Looking back as Intelsat 603 mission ends in satellite “graveyard”
Intelsat 603 has officially reached its end. For 23 years, the Intelsat 603 satellite, or IS-603, relayed telephone calls using HS-376-type transponders which could relay an estimated 120,000 telephone calls at the same time. In January of 2013, the satellite was deactivated and was removed from geostationary orbit (GEO), but it was another two years before it was finally shut off.
On Jan. 23 of this year, the final command in a sequence to “deorbit” the craft was sent to IS-603, which in this context means pushing it upward into a graveyard orbit more than 200 kilometers above geostationary. In February of 2015, Intelsat confirmed that the satellite had indeed been deorbited. Though it had been monitored up to that point, it was turned off when it reached its final resting place. With that, a legacy of more than two decades of service drew to a close.
IS-603 was the second of five Intelsat VI satellites to be launched. Like the Leasat series that came before it, the Intelsat VI series used a HS-393 bus, a “taller” version of the HS-381. The HS-393 was designed for the width of the space shuttle payload bay, but because of the Challenger disaster in 1986, Intelsat 603 was launched not with a shuttle, but on a commercial Titan III rocket (CT3) from Cape Canaveral Air Force Station’s Space Launch Complex 40 (SLC-40), currently used by SpaceX to launch its Falcon 9 rockets.
It was only the second launch of a CT3, and it did not go well. The deployment system was incorrectly wired, so the satellite did not separate from the booster’s upper stage. It separated from its perigee-kick motor and used its own thrusters to reach low-Earth orbit (LEO), but since it had been designed for Geosynchronous Orbit (GSO), it was useless.
The first flight of the Space Shuttle Endeavour, STS-49, in May of 1992, was tasked to rescue Intelsat 603. The problem was twofold: the satellite was huge—over nine feet (2.8 meters)—and it was rotating. So a way had to be devised to capture the giant spinning top.
The solution was a capture bar with a trunnion pin. But when astronaut Pierre Thuot tried to capture the satellite, he was unable to arrest its spin. It turned out that the liquid propellant retained the satellite’s spin. Two extra-vehicular activities or “EVAs” failed to capture the satellite. Finally, the crew determined that the best tool to capture the satellite was the human hand.
So, Thuot stood on the end of the robotic arm while Commander Dan Brandenstein maneuvered Endeavour to within about six feet (1.82 meters) from the rotating satellite. Thuot, Tom Akers, and Rick Hieb grabbed the spacecraft and held it while the liquid propellant lost its spin. The trio then carefully let go while Hieb attached the bar. Then, with Akers acting as an anchor, Thuot maneuvered underneath and attached bolts to complete the attachment. Akers let go, and Bruce Melnick used the robotic arm to bring the satellite to the motor that would boost it to GSO. The image of astronauts grabbing the giant, spinning satellite is one of the most striking in the 30-year history of the Space Shuttle Program.
STS-49 marked a series of firsts: it was the first flight of NASA’s youngest orbiter, Endeavour, it was the first time a three-person EVA was conducted, it was the first shuttle mission to have four EVAs, the first time a shuttle had to rendezvous with another spacecraft three times, and incidentally was also the first use of a drag chute on landing.
When Kathy Thornton sent the command to eject the Intelsat 603 satellite from its cradle, nothing happened at first, but fortunately the backup circuit worked. The motor activated and the communications satellite set off for GSO.
Now that Intelsat 603’s day is over, Intelsat’s next generation satellite is Intelsat Epic, which utilizes C-, Ku-, and Ka-bands, wide beams, spot beams, and frequency reuse technology to power Internet connectivity throughout the world at a rate of 25-60 gigabits per second. However, it is unlikely that this new spacecraft would have been as successful without the lessons learned on STS-49.
Video courtesy of NASA STI Program
Collin R. Skocik has been captivated by space flight since the maiden flight of space shuttle Columbia in April of 1981. He frequently attends events hosted by the Astronaut Scholarship Foundation, and has met many astronauts in his experiences at Kennedy Space Center. He is a prolific author of science fiction as well as science and space-related articles.
In addition to the Voyage Into the Unknown series, he has also written the short story collection The Future Lives!, the science fiction novel Dreams of the Stars, and the disaster novel The Sunburst Fire. His first print sale was Asteroid Eternia in Encounters magazine. When he is not writing, he provides closed-captioning for the hearing impaired. He lives in Atlantic Beach, Florida.