Potomac School students take photos of Earth's curvature with help from iPad

Students from the Potomac School in McLean, Va., took photos of the Earth's curvature with help from an iPad.
Tuesday, July 13, 2010

At the Potomac School in McLean this past school year, 13 seventh- and eighth-graders signed up for a biweekly science elective that proposed this challenge: Take a photo of the curvature of the Earth and spend just $200 to do it.

Science teacher Bill Wiley knew the kids could research online what tools they would need, including a weather balloon and a styrofoam cooler. But that was the easy part. They still had to figure out how to put it together. "I figured there was about a 60 percent chance they would pull it off," Wiley said.

In the end, the group got incredible pictures. And the experience of launching and tracking the device was like a scene right out of Hollywood, Wiley said, as the kids tracked the device in real-time using a student's iPad.

"It was like one of those scenes you see on TV where they do these things [with technology], and you go, 'That can't be real,' " Wiley said.

The students met every other week throughout the year. They started with a digital camera, which they programmed to shoot photos and video several times a minute. They bought a cellphone that had a GPS function and loaded software that regularly relayed the phone's location to the Internet through a program called InstaMapper. Both phone and camera went in the cooler, along with hand warmers to keep the electronics warm in the stratosphere, where it would be 70 degrees below zero Fahrenheit. Finally, the kids had to figure out what angle to hang the cooler so that the camera would get shots of the Earth's edge, not just a bunch of clouds. "It pushed all their math ability," Wiley said.

On the day of the launch, June 5, four students drove with Wiley to Chambersburg, Pennsylvania, to launch the balloon and its payload. Wiley had asked the kids to bring their laptops so they could use WiFi signals to get online and track the camera's movements on InstaMapper. But seventh-grader Will Prout brought his father's iPad, which was able to connect to the Internet through a regular cellphone network. That meant they could follow the signal while driving around.

"I didn't expect we would use the iPad that much, but it really saved us," said Will, 13.

After the balloon rose above the clouds, the cellphone signal faded, so the group toured the Gettysburg battlefield. In the thinner atmosphere high above the Earth, the lack of pressure would cause the balloon to expand from six to 15 feet in diameter and eventually pop. Then the cooler, cellphone and camera would fall down to Earth with a small parachute.

The kids constantly checked the iPad to see if a signal had reappeared, marking the cooler's reentry. It finally showed up, three hours later, but on the other side of the Chesapeake Bay! The weather models that the kids had used to predict the descent hadn't worked so well -- they thought it would land north of Baltimore.

The group headed to Delaware, driving toward the cooler's location on InstaMapper. They drove on rural roads, closing in on the cellphone's GPS signal, until they finally spotted the bright orange parachute in the middle of a strawberry field. A few anxious moments later, they turned on the camera and looked through the pictures.

Mission accomplished.

-- Margaret Webb Pressler

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