Investigators probe Sea Launch rocket anomaly
BY SPACEFLIGHT NOW
Posted: July 5, 2004
The Russian space company Energia and an independent board are investigating last week's early engine shutdown during a commercial Sea Launch rocket flight that left an Asian communications satellite 9,000 miles short of its planned orbit.
The rocket was launched from the Odyssey platform floating in the equatorial Pacific Ocean at 0359 GMT June 29 carrying the Telstar 18 spacecraft for operator Loral.
The first stage fired for two-and-a-half minutes before separating as the second stage ignited for its multi-minute burn. About nine minutes after liftoff, the spent second stage was jettisoned from Block DM-SL upper stage.
The Russian-made upper stage motor ignited for the first of two firings during the launch, achieving a temporary parking orbit around Earth. The stage and attached satellite payload then coasted through space for about 36 minutes before the stage's single-engine was re-started for what was supposed to be a six-minute burn to place Telstar 18 into its intended orbit stretching from 22,237 miles at its highest point, or apogee, to 472 miles at the lowest point, or perigee.
But that critical boost to geosynchronous transfer orbit suffered a problem, causing the Block DM-SL stage to shut down nearly a minute early. The result was Telstar 18 being deployed into an orbit with a high point of only 13,425 miles about an hour after liftoff.
"The Sea Launch team is gathering and reviewing Telstar 18 mission data to understand the sequence of events that led to a premature shutdown of the Sea Launch Zenit-3SL upper stage during that mission," the international consortium said in a statement.
"Based on preliminary flight data, all Sea Launch system flight parameters were nominal except that the upper stage of the launch vehicle shut down about 54 seconds prematurely, following the second of two planned burns of the upper stage."
What triggered the malfunction is being probed.
"The cause of the rocket's upper stage premature shutdown is under investigation by an Energia-appointed commission. Sea Launch will also form an independent review board to evaluate all findings and confirm that any corrective actions associated with the upper stage performance on the Telstar 18 mission are complete, satisfactory and verified."
Controllers established contact with Telstar 18, which was reported to be operating properly. The satellite was already scheduled to use its own onboard engine to circularize its altitude at 22,300 miles above the planet in geostationary orbit. Loral says the craft has enough fuel to compensate for the launch vehicle's shortfall without impacting Telstar 18's life expectancy.
"Loral Space & Communications has re-planned the mission and, if successful, the satellite has sufficient onboard fuel to bring it to its final orbital position and meet or exceed its 13-year specified life," the Sea Launch statement said.
Sea Launch, which has performed three missions so far this year, says it hopes to conduct two additional flights by the end of 2004.
"At this point in time, Sea Launch is optimistic it will conclude the board's investigation and complete two more launches this year, as originally planned.
"Sea Launch remains highly confident in the robust capability of the Zenit-3SL system, including the upper stage. This component remains one of the premiere upper stages in the industry, with an overall success rate of approximately 97 percent."
Telstar 18 is designed to provide television, Internet services and other telecommunications across the Asia-Pacific region.
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