
Why We Don't Shoot Earth's Garbage into the Sun (2019) - nkurz
https://www.forbes.com/sites/startswithabang/2019/09/20/this-is-why-we-dont-shoot-earths-garbage-into-the-sun
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dTal
This is like asking why we don't use the Large Hadron Collider to make toast,
and then answering by going into detail about how tricky it would be to coax
the LHC into making toast of acceptable quality.

We don't do it because you don't use hyper-expensive mega-engineering to solve
mundane problems with easy solutions, like "where do I put my banana peel".

~~~
blablabla123
Not to mention radiation at LHC...

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dmurray
How can this really be a question? It's obvious that it's expensive to launch
things in rockets: that has very little to do with the orbital mechanics
nerding out of "actually you can't just fall into the sun, you need a
surprising amount of delta-v" and everything to do with the cost of building
skyscraper-sized shiny single-use machines that are 90 parts fuel, 9 parts
expensively machined metal, and 1 part "garbage" payload.

In other words, launching garbage in any kind of rocket is incredibly
inefficient compared to dumping it on the ground or into the ocean, so the
consideration of "would it be cheaper to send it to the Sun or Jupiter"
doesn't really come into question.

~~~
coldcode
But could we accelerate the payload using something other than a rocket? After
all G-forces are not an issue for garbage. Assuming you could get to orbit,
how much fuel would it take to get it going in the right direction and then
have gravity do all the work?

~~~
coldtea
> _But could we accelerate the payload using something other than a rocket?_

As in?

~~~
throwaway744678
A giant slingshot?

~~~
willis936
A giant thermonuclear slingshot.

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cletus
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]: [https://external-
preview.redd.it/U5iH7huE5qKth7ZFvipXt8vzaFO...](https://external-
preview.redd.it/U5iH7huE5qKth7ZFvipXt8vzaFOO99qHFh9o9_SkLLk.png?auto=webp&s=d145ac9ae496abe35fae86fc11a584d62fe42592)

[2]:
[https://www.youtube.com/watch?v=LMbI6sk-62E](https://www.youtube.com/watch?v=LMbI6sk-62E)

~~~
me_me_me
> 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.

That's true, after all we are still stuck trying to invent materials light
enough to make areoplanes actually fly /s

Sorry couldn't help it :)

Pushing what is currently impossible is how we got where we are. We already
have viable tech to capture asteroid that could be used as counterweight for
space elevator.

~~~
cletus
> Pushing what is currently impossible is how we got where we are.

This is a tired cliche at this point. Yes the track record for what is
"impossible" (flying, going to the Moon and so on) could lean one towards
saying nothing is impossible but take that to the extreme and what's left? Is
breaking the second law of thermodynamics "impossible"? Time travel?
Wormholes? FTL?

Engineering is ultimately limited by physics and the physics for a space
elevator are dire. You need a material with a tensile strength such that it
can withstand the centrifugal forces of being 35,000km+ long including having
a counterweight pulling on it to counterbalance the force of gravity acting on
the mass of that.

At this point only theoretical materials come close to that.

But even if you can solve the tensile strength problem (and that may well be
solvable) you're left with a structure that isn't really as useful as you
might think.

Even getting between the geosynchronous point and the Earth requires speeding
up and slowing down for a distance of 35,000km+. Average 1000km/h and you're
still talking 35 hours. 1G of acceleration and deceleration could cover this
distance a lot quicker but there are limits to how fast you can go when you
need to stay attached to a column the whole way.

But let's say you can solve that problem and get to geosynchronous orbit in
reasonable time. Now what? Well if you want to go anywhere you need to
accelerate. You need to bring the fuel for that.

Now compare this to an orbital ring. An orbital ring:

\- doesn't require any magical materials. The core of it is nothing more than
copper or iron cabling;

\- will get you get to and from different points on the Earth much faster;

\- provide LEO space to live and work on the stationary (relative to the
surface of the Earth) platform. At 20 meters wide you're talking ~1 billion
square meters of area, which is almost as large as the land area of Los
Angeles;

\- allows for huge amounts of solar power to be generated and sent to the
ground via transmission cables;

\- provides you with enough delta-V to escape the Solar System for almost no
cost; and

\- has significantly more attractive failure modes. If an orbital ring severs
it'll likely fly off into space based on inertia. If a space elevator severs
part of it is likely to fall to the ground, which would be... bad.

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alexandernst
There might be a slightly modified version of this question which might
actually make sense: "Why we don't shoot nuclear waste into the Sun".

Surely, the cost of storing that type of waste here (on Earth) is very
expensive, both from economical perspective and from risk management
perspective. It could be very interesting to compare the costs of sending 1kg
of nuclear waste into the sun (or out of our solar system, if that makes it
cheaper) compared to storing 1kg of nuclear waste anywhere here on Earth, +
adding the cost of the infrastructure that is required to actually store and
preserve that waste, + adding the cost of people that are required to protect
that infrastructure (a facility of some sort), etc...

~~~
08-15
No infrastructure or crew is required to "protect" the "infrastructure" around
a glass log on the ocean floor for the ~500 years it takes it to become as
radioactive as natural uranium ore.

Why don't we discuss this easy disposal option seriously? Why do we instead
ask seriously about launching it into the sun instead?

Because nuclear waste has been politicized to such an extent that most people
have no idea what it is composed of, what the halflifes of its constituents
are, how radioactive it is, how chemically reactive it is or even what state
of matter it is in. But everyone knows that, like, it is, like, totally
dangerous!

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atarian
Even if we had a cheap, reliable way of sending garbage to the sun I am
skeptical of the idea that the garbage would just magically disappear. It
would probably accumulate into another problem later down the road.

~~~
TheSmiddy
Exactly, our garbage is made up of the most valuable elements on earth, as
proven by the fact that they were used to make useful products, eventually we
will be mining garbage to extract the value once the cost is cheaper than
traditional mining. If we launch it into the sun eventually there will be a
resource shortage of some kind.

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ragebol
Even if it would be cheap to launch junk into space, we'd still have to solve
some of the same issues we'd have to solve now as well: collection. To put it
on a rocket, you'd have to collect the junk first, which we currently don't do
well (except in a couple of countries). Nuclear waste is well collected
though, I'd say.

Breaking that down to it's constituent protons and neutrons would make it
harmless right? Though I have no idea how much energy that would cost, only
that the lower bound is probably well above what is reasonable.

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Aardwolf
If it ever gets that far, I'd rather see it launched in an orbit around the
sun than into the sun, the material could still be useful later

~~~
jadell
If we're saving it for later (but for some reason don't want it on Earth) we
should just launch it into orbit around the Earth. Why waste the fuel to send
it outside Earth orbit just to need it back later. Even if we wanted to use
the materials somewhere else in the solar system, just park it in orbit around
Earth until its time to move it.

~~~
Aardwolf
Possibly to avoid this Futurama scenario:

[https://en.wikipedia.org/wiki/A_Big_Piece_of_Garbage](https://en.wikipedia.org/wiki/A_Big_Piece_of_Garbage)

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guiltygods
One alternative could be instead of shooting surface based garbage into the
Sun can we not not just sequester the thousands of
dead/decommissioned/dangerous human launched objects orbiting around our
planet and launch them towards Sun?

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JoeAltmaier
Cheaper in energy to burn it or bury it, than to put it into orbit, _and then_
accelerate it enough to fall into the sun. Yes, accelerate.

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2OEH8eoCRo0
Simple. The goal is to get rid of trash. This accomplishes the goal but others
ways accomplish the same goal at much lower expense.

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bobwernstein
why don't we build a chimney up to space and release all that co2 into space?

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JoeAltmaier
Not as silly an idea as it might seem. Even releasing it into the upper
atmosphere (a few miles up) would make a difference.

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t0ddbonzalez
Humanity in a nutshell: "Why change our polluting ways when we could just
blast our junk into space?"

Why do we think we have the right to blast our junk into space?

Who does the cleanup when a rocket explodes after launch and covers
Florida/Guyana/Khazakstan in used diapers and hypodermic needles?

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JoeAltmaier
Too late; already covered.

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t0ddbonzalez
Really? How so?

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JoeAltmaier
Isn't the whole issue, get the trash out of our ecosystem and put it 'into
space'? That's the entire topic.

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amelius
If only we could shoot all those rocket exhaust fumes into the Sun.

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NikolaeVarius
TLDR: It takes a ton of fuel to slow down enough to get a payload to fall into
the sun.

~~~
coldtea
It would be burned to a crisp long before it reaches the sun, so that's a moot
point. Doubly so since it's also extremely expensive to escape our orbit...

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101404
Because 1 kg to orbit costs 5000 USD.

~~~
senectus1
goes down by quite a bit when /if we build a tether (space elevator).

but would still be a stupid idea. _everything is recyclable_

