So, this line of thinking started when I found a cool little magicians prop on Amazon. It’s basically a walking stick that ‘appear’s out of thin air.
The trick is it’s one big spring and when you let go (or throw it in the air) it instantly ‘snaps’ back to its original position, almost instantaneously.
Anyway – this got me thinking more about springs, and then trying to calculate how big of a spring you’d need to launch a ‘space craft’ into space (basically, reach escape velocity).
Probably not a practical way to launch, and the math was a bit out of my depth – but it kicked off an interesting search into alternative launch methods for spacecrafts, which in turn sparked some other cool ideas.
One of the main problems with existing space launches / spacecrafts is that fuel is heavy, it’s expensive to carry, it takes up a huge part of the spacecraft, and you need to carry the entire journeys fuel (there, and back) from the start.
That’s a lot of restrictions.
So the question becomes how can you send more ‘fuel’ to a spacecraft without the fuel actually being on the actual craft itself?
There aren’t many raw materials in space that we can use without specialized machinery or a huge power plant, neither of which we have room for on our spacecraft.
I’m thinking the easiest way is to use lasers.
Lasers can generate heat – we’ve all seen lasers popping balloons and lighting match sticks.
This is interesting because we know we can shoot lasers long distances, very quickly, and very accurately – especially in the vacuum of space.
So, what if we used a laser on earth to send ‘heat’ to a spacecraft, which it would convert into electrical energy & use to generate propulsion.
This way, the ‘fuel’ or energy the craft uses to push itself forward is supplied, stored and created back on Earth.
Now, shooting a laser all the way to saturn to get a little heat to a spacecraft is hardly an efficient use of energy, but the system breaks down a slightly more important bottleneck – the ability to transmit energy virtually anywhere.
This would also probably enable ‘deep space’ travel, as you could be 100 light years away and the lasers would still theoretically be able to reach you from earth (granted it’s been active since you left, and your ship isn’t obstructed by any objects).
Imagine a huge power plant on earth that shoots a high powered laser to a satellite w/ mirrors, which then reflect the beam towards whatever object(s) it wants to power.
We would use thermocouples on the spacecraft to convert the laser-heat into electricity without any additional moving parts.
Next, use the electricity generated via thermocouples to power an electric motor that’s capable of working in vacuum (which, I think still has some issues).
The essential point is to offload the bottleneck of fuel from being a constraint of the actual spacecraft, to something we can manage on Earth.
Creating and storing high amounts of electricity / heat on earth isn’t that hard – it’s a solved problem for us.
Doing the same in space, with no equipment, on a small spacecraft, is much more difficult.
Essentially – we want an energy transmission system that works across long distances, and can be pin-point accurate.
Efficiency is something we’re willing to sacrifice in order to achieve this long-distance ‘wireless’ transmission.
In the designs I’ve looked at, this seems somewhat similar to whats being described as a ‘solar sail’ – but I’m not 100% sure it’s the same.
Anyway, it doesn’t hurt to think the concept through regardless of if someones already come up with the idea before.
I’ve noticed that one failure of the typical solar sail is that it uses solar power to generate electricity, which isn’t available once you’re past Jupiter & Saturn.
This makes the solar sail method very efficient (free E from Sun), but not so good as it has significant range limitations.
I’ve seen some solutions which use microwaves in place of solar energy, but haven’t taken a deep dive into those yet.
It’s interesting to note that todays satellites past Jupiter use a power generation method called radioisotope thermoelectric generators (RTG).
Basically RTG uses radioactive materials, like plutonium, to generate heat over a long period of time (decay), and then uses thermocouples to convert that heat to useable, electric energy.
Everything is basically a game of converting some existing source of potential energy (raw materials) into a type of energy that we can use / manipulate more easily (electricity, controlled combustion, etc.).
Two other use-cases that come to mind for this type of laser/heat/transmission technology:
The ability to allow certain types of aircraft (on earth) to stay airborne indefinitely.
With a constant supply of ‘fuel / energy’ being sent up via laser(s), both small and large sized crafts would be able to exist in flight indefinitely.
Our accuracy with these lasers would need to be precise for this system to work (i.e follow a moving plane), but I have a feeling that’s a solved problem.
This could work for small quadcopters delivering mail, or large aircraft carriers.
Or even cities in the sky – like the Jetsons. Need that!
The second use case would be to easily by-pass the electricity grid in cases of emergency.
Lets say a Tsunami hits, and all the electricity is wiped out. In order to get a towns grid back, it’s going to take months of rebuilding.
The easy solution would be to have a system setup that’s ready to accept the heat from our laser (a simple photovoltaic panel).
A PowerPlant in California could point their laser to a remote island in Cambodia and send them a constant stream of concentrated heat for conversion.
It’s like Wi-Fi for sending large amounts of heat which is converted to electricity. So, Wi-Fi for Electricity.
It wont be anywhere as efficient as being hardwired to a power-grid (or not having to re-convert from heat) – but we don’t always have that luxury.
The basic flow would likely be:
Raw Materials -> Heat -> Electricity -> Laser -> Heat -> Electricity
We give up some efficiency in the conversion process, but gain a huge amount freedom in disconnecting the wires.