The Space Resource Compendium
The “Return” Problem
Bringing Space Resources Back To Earth?
Whether it is a bird, a plane or even an astronaut, gravity makes it extremely challenging to leave the planet’s surface. It takes a massive amounts of energy to overcome the pull of gravity and make it into orbit.
Rocket fuel provides enough energy to escape gravity. But, it is expensive.
Historically, escaping gravity was so costly that only large government agencies could afford to do it. However, in the last decade, several private companies (e.g., SpaceX, Blue Origin, Rocket Lab, etc.) have developed their own rockets; dramatically lowering the cost of launching things into space.
In 2023, the cost to launch a spacecraft into orbit was ten times cheaper than it was in 2013. This cost is expected to decrease further in the coming decade (re. Starship).
The rapid decrease in launch costs has gotten the space industry into a sort of frenzy. Commercial space ventures are becoming viable. Among these, some companies aim to acquire “space resources” from places like the Moon, Mars, and even asteroids (with some help from government agencies, like NASA).
Why Space Resources?
There are two primary uses for space resources.
Firstly, we can use the resources in space where we find them. This is strategy is known as in-situ space resource utilization (ISRU).
Using resources in space for space exploration means we do not need to bring resources from Earth. This could potentially have huge energy savings in the long term.
The second option is to bring space resources back to Earth and use them here. This idea is popular with those who see space as a means to improve life on Earth. For example, Jeff Bezos, the owner of Blue Origin, has touted the possibility of eventually relocating all heavy industry and mining to space, transforming the Earth into a “residential Eden”.
If we can mine and manufacture goods in space, we avoid polluting and exploiting our Earth. This could be an environmentally good option for Earth (in the long-term).
However, it is a lofty dream because…
Bringing things down to Earth’s surface from space is highly challenging, expensive, and dangerous.
What Goes Up, Must Come Down
Getting from space to Earth’s surface is straightforward. It requires no energy input.
Gravity does the work.
All meteorites follow this principle, allowing Earth’s gravity to pull them down to the surface. If they don’t fully burn up as they fall through the atmosphere (i.e. shooting stars), then they approach the surface with tremendous speed. That can cause some destruction.
Now if you want to get from space to the surface unscathed, then you need to slow the descent of your spacecraft.
To slow down, you can induce atmospheric drag with parachutes or gliding belly flops (e.g., space shuttles). Otherwise, you can use chemical propulsion like retrorockets. Depending on the mass of your spacecraft, you might be able to use just parachutes or gliding methods. But, bigger masses needed more energy to slow down.
Any of these strategy requires complex engineering, expensive materials, and detailed risk assessments.
The Return Problem
The idea of acquiring gold, platinum, and other valuable shiny metals from space is tantalizing. But, how much would we need to bring back to supplant the mines on Earth?
Let’s consider the platinum group metals (PGMs) (platinum, palladium, rhodium, ruthenium, iridium, and osmium).
The estimated global PGM production in 2023 was 400 metric tons. To meet demand, we would need to get this amount of PGMs from orbit to Earth’s surface each year.
When it operated, a NASA space shuttle could return between 14 and 30 metric tons of cargo to Earth’s surface from orbit. Assuming that 25 metric tons of pure PGMs could be transported via the space shuttle, we would need 16 space shuttle return missions. This could be achieveable.
What about using SpaceX’s Starship? If it performs as proposed (unproven as of yet), it might provide 70 metric tons of return cargo per flight back to Earth. That means we only need about 6 return flights. Not unreasonable, right?
But, what about all the other metals? Like iron, aluminum, REMs, etc…
Well, let’s check out the following graphic from Elements.
That’s ~1.7 billion metric tons of metals mined (adjusted for Fe ore vs Fe). Just in 2023. (Please note how PGMs are just a dot at the bottom of the graphic).
If we wanted to completely replace terrestrial mines with space-based mining, we would need to get (conservatively) 1.7 billion metric tons of metal from space back to Earth’s surface.
Using Starship to deliver the metal safely to the surface (~70 metric tons of cargo each), we would only need about 25 million Starship return missions.
Yikes! That’s about 70,000 launches per day.
Even if we wanted to just supply a modest 10% of metals from space, that is still 2.5 million Starship launches with ~7,000 daily launches.
Not only would 7,000 daily launches be a logistical nightmare, but also incredibly expensive both financially and energetically. It remains unclear whether this strategy would be more sustainable than our current terrestrial mining endeavors.
Space Resources Are For Space
The allure of mining on other planets, manufacturing goods in space, and bringing riches back to a clean, green Earth is captivating. I, too, would love to see polluting industries relocated offworld.
However, realizing this vision is no quick endeavor…
It is a long-term goal. Improbable in the short-term.
I will point out that we do get some resources from space. For example, Flawless Photonics recently produced ZBLAN (a type of glass used for communications) on the International Space Station.
But, this is just a drop in the bucket compared to the billions of tons of resources mined from the Earth each year.
Transplanting a global mining industry into space will take time and lots of resources (mostly from Earth).
So where do we go from here?
We focus on in-situ space resource utilization (ISRU).
As we expand beyond the confines of Earth’s gravity, we should use the resources available on other planetary bodies to fuel and sustain our exploration.
Rather than bringing rocket fuel from Earth, fighting against gravity for every kilogram, we can make fuel in space. Rather than hauling food millions of kilometers across empty space, we can grow it where we land. Rather than lugging factories into space, we can build them in space, from materials already in space.
Over the next half-century, humanity must focus on developing the infrastructure necessary to make space exploration possible. This includes developing the technologies needed to extract and use resources in situ, whether that be on the Moon, Mars, or other planetary bodies. These technologies must be sustainable: economically, environmentally, and socially.
The technologies and infrastructure we develop for space can also be used here on Earth. This will hlep to make Earth a better place to live even if we don’t bring any space resources back home.
The Long Short
The exploration of space, once a realm exclusively for large government agencies, has now become a frontier open to private ventures thanks to advancements in launching technologies. With plummeting launch costs, the prospects of space resources have become tantalizing.
Yet, the dream of bringing vast quantities of metals and other materials back to Earth to supplant terrestrial ventures faces significant challenges. Even with the promising potential of spacecraft like SpaceX’s Starship, the clear technical and financial hurdles hindering such dreams create a daunting return problem.
Rather than diminish the allure of space resources, this return problem underscores the importance of focusing on in-situ space resource utilization (ISRU). Utilizing space resources where they are found, rather than bringing all our supplies from Earth, gives us a chance to expand into the cosmos sustainably.
By investing in technologies for space exploration and resource extraction, we pave the way for a future where humanity thrives both in space and on our home planet. The journey to harnessing the resources of space is not just about bringing riches back to Earth but also about building a sustainable future for the generations yet to come.
An Extra Consideration
If you have read this far, firstly, thank you for taking the time to read. You are the 1% of readers who have made it this far. Please considering leaving a comment and sharing your opinion with me.
As Always:
We are reminded that all humans, regardless of their input, will feel the impacts of future space activities. As such, Space should be a place where humanity’s progress is reflected not just in technological advancements but in our commitment to justice and equality for all.
