
A superconducting shield for astronauts - user_235711
http://home.web.cern.ch/about/updates/2015/08/superconducting-shield-astronauts
======
ChuckMcM
_" Captain, magnetic shields at 50%! We've got to pull back."_ \-- some future
space traveler.

I remember some interesting discussions about magnetic shields in the NASA
technical journal, but there were issues with things like electronics inside
the shield and conductive cabling going through it to sensors outside of it.
Even in the more detailed site
([http://www.sr2s.eu/2013-08-01-15-34-14](http://www.sr2s.eu/2013-08-01-15-34-14))
I didn't see a lot of info on those sorts of "known" issues.

------
InclinedPlane
This appears to be merely a mag-sail, but used as a radiation shield.

It seems to be in every way inferior to the m2p2 concept, which uses a mini-
magnetosphere (instead of just a magnetic field) for the same purpose [1]. The
advantage being that we could build and field such systems using existing
technology at reasonable cost.

1:
[http://earthweb.ess.washington.edu/space/M2P2/rad.shielding....](http://earthweb.ess.washington.edu/space/M2P2/rad.shielding.pdf)

------
curtis
Just out of curiosity, I wonder if it would be possible to embed the
superconducting magnets in a spaceship's liquid hydrogen tank. This would
eliminate the need for "exotic" high temperature superconductors.

~~~
jccooper
A long-range spacecraft would probably not have LH2 on board. It evaporates
quite quickly unless you want to install cryo cooling systems and the power to
run them.

~~~
curtis
Boil-off is a bigger problem with LH2 than with liquid oxygen or liquid
methane. However, I'm under the impression that it's a tractable problem out
to months or maybe even years. Apparently the Spitzer Space Telescope
maintained a supply of liquid helium for about five years [1][2].

A lot of Mars manned-mission proposals (starting with Zubrin's Mars Direct
plan) depend on the use of a Sabatier reaction which would convert hydrogen
brought from Earth into Methane and Oxygen. So the experts must think they can
at least minimize boil-off over at least 8 or 9 months. [3]

[1]
[https://en.wikipedia.org/wiki/Spitzer_Space_Telescope](https://en.wikipedia.org/wiki/Spitzer_Space_Telescope)

[2] [http://www.spitzer.caltech.edu/news/436-ssc2009-12-NASA-s-
Sp...](http://www.spitzer.caltech.edu/news/436-ssc2009-12-NASA-s-Spitzer-
Begins-Warm-Mission)

[3] [https://en.wikipedia.org/wiki/In-
situ_resource_utilization#M...](https://en.wikipedia.org/wiki/In-
situ_resource_utilization#Mars)

~~~
jccooper
Mars Direct uses suspiciously low boil-off rates for LH2. Certainly well past
current state of the art. Best achievable (not flown, but could be) is
0.1%/day, and Mars Direct wants 0.1%/month. You don't lose a lot at 0.1%/day,
but it adds up.

~~~
curtis
At 0.1% per day, I get 30% boil-off in 1 year (0.999 ^ 365 ==> 0.694), which
is expensive but probably still a net win. I don't think boil-off is a problem
once you're on Mars because you can probably just use the hydrogen gas as
feedstock into the Sabatier process.

Which is not to say that Mars Direct isn't overly optimistic, possibly about
many other things as well.

------
louithethrid
Now, if you would please strip your spacestation of all metalls and arrange
for propulsion to counter the small drag of earths magnetosphere upon the
system...

Or are the magnetic fields generated and the corresponding heat from induced
eddys not so strong? The sceptic in me wants to know more before feeling
optimistic..

Supraconducting magnets allready exist in Magnetic Resonance Tomography and
the idea of a cookoff in space after a micro asteroid impact...

------
krohling
Is power consumption a problem here? It seems like power production on a space
craft would be quite limited (solar, plutonium?) and this thing would consume
a lot of it. Is the idea that this would always be on or only on in an
emergency? Also, is interference w/ electronics on the craft a problem?

~~~
jccooper
It's easier to supply power than mass in space, and mass shielding is the
alternative.

Solar is problematic on Earth but is actually quite good in space. Lots of
reliable energy right there, especially if you're not in Earth orbit (where
the shadow occasionally gets you).

~~~
Quanticles
If you're in deep space then you're not near any particular star. That's going
to reduce the available starlight by several orders of magnitude, right?

~~~
jccooper
When people designing real spaceships say "deep space" they mean "beyond Earth
orbit", but usually not past Mars.

In sci-fi deep space, yes, you'd have next to no solar power. (In fact, it's
minimally useful in the solar system past Jupiter.) But if you can get there
at all, you're probably not worried about that.

~~~
Quanticles
Makes sense, thanks

------
ars
Is it possible to make a magnetic configuration that will repel all charged
particles?

Won't particles moving in the right direction be attracted and you'll
irradiate everyone inside when they slam into the shield, with some extra
energy from it?

~~~
Steuard
The nice thing about magnetic fields is that _all_ charged particles are
deflected: the positive ones bend one way, and the negative ones bend the
other.

In a lot of situations, the particles will actually spin along helical paths
whose net motion is _along_ the magnetic field lines. In the case of Earth,
that means that the charged particles eventually make their way to one or the
other pole... and as the field lines descend into the atmosphere, those
particles create auroras. Neat stuff!

~~~
euyyn
That's why the comment you've replied to says "particles with the right
direction", not "particles with the right charge".

------
the8472
I wonder how much cooling superconductors need in space.

Basically, how warm is the interior of a satellite with a high albedo (gold
foil?) in the inner solar system?

~~~
delibes
Thermal management in space is a big issue. The ISS has big radiators on the
long truss, and lots of plumbing for cooling.

For a superconducting magnetic shield, it depends how much power is used to
maintain it. MgB2 supports high currents compared to cuprates, so I guess once
it's turned on it doesn't need much?

