Before the White House, the Loki Lego Launcher was just a family project. The girls built the craft at home, with equipment and instructions they found online. They made it out of plywood, arrow shafts, rope, a helium balloon and some styrofoam feet "in the event of a water landing."
The craft's name came from two pieces of cargo: a Lego figurine of R2D2 and a picture of their late cat, Loki. There was also a flight computer, a GPS tracker, a temperature and pressure sensor and two GoPro cameras.
The two sisters released the ballooncraft in September 2015 outside Ritzville, Washington. It traveled to near space at 78,000 feet.
The camera captured a clear view of the Yeung girls' keepsakes floating in front of the blackness of space. When the balloon burst, the craft fell back to Earth and landed in a field -- near, but not on, a cow pie.
The sisters made a video about their experience and posted a list of "lessons learned," including "don't guess, rely on data."
The White House invited Rebecca and Kimberly to present their creation Wednesday at President Obama's sixth and final White House Science Fair.
The AP reports that President Obama came over to Kimberly and Rebecca's table and, after examining the Loki Lego Launcher, said "but cow poop didn't get on this? You're sure?"