A 1,200-gram weather balloon, the crucial role of gravity, quiver-reducing ropes, Styrofoam’s versatility, burst altitude, a University of Wyoming website and a free software program for shutterbugs were part of the formula Mathew Ho and Asad Muhammad, both 17, used to launch, film and land the patriotic, flag-bearing Lego Man.
The duct-taped Styrofoam capsule was released three weeks ago at a Newmarket soccer pitch by the Grade 12 students from Agincourt Collegiate Institute.
It soared 24 kilometres into the stratosphere via balloon then landed 97 minutes later in dense bush near Rice Lake, south of Peterborough — a remarkably close return considering January’s winter winds were howling.
“We actually had a lot of control on that factor,” says Ho of Lego Man’s capsule touching down 122 kilometres away from the soccer pitch.
“The thing is, the more you fill your balloon, the faster it will go and the sooner it will pop.”
A helium-filled balloon pops at what’s called the burst altitude, says Barth Netterfield, a professor in the departments of physics and astronomy at the University of Toronto. The higher the altitude, the lower the air pressure and the greater the gassy force within the balloon pushing out on the latex.
“You’ve got a balloon and you’ve got a fixed amount of helium in it. So as the balloon goes up, the pressure outside is going down so the balloon is going to stretch,” explains Netterfield.
“The higher you go, the more the balloon expands until, eventually, the rubber isn’t strong enough and it bursts.”
Lego Man’s cream-coloured latex balloon was 2.6 metres in diameter at launch. Netterfield estimates it could have expanded about 10 times that size just prior to bursting.
The students didn’t want their tiny, stiff-limbed captain to be blown too far away — or into water — because they wanted to retrieve him. So Ho and Muhammad planned for Lego Man to hit burst altitude quickly.
The boys emptied a 931-cubic-foot tank of helium into the professional quality weather balloon they bought online, filling it to capacity.
“If you fill your balloon, say, halfway, it will reach a higher max altitude but then obviously it’s got a lot more time in the air so it has a lot more time that it could be affected by wind,” explains Ho.
“A perfect flight plan would be just up and down, on the same spot. The less we had to drive (to retrieve Lego Man) that was our goal, especially since we’re surrounded by so many lakes. There were so many problems that could go wrong.
They found a second method to estimate their project’s likely landing by typing “weather balloon trajectory forecast” into Google.
“It’s almost a bare page, it’s extremely cool,” Ho says of the University of Wyoming’s weather balloon website. It calculates trajectory based on conditions like prevailing winds, launch coordinates and balloon engineering.
“You can enter the coordinates of your launch site, your predicted altitude and it will actually map it on Google Earth.”
Falling to Earth involved another bit of science — plus a trip to a strip mall.
The boys purchased blue and red rip-stop nylon at a Fabricland store in Scarborough and stitched it into a parachute.
They sewed a handle into the centre point of the parachute’s top, which was then tied by rope to the weather balloon bottom (the balloon was secured with three zip ties over the folded latex opening; there is no knot to tie like regular balloons).
Eight five-metre-long ropes were tied to nylon straps that Ho and Muhammad sewed around the sides of the parachute at equal distances.
Once ready, they used the flight simulator website to pinpoint a landing spot. Four different times it calculated the parachute would land near Rochester, N.Y. On Jan. 7, it showed conditions that favoured a Peterborough drop site — liftoff day for the three-tiered craft.
As the balloon rose, it pulled the collapsed parachute beneath it. The parachute’s eight ropes, in turn, pulled the Styrofoam capsule and Lego Man.
When the weather balloon burst, gravity took over. The parachute — balanced perfectly — filled with air and began a rapid descent.
Ho and Muhammad roughly estimated, based on two sets of GPS coordinates, that Lego Man’s average speed upon return was 26.22 kilometres per hour. That’s a bit faster than his average ascending speed of 22.93 km/h.
What’s most remarkable about the boys’ project is the photography — breathtakingly clear images of Lego Man, staunchly holding his Canadian flag, soaring above Earth’s cloudy layers in sub-zero temperatures.
“We had no idea the results would be that fantastic,” says Ho, who saw other attempts to photograph images in the same way when he and Muhammad were researching their project.
“For some reason, our images were extremely crisp and extremely stunning.
A couple of things worked in their favour — including the parachute ropes.
In order to take a steady stream of digital photographs, about 1,500 in all, the students downloaded the Canon Hack Development Kit onto the SD cards of their point-and-shoot Canons. The free program allows users to take interval shots. The students’ camera shutters were timed for 20-second intervals.
Two cameras for videotaping were also packed into the Styrofoam, which Ho describes as a “great insulator.” Three packets of hand-warmers were activated and placed in the capsule, along with fluffy green polyester material, to keep the cameras’ electronic guts from freezing. At the package’s highest point, the air temperature would be about minus 20 Celsius.
The only failure was in the Go Pro, which has a wide-angle lens and required a bigger opening than the other three cameras. Condensation distorted the images, with Ho thinking the Styrofoam hole may have been cut too large.
But how did the capsule not shake and blur the images?
“The ropes had a huge role to play because if the box was too close to the balloon, it would act like a giant sail (and) any wind would cause the box to shake violently,” Ho says of the eight five-metre lengths of rope that secured the capsule to the parachute and balloon (before it burst).
“By having a long string, it acts as a damper. The top object moves, then there’s a time delay before the bottom object moves. So even though the balloon shook, the box remained almost stationary because the rope added that cushion for dampening.”
The box also held a cellphone with a downloaded GPS app. When the boys inflated the balloon then let it go on Saturday afternoon, the GPS signal cut out at about seven kilometres when it floated past cellphone tower range.
At 4:12 p.m. that day, Ho’s iPad started to beep when Lego Man came back into cellphone range. Within minutes, he’d landed near Rice Lake.
But Lego Man wasn’t easy to find. That night, Ho’s dad, David, drove the boys out to Rice Lake. At 7 p.m. — it was already dark — they began searching for him amid dense shrub and trees. Area cellphone service was spotty and the GPS signal was lost.
The trio gave up at midnight, exhausted, cold, wet, disappointed.
“We were just hiking in the forest, we had no cell reception, our GPS wasn’t working, we had to cross rivers and no one had rain boots — it was an extreme adventure in the forest. It was just ridiculous,” Ho recalls.
The boys waited until the next weekend (“We had school so we couldn’t go during the week”), going in daylight, better dressed and equipped. They spotted their prized project quickly and were elated when the cameras spat out high-quality images.
Media outlets have clamoured for Ho and Muhammad, with international calls coming from the BBC and Good Morning America.
Netterfield says the boys should be commended on the enterprising spirit of their project.
“They should be really happy they did such a cool thing,” Netterfield says.
“There are probably lots of high school students who could do it — but would never think of doing it or bother doing it. And they did.”