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.
Sunday, November 14, 1999
Sunday, November 7, 1999
Keeping the planes apart
Published in the Antarctic Sun
It’s a blue-sky day out on McMurdo Station’s ice runway, but the world’s turned upside down in the tower.
An LC-130 is leaving for the South Pole and the tower crew is thinking “north.”
“Planes fly north to the South Pole,” air traffic controller Heidi McCaffray said, watching the aircraft head between Black Island and White Island.
Here, that statement makes sense. Close to the magnetic poles of the earth, navigation by compass is unreliable at best and dangerous at worst. Navigation is by “grid,” based on calculations involving the longitude of a current position in relation to the 180-degree longitude line, explained air traffic controller Robert Virgil.
Since McMurdo is so close to 180 degrees of longitude, “grid north” is very close to true south.
Oddly, though, helicopters use true north and south for their navigation. It means the tower has
to keep straight not only the type of aircraft on the radio, but also its direction— in real space and on its map.
They manage to do this with ease, fulfilling their basic mission. According to tower manager Mike
MacLean, “We keep the airplanes apart.”
That’s may not seem too tough at an airport which deals with only about a dozen different planes all season. But it’s not all that easy.
Runways are busy places, even when there are no planes around. Surveyors are out on the runway checking the sea ice movement, snow plows are keeping the path clear, maintenance workers are checking lights and navigational equipment, and the decelerometer crews are measuring the braking qualities of the ice.
Any time a plane comes near, to take off or land, the tower clears the runway of all people and equipment and calls out the fire department’s crash vehicle in the event of a mishap.
It’s all done by radio, and largely without the aid of tower radar, except in bad weather. Then the machine in the downstairs closet goes to work. It’s the pilot’s eyes, connected to the airplane only by the voice of the tower controller, every five seconds during final approach in bad conditions.
Of the 15 controllers on staff, two are on duty at any given time. Sometimes there are more, if they’re training or checking equipment. There’s a bed in the tower, too, in case the controllers get stuck at the runway. They don’t go home until all the planes are in.
There’s also a weather person in the tower, taking readings on the instruments outside and observing conditions on the sea ice.
Sandra Lorenzana, one of the tower’s rotating weather crew, said she does hourly observations as well as special reports and more frequent full reports if the weather is changing rapidly. These are called into Mac Weather and Mac Center, she said, to assist them in determining severe weather conditions and informing the pilots of what to expect during approach and landing.
A bit later in the season, MacLean said, there will be two towers operating around McMurdo; one will be at the ice runway until it shuts down, and the other will be at Williams Field. Last year they just had one tower and were unable to move it and set it up again in time for flights to
arrive on schedule. Now, with an extra tower (which is presently at the ice runway, just next to the operating tower), Williams Field will be up and running with fewer delays.
It’s a blue-sky day out on McMurdo Station’s ice runway, but the world’s turned upside down in the tower.
An LC-130 is leaving for the South Pole and the tower crew is thinking “north.”
“Planes fly north to the South Pole,” air traffic controller Heidi McCaffray said, watching the aircraft head between Black Island and White Island.
Here, that statement makes sense. Close to the magnetic poles of the earth, navigation by compass is unreliable at best and dangerous at worst. Navigation is by “grid,” based on calculations involving the longitude of a current position in relation to the 180-degree longitude line, explained air traffic controller Robert Virgil.
Since McMurdo is so close to 180 degrees of longitude, “grid north” is very close to true south.
Oddly, though, helicopters use true north and south for their navigation. It means the tower has
to keep straight not only the type of aircraft on the radio, but also its direction— in real space and on its map.
They manage to do this with ease, fulfilling their basic mission. According to tower manager Mike
MacLean, “We keep the airplanes apart.”
That’s may not seem too tough at an airport which deals with only about a dozen different planes all season. But it’s not all that easy.
Runways are busy places, even when there are no planes around. Surveyors are out on the runway checking the sea ice movement, snow plows are keeping the path clear, maintenance workers are checking lights and navigational equipment, and the decelerometer crews are measuring the braking qualities of the ice.
Any time a plane comes near, to take off or land, the tower clears the runway of all people and equipment and calls out the fire department’s crash vehicle in the event of a mishap.
It’s all done by radio, and largely without the aid of tower radar, except in bad weather. Then the machine in the downstairs closet goes to work. It’s the pilot’s eyes, connected to the airplane only by the voice of the tower controller, every five seconds during final approach in bad conditions.
Of the 15 controllers on staff, two are on duty at any given time. Sometimes there are more, if they’re training or checking equipment. There’s a bed in the tower, too, in case the controllers get stuck at the runway. They don’t go home until all the planes are in.
There’s also a weather person in the tower, taking readings on the instruments outside and observing conditions on the sea ice.
Sandra Lorenzana, one of the tower’s rotating weather crew, said she does hourly observations as well as special reports and more frequent full reports if the weather is changing rapidly. These are called into Mac Weather and Mac Center, she said, to assist them in determining severe weather conditions and informing the pilots of what to expect during approach and landing.
A bit later in the season, MacLean said, there will be two towers operating around McMurdo; one will be at the ice runway until it shuts down, and the other will be at Williams Field. Last year they just had one tower and were unable to move it and set it up again in time for flights to
arrive on schedule. Now, with an extra tower (which is presently at the ice runway, just next to the operating tower), Williams Field will be up and running with fewer delays.
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