Over the Labor Day weekend, lots of kids enjoyed the break from school and the last weekend of summertime fun with picnics, pool parties and backyard BBQs. But not Kimberly and Rebecca Yeung. They set their sights a little higher. All the way to the stratosphere, in fact.

The two girls — Kimberly, 8, and Rebecca, 10 — built a weather balloon and decked it out with GoPro cameras and a data-tracking computer and they launched it over the holiday weekend. Why? Because they said it sounded like fun.

So how does one even begin a project such as this? Kimberly and Rebecca found plans to build a weather balloon on a website called High Altitude Science. They modified the plans during construction when they realized that their first prototype, which used PVC pipe for the base, would be too heavy for their needs. The girls used broken arrow shafts instead. They christened their craft the Loki Lego Launcher. They named it after Loki, their cat. They attached an image of him to an R2-D2 Lego figure to serve as the mission's only passengers.

After the girls finished the Loki Lego Launcher, they loaded it up with two GoPro cameras — one pointed sideways and one pointed down — as well as a flight computer so that they could collect data on everything from altitude to speed to temperature.

And then they launched it into space.

Thanks to the onboard flight computer, the girls learned that their craft rose to about 78,000 feet, which is twice as high as commercial airliners fly. It traveled for 4 hours and 20 minutes and had an average speed of around 35 kilometers per hour. They also tracked the temperature as it decreased with elevation while the craft was in the troposphere but then began to increase when it hit the stratosphere. After the balloon popped, the girls were able to use the GPS to locate it — in a field in central Washington.

The data that they collected is impressive, and worth it's weight in STEM activity gold. But most importantly, Kimberly and Rebecca learned how to plan a project and see it through from the research stages to completion, taking notes such as "don't stop trying" and "always be optimistic," along the way. There's no doubt that those are lessons that will stick with them as they plan their next big project, whatever that may be. It's safe to say, the sky is NOT the limit.

Girls launch weather balloon into the stratosphere
For fun, the tweens built the contraption and decked it out with data-tracking gear.