Isaac Arthur
4 HN recommenders · recommended in 17 months, 2017–2025
30:36 · 421K views · Jun 29, 2017
Isaac Arthur explains the orbital ring, a megastructure launch-assist system that could move bulk cargo cheaply to orbit and beyond. He compares it with space elevators and discusses power transmission.
HN commenters offer it as the likely future of cheap access to space, feasible without exotic materials.
18 comments from Hacker News
This is totally right. You might really like Isaac Arthur on YouTube if you don't know him already. "Orbital rings" [1] in his "Upward Bound" series might be just right your alley. Of course, there's so much more he produced, it's even hard to keep up. I personally dream of some "Megastructures" he suggests... Actually already began myself to think of a Dyson Swarm around Earth (for starters) which could then serve as a positional basis for future orbital rings. He really inspired me to think bigger, now. [1]: this video
Here is my hope (and my belief): the ultimate end here is orbital rings [1]. To summarize the video, you can put copper cabling in orbit, run a current through it and keep things in place (relative to a point on Earth) with magnetic levitation. The most important part of this is that you can have things in LEO that are fixed to Earth points. Why does this matter? No longer do you have to speed up to Mach 30 to reach orbital speeds. You could technically run a cable from 150km up and carry people and goods from Earth into LEO and back. This could revolutionize long-distance travel on Earth too. It's estimated that a space-based power collector could create about ~7 times the energy of an Earth based collector due to less power loss from the atmosphere and night (to be clear, a solar collector in orbit would still occasionally be occluded by the Earth but it won't be half the time). You can get power down to Earth in two ways: you can transmit it. This is actually viable but is not ideal. Alternatively, if you have an orbital ring, you can attach it to that and just run cables down to Earth. We use longer power transmission lines than that on Earth already. All of this requires no new physics, no magical materials (eg space elevators do) and are just (admittedly massive) engineering projects. If you can get solar panels into orbit for <$10/kg payload costs and run cables down to Earth, you'll solve the variance issue with solar and create cheap power on a massive scale. And non
Weird, I didn't find the term "delta-V" anywhere in the article. Most on HN probably know this but delta-V is the change in velocity required to reach some goal. Fun fact: it requires more delta-V to hit the Sun than it does to leave the Solar System. For giggles, here's a delta-V map of the Solar System [1]. Of course there's the issue of getting things off Earth to begin with but even if you take that as (economically) solvable the detla-V problem remains. Site note: there are lots of proposals for cheaper LEO solutions (in $/kg terms). Probably the most famous is the space elevator but that's actually a bad solution for many reasons and possibly not even feasible since we'd have to invent a material strong enough. What could well reduce that from $thousands/kg to <$10/kg is an orbital ring [2] (and check out the rest of his Uplift series if you're interested at the other options). The beauty of this is it doesn't require any magical material ( cough graphene cough ) and requires no new physics. It's largely just an engineering problem. Granted it's a massive engineering problem. To be fair, the article does mention how much energy you'd have to lose but it strikes me as just being so much easier to explain in delta-V terms. [1]: [LINK] [2]: this video
For another view on how this will change things, consider the delta-V map of the Solar System [1]. As an example you need 45km/s to reach Saturn, roughly 20% of that is just spent getting to Low Earth Orbit. Now consider the long-term trend in the payload cost (by weight) of getting to LEO [2]. This is why people such as myself are so bullish on spaceX (despite quite reasonable qualms about Elon Musk as a person). The impact this has had and will continue to have on reducing this number cannot be overstated. But all of this are still interim steps and we can potentially get the payload to LEO cost under $10/kg. If you want to go down the rabbit hole of this, I strongly recommend Isaac Arthur's Upward Bound series [3], I consider the ultimate end to this to be Orbital Rings [4]. Even if you don't believe there's a reason for humans to go to space en masse (which I disagree with), this will greatly impact life on earth, for example with space-based solar power collectors. [1]: [LINK] [2]: [LINK] [3]: [LINK] [4]: this video
Lot of talk about how 1. a Moon elevator is pointless without an Earth elevator, and 2. we can't build an Earth elevator with today's technology. However we can build an orbital ring around Earth with today's technology, and it'd be much better than space elevators. [Video] this video [Paper] [LINK]