IEEE Spectrum November, 2013 - 20

resources_Geek lIfe

NoV 2013

NorTH AMerIcAN

sPecTruM.Ieee.orG

sPace on $35 a day
citizen-science
satellites alloW
anyone to run
experiments in orbit

n 1957, Arthur Frommer trAveled europe
on US $5 a day, and the Soviets launched Sputnik 1.
Today, $5 scarcely covers an espresso at a Parisian
café, but it could buy 3 hours on a satellite packed
with technology that would have seemed like science fiction to
Cold War rocketeers. * In August, two small satellites were sent
to the International Space Station (ISS) and will be launched
into their own orbits in November. At a cost of about $35 to $45
per day of run time, purchasable in blocks of three days or more,
students and hobbyists can run experiments with the satellites.
These ArduSat spacecraft, from the start-up NanoSatisfi, were
developed from an open-source design based on the Arduino
microcontroller. Each is a cube 10 centimeters on a side and
has a magnetometer, a spectrometer, temperature sensors,

nanosatisFi

antenna, and a more discreet short-range edition
that has a button adapter. In addition to an adapter,
each kit comes with a Model B Raspberry Pi microcomputer; a case; an FTDI serial communications
cable; a micro USB cord and mains adapter (to supply power); an Ethernet cable; and a 4-gigabyte SD
card loaded with a version of Linux that is optimized
for the Pi (but doesn't have the Tor software installed).
Putting the hardware together is trivial: Pop the SD
card and Wi-Fi adapter into their slots, and then hook
up the micro USB cord and Ethernet cable to the mains
adapter and a router, respectively.
Getting the software running is a different story.
Adafruit supplies a detailed set of tutorials online, but
using them can sometimes feel like going down a series of rabbit holes. Adafruit designed each tutorial to
be self-contained, so it can be used with different kits.
So there's one generic tutorial for initially configuring
a Raspberry Pi, another for setting it up as a Wi-Fi access point, and so on. And some tutorials direct you
to complete another tutorial midway through. Some
of the tutorials are also best completed using graphical-interface-based tools, so you'll probably want to
hook the Pi up to a keyboard and mouse and an HDMIcapable TV for at least part of the process.
You'll also be editing a fair number of text-based
configuration files. Fortunately, you can avoid a lot of
error-prone typing by using the FTDI cable to connect
the Pi to whatever computer you're using to read the
online tutorials. Then it's mostly just a matter of cutting and pasting various alphanumeric gobbets into
configuration files via an old-school terminal window.
There are also traps for the unwary during the process: For example, the British-made Pi has a U.K. keyboard set as the default. This caused a problem when
I dutifully changed my log-in password as my first step
and later changed the keyboard settings to "U.S." After
rebooting the Pi, I had difficulty logging back in because
some of the symbols I'd used for my password are in
different places on a U.S. keyboard. Another example
is when I tried powering the Pi using the FTDI cable
alone. This feature would have been convenient, but
it turns out the cable doesn't supply enough juice to
sustain an Ethernet connection. It took me a while
to figure out why my network had stopped working.
Once configured, however, the Onion Pi is easy to
use: Just power it and plug it into an active Ethernet port.
Certain services are blocked to preserve anonymity,
such as the "ping" command used to test connections,
but in general the Onion Pi behaves like any other Wi-Fi
access point. There's one big difference, though: speed.
Tor anonymizes traffic by encrypting it and sending
it to a relay. The traffic then bounces around at random
within the Tor network until it is decrypted at an exit
gateway somewhere around the globe and passed
to the Internet at large. The outside world sees the
IP address of this exit gateway as your IP address. All
this takes time, and the Tor network has only so much
bandwidth, so attempting to download a video file, for
example, can be an agonizingly slow process.
There are also limits to the veil of anonymity provided.
If you transmit identifying information-such as your
name-to an external server, then you've rendered the
system moot. What's even more insidious is that if you
use the same browser for accessing the Tor network
as you do for regular surfing, you could be "clickprinted"-that is to say, identified by such things as cookies
stored on your computer or the precise configuration
of your plug-ins. Browser, beware. -STEPhEN CASS

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Table of Contents for the Digital Edition of IEEE Spectrum November, 2013