Balloons
Most groups choose the Kaymont 1,500g sounding balloon
(
kaymont.com, $105). It’s relatively inexpensive, can
lift 3.8kg, and is rated for a bursting altitude of 34.2km,
or more than 110,000 feet. (It’s possible, but not
recommended, to eke out more lift by overinflating your
balloon.) For helium, rent a tank from a local
industrial/medical gas supplier.
A
Radar Reflector
The hackers track the balloon on laptops as it rises to black-sky
altitudes 20 miles up, whereupon the balloon bursts and the payload floats
down. Team members on dirt bikes race to recover the package, checking
their mobile phones for SMS texts containing GPS coordinates of the
landing site.
While this sounds like a scene from some hacker novel, launching and
recovering near-space balloon probes is easier than ever, and dozens of
amateur groups — ham radio enthusiasts and hackers alike — are doing
it now.
A bunch of hackers drive into the desert with a trunk full of equipment: a weather balloon, a tank of helium, and a styrofoam cooler loaded
with cameras and sensors. After filling the balloon, they release it and
watch it hurtle skyward, the cooler and a parachute dangling beneath.
Legal flights require a cut-down mechanism to separate the balloon from its
payload and parachute after a set time or in response to a signal. One simple
cut-down circuit uses a relay to discharge a dedicated 9-volt battery through
a high-resistance Nichrome wire coil that’s wrapped around a nylon cord.
Close the relay, and the coil melts the cord.
E
Cut-Down
An enclosure protects payloads from the extreme temperatures of the upper
atmosphere and the impact of hitting the ground. Most amateurs use a foam
cooler or construct an enclosure out of extruded polystyrene (XPS), which
costs a pittance and doesn’t crumble. You can also use small Pelican cases
(
pelican.com, prices vary) to protect individual devices, but this adds weight.
A coat of day-glo paint will make enclosures easier to spot; be sure to write
your phone number prominently on the outside of all enclosures.
F
Enclosures
54 Make: Volume 24
