
E.Deorbit (2016) - acqq
http://www.esa.int/Our_Activities/Space_Engineering_Technology/Clean_Space/e.Deorbit
======
acqq
"The mission is being prepared for approval during the next ESA Council at
Ministerial level in late 2016"

Anybody knows what happened then? What's the current status?

~~~
wlkr
A set of slides from a presentation given by Luisa Innocenti, head of the
Clean Space program at ESA, seems to indicate ongoing testing and a 2024
launch date. I couldn't find anything more concrete, unfortunately.

[http://www.jsforum.or.jp/stableuse/pdf/26%20Innocenti_eDeorb...](http://www.jsforum.or.jp/stableuse/pdf/26%20Innocenti_eDeorbit_CleanSpace.pdf)

~~~
acqq
Thanks, very good presentation!

There's also a link to the "cleanspace" blog there at the end:

[http://blogs.esa.int/cleanspace/](http://blogs.esa.int/cleanspace/)

Last post July 6, 2018, the project lives.

Then from there, "The Clean Space Industrial Days 2018" event

[https://indico.esa.int/event/234/](https://indico.esa.int/event/234/)

will happen: "23-25 October 2018 ESTEC"

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bumholio
Once the proof of concept is demonstrated, an interesting development is to
use a robotic arm to disassemble the junk and grind it into fine dust that can
be used as propellant for an electrostatic engine:
[https://arxiv.org/abs/1511.07246](https://arxiv.org/abs/1511.07246)

This way, a single mission can hop from orbit to orbit bringing down hundreds
of targets instead of a sole suicidal mission.

Another way for serial junk cleanup is to have a number of electrodinamic
tethers and attach one on each target after de-tumbling. Even a few hundred
meters of conductor materials (carbon fibre) would drastically reduce time in
orbit.

~~~
acqq
“This paper has been withdrawn by the author due to a crucial sign error in
figure 1”

~~~
bumholio
Sorry, here's a cached copy:
[http://erewhon.superkuh.com/library/Space/Spacecraft/Debris%...](http://erewhon.superkuh.com/library/Space/Spacecraft/Debris%20Engine_%20A%20Potential%20Thruster%20for%20Space%20Debris%20Removal_%20Lei%20Lan_%20Jingyang%20Li_%20Hexi%20Baoyin_%20arxiv151107246.pdf)

Regardless of any redaction errors, the basic idea is sound. While the
particle engine is not able to produce the large impulse of ion drives (low
specific ionization), it turns out the optimal impulse for such an application
is in the 100-200 range. Any higher and the thrust drops too much prolonging
the mission duration, for a given amount of electric power available.

For this application the opposite is true: you want maximize thrust and throw
away the full mass of the previous target before reaching the next one to be
consumed.

~~~
acqq
“Regardless of any redaction errors, the basic idea is sound.”

As far as I know the basic physics, the whole energy for the movement would
still NOT come from the crushed satellite pieces but from some energy source
in the satellite destroyer.

~~~
bumholio
Of course, it's electric propulsion so most likey solar. But the unlimited
propellant mass allows for a much higher thrust than typical for satellites
and quick (days, weeks) orbital hops.

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AllegedAlec
Using nets or arms seems wasteful to me, to be honest; you'd need to bring a
new satellite up there for every piece of debris you want to get rid of.
Wouldn't it be a lot more convenient to use something like laser ablation to
slow down the debris and make it burn up in the atmosphere on its own?

~~~
msadowski
I don't know the process of laser ablation. How would you use it in the
context of this mission?

~~~
AllegedAlec
With laser ablation you fire a high-wattage laser as something to turn a very
small surface layer to plasma. The expanding plasma cloud imparts an impulse
onto the surface it is ablating, which can be used to slow down debris.

[https://en.wikipedia.org/wiki/Laser_propulsion#Ablative_lase...](https://en.wikipedia.org/wiki/Laser_propulsion#Ablative_laser_propulsion)

------
msadowski
Surprised to see this posted here! As a student I had a chance to take part in
e-deorbit symposium in 2014. Back then they were considering 3 methods for
capturing satellites: a net, robotic arm and a harpoon of sorts.

What struck me the most from this conference is realizing how big of an issue
space junk can be. From back then I remember the was no rules on disposing of
satellites, the owning body could decide for a nice approach and use the fuel
to put the satellite in a higher orbit, or slow it down so that it burns in
Earth atmosphere. Or they could not give a shit and use the remaining fuel for
operations, maximizing the profit.

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ur-whale
Are we saying that in the last 70 years or so, we managed to litter space so
bad that this is actually a problem?

Help me understand here: aren't we talking about a volume of space with a
radial cross section significantly larger than the surface of the earth?

I find it hard to believe we've launched so many things that collisions have
become likely.

Any actual data out there on the number of objects in orbit and the likelihood
of collision?

What am I missing?

~~~
acqq
You miss that the kinetic energy is proportional to the square of the speed.

[https://www.quora.com/Which-one-makes-a-bullet-dangerous-
its...](https://www.quora.com/Which-one-makes-a-bullet-dangerous-its-kinetic-
energy-or-its-momentum)

The speeds at which even the smallest debris hit other satellites are immense,
compared to what we are used to in our surroundings. International Space
Station moves at the speed of 17 thousand (!) miles per hour. Even the small
pieces of something else moving at the different speed or direction will be
extremely destructive, see again the explanation about how the bullets "work."

Then consider the number of the pieces there and the fact that their movements
are "unstable" (as in not keeping the trajectories that are always at the same
distance from the Earth).

Only once you understand all that read about:

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

------
Zarathust
China showed a few years ago that blasting satellites with missiles is neither
subtle or sustainable. This kind of thing could be weaponized much more
efficiently

