
The race to destroy space garbage - CarolineW
http://www.bbc.co.uk/news/world-us-canada-39521406#
======
drdeadringer
I wonder if, in the future, something like 'Planetes' would become reality.
Space janitors in some sense policing space junk in orbit be it operators
controlling collection robots or actual human space-walk collectors
themselves.

~~~
sandworm101
Collisions are the problem. When to large things collide they create hundreds
of little things. So any space janitors, as large things themselves, would
only increase the number of collisions and thereby exacerbate the problem.

The relative speeds of any two objects in low orbit means that physically
catching much of anything is horribly inefficient. The DeltaV requirements for
a robot grabbing one thing, then moving to grab another, means you are
probably better off launching a separate robot for each target. Any complete
answer must therefore involve some means of moving debris without physically
touching it. Magnets and lasers are the only hope.

~~~
EGreg
Disagree. What about a large elastic net?

~~~
lambdadmitry
They will not work on the scale of kinetic energies involved. Stuff with
orbital velocities has so much energy that even metals start to behave like
fluids, so an elastic net will be torn after the first impact.

~~~
Retric
This is not true because most satellites are in similar orbits, largely
because it's easer going east due to earths rotation. Similarly, you could
cheaply visit every satilite in geosynchronous orbit. Further, you can pick
trash up in an order designed to minimize delta V, and use thing she like
solar sails or ION drives.

Polar orbits are something of an exception, as are consolations designed for
total coverage of the earth.

~~~
sandworm101
Similar orbits, similar inclinations, but still radically different relative
inclinations. They arent all lined up in one big disk. They are in similar
orbits spread out in time. So they are still aproaching each other at speed.

~~~
Retric
I agree there are a lot of useful orbits, but the most useful orbits like
Geosynchronous orbit look like a thin donut/torus and have a lot of satellites
all have the nearly the same vector just time shifted.

GPS satellites for example have basically a hot spare that can easily replace
another satellite in each of the 6 planes. So, if you start out next to one
GPS satellites there are 4 more you can easily reach. AKA visiting all 33
active ones would take 5 major burns, and lot's of tiny ones.

Sure, after a collision you can end up with a shotgun blast that would take a
lot of effort to de orbit. But, having say 20 tugs that all deorbit the
largest debris but getting them to LEO is a lot more manageable than you might
think.

PS: The very tiny stuff is cleaned up by the solar wind over time and mostly
not a problem in the first place.

~~~
sandworm101
Geostationary orbits have no physical debris problems. There is far more real
estate up there and relative speeds far less. Only a few low orbit groups
share an exact orbit. Even sats launched on the same rocket drift into
different planes over years unless they actively work to stay together.

~~~
Retric
To be clear, the near earth part of LEO gets cleared from simple drag though
slower with increasing altitude. And even MEO is reasonably safe simply
because we have yet to put a lot of junk there and there is more room.

So, even if the orbits where random you could simplify the problem by just
sending more craft which would then need a smaller range of orbits. But, even
within that model things are still far from random even though you will get a
lot of drift over time.

------
okket
See also "Kessler syndrome":

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

And, if you speak German, yesterdays "Sternengeschichten" podcast by Florian
Freistetter is about this problem:

[http://scienceblogs.de/astrodicticum-
simplex/2017/04/07/ster...](http://scienceblogs.de/astrodicticum-
simplex/2017/04/07/sternengeschichten-folge-229-das-kessler-syndrom/)

~~~
loeg
Is that basically the premise of Seveneves?

~~~
SideburnsOfDoom
The moon is destroyed on the first page of Seveneves. So not quite.

~~~
harperlee
(spoiler ahead - go read the book instead of this post)

The moon breaks in half in the first page, but a cascade event happens about a
hundred pages into the book, then further changes happen :) . So I think it is
accurate to say that it is analogous!

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AndrewKemendo
Just like all externalities, addressing the challenge comes down to who is
willing to pay for it and the resultant free rider problem.

There would be obvious value in creating a space junk collection/elimination
capability, but the expense when compared to the individual offset/mitigation
solutions, keeps everyone from being the first mover on this.

It's clearly not a big enough problem for there to be enough economic
incentives to solve it.

~~~
jessriedel
There are only a handful of countries with the capabilities to launch things,
there are essentially no entrenched interests who benefit from space debris,
and the science is rather clear. I think this is substantially easier than
other purported free-rider problems that have been solved by international
agreement, e.g., the ozone layer.

~~~
tonyedgecombe
It should be quite easy to define, if you send something up then there must be
provision for returning it at the end of its life.

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sargun
The telescope described in the article is part of the US Space Surveillance
Network. They have an incredibly beautiful installation in Hawaii:
[https://upload.wikimedia.org/wikipedia/commons/d/d2/Ground-B...](https://upload.wikimedia.org/wikipedia/commons/d/d2/Ground-
Based_Electro-
Optical_Deep_Space_Surveillance_%28GEODSS%29_in_Diego_Garcia.jpg)

------
idlewords
The movie 'Gravity' has some amazing images of what a cascading series of
collisions at orbital velocity would look like:

[https://www.youtube.com/watch?v=vKW-
Gd_S_xc](https://www.youtube.com/watch?v=vKW-Gd_S_xc)

------
hourislate
On one of Joe Rogans Podcasts, Neil Degrasse Tyson had said that there is a
very good chance we will trap ourselves on Earth before we can become a true
space faring civilization.

Sad when you think about it.

~~~
parcec
I study orbital debris for a living - I'd like to assure you that you don't
need to feel too worried about that. Orbital debris is generally consolidated
in very thin altitude bands. Rockets on an escape trajectory spend very little
time in these shells, only in passing. Compare that to satellites with
lifetimes of 15 years.

Niel's statement is analog to saying "The LHC could create a black hole that
kills us all". Yeah... I guess on some theoretical level it's possible... but
it's extremely unlikely. Same concept applies here. I'm quite disappointed in
him saying "There's a very good chance", because that is far from true.

~~~
hourislate
Here is the clip from when they start speaking about the space junk. My memory
did not quite remember the exact words Neil used so what I wrote was not
entirely accurate. Apologies.

[https://youtu.be/PhHtBqsGAoA?t=6285](https://youtu.be/PhHtBqsGAoA?t=6285)

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syphilis2
Anyone curious can download the current space catalog from [https://www.space-
track.org](https://www.space-track.org) (signup is required). It's a good
resource if you want access to formatted data about what's up there, and
where.

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sprash
Obligatory: [http://stuffin.space/](http://stuffin.space/)

~~~
FraKtus
Amazing, thanks for sharing!

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ProfessorLayton
I've often wondered something related to this, could a hostile nation ruin
space orbit for everybody? What if a nation deliberately trashed space?

Additionally, I wonder if nations with things in orbit have also considered
that possibility.

~~~
Klathmon
Space is really really big.

It would take a LOT of junk and a lot of money and time to ruin all orbits.

Even LEO is at least as big as the surface of the earth, and getting debris to
stay in that orbit for more than a few months takes thrusters to keep it from
decaying.

~~~
idlewords
You could do this pretty easily. All orbits at the same altitude eventually
intersect, and high LEO orbits take decades or more to decay. Moreover, at
orbital velocities, even tiny fragments can destroy a satellite.

So if you fill an altitude range with enough orbiting shrapnel, you can ruin
the party for everyone. The movie 'Gravity' has some breathtaking visuals of
how such a runaway event would look.

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swashbuck1r
I have a picture in my head of a fleet of Katamari Damacy inspired satellites
gobbling up space debris using magnetic 'glue' and ejecting wads of collected
mass back to earth as part of moving to new paths that will intersect debris
fields. Occasionally a space vehicle grabs hold of the growing debris ball and
moves it to another orbit that needs to be vacuumed.

~~~
JoeAltmaier
Is any of a satellite magnetic? Mostly aluminum etc.

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andrewflnr
If you're a satellite, could it ever be effective to use active radar to
detect small, fast incoming debris and smack it with a laser? There's
obviously a question of power, but do we even have good enough sensors and
weapons? Can you get enough warning to react in time, without making it worse?

~~~
mabbo
That's a neat idea, but it misses an important step: after the laser hits the
debris, what's changed? Now instead of a small piece of cold metal coming at
you, you have a very hot blob of molten metal moving at roughly the same
direction and speed.

~~~
maxerickson
With high enough power, the debris might eject some material (pushing it into
a different orbit).

[https://en.wikipedia.org/wiki/Kessler_syndrome#Avoidance_and...](https://en.wikipedia.org/wiki/Kessler_syndrome#Avoidance_and_reduction)

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

I guess it isn't something that would be on lots of satellites. But it
wouldn't need to be.

------
oh_sigh
How about autonomous satellites which cannibalize space junk's orbital
velocity to de-orbit the junk, and maintain the satellite's orbit?

Imagine, a satellite is collecting space junk it encounters, and compressing a
big spring using solar power. Once it gets enough junk, it launches the junk
backwards, giving it momentum and sending the junk into an unstable orbit.

~~~
snovv_crash
Rather than a spring, a coil gun would work with any conductive material quite
effectively. I imagine that the difficulty is repeatedly changing orbits -
this will probably require more propellant than can be derived from junk.

I was wondering if SpaceX couldn't use its second stages to grab some junk
while it is deorbiting. That would be some seriously good publicity.

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userbinator
I wonder if there's a way to collect and recycle it, especially the larger
objects, since from what I know aerospace components contain plenty of
exotic/expensive materials.

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dsfyu404ed
Eh, if it becomes a real problem I'm sure someone will figure out how to
vaporize it with a big laser.

