Intelsat 29e Launch: In Orbit Testing Underway
By Richard Laurie, Senior Program Manager, Space Systems Acquisition
Without question, the launch of Intelsat 29e (IS-29e) on 27 January was an incredible moment. However, that was merely a prelude for those of us responsible for putting IS-29e into service. It’s been a busy couple of weeks!
As planned, we used most of the propellant on board the satellite to raise the orbit of IS-29e from its transfer orbit (where the Ariane 5 rocket placed it in space 250 km from the Earth) to geostationary orbit (35,786 km above the Earth). Then, we needed to execute nine firings of the main engine when the satellite was at its apogee — the farthest point from the Earth. As the satellite circled the Earth, it could reach its apogee at any time of day or night so it is fair to say that I was on constant “apogee alert.” Fortunately, I only live 10 minutes away from the Boeing offices in El Segundo, California, so I could be on site for each firing.
On 10 February, after more than a week of orbit raising maneuvers, IS-29e reached its payload in-orbit test location at 310.3° East. In the process, the orbit period (the time to circle the earth once) grew from approximately 10 hours to 24 hours, so the satellite now appears stationary above the Earth (hence, the “stationary” in geostationary).
Once the orbit raising was complete, we had to deploy the antenna reflectors and the solar array wings that had been stowed so the satellite could fit into the launch vehicle’s fairing. Here’s a video simulation of what that sequence looked like in space.
For each reflector, explosive devices were fired to sever the bolts holding it tightly to the body of the satellite. Then it was extended to its fully deployed position by a spring mechanism. As each reflector deployed, we watched the spin rate of the satellite slow in the same way that a spinning skater slows his/her rotation by extending his/her arms.
Deployment of the solar array wings was the next critical step. Each solar array wing consists of four large panels; when fully extended, the distance from wing tip to tip is over 42 meters (140 feet). For each wing, we fired explosive devices to sever the bolts that locked it tightly to the body of the satellite. As the wing extended, we watched the current increase. This is because, when the wing is fully extended, the current is four times greater than when it is stowed and only the outer panel sees the sun.
Once the solar array wings were extended, we performed some initial electrical tests. After that, the satellite reoriented itself to point at the earth, its normal mode of operation. Unlike some other satellites, IS-29e has no Earth Sensor to keep it oriented properly in space. Instead, this new generation of high throughput satellites maintains precise service orientation based upon location in orbit and attitude with respect to the fixed stars (as determined by an on-board star tracker).
After further tests of the IS-29e computer systems, we were ready for payload testing. That process is ongoing out of our East Coast Operations Center in McLean, Virginia. My colleague, Duy Nguyen, is on site at our offices there and will provide the next update as we work to put IS-29e into service.