Children at St. Mary on the Hill Catholic School visited the space center in Houston on Friday but never left their desks.

Through a NASA virtual learning program, the sixth-graders watched as an instructor in Houston taught them about the solar system and the space program, using a camera to watch the class and a projector for the class to watch her demonstrations.

Taking a trip to Houston wasn't practical, sixth-grade science teacher Marguerite Mosner said. Friday's program allowed her pupils to learn about the planets in a way that is much less expensive.

The pupils interacted with instructor Tara Smith by asking and answering questions through video conferencing. She also led them through a brief experiment using a string and washer to learn about planetary orbits.

Astronauts must maintain a speed of 17,500 mph to remain in orbit around Earth, Ms. Smith said.

"If they go faster than 17,500 miles per hour, they will shoot off into space," she said. "If they go slower than 17,500 miles per hour, they will start to come back to Earth."

Pupils spun their washers around on the string, changing the length of the string to simulate the change in the length of the orbit between different planets.

The pupils also learned to identify planets using satellite imagery. In a game of "Earth or Not Earth," the pupils had to determine whether the images were of this planet or another in the solar system.

"The reason we did it is because this is what scientists do everyday," Ms. Smith told the class.

Morgan Davis, 11, said it was cool learning about the NASA satellites and probes that took the images.

"I learned a lot from the part on Mars," she said.

Thomas Bedenbaugh, 11, was also interested in the Red Planet. "I had never seen the surface of Mars before," he said.

Ms. Smith told the class that they could be the first people to land on that planet when NASA plans a trip there in 2030.

"We are building your rocket and planning your Mars colony right now," she said.

Reach Greg Gelpi at (706) 828-3851 or greg.gelpi@augustachronicle.com.