MagSail is the Electric sail (or e-Sail) which is being investigated by the ESA as a way to propel spacecraft to the outer solar system, it uses many thin wires spreading out from the craft, and an electron gun in the centre fires electrons away (shown blue below) thus creating a current which flows in from the wires to the centre - this creates a magnetic field which makes an obstacle to the solar wind - rest is as for the MagSail, here is an artist's impression. 

Paper about esail  - Slide presentation about it

There are many ideas around for interstellar travel.

The paradoxical thing about interstellar travel is that so long as the timescale is of order of centuries, it's worth your while waiting for the technology to improve as otherwise later departures get there before you - until the time required goes down to a few decades. But if timescale was just 44 years, could be worth setting off right away.

Surely we will send unmanned probes first before we attempt humans with all their life support?

An even faster way to get there is being explored at the University of Michigan, the Nanofet drive, which fires minute particles at close to the speed of light, originally designed for tiny spacecraft

Nano-particle field extraction thruster

Theoretically these could let nano spacecraft fly at almost light speed - and the same technique, using millions of these thrusters, could work for larger craft also

Firing Off Charged Nanoparticles Might Allow Spaceships to Move at Near-Light Speed

There would be many practical issues with a big spacecraft going close to light speed through the interstellar medium, but this at least gives a possible future method you could achieve those velocities.

Another more way out idea being researched, Quantum vacuum plasma thruster
- idea is - to separate out particles from quantum fluctuations on the vacuum and accelerate this as your reaction mass so you don't have to carry it with you..

and lots of other ideas.


Personally I'm not at all sure we should colonize the galaxy, though great to explore it. The problem is, that if, as the author of that paper suggests, humans fill the galaxy quickly, say in a million years or so, then - what would all those humans turn into?

We worry about aliens invading Earth. But it's pretty clear that no alien species have colonized our galaxy yet, and it would be just an extraordinary coincidence for one to arise today, within a million years or so of humans, out of the billions of years since the galaxy was born. If they were at all like humans as we are now, and colonized the galaxy, then some of them at least would probably have colonized Earth itself long before we evolved, and transformed it to their liking (maybe changed atmosphere and planted their own biology).

Actually, an ET probably wouldn't bother to take over the Earth, they'd have the technology to easily reproduce anything they want  - and you can use the materials from comets and asteroids to make habitats in space which would give far more living area than the surface of a planet.

With the technology an ET would have after a few million years of development they could do that easily at almost no time cost to themselves, just set some automated robots working for a few years and you have your Stanford Torus or whatever in space to live in, and probably only a few years after that, exponential growth, have living area as large as they want of these habitats scattered through the solar system, made of materials from the asteroids and comets, hundreds or (if they used materials from the Oort cloud for instance) thousands of times the surface area of the Earth.

So, if they were like us, and really were also keen to colonize the galaxy, then by now the entire solar system should be full of their free floating habitats in space. You just need to look up at the night sky - that we don't see the sky filled with bright lights of ET spacecraft and space colonies shows that no ET has set out to colonize the galaxy - or at least not successfully.

If there are ETs then for whatever reason, they clearly aren't the galaxy colonizing or planet occupying type.

Humans, though, if we spread at our present stage of civilization, some of use at least are like that, and they would be the ones who would end up doing the colonization, if they survived.


So, I think we should instead worry about future humans and things they create - as potential Earth invaders rather than ETs. Just because they are our descendants a thousand generations removed, doesn't mean that they are going to be kindly disposed towards Earth and leave it alone, and be more gently disposed to us than ETs.

Plus, they could also trash the galaxy by accident. We almost have the technology to do that already - if you can make a self replicating self improving "Von neumann" machine, basically just a nanoscale 3D printer able to print out a computer chip and to make copies of itself - and it could spread just as life does, but using asteroids and comet materials to make copies of itself.

Rep Rap printer making a copy of itself (the "Child" in the photograph).

The RepRap can only make about 50% of its components so far, but the Rep Rap project is working on ways to increase this - eventually once they can print out electronics, 3D printers may be able to make a complete copies of themselves, and then rudimentary Von Neumann machines may not be far away.

If you let it loose on the galaxy, it could turn entire galaxy into copies of itself, or making something pointless that it's been programmed to do, e.g. turning all the galaxy into paperclips as in Neil Bostrom's whimsical "Paper clip event horizon" catastrophe

A future Von Neumann machine could be programmed to make paperclips as well as copies of itself and to improve itself in evolutionary fashion to get ever better at making paperclips.

If set loose on our galaxy without proper controls, it might turn the entire galaxy - asteroids, planets, dust clouds - eventually stars, turn everything into paperclips - all the time getting better and better at doing that as time goes on - and from something simple and crude created by a paperclip factory owner with interests of profit, evolve, like life, into things powerful and almost impossible to stop.

Von neumann machines are great assets of course under proper control, could enable us to do mega-engineering projects of great benefit to humanity at almost zero cost. E.g. self replicating solar panels in space, or on the ground, making solar panels for instance, from desert sand and using sunlight as the energy source (some future version of the Sahara Solar Breeder project perhaps).

But they do need care also. Perhaps a galaxy full of human colonists couldn't be totally relied on to take that level of care with them, someone amongst those countless trillions slips up and you end up with a paperclip event horizon or worse.

This may seem like science fiction to you. But many things that are part of our daily lives now were similarly science fiction fifty years ago or even twenty five years ago. Von Neumann machines do seem to be things that are engineering possibilities in the not too distant future, and once you have them, even on a macro scale, not the more exotic microbe like nanoscale von Neumann machines, then it opens out possibilities like these.


I don't know why people simultaneously want to colonize the galaxy - and then - worry about ETs invading Earth. It seems an inconsistent point of view to me.

The only ETs likely to be a nuisance to us are ones that want to colonize the entire galaxy. So we worry about them, and hope they don't exist. But at the same time, want to turn into such an ET ourself.

Although of course it isn't presented like this - seems to me that if you look at this without Earth chauvinist spectacles, that it would seem, for instance to any ET who listens into our discussions, as if we keenly desire to become the very type of alien monsters for the rest of our galaxy, that we worry might, as ETs, cause a nuisance for our own world.

If that's it, maybe it's just because we are a young species. Perhaps all ETs go through this stage in their youth as a technological species?

Or, maybe I've just missed something obvious. If so what is it?

I've posted about this a few times in various places, mainly comments on my column at Science20. It's generated a fair bit of discussion but to date, I've not had any truly reassuring answers to explain how we can colonize the galaxy in a safe way and be sure this won't happen.

Do you have an answer to it? I'd love to hear it if you do. Say so in the comments below. Any ideas for how colonizing the galaxy by humans can be done safely, without a significant risk of trashing it both for ourselves and any future evolving ETs around other planets in our galaxy?


Of course if you stick to just exploring, not settling down anywhere except a few firmly delineated safe places, with some way to be pretty certain that humans won't spread beyond them permanently - but can explore as much as they like - it's not a problem.

Also nomadic colonies traveling through the galaxy are fine, so long as there is something that limits them, prevents them from splitting up into more colonies as time goes on - or do so only very very slowly like very few billion years.

Perhaps this is what ETs do, if they exist. Perhaps reckless ETs destroy their civilizations at an early stage, and if not destroyed already, destroy themselves as soon as they colonize space, through space wars.

While more cautious ETs, maybe they are also naturally far seeing, and ask themselves, what will the consequences be of colonizing the galaxy a few centuries, millennia or millions of years down the road?

They may also have learnt to extend their lives by then so they have lifetimes of thousands or millions of years - making these consequences not just for their descendants, but things they might encounter themselves later in their lives.

They might live long enough to see many spins of our galaxy

and the most long lived ETs might well expect to still be around to see the collision of the Andromeda Galaxy with the Milky Way. 

That's likely to give you a different perspective on colonization and exploration of the galaxy. They may not need FTL (Faster than Light) travel. You'd be able to do a galaxy tour in your own lifetime at liesurely sublight speeds, if you so wished. 

Conversations between ETs could also be leisurely things that last for millennia. Maybe we are due a visit by an ET, but next time they come this way will be a few thousand or million years from now, a short time for them. Maybe they will say "Hi" to us some time in the next thousand years or million years.

I think that's actually pretty likely, that an ET with millions or billions of years of civilization, would have learnt to extend their life-spans, and so have a much more leisurely pace of life than us.

Though, perhaps equally likely that we are the first ET to evolve in our galaxy with spaceflight and astronomy.

There might be non technological ETs or ETs that are living in subsurface oceans of icy moons like Europa that don't know the rest of the galaxy exists. Again I feel that's quite likely, depending on how likely it is for life to evolve in such places. There are probably many more habitable subsurface oceans in the galaxy than habitable planets. If so then we may be unusual as a surface dwelling species.


There's a connection here with the famous Fermi's paradox of course, the paradox that the galaxy seems old enough for many ET civilizations to have arisen, yet it would just take one of them to colonize the galaxy, within a few million years at most. So why aren't they here?

This could be one solution, that they are long lived, far forward looking, and see long term hazards for themselves and other ETs if they colonize. But there could also be many other reasons why we don't look up into the sky and see ET spaceships overhead. See also my article: Why Didn't ETs, Or Self Replicating Machines, Colonize Our Solar System Millions Of Years Ago? and  David Brin's articles and talks and sci fi stories on Fermi's paradox, including his Great Silence paper overview of many of the possible reasons for it.and the Wikipedia entry on Fermi's paradox to find many more solutions.

I don't want to go into that here, the main focus here is, can humans colonize the galaxy safely, or is that impossible, should we make sure we don't colonize and only explore?

It's a possible explanation for why the ETs aren't here. But they might not be here for many other reasons including the possibility that we are the first technological ET in our galaxy with the capability of space flight. We would still be faced with this question, can we safely colonize the galaxy - safely for ourself - and safely for any other potentially vulnerable ETs there may be in the galaxy?

There might be highly intelligent, peaceful, civilized ETs for instance, maybe far beyond us in the realm of mind and thought and ideas - and lifetimes of thousands or millions of years, maybe their medicine also is far beyond us  - perhaps largely based on holistic methods  - with almost nothing we recognize as technology. Maybe they live as dolphins or whales or octopuses in oceans. Maybe they are terrestrial but small and weak like intelligent parrots, without the dexterity or strength to build spacecraft. There might be many possibilities for intelligence, awareness, feeling, kindness, abilities far beyond ours. 

Yet they might still be vulnerable even, say, to a single Earth microbe invading their planet, loaded with what, to them, is XNA. For them, we, or our microbes even, would be the terrifying, alien ET monsters.


I am cautiously optmistic that somehow we'll find a way through all this. Maybe we will make contact with ETs in our galaxy, or detect signals from ETs in another galaxy who have already encountered these issues. 

Maybe we'll even spot a distant galaxy that's been overrun by Von Neumann machines or been totally colonized by ETs and so have an idea of what is likely to happen to our galaxy if that happens. 

But it might be that we are the first or almost the first in our galaxy, even in the universe, to face these problems. Or it may be that other ETs are just too far away and communicate too rarely to be of much use to us as a way of learning what can go wrong. 

If so we'll need to find a way through by ourselves, and it will, I think, be a matter of much discussion over the next few decades and centuries, if we continue as a technological species.

Maybe we'll find a way to colonize safely. Or maybe, we'll decide we have to explore the galaxy only, and evolve a "prime directive" of non interference much like Star Trek.

I don't expect any final answers, but what thoughts do you have on all this?