Category Archives: space

Artificial muscles using folded graphene

Slide1

Folded Graphene Concept

Two years ago I wrote a blog on future hosiery where I very briefly mentioned the idea of using folded graphene as synthetic muscles:

https://timeguide.wordpress.com/2015/11/16/the-future-of-nylon-ladder-free-hosiery/

Although I’ve since mentioned it to dozens of journalists, none have picked up on it, so now that soft robotics and artificial muscles are in the news, I guess it’s about time I wrote it up myself, before someone else claims the idea. I don’t want to see an MIT article about how they have just invented it.

The above pic gives the general idea. Graphene comes in insulating or conductive forms, so it will be possible to make sheets covered with tiny conducting graphene electromagnet coils that can be switched individually to either polarity and generate strong magnetic forces that pull or push as required. That makes it ideal for a synthetic muscle, given the potential scale. With 1.5nm-thick layers that could be anything from sub-micron up to metres wide, this will allow thin fibres and yarns to make muscles or shape change fabrics all the way up to springs or cherry-picker style platforms, using many such structures. Current can be switched on and off or reversed very rapidly, to make continuous forces or vibrations, with frequency response depending on application – engineering can use whatever scales are needed. Natural muscles are limited to 250Hz, but graphene synthetic muscles should be able to go to MHz.

Uses vary from high-rise rescue, through construction and maintenance, to space launch. Since the forces are entirely electromagnetic, they could be switched very rapidly to respond to any buckling, offering high stabilisation.

Slide2

The extreme difference in dimensions between folded and opened state mean that an extremely thin force mat made up of many of these cherry-picker structures could be made to fill almost any space and apply force to it. One application that springs to mind is rescues, such as after earthquakes have caused buildings to collapse. A sheet could quickly apply pressure to prize apart pieces of rubble regardless of size and orientation. It could alternatively be used for systems for rescuing people from tall buildings, fracking or many other applications.

Slide3

It would be possible to make large membranes for a wide variety of purposes that can change shape and thickness at any point, very rapidly.

Slide4

One such use is a ‘jellyfish’, complete with stinging cells that could travel around in even very thin atmospheres all by itself. Upper surfaces could harvest solar power to power compression waves that create thrust. This offers use for space exploration on other planets, but also has uses on Earth of course, from surveillance and power generation, through missile defense systems or self-positioning parachutes that may be used for my other invention, the Pythagoras Sling. That allows a totally rocket-free space launch capability with rapid re-use.

Slide5

Much thinner membranes are also possible, as shown here, especially suited for rapid deployment missile defense systems:

Slide6

Also particularly suited to space exploration o other planets or moons, is the worm, often cited for such purposes. This could easily be constructed using folded graphene, and again for rescue or military use, could come with assorted tools or lethal weapons built in.

Slide7

A larger scale cherry-picker style build could make ejector seats, elevation platforms or winches, either pushing or pulling a payload – each has its merits for particular types of application.  Expansion or contraction could be extremely rapid.

Slide8

An extreme form for space launch is the zip-winch, below. With many layers just 1.5nm thick, expanding to 20cm for each such layer, a 1000km winch cable could accelerate a payload rapidly as it compresses to just 7.5mm thick!

Slide9

Very many more configurations and uses are feasible of course, this blog just gives a few ideas. I’ll finish with a highlight I didn’t have time to draw up yet: small particles could be made housing a short length of folded graphene. Since individual magnets can be addressed and controlled, that enables magnetic powders with particles that can change both their shape and the magnetism of individual coils. Precision magnetic fields is one application, shape changing magnets another. The most exciting though is that this allows a whole new engineering field, mixing hydraulics with precision magnetics and shape changing. The powder can even create its own chambers, pistons, pumps and so on. Electromagnetic thrusters for ships are already out there, and those same thrust mechanisms could be used to manipulate powder particles too, but this allows for completely dry hydraulics, with particles that can individually behave actively or  passively.

Fun!

 

 

Advertisements

A revolutionary new space launch idea: Introducing The Pythagoras Sling

The Pythagoras Sling uses a lengthy graphene string pulled via two hoops suspended from simple parachutes to rapidly accelerate a projectile into orbit. Graphene string will likely become widely available over the next two decades. If it works as expected, the Pythagoras Sling launch system could greatly reduce the cost of getting into space compared to any current rocket-based system and could help accelerate space development. Total cost of the fully reusable launch system could be as low as $1M for small and medium sized satellites so cost per kg could be two orders of magnitude cheaper than today. Apart for human spacecraft or more delicate satellites that need low g-forces, the system needs little or no fuel to achieve orbit, only ground electricity, so would be safer and more environmentally friendly as well as cheaper than current rocket-based approaches.

The breakthrough was to see that large parachutes could be used as effective temporary ‘sky anchors’ for hoops, through which tethers may be pulled that are attached to a projectile. The parachutes will of course fall, but will remain high enough to fill their purpose during the entire launch. No other space launch concept has ever used parachutes in this way.

This system is not yet feasible because of limitations of current materials, but will quickly become feasible in a wide range of roles as materials specifications improve with ongoing graphene and carbon composite development. Eventually it will be capable of launching satellites into low Earth orbit, and greatly reduce rocket size and fuel needed for human space missions. The system was invented by UK futurologist Dr Ian Pearson will the kind assistance of Prof Nick Colosimo. Graphene itself was also a UK discovery.

Pythagoras Sling Concept

The Pythagoras Sling

More detail is here: Pythagoras Sling article

Using Inverse Rail Guns for assisted space launch

Following on from the last article on skyline hypersonic travel, Carbon Devices will shortly announce a future space launch system with variants covering a wide range of capabilities. These will range from ultra-cheap launch of lightweight satellites into sub-orbital trajectories up to full orbital launch of large satellites or spacecraft with human crews. The system relies on novel carbon materials only in development today, but that will be routinely available in a decade or two. Once they are, this new system will offer space launches orders of magnitude cheaper and safer than current space launch systems and avoid the environmentally damaging emissions or water vapour in the high atmosphere associated with primitive rocket technology. With far lower launch costs and improved safety, the space industry will flourish.

In the next few posts, several inventions will be disclosed that may be used in our launch systems and weapons. In this article, we explain the first of those, a new technique for driving a tape through a motor at high speed using only electricity. It is related to the rail gun, currently the highest powered artillery system in action, with today’s guns able to launch 10kg metal slugs at over 2km/s, with energy of around 32MJ. By comparison, the Carbon Devices inverse rail gun will be able to launch 60kg slugs at over 50km/s and that is just the scaled down land-based variant. If you believe as we do that the route to peace is to talk softly but carry a big stick, then this is one of our big sticks. We need to learn to talk more softly to each other, because future battlefields will use weapons hundreds or thousands of times more powerful than today’s. The gulf between conventional and nuclear weapons will fully close by mid-century. This pic is a crude example of a fairly modest space weapon with a short tape. Even this would have 3TJ energy, about 100,000 times more than today’s rail gun and 0.75 kilotons of TNT equivalent. This version would only work in space but that’s where some battles in future wars will be fought. Anyway, enough about weapons, the best use of this tech is to launch spacecraft, both from space and into space.

Slide33

The Carbon Devices inverse rail gun uses exactly the same linear motor principle of the conventional rail gun, with current passing along and between the rails via the ‘slug’, but effectively inverts the idea of a slug by using a continuous tape of engineered graphene, through which high current is passed to generate the pulling magnetic field. As each short segment of the tape is pulled forwards, the rest follows behind, and although the short segment being driven suffers high heating levels due to the high currents involved, new segments of tape are continuously pulled into play as heated segments exit. The tape as a whole will survive because only a small segment at any time is being subjected to high current, but of course the entire length of tape following is accelerated, along with the attached payload. The length of the tape and thus the exit speed achievable is only limited by practicality. The tape drive has a wide range of applications from ultra-high powered rail guns with exit energy hundreds of times that of current weapons, right up to a super-fast multi-motor space system that will one day deliver crew members or supplies such as water or materials to Mars bases in just 5 days, with a launch speed of 800km/s. Even that speed is limited mainly by the slow acceleration forces that humans can cope with. Another variant that fires inert payloads is an asteroid defense system and the achievable speeds for that could be far higher. This pic gives a crude idea of the concept, using many low powered ‘rail gun’ motors.

Slide34

This powerful propulsion system is scalable  (the system shown uses multiple motors and a very long string), and exit speed is only limited by the practical size and cost of the system. 800km/s is a sensible compromise size for routine space missions, since the size of the system scales with the square of the exit speed needed. Because of that, it can not be any practical use for interstellar missions, where technology such as light sails offer much greater suitability. Even if used in conjunction with a light sail, it could only knock a few weeks off a 100 year flight time. (For those of you with weapons interests, the Mars commute system carries about 360TJ, or 85 kilotons of TNT energy equivalent, well into nuclear territory. I haven’t bothered to calculate how powerful it would be if militarized instead of running at just 5g acceleration. ‘Very’ is a good enough guess.

In space, the tape will naturally start very cold which will be an advantage, and of course the tape can also be laid out in a long line to avoid assorted mechanical issues. All of that makes high speeds reasonably feasible. On the Earth however, it is very hard to arrange for a tape to be laid out in a long line, and spooling and indeed unspooling speeds present a huge mechanical engineering problem, not least of which is that a spool spinning at high rpm is dangerous in itself. Aerodynamic heating is also a huge issue for ultra-high speeds. Therefore, land-based variants need to be greatly scaled down. A number of people over the years have suggested using rail guns to launch things into space, and heating is always a severely limiting problem. The novel system we will announce isn’t a rail gun launch and neatly circumvents this problem.

Having said that, rail gun space launch is not impossible and we have devised two novel launch variants using the rail gun linear motor principle. Carbon Devices’ graphene foam invention in 2013 outlined a solid foam that could be made lighter than helium, that would be ideal for supporting loads in the high atmosphere. MIT have more recently produced a lightweight 3d-printed matrix that could be used to print larger shells containing only vacuum (and they could even be printed at high altitude to avoid collapse in the high pressure lower atmosphere).

Slide7If circuits for a linear motor are made from graphene and on a graphene substrate, all supported by such floating platforms, then a long, vertical, linear motor could be made and supported in the air that could accelerate a sled with a disposable heat shield front end, holding a rocket. Depending on acceleration tolerable, fairly high speeds can be obtained, and although not fast enough for orbit, would greatly reduce the size of rocket needed to achieve orbit.

Slide38

The first variant is entirely vertical. The rocket and crew or satellite payload would be attached to a sled, and the reusable sled would accelerate up the linear motor. With a few system engineering tweaks, it is feasible to make the path at least 35km high, with an exit speed of around 4000mph (1750m/s) for the 5g acceleration launch that is acceptable for astronauts. Although 4000mph is fast, it is no more than a useful starter push for a rocket that needs to reach the 17,500mph of the space station. Additionally, vertical speed is a useful boost, but no use in itself for orbit – a rocket travelling vertically would simply fall back to Earth eventually unless it gets high horizontal speed.

However, our second variant curves the track into a horizontal path at high altitude, again supported along its entire length by floating platforms made from carbon foam.

Slide39Assuming a 150km track, most of which is 35km high, we would have an expensive but reusable launch system that could accelerate humans up to 8600mph (3800m/s), about half way to orbital speed, and that would all be horizontal speed. It is easily possible to engineer the final sections of track to be higher in the atmosphere, and a slight incline would get our rocket out of atmosphere quickly to minimise heating issues, but the main benefit is that most of the high speed happens in the cold and thin high atmosphere. Such as system is feasible and would greatly reduce launch costs for human spacecraft. For a non-human payload, a 150km track can give full orbital speed for payloads that can tolerate in excess of 20g acceleration. Very many fall in that category, so this system could one day be used to achieve a fuel-free orbital launch.

As mentioned, these are only early system designs and forthcoming articles will outline more advanced Carbon Devices systems with greater potential to accelerate space development.

Ultra-tall structures – from ground into space

I was 8 when Armstrong and Aldrin set foot on the moon. It was exciting. My daughter is 18 and has never witnessed anything of the same order of excitement. The human genome project was comparable in some ways but lacked the Buzz.

There is excitement about going back now. We will, and on to Mars. We can do space so much more safely now than back in the 60s.  Commercial companies are pioneering space tourism and later on will pioneer the mining bits. But the excitement recently is over the space elevator. The idea is that a cable can stretch all the way from the surface out into space, balanced by gravity, and used as a means to cart stuff back and forth instead of having to use rockets, making it easier, less expensive and less dangerous.

It will happen eventually on Earth. We need to make new materials that are strong enough. Carbon nanotube cables and other fancy materials will be needed that we can’t make long and strong enough yet. But the moon has lower gravity so it is much easier there and will likely happen earlier.

There are plenty of web articles about space elevators already so I don’t need to repeat everything here. But a space elevator is supported from above, a regular building is supported from below. How can we build one very tall from the ground?

I recently issued a report on 2045 construction that among other things also discussed spaceports up to 30km tall:

https://timeguide.wordpress.com/2015/10/21/2045-constructing-the-future/

A 30km tall spaceport on Earth could make use of atmospheric buoyancy for the lower end which of course we wouldn’t get on the moon for the spaceport coming home, but we also wouldn’t get wind on the moon to add stresses. On the moon gravity is less so the structure could be much taller. On the moon a graphene structure could form as much as the bottom 150-200km of the climb. It might offer a nice synergy. The diagram above shows some of the possible structure for the columns, biomimetically inspired by plant stems, though this is just one suggestions, and there are very many ways they could be designed.

This could be enhanced by filling columns with graphene foam:

http://timeguide.wordpress.com/2013/01/05/could-graphene-foam-be-a-future-helium-substitute/

Since I wrote that, carbon foams have been made and they are 6 times lighter than air.

So how about a 30km tall building? Using multilayered columns using rolled up or rippled graphene and nanotubes, in various patterned cross sections, it should be possible to make strong threads, ribbons and membranes, interwoven to make columns and arrange them into an extremely tall pyramid.

This could be used to make super-tall structures for science and tourism or spaceports, or a home for celebrities, well out of sight of the Paparazzi.

Think of a structure like the wood and bark of a tree, with the many tubular fine structures. Engineering can take the ideas nature gives us and optimise them using synthetic materials. Graphene and carbon nanotubes will become routine architectural materials in due course. Many mesh designs and composites will be possible, and layering these to make threads, columns, cross members with various micro-structures will enable extremely strong columns to be made. If the outer layer is coated to withstand vacuum, then it will be possible to make the columns strong enough to withstand atmospheric pressure, but with an overall density the same as the surrounding air or less. Pressure is of course less of an issue higher up, so higher parts of the columns can therefore be lighter still.

We should be able to make zero weight structures in the lower atmosphere, and still have atmospheric buoyancy supporting some of the weight as altitude increases. Once buoyancy fails, the structure will have to be supported by the structure below, limiting the final achievable height.  Optimising the structures to give just enough strength at the various heights, with optimised mesh structure and maximal use of buoyancy, will enable the tallest possible structures. Very tall structures indeed could be made.

So, think of making such a structure, with three columns in a triangular cross-section meeting at 43 degrees at the top (I recall once calculating that is the optimal angle for the strongest A frame in terms of load-bearing to weight ratio, though it ignores buoyancy effects, so ‘needs more work’.

30km tall structures would not be ideal for large scale habitation, since much of the strength in the structure would be to support the upper parts of the structure itself and whatever platform loading is needed. But for a celebrity home, small military observation base or a decent sized lab, it might be fine. The idea may be perfect for pressurised platforms at the top for scientific research, environmental monitoring, telescopes, space launches, tourism and so on. The extreme difference in temperature may have energy production uses too.

Getting the first 30km off the ground without needing any rocket fuel would greatly reduce space development costs, not to mention carbon and high altitude water emissions.

A simple addition to this would be to add balloons to the columns at various points to add extra buoyancy, but they cannot give much extra lift once the atmosphere is too thin so probably wouldn’t make much difference.

Nevertheless, the physics limits are pretty good. 30km is a reasonably achievable goal for a 2045 spaceport, but given the known strength of graphene and carbon nanotubes, a 600km tall building on Earth would be the limit, and that is higher than the Hubble telescope!