
Russian Physicists Solve Radio Black-Out Problem for Re-Entering Spacecraft - Anon84
http://www.technologyreview.com/blog/arxiv/26222/
======
gvb
Trivia: the space shuttle avoids the blackout by its shape, which allows it to
communicate _upward_ to the TDRSS satellites.

[http://en.wikipedia.org/wiki/Communications_blackout#Reentry...](http://en.wikipedia.org/wiki/Communications_blackout#Reentry_communications_blackouts)

"[T]he Shuttle can communicate with a Tracking and Data Relay Satellite during
re-entry. This is because the shape of the Shuttle creates a "hole" in the
ionized air envelope, at the tail end of the craft, through which it can
communicate upwards to a satellite in orbit and thence to a ground station."

~~~
electromagnetic
I sincerely thank you, it's something I've always wondered about but never put
in the time to actually look it up.

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dstorrs
One thing they did not mention is that this solves the primary problem with
orbital crowbars (fictionally called "Rods from God", "Thor", KEWs, and
various other things). You could drop a kinetic warhead (basically a crowbar)
from orbit to kill a tank / bunker / whatever, but you could also use them for
a variety of peactime missions such as mining, emergency flood control
(digging drainage ditches, causing controlled landslides), etc.

Each crowbar would need some sort of minimal steering system to account for
atmospheric turbulence. This steering can't be locally controlled because the
device can't see past the plasma sheath. It can't be remote controlled because
the plasma sheath stops transmissions. With this new "plasma aerial"
technology, you could steer each crowbar individually from the launcher
platform.

~~~
borism
interesting! what kind of materials need to be used so that crowbar doesn't
burn-up on reentry? isn't it a little bit more expensive than using
traditional explosives?

~~~
dstorrs
If you made it out of steel, it would survive just fine -- there would be some
ablation, but it would still get to the ground.

As to the "more expensive"...no, not really. Basically, it's just a crowbar
with a simple camera and some fins on it. Using this technology it would trade
in the camera for a radio back to the launch vehicle. You'd need all the same
bits on a missile, plus more besides, and the missile would need to be larger.

~~~
borism
yes, but you don't need a missile to build a dam :)

sure, it will be less expensive to kill a lot of people with this. those are
not cost savings I had in mind.

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igravious
That should read _Theoretically Solve_ but I admire the ingenuity nonetheless
and hope that the road from theory to practice is short and uneventful.

A shame this hack has military applications, it would be nice if every now and
again scientists patented their discoveries and precluded military use in
doing so. [ Please don't downvote me for expressing this sentiment :) ]

~~~
viraptor
I thought there was a clause making all technology available for national
defence, regardless of patents... but can't find the source. Anyone?

~~~
igravious
That may be true in the US but what about in other jurisdictions? I mean
doctor's have the Hippocrates oath of do no harm to the patient but (and not
to come over all tree-hugging peacenik like) why do
chemists/bioengineers/physicists not have a similar oath with respect to the
our species or other species in general or the planet in its entirety? But I
guess the scientists do the theorizing and the engineers and coders build
weaponize or apply the theoretical results in military applications so what
good would it do ... Hmm, maybe the New Year is making me come over all
compassionate and fuzzy :)

~~~
sp332
In Canada, there is a Ritual Calling of the Engineer, which has an
"Obligation" which is not exactly an oath.
[http://en.wikipedia.org/wiki/The_Ritual_of_the_Calling_of_an...](http://en.wikipedia.org/wiki/The_Ritual_of_the_Calling_of_an_Engineer)
I'll paste the text here if I can find it.

~~~
rbanffy
It's a beautiful tradition. On my graduation all soon-to-be engineer
colleagues also made a solemn promise more or less like the ones other
engineers take in other countries and schools.

I also like the idea of passing the iron rings down through generations of new
engineers. In Brazil we don't. It reminds the ones new to the career that
others came before them and that others will come after them and of the
obligations we share. That's one thing many of us forget much too frequently.

~~~
sp332
In Canada, I've heard it's more "traditional" to let the newer engineers wear
shinier rings, so the more experienced ones have tarnished rings. One of the
older engineers lost his in some machinery and had to get a new one. He hated
it, said it made him feel like a n00b :-)

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haribilalic
It reminds me of the Navy's sea water antenna system
([http://www.public.navy.mil/spawar/Pacific/TechTransfer/Produ...](http://www.public.navy.mil/spawar/Pacific/TechTransfer/ProductsServices/Pages/SeaWaterAntennaSystem.aspx)).

I know nothing about this thing, but I would have thought the plasma would be
on the underside of the craft, allowing any antennae on the top to communicate
with a satellite that could relay everything to/from the ground station.

~~~
jared314
Wouldn't the plasma flow around the craft from bottom to top like a bubble?

~~~
lutorm
Yeah, it does.

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iwwr
I stumbled onto this a while ago:
<http://en.wikipedia.org/wiki/Plasma_antenna>

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pavel_lishin
Anyone else see a weird font used for double-F's?

<http://i.imgur.com/EpolQ.png>

~~~
chronomex
The document uses a ligature (
<http://www.fileformat.info/info/unicode/char/fb00/index.htm> ) for ff.
Apparently the font your browser uses by default doesn't have it. Some font
replacement algorithm decided that the script font you're seeing is the
closest! :-)

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eps
This might be a completely dumb idea and it must've been explored before, but
how about attaching the antenna to a string and trailing it behind the ship at
a considerable distance to clear the extent of the plasma shield. Is it that
no string is strong or plasma-resistant enough?

~~~
elwin
When re-entering, spacecraft are being decelerated, so anything towed behind
the spacecraft will catch up with it. A rigid pole might work.

~~~
dstorrs
They mention this in the article, where they talk about extending an aerial
out past the plasma sheath. They then say "this allows communication until the
aerial ablates."

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TGJ
One thing that has always seemed to rub me wrong in space exploration is the
giant need to stay in touch with Earth. Supposedly the space shuttles are
crewed by the great explorers of our time, but it always seems that everything
is governed by people on the ground and not in the air.

~~~
Nick_C
Basically it's resource management, both human and materials. I'll leave the
human side out, but recommend Gene Kranz book _Failure Is Not an Option_ for
more info on why ground controllers are important.

It costs a huge amount of money (in fuel) to lift anything up, even just a
kilo or two. You're better off lifting only a telemetry system and putting all
the processing, display and engineering on the ground. That means having
ground controllers to manage it.

Of course, in the early days, you couldn't physically fit computers in the
capsule. Now we can, but it is still more economical to have most of it on the
ground and just use radio to let the systems communicate.

