Immediately after the Space Infrared Telescope Facility launches in January
2003, mission planners anticipate a four-hour communication gap when their
tracking system wont be able to "talk to" the observatory. This could be a
nerve-wracking time for those who’ve worked so hard on the mission, an
infrared telescope that will study the early universe, old galaxies and
forming stars, and detect dust disks around stars where planets may be

The solution to their problem lies within the Council for Scientific and
Industrial Research Satellite Applications Center, a satellite tracking
facility in South Africa formerly used by NASA. Located in Hartebeesthoek,
60 kilometers (37 miles) north of Johannesburg, the Satellite Applications
Center will track the Space Infrared Telescope Facility for up to 4 hours,
or until the Deep Space Network’s tracking station near Madrid, Spain,
acquires a signal.

"No one wants to sit on pins and needles for four hours," said Pat Beyer,
telecommunications and mission systems manager for the Space Infrared
Telescope Facility at JPL. "So we contracted with Hartebeesthoek, which has
a smaller antenna that can’t track in deep space as well, to fill in the

The Deep Space Network is an international network of antennas that supports
interplanetary spacecraft missions. The network has three tracking stations
at Goldstone, Calif., in the Mojave desert; at Robledo de Chavela, Spain, 60
kilometers (37 miles) west of Madrid; and near the Tidbinbilla Nature
Reserve, 40 kilometers (25 miles) southwest of Canberra, Australia.

The Satellite Applications Center in South Africa uses smaller antennas than
the Deep Space Network. The larger the antenna, the better the ability to
track objects in deep space. The Space Infrared Telescope Facility will use
the South African facility’s 5.4-meter (18-foot) and 12-meter (39-foot)
antennas. The Deep Space Network antennas being used measure 34 and 70
meters (111 and 230 feet). Deep Space Network facilities can track
spacecraft traveling more than 16 billion kilometers (10 billion miles) from

The Deep Space Network tracking facilities use antennas that continuously
compensate for the earth’s rotation. Once a spacecraft reaches space, it
does not rotate with earth, but at its own pace. A spacecraft is only in the
"line of sight" with one facility for a maximum of 10 to 12 hours a day
before being handed off to another facility.

"The Space Infrared Telescope Facility is a different animal than we’ve
dealt with in the past because it’s an observatory, not an orbiting
planetary mission," Beyer said.

Normally, when a spacecraft launches, it travels through the sky in a
southeast direction, from Cape Canaveral, Fla., to Canberra. But the Space
Infrared Telescope Facility will move so slowly in this direction that the
rotation of the earth will overtake it. Its resulting course will veer to
the west before reaching Australia. The Madrid tracking station will not be
able to track the observatory until after four hours have elapsed.

The Space Infared Telescope Facility is the first new mission of NASA’s
Origins Program, which strives to answer the questions: Where did we come
from? Are we alone? It is also the fourth and last of NASA’s Great
Observatories, a program that also includes the Hubble Space Telescope, the
Chandra X-Ray Observatory and the Compton Gamma Ray Observatory. JPL manages
the Space Infrared Telescope Facility for NASA.

The Satellite Applications Center has been managed by South Africa’s Council
for Scientific and Industrial Research since 1958. From 1960 to 1975, it was
known as the "Joburg Minitrack Station" and became part of NASA’s worldwide
scientific satellite tracking and telemetry network, operated by NASA’s
Goddard Space Flight Center in Greenbelt, Md. It then became part of the
French National Space Agency (le Centre National d’Études Spatiales)
worldwide tracking network. Since 1989, it has been a program within the
South African Council for Scientific and Industrial Research’s Information,
Communications and Technology division.