Interstellar Flight: Perspectives and Patience

The comment by Benjamin Stockton on the article page is spot-on:

>I just wonder if humanity’s adventurous nature is leading us away from a proper focus on the sustainability of our civilization, our specie, and our fragile planetary environment?

But we still need spaceflight at least for planetary defense against asteroids, mining asteroids(so we don't have to mine Earth), etc.

What resources are on asteroids that justify the energy expenditure to get from space and back? Can't be many of them...

> What resources are on asteroids that justify the energy expenditure to get from space and back?

With chemical rockets, not much.

With "a propellant-less propulsion propulsion system such as solar sails or electric sails," bringing water (propellant) to low-earth orbit starts making sense [1], as does mining platinum, but only if "the quantity of platinum from space would substitute an equal quantity of terrestrial platinum," i.e. moving heavy industry off the Earth's surface [1].

Given asteroid-mining profitability is dominated by "the throughput rate, which depends on the mining process," it's possibly to see a path to certain rare-earth minerals becoming profitable to mine in space if environmental controls on Earth are tightened while constant-thrust propulsion technologies advance.

[1] https://arxiv.org/pdf/1810.03836

> With chemical rockets, not much.

The energy involved in chemical rocketry is actually not that much. Getting a kilogram to LEO is roughly as expensive (in energy) as flying it to the other side of the world in an airliner. Getting stuff back from an earth-crossing asteroid can also be very cheap energetically, with very small delta-V (if one is willing to wait long enough).

But we don’t ship mined materials around via aircraft… because it’s obscenely expensive…

And the delta-V back from a NEO is as little as 1% of that to get to LEO from the Earth's surface.

Also, the materials we're talking about from asteroid mining, like platinum group elements, probably are shipped by air, just for security.

This whole argument is reminding me of the facile and bogus argument that launch to earth orbit from planet's surface is expensive because of the energy needed.

If it's a bogus argument then mount a counterargument. The question is simple: what is worth mining in space?

So far we have... "maybe platinum." Maybe!

Aside from the conspicuous absence of math, "maybe platinum" isn't remotely important enough a factor in earthbound mining to justify asteroid mining on the basis of preserving earth, obviously.

I recently read "Delta-v" and the sequel "Critical Mass: A Novel" by Daniel Suarez. They're very much fiction but there is a certain amount of science underpinning the arguments and I enjoyed that aspect. And the author even states that he's trying to get across, with solid arguments, why humanity should begin planning asteroid mining ASAP. In brief, the arguments are:

Firstly we're now at a point where we have lots of cheap energy available, principally chemical. Depending on many factors it's conceivable that we are in fact at or near peak human energy output (e.g. WW3 or civilization collapse - the next iteration of civilization won't have so much cheap oil to exploit).

Secondly LEO is not yet full of junk, meaning that it's trivial to find launch windows to LEO and beyond. That could easily change very much for the worse in a relatively short time (I infer decades from the books).

Finally it's unrealistic to expect us to colonize the Moon or Mars using only Earth-mined materials. You can launch a spacecraft to Mars easily, but to launch a small city's amount of construction equipment and raw materials is beyond our capabilities.

Conclusion: now is the best time to mine asteroids. We can do all of the processing and much of the construction in LEO (or even better at Earth-Moon or Earth-Sun lagrange points) and then, with relatively low delta-v, we'd actually have a chance of becoming an interplanetary species!

But, the novels warn, the window of opportunity will eventually ("soon") close. Well worth the read.

Maybe someone else more familiar with the arguments, who has also read these novels, can offer a critique?

This is predicated on it being worthwhile to colonize the moon or Mars, no?

No. The best thing you can do with a lot of mass in LEO is construct solar power stations that beam energy down to Earth in the form of microwaves. This is what the second book, Critical Mass, gets into. Receivers on Earth wouldn't provide as much power as solar, but would be much easier to construct and work 24/7, no matter the weather. This would be highly useful for reducing climate change and increasing climate resilience.

NASA did a feasibility study of this even accounting for future technology improvements/cost reductions and it doesn't seem to come close to earthbound alternatives, especially nuclear fission.

Nuclear fission is more stable, less maintenance, less risky, less upfront and ongoing environmental damage, less vulnerable to all sorts of risks, and produces way way more energy.

> We find the SBSP designs are more expensive than terrestrial alternatives and may have lifecycle costs per unit of electricity that are 12-80 times higher

https://www.nasa.gov/wp-content/uploads/2024/01/otps-sbsp-re...

I was talking about having mass in orbit from mined asteroids (or the moon), like the grandparent comment. This survey is based entirely on launched SBSP:

> This study assessed lifecycle cost and emissions based on the following scenario: SBSP systems are developed on the ground in the 2030s and launched to low-Earth orbit (LEO), and then transferred to and assembled in geostationary orbit (GEO) in the 2040s.

Furthermore, one main benefit of SBSP over nuclear is that the receivers don't need to be connected to the grid; each household or piece of infrastructure can have one. This would help manage situations like the power outage in Spain earlier this year or the situation at the start of KSR's Ministry for the Future where a deadly heatwave in India is made 10x worse by coinciding power outages.