
Receiving Dead Satellites with the RTL-SDR - pavel_lishin
http://www.rtl-sdr.com/receiving-dead-satellites-rtl-sdr/
======
32faction
hey i did my senior undergraduate thesis on orbital debris removal and
mitigation. specifically on mitigating the effects of the Kessler Syndrome.

..and it's a lot harder than just shooting another satellite up to bring the
old one down. you have to match not only the speed of the target satellite,
but the altitude and orbit it's in too.

once you've done that, you can't just attach to it, fire off thrusters and
deorbit it; Newton's law still applies. You'll bump into it and according to
the 3rd law the target will apply an equal and opposite force. you can't shoot
it with a harpoon cause that'll cause more debris.

but let's say you do attach to it somehow or utilize something like
electrodynamic tethers (which is what the Japanese Space Agency, JAXA) is
using. you can't just throw it back to earth and hope the atmosphere does the
rest; you have components that may not completely break up and may rain down
upon populated areas(c1).

usually once a target satellite is acquired, it is moved to a graveyard orbit
away from operational satellites.

i was going to submit an application to YC to startup a space company
dedicated to space debris mitigation but it seemed a bit too complex.

(c1)-This is why most of our spaceflight launch locations (Cape Canaveral,
Vandenburg, Wallops) are on the coasts; they fire away from CONUS so just in
case there is a catastrophic failure, the debris doesnt rain down on your
house.

~~~
kartikkumar
If you're interested in pursuing the idea of a (YC) startup on the topic
still, feel free to drop me a line. See [1] for a bit of background on me.
Active Debris Removal as a service (ADRAAS?) is going to be HOT. I know a few
companies in the space already, and there are plenty of problems to address.

[1]
[https://news.ycombinator.com/item?id=8573800](https://news.ycombinator.com/item?id=8573800)

~~~
32faction
Hey yea definitely! Is there a email/FB or other contact point I can
communicate with you on?

"ADRAAS" haha I love it. I prefer to call it ODRAAS though (orbital debris
removal as a service) to distinguish the 'orbital-ness' of the debris haha.

~~~
kartikkumar
ODRAAS works too :) My email is in my profile.

~~~
spoon16
It's not. You have to explicitly put contact info in your about section if you
want it to be visible to anyone except the YC admins.

~~~
kartikkumar
Ah, didn't realise that it's only admins that can see that. Thanks for the
tip.

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CapitalistCartr
For those of you interested in orbital debris, there is a newsletter put out
by NASA on the subject worth subscribing to. It's a free quarterly PDF.

[http://orbitaldebris.jsc.nasa.gov/newsletter/newsletter.html](http://orbitaldebris.jsc.nasa.gov/newsletter/newsletter.html)

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diydsp
> An audio example of Transit is over here
> [https://dl.dropboxusercontent.com/u/124465398/Transit5b_5_20...](https://dl.dropboxusercontent.com/u/124465398/Transit5b_5_2014_09_06.rar)
> (my recording) it sounds like some kind of melody song.

This is in fact quite incredible to listen to. There seems to be a lot of
"character" encoded in it. It goes through long and slow periods, parts with
rapid notes, etc. Definitely worth a listen and pondering what kind of data
it's "talking" about.

------
frandroid
> There are many shutdown Satellite’s who apparently having a life of their
> own varying from Military, Navigation, Experimental, Weather, and also
> Amateur ones.

Wait, there are amateur satellites?

~~~
LeonM
Yes, there are, most of them are from universities, like this one:
[http://www.tudelft.nl/en/current/latest-
news/article/detail/...](http://www.tudelft.nl/en/current/latest-
news/article/detail/tu-delft-lanceert-satelliet-delfi-n3xt/) Also some hard-
core HAM operator clubs are known to have launched their own amateur
satellites

~~~
blueintegral
There's actually a whole organization dedicated to launched amateur radio
satellites: [http://www.amsat.org/](http://www.amsat.org/)

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hapless
Transit 5B-5, one of the two very early satellites mentioned, seems to have
carried a very early RTG.

I wonder if it is still running on its nuclear power.

~~~
sublimino
For those that were wondering:

> Radioisotope Thermoelectric Generators, or RTGs, provide electrical power
> for spacecraft by converting the heat generated by the decay of
> plutonium-238 (Pu-238) fuel into electricity using devices called
> thermocouples. Since they have no moving parts that can fail or wear out,
> RTGs have historically been viewed as a highly reliable power option.
> Thermocouples have been used in RTGs for a total combined time of over 300
> years, and a not a single thermocouple has ever ceased producing power.

Source:
[https://solarsystem.nasa.gov/rps/rtg.cfm](https://solarsystem.nasa.gov/rps/rtg.cfm)

~~~
S_A_P
I had to look it up as well. I am amazed that voyager 1 is running on about
470 watts of power and is still able to transmit an intelligible signal to
earth. Im also wondering how much a transmitter that was capable of the Ghz
range cost back in the mid 70s when it was built. Incredible stuff.

~~~
geofffox
The two Voyagers are often seen downloading data through NASA's Deep Space
Network. Here's a real time DSN status page:
[http://eyes.nasa.gov/dsn/dsn.html](http://eyes.nasa.gov/dsn/dsn.html)

~~~
heywire
What a neat website! Anyone who is reading down the comments and hasn't
checked it out, you should!

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S_A_P
So I know there are some initiatives and even a Swiss company that wants to
clean up our space junk. Has there been any thing written(and Im sure there
has, Im curious to read it) about when we will hit a tipping point that it
becomes dangerous to even launch into space?

~~~
kartikkumar
There are a lot of papers that have been written on the topic, dating back all
the way to Kessler and Cour-Palais [1]. There's a recent NASA technical report
that catalogs a lot of the work that is being done on debris population
studies that's worth glancing at [2].

I'm involved in the European Stardust network [3] and am working on
remediation technologies for space debris. There are some particular
candidates for active removal that we know pose a great risk. One of the
highest-risk objects is Envisat [4]. There's a concerted effort in Europe
through the Clean Space Initiative and the e.Deorbit mission in particular to
figure out how to remove large, dead satellites like Envisat [5].

For the last six months, I've been working on building a model for preliminary
design of missions that could potentially target multiple debris objects in
one shot [6][7]. Turns out that it might be more cost-effective to design
multi-target debris missions (paper will be o arXiV by the end of the year).

As of next month, I'm going to be leading a new project called Scarab that'll
last 12 months. I'm going to be working with a team to develop an end-to-end
simulator for the removal of dead rocket bodies (e.g., Ariane) that pose a
significant risk to operational satellites, focussing on robust Guidance,
Navigation & Control for proximity operations.

So yea, there's a lot of work being done in the field and there's a general
consensus that we need to act now to subvert the doom scenario of an
uncontrollable collisional cascade that will most definitely render vital
orbital bands useless.

[1]
[http://onlinelibrary.wiley.com/doi/10.1029/JA083iA06p02637/a...](http://onlinelibrary.wiley.com/doi/10.1029/JA083iA06p02637/abstract;jsessionid=CAC1E636BC68A16EA7D2C25569A4AAEC.f03t03)
(paywall)

[2]
[http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/2014000...](http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20140006500.pdf)

[3] [http://www.stardust2013.eu](http://www.stardust2013.eu)

[4] [https://earth.esa.int/web/guest/missions/esa-operational-
eo-...](https://earth.esa.int/web/guest/missions/esa-operational-eo-
missions/envisat)

[5]
[http://www.esa.int/Our_Activities/Space_Engineering/Clean_Sp...](http://www.esa.int/Our_Activities/Space_Engineering/Clean_Space/How_to_catch_a_satellite)

[6] [https://github.com/kartikkumar/atom](https://github.com/kartikkumar/atom)

[7] [https://github.com/kartikkumar/d2d](https://github.com/kartikkumar/d2d)

~~~
32faction
there's definitely a need to reduce and mitigate orbital debris, but the
monetization is polarized to NASA, ESA, SpaceX, and possibly Bigelow Aerospace
when they get their structures operational and I think YC will want something
that's not restricted to a few agencies and space companies. I'm jus tthikning
out loud however

~~~
kartikkumar
Not entirely. Space law is moving pretty fast at the moment, so I think it's
safe to say that commercial ventures that launch satellites will be required
to guarantee safe de-orbiting in some fashion. There are significant monies in
Europe at the moment through ESA and the EU, but I'm convinced that new money
streams will open up within the coming 5 years. The public funding
opportunities also provide some sort of a basis for a business model centered
on providing active removal services. I'm going to be at the CODER workshop in
a couple of weeks at University of Maryland to present my work, and there are
a number of companies that are going to be present too [1]. One of the panels
will specifically address "entrepreneurial opportunities" (Panel 7).

[1]
[http://www.coder.umd.edu/workshop/program](http://www.coder.umd.edu/workshop/program)

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taylorbuley
This chip -- designed as a digital TV radio receiver -- is truly fantastic. So
is the story behind it's instruction set "discovery."

~~~
lfam
Could you link to the story about the discovery of its instruction set? That
sounds really interesting but I can't find it.

~~~
taylorbuley
I'm not sure where I learnt of it now, but here's what I believe to be the
email that started it all: [http://thread.gmane.org/gmane.linux.drivers.video-
winput-inf...](http://thread.gmane.org/gmane.linux.drivers.video-winput-
infrastructure/44461/focus=44461)

If I remember it correctly, Realtek made this board as something to market as
capable of receiving public digital TV waves. It was widely manufactured,
likely as part of the big U.S. digital switchover, so volume was high and
costs accordingly low, saving passed on to the consumer in the form of cheap
hardware. As far specs, using for "just" digital TV was like putting a Ferrari
engine in a Prius. But it lay mostly dormant because the chip's API wasn't
published except to the handful of vendors who likely paid millions for the
spec.

But curiously sniffing around the simple device, in true hacker style, someone
found traces of something far more awesome and dashed off the above email to a
public mailing list. From there, the a community of software radio enthusiasts
together reverse engineered enough of the API to make the extremely low cost
(~$20) consumer hardware usable with open software such as the software
defined radio (SDR) application Gnuradio. For a lot of the cooler applications
of SDR you need two radios - one to transmit and another to receive - and
previously the cheapest options were USRP brand radios from an outfit that did
wonderful engineering but whose hardware was prohibitively priced for
amateurs.

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S_A_P
So this has occupied my thought all day- What are these signals? What "data"
is being transmitted here?

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kitd
Wow! Didn't realise these chips could be used for SDR.

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jacinda
Obligatory XKCD: [http://xkcd.com/1337/](http://xkcd.com/1337/)

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nickthemagicman
Would it be possible to have a two way conversation? Get a command line
somehow?

That would so cool.

Also, what are the speeds of these signals? How long would it take to load The
Pirate Bay site from a sattelite?

Badass potential.

~~~
doctorshady
As a satellite internet customer, I can say you're not missing a whole lot.
There are indeed command frequencies for them, though. So long as they're
farting all over the radio spectrum, it'd be nice to make them transmit
something other then an unmodulated carrier.

~~~
nickthemagicman
Man I wonder what the plain text transmit speed would be for a sattelite.

Talk about avoiding all government censorship. lol.

