Sunday, November 14, 1999

NASA goes ‘bird’ watching

Published in the Antarctic Sun

In a small office in Crary Lab, talking to satellites is more common than talking on the phone.

From the outside, it looks like any other office—except for the NASA sign. Inside, the people call it the McMurdo Ground Station.

“We’re the only ones down here that can actually see satellites from this part of the world,” said Chuck Seman, a member of the team sent down by NASA to provide satellite communications service.

They work with U.S., Canadian and European satellites in coordination with a network of ground stations in Alaska, Norway and Virginia. The network monitors satellites on what are called polar orbits—the track circling the earth from pole to pole.

Most of what the McMurdo station does involves making sure the satellites, or “birds,” are still working properly. Data is usually transferred earthward from the satellites in the Northern Hemisphere, because of better access to high-speed communication links.

The technicians at the ground station are a vital link in the satellite support process. For some satellites, the process at McMurdo begins even before launch.

In those cases, they track rockets from the launch pad through the point where they release the satellite to fly on its own.

In most cases, though, the office gets a list of satellite contacts to make. Most links last between three and 15 minutes.

The connections involve incredible feats of behind-the-scenes electrical engineering. It takes a lot to track a satellite more than 400 miles high, moving so fast it circles the Earth every 90 minutes.

On the ground at McMurdo, computers and engineers are moving a dish antenna 10 meters wide in a huge arc to follow the satellite. At the same time, they’re receiving data at rates up to 105 megabits per second—about 3,000 times as fast as the average home computer modem.

One of the tasks that keeps McMurdo Ground Station busy is an upcoming rescue mission for a satellite that has its solar panels pointing the wrong way.

Its owners are hoping that the sunlight bouncing off the ice cap will power the satellite enough to move it into proper position.

The station will attempt to contact the satellite and then be a bridge between it and the satellite’s controllers back in the U.S. It’s not a regular task, but neither is it unheard-of.

“We tried that before ... it failed,” Seman said.

There are two other major projects on the calendar at the moment. The first is a new 13-meter dish, which will be arriving on the resupply vessel this summer. It will help the U.S. government get 24-hour weather coverage worldwide. It is unclear at the moment how that will affect the six-hour satellite blackout Mac Weather has each day, Seman said.

The second project is another Antarctic mapping project like the one which just finished, in collaboration with Canada’s RADARSAT satellite, gathering high-resolution images of the Antarctic continent even through cloud cover.

“We’re the only project down here year-round,” said technician Jaime Gallo.

A lot of what goes on in the office is monitoring and preparing equipment to do the work. This can involve repairing equipment, manufacturing new parts from old machinery in storage, or just making small changes to the process to weed out potential problems.

“We’re not beakers, we’re like tweakers,” Gallo said, laughing.