Recently, Hack Week hit Dropbox in a big way. As interns, the two of us hadn’t experienced the awesomeness of a Dropbox Hack Week, but when we were told that we could work on anything–absolutely anything–we knew we had to think big. We played around with a ton of project ideas, from real time collaboration tools to a Dropbox for Xbox app. But we decided to roll bold with a crazy idea: For years, Dropbox has let people take their stuff anywhere on Earth. But why stop there? Why not take Dropbox to space?
To do this, we decided to launch a high altitude helium balloon into the stratosphere. Attached were two Android smartphones: one programmed to take periodic photos, and the other to record video of the entire flight. At 100,000 feet above the ground, these photos and videos would capture the curvature of the Earth! In true Dropbox spirit, there’s also an added twist: we wanted the balloon to have Internet the entire flight. With an Internet connection, we’d be able to use Dropbox’s brand new Camera Uploads feature to beam live photos from our balloon back to “mission control.”
And it worked! Sort of.
Research & Preparation
About two weeks before Hack Week started, we began researching high altitude weather balloons and the legendary shopping list needed to launch one — from the balloon itself to radar reflectors, parachutes, and oversized helium tanks. Thanks to a few pleading phone calls and lots of overnight shipping (thanks Amazon Prime!), everything arrived in time for Hack Week.
Our next challenge was figuring out how to hook our balloon up with Internet. Since standard cell phone 3G fails at high altitudes, we needed to find an alternative Internet source. We first considered using amateur radio. TCP/IP, the communication protocol of the Internet, has been implemented over amateur radio before, but for us to do so would probably require a Hack Year instead of a week. After (very) briefly investigating a 50-mile long Ethernet cord, we settled on WiFi–the very same WiFi you use every day.
Researchers have successfully broadcast a WiFi signal several hundred miles, so we were optimistic that we’d be able to shoot for a modest 50 miles. Although we expected our balloon to rise only 15 miles vertically, wind could carry it anywhere from 40 to 100 miles laterally, greatly increasing the needed range of our WiFi connection. We purchased a large parabolic dish along with other long-range WiFi equipment from Ubiquiti Networks.
Due to the tight power and weight restrictions on our balloon, our WiFi system was pretty complex. On the ground, we tethered a 4G Android smartphone to a laptop as our Internet source. The laptop was then connected to an antenna on our balloon which was connected to an extremely lightweight wireless router. Unfortunately, the wireless router aboard the balloon sported only an Ethernet jack, with no way to connect it to the Android phone.
Our solution was to connect yet another small wireless router to rebroadcast a wireless network for the onboard phone to pick up. And because there were no power outlets on the balloon, we cut open the Ethernet cord connecting the two wireless devices and spliced in two battery packs, one for each wireless device.
We also got a handheld radio with GPS to track our balloon in real time and properly aim our dish from the ground. Our plan was to use the GPS data from the balloon, our position, and trigonometry to aim the dish, even once we could no longer see the balloon. The radio would broadcast GPS information over an amateur radio network. Other radio enthusiasts would pick up the signal, and the balloon’s position would ultimately be displayed on a website where we could view the position on Google Maps. We hoped that the balloon’s altitude, high above the usual obstructions, would give us a consistent GPS signal.
With only two days before launch, we finally received our wireless equipment and started a mad dash to assemble it. Since the clock was ticking, we didn’t get a chance to fully test our setup; the farthest distance we attempted was about half a mile. Come launch day, we could only hope that our setup would work over longer distances.
Early Friday morning, we drove out to our launch site in Vacaville, CA. We chose Vacaville because we wanted a place that wouldn’t carry our balloon into any urban areas or large bodies of water. We arrived in time for sunrise, but spent several hours looking for a clear, flat launch site with strong 4G coverage. Eventually, we were able to set up on a dead end road next to a small hotel.
We slowly began assembling the balloon starting with our wireless equipment. After a stressful couple of hours with several mysterious network failures, we secured the cameras and wireless devices in the styrofoam payload container. Next we began to inflate the balloon. Minutes before launch, we discovered that our GPS transmitter was busted. With no other choice, we packed the GPS device into our payload anyway, hoping that the strong signal it’d get from high up would result in successful transmissions. We wrote our names and phone numbers on the sides of the container. If we were lucky, we’d receive a phone call if our balloon was found after a nice, gentle landing (it’s probably best not to imagine what could have happened if we were unlucky :P).
Fully inflated, our balloon reached a size of about 8 feet in diameter. With the wind picking up, it was actually incredibly difficult to hold on to. We tied the payload, parachute, and radar reflector to the balloon, and after confirming that photos were appearing in our Dropbox account in real time, we were ready for launch. We aimed our dish, crossed our fingers, and let go of the balloon. At almost exactly noon, several hours behind schedule, we launched!
The first few minutes after lift off were incredibly exciting. The balloon rose quickly (more than 15 feet per second) and in just minutes was a small speck in the sky. For several minutes we successfully aimed our dish at the balloon, feeding it a WiFi signal which resulted in live photos uploaded over Dropbox. But the GPS data never materialized and eventually we were flying blind! We were soon left to search the sky with our dish, waving it back and forth and monitoring the strength of the connection, our only feedback for finding our increasingly invisible balloon.
We received photos in real time from our balloon for the first 3 or 4 minutes. While we maintained a network connection for many miles, we lacked the bandwidth to continue transmitting full photos as the balloon rose higher and higher. Nonetheless, we were incredibly excited by the few photos we received in real time.
After attempting to recover an Internet connection for an hour or so, we decided to drive in the direction of our balloon’s predicted landing. Incredibly, two hours into the flight of the balloon and likely moments after landing, we received a phone call: our balloon had been found! The caller informed us that she’d gone outside to investigate a commotion among her horses when she discovered our balloon! Unbelievably thrilled, we drove to her farm to retrieve our equipment and upload the remaining photos and videos to Dropbox. After conveying our many thanks (and converting a new customer to Dropbox!), we sped back to Dropbox HQ in time for Hack Week’s closing ceremony.
We’d like to give a big shout out to everyone who helped us turn an ambitious project idea into reality. Thank you!
What we used:
- 1200g Kaymont weather balloon: http://www.kaymontballoons.com/Near_Space_Photography.html
- Radar reflector: http://davisnet.com/marine/products/marine_product.asp?pnum=00151
- 6ft Parachute: http://www.the-rocketman.com/recovery.html
- 2 Android Galaxy Nexuses
- Rocket M5: http://www.ubnt.com/airmax#rocketm
- Rocket Dish: http://www.ubnt.com/airmax#dish
- Bullet M5: http://www.ubnt.com/airmax#bulletm
- PicoStation: http://www.ubnt.com/airmax#picostationm
- AA and AAA Lithium Batteries
Some good resources: