spacetoday.net: Zenit upper stage failure places satellite in lower orbit

Posted: Tue, Jun 29, 2004, 8:39 AM ET (1239 GMT)
Zenit 3SL launch of Galaxy 3C

A Zenit 3SL booster launched a commercial communications satellite for the international Sea Launch venture Monday night, but an upper stage problem placed the satellite into a lower-than-planned orbit. The Zenit 3SL lifted off from the Odyssey floating launch platform on the Equator in the Pacific Ocean at 11:59 pm EDT Monday (0359 GMT Tuesday), carrying the Telstar 18 satellite. While the launch initially appeared to be a success, launch controllers later reported that the booster's upper stage shut down prematurely or otherwise underperformed, placing the spacecraft in a transfer orbit with an apogee of 21,000 km instead of the planned 36,000 km. Engineers are meeting to address the issue, and believe that the spacecraft can reach GEO using its own stationkeeping thrusters, a process that would reduce the spacecraft's on-orbit lifetime. The Zenit 3SL uses an Energia Block DM-SL upper stage, similar to the Block DM upper stage that has been used on a number of Proton missions. The Block DM has suffered several failures in recent years, including a November 2002 Proton launch that stranded a communications satellite into a useless low Earth orbit. Telstar 18, also known as APStar 5, is a Space Systems/Loral 1300-series spacecraft with 16 Ku-band and 38 -band transponders, and is designed to serve markets in East Asia, Australia, and the Pacific from 138 degrees east.