Because I just finished the book “Mining the Oort” by Frederick Pohl, my favourite science fiction author by the way, and because of Philae’s landing on the Comet 67P/Churyumov–Gerasimenko I would like to take a look at the feasibility of comet mining Oort cloud and other wise.
Content
But first a look at the book that inspired this article.
Book Review
Mining the Oort
by
Frederick Pohl
(1992)
Synopsis
Mining the Oort tells the story of young Martian-born Dekker DeWoe. He witnesses the first asteroid crashing onto Mars surface by the Oort mining program to replenish the atmosphere of the planet, in the hope to terraform it into earth’s breadbasket.
But there is trouble ahead! Mars future is in jeopardy as Mars futures, intended to fuel the solar system wide endeavour, plummet at the stock market as the Japanese develop their alternative earth orbiting farm program.
Follow Dekker as he applies for the training program to become an Oort miner himself and learn everything there is to know about hurtling comets from the Oort cloud into the inner solar system in the hope to change the bleak future of his home planet. Unfortunately that means he has to go to Earth, an inhospitable place for a Martian not only for its crushing g-forces.
Review
Mining the Oort is not the best sci-fi novel Frederik Pohl has ever written, however, it is a solid work. One realizes how good a story it is, when compared to his earlier works or to other science fiction writers. The main story is of Dekker DeWoe whom we follow on his way to become an Oort cloud miner. Here the story brilliantly explains all the finer details and the knowledge necessary to mine the Oort, from dangers of space travel to life in zero g. This in on it self would be a story for a whole book. Frederik Pohl, however, adds additional layers by telling the story of the two worlds Mars and Earth and of the discrepancies between them on a social, economical and cultural level.
The situation becomes dire when Japan pushes for different solution to feed the planet.
Cover Art
Unfortunately I still live in Germany. Here, if one wants to show the book cover of a book together with the book review, – which, – duh! – would make sense, how else would you easily identify the book online or in a second-hand book shop -, one needs to also review the art work on the cover to be legally on the save side. So here is the review of the cover art:
Besides that half of the cover is plastered with grater then live solid letters of the author’s name and the title of the book we see actually one of the starting scenes as it might unfold in the book. People in space suits covering what appear to be solar cells in front of a giant tall space antenna / space station entrance while an icy comet is approaching in the back.
Somebody has done their homework and that somebody is unfortunately not mentioned anywhere in the book.
Please if your book uses artwork don’t forget to mention the people producing them. Thanks.
I hope that is sufficient review of the artwork. Fingers crossed.
If-ics
We are here at if-ics|sci-fi and therefore interested in the technologies and ideas presented in the novel.
Because of the recent landing of the space probe Philae on the Comet 67P/Churyumov–Gerasimenko everybody thinks now that mining comets is all the rage. But besides that flying Rosetta for over 10 years through the solar system and finally catching the orbit of its comet and then sending Philae onto its surface. That is an amazing achievement. I cannot even fathom how much work and thought went into that kind of project.
Now to do that reliably and economically viable over such a large timeframe is absolutely ludicrous.
“Yes, your comet will be here shortly. It will only take 70 years till he is back in the neighborhood.”
Covering the distance and actually flying out into the Oort cloud and mining the comets there is just not feasible.
Therefore, it is and it will never be feasible to mine the Oort cloud for comets. There are two major problems: 1) The Oort cloud is unfathomably far away from earth and 2) even though it is called the Oort cloud, comets in the Oort cloud are so sparse compared to the vast space between them, the whole endeavour becomes ludicrous.
Distance to Neptune (and beyond)
The only man-made objects that ever travelled beyond Neptune are the two Voyager space probes 1 & 2, Pioneer 10 & 11 and now of cause New Horizon with its mission to Pluto. New Horizon is by far the fastest of the bunch and it took “only” a little over 9 years to reach Pluto and Charon in the Kuiper belt. It is reasonable to assume that a society capable to establish several habitable “cities” on Mars could cover the distance a little bit faster than that. So we can travel beyond Neptune, the last planet of our solar system, and reach the Kuiper belt reaching out from approximately 30AU (orbit of Neptune) to around 50AU, which was discovered in 1992, which is by coincidence also the year “Mining the Oort” was published. The Kuiper belt would be a much closer but still unfeasible mining ground for comets with an attached traveling time of minimum of 20 years. How would they come back though? There are no big objects that could gravity-slingshot you back home. So you better bring a huge amount of fuel other wise you would be stuck out there. If one does not turn home from here one reaches at some point the alledged Oort cloud.
The Oort cloud however is a hypothesised spherical cloud of predominately icy comets approximately 1000 times further away than the Kuiper belt. Meaning it stretches out into space ¾ of a light year, which is a little bit more than a sixth of the way to the next neighbouring star α Centauri. The closest part of the Oort cloud is thought to be at 2000-5000AU from the Sun. That would mean it will take voyager 2 800 years to reach it. If Genghis Kahn would have started a space probe together with his invasion of China we could expect the space probe to reach the Oort cloud any minute now give or take few 100 years.
Mining nothing or the vastness of space
If the Oort cloud is hypothesised it is only natural that the amount of comets in it is approximated. It is of cause somewhere in the illions. Trillions of comets size 1km and Billions larger than 20km as it is stated on Wikipedia. Overall they all amount to approximately 5 Earth masses, which might sounds a lot until one factors in the space this mass is distributed in. Let’s calculate how far apart they would be.
Math time!
Matter
Mass of Earth: 6×1024 kg
Volume of Earth: 1×1012km3
Density of Earth: 5.52 g/cm3
Density of ice: 0.917 g/cm3
Five Earth masses amount therefore to 3×1013 (30 trillion) 1km3 boulders. If the density of the boulders would be the same as earths that is, which is of cause not the case. Therefore, we need to adjust the amount of comets according to the density and get around six times more comets, which amounts to 180 trillion.
Space
50.000AU creates a volume of 1,8×1039 km3
Fun fact: It doesn’t matter if one subtracts the volume of the solar system and the Kuiper belt and the rest, it still amounts to the same volume.
So an icy comet of 1 km3 can be found every 215 million km. To put it into perspective 150 million km is earth distance to the sun. So between one comet and the next one can fit easily Mercury and almost Venus (only 3 million km short) orbiting the sun.
So mining the Oort is not feasible. There is basically nothing there to mine nor can the distances be travelled with in a reasonable time frame like a human lifetime. It would only be feasible if one would possess an exorbitant amount of fuel to accelerate and decelerate for years.
Hail Halley!
For now the comets are up in the sky but the question remains:
Is mining the comets with in our solar system economical?
At the moment I can not see how. I like to quote Elon Musk:
Just to keep in mind the Rosetta program took 10 years to finally arrive at the Comet 67P/Churyumov–Gerasimenko. To do so reliably and economically sound is way beyond our capabilities at the moment and probably for years to come. The biggest problem is of cause that to be feasible the comets need to carry something so valuable and precious we would do anything to get to it.
Here Frederik Pohl has a good reason. Terraforming mars with a bombardment of much-needed influx of water is actually brilliant. The water would thicken the atmosphere and would retain additional warmth from the sun as well as from the impacts itself, which would help to release additional CO2 into the atmosphere warming Mars even further.
That said the rest of the book is rather remarkable. Everything else seems rather sound or as my non space flight, zero experience in zero gravity, never suited up in a space suits or any other form of traveling in outer space besides sitting on a tiny rock called earth.
So think about that for a change on your way to work. You are already a space traveler on a tiny pale blue dot carrying everything and everyone that ever mattered to us. (Sorry for butchering Carl Sagan).
So happy space travels where ever it may leed you.
And I’ll see you in the future.
Naso
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