
Beyond Gravity: the complex quest to take out our orbital trash - zerny
http://arstechnica.com/science/2014/05/beyond-gravity-the-complex-quest-to-take-out-our-orbital-trash
======
Ygg2
Have they considered some kind of super heavy gravitational mop. Something big
enough to attract enough small particles and just 'mop' them up and send them
into the sun or towards Earth?

~~~
exDM69
I'm sure the idea has been considered - and then ignored as completely
ridiculous when you do the math.

The biggest rocket ever built (the Saturn V) could take 140,000kg to low earth
orbit. That's nowhere near big enough to have any kind of significant
gravitational attraction to "mop" objects away from their orbits. Some kind of
magnet would be more feasible, but still not practical because operating a
huge magnet in the Earth's magnetic field would affect the spacecraft itself.

Finally, once you would have "mopped" these objects into neat bunches, it
would take 4 km/s additional velocity to escape the earth and a whopping 30
km/s to send things towards the sun (without any gravitational slingshot). Now
you can calculate the amount of propellant (using the Rocket Equation) that it
would take to send any meaningful payload that distance.

------
pirateking
Planetes: a hard science manga with space debris as a core story element.

[http://en.wikipedia.org/wiki/Planetes](http://en.wikipedia.org/wiki/Planetes)

------
guard-of-terra
Why can't we launch something like blobs of clay. Let objects stuck in it, and
then it would deorbit on its own.

~~~
iSnow
They're too fast I guess. Try catching a rifle bullet with a blob of clay. And
space debries can be way faster, i.e. have more kinetic energy.

------
EGreg
Why can't we gradually push the largest objects away from earth into a
graveyard orbit and make them spiral out and away from earth over time?

~~~
exDM69
It requires energy to move objects in space, you'd need to add velocity (in
the order of kilometers per second) to move objects out to a graveyard orbit.
And once they are at a graveyard orbit, nothing would make them "spiral out
and away" from earth. The lunar gravity is not strong enough at practical
altitudes to do this (this is known as a Lissajous orbit [0], used sometimes
to put objects to Earth-Moon L2 point).

Geostationary satellites are put into a graveyard orbit a little bit above the
geostationary orbit (but they stay there).

Moving objects from lower altitudes up is not feasible due to the propellant
requirements and the fact that the old satellites/debris are not made for
that.

And you can't just chuck stuff away from Earth either (that needs 11km/s of
velocity w.r.t the Earth in the first place), they will remain in a
heliocentric orbit near the Earth and perturbations from the Earth, the Moon,
and the planets may bring those objects back, travelling at interplanetary
velocities. For example, the S-IVB stages of Apollo missions were sent to
heliocentric orbit (with a gravity assist from the Moon), but the third stage
of Apollo 12 eventually came back to Earth orbit in 2002 (and may come again
in 2040) [1]

[0]
[http://en.wikipedia.org/wiki/Lissajous_orbit](http://en.wikipedia.org/wiki/Lissajous_orbit)
[1] [http://en.wikipedia.org/wiki/J002E3](http://en.wikipedia.org/wiki/J002E3)

------
marincounty
Let's clean up our oceans first? That plastic island out there has irritated
me for years. Oh yea--and maybe stop eating so much fish? That includes Sushi.
I had a girlfriend who called herself a strict vegetarian, but fish don't
matter. Yea, we had numerous arguments about the power of denial.

------
qwerta
This article is junk. It describes in very alarming way space junk, but it
never even mentions atmosphere drag at LEO and natural orbital decay. ISS has
to periodically increase its orbit and it already brought down Skylab and to
some extend Mir.

> and amped the volume up to 11 for dramatic purposes. The filmmakers kept
> only as much science as they felt like keeping

> We’ve already reached the point where the growth of debris in low Earth
> orbit (LEO) has become self-sustaining.

~~~
acqq
The problem will not solve itself if it's ignored. All the current
calculations of future positions of course include the effects of the changes
of the orbits.

~~~
qwerta
It would in a few decades.

~~~
rosser
Only if we stopped putting more crap up there for those few decades (where a
"few" is probably more on the order 10 to 100 ... yes, _decades_ ). Human
exploration and exploitation of space resources is far too important to the
short and medium term benefit of mankind — leaving entirely aside its
implications for our _long term survival_ — to wait it out.

~~~
XorNot
Or put it another way: the GPS system is used to synchronize power phases,
guide aircraft, cars, people, ships. It's built into emergency transponders,
military drones and bombs.

Without that system, we're back to compasses, line of sight and dead
reckoning. We lose the current insane advantage of realtime positioning
anywhere on the planet.

That's 1 18 satellite system - and we absolutely can't run a modern
civilization without it.

~~~
contulluipeste
Actually, nowadays a system of ground stations and high altitudes atmospheric
floating balloons can be made to serve the very same purpose. The ground
stations would serve for triangulation of balloon's position and those at
their turn could serve the rest of the service-consumer base. As a bonus, the
balloons would be obviously more manageable compared to satellites, the cost
of taking them into operation would be of course much lower (no more
atmospheric pollution), and be disposed cleanly without causing the problem
discussed in the article.

