Is it a possibility that the reason of the apogee propulsion failure might link to the soldering defect that shuffled it two launches behind schedule?(MUOS 5 is known as SV-3)
The soldering issue was discovered last spring during thermal vacuum testing on a component of the MUOS legacy UHF payload provided by Boeing Space and Intelligence Systems of El Segundo, Calif. Boeing, which built the Navy’s earlier-generation UHF Follow-On mobile communications satellites, is a subcontractor to Lockheed Martin on MUOS. - See more at: http://spacenews.com/39833bad-soldering-pushes-3rd-muos-satellite-toward-end-of-the-launch-queue/#sthash.AcQnqiBh.dpuf
<snip> though anomalies on govt satellites are classified. <snip>
In an unrelated, important military space development, AmericaSpace has also learned exclusively that the Navy/Lockheed Martin Mobile Objective User System MUOS-5 communications spacecraft has begun climbing, after earlier being stuck 12,000 miles below its intended geosynchronous orbit checkout location over the Pacific Ocean.The problem, likely involving propulsion and possibly control as well, occurred when the 7-ton spacecraft was halfway up its planned nine-day transfer to geosynchronous orbit following launch from Cape Canaveral on an Atlas-V on June 24 (see AmericaSpace report June 25).Navy spokesman Steve Davis at the Space and Naval Warfare Systems Command in San Diego said the Navy is not yet ready to release details on the problem.Sources told AmericaSpace, however, that an initial maneuver this month was able to move the spacecraft 25 miles higher, brightening hopes that the $611 million satellite can be eventually elevated to geosynchronous orbit even if it has to inch its way up.
I'm not up on the satellite tracking so I'm not sure if that slight raise would be noticeable to amateur observers.
But in an Aug. 2 statement, the Navy said the satellite “experienced a failure of the orbit raising propulsion system,” five days into a 10-day climb, halting the transfer maneuver that would push the satellite from its initial elliptical launch orbit to geosynchronous orbit.As a result, the Navy is “considering alternate orbit adjustment options, calculating mission impact and investigating all options before proceeding,” said Steven Davis, a spokesman for Space and Naval Warfare Systems Command.“The MUOS 5 satellite is currently stable, safe and under positive control,” he said.
But it appears the satellite has performed some orbit-raising in recent days, albeit tiny compared to large-scale maneuvers. The Navy has not confirmed any movements, but hobbyists keeping tabs on the stricken satellite have seen the tell-tale signs.“When Scott Tilley observed MUOS 5 on July 21 near 11:00 UTC, it was still in the orbit in which it had been stranded by the propulsion system failure on June 29. When he next observed it, on July 30 at 10:00 UTC, it was nearly 17 minutes late relative the orbit it had been in on July 21. That is an indication that it made one or more maneuvers in the interim. The orbit change probably was not large. A precise determination is pending further observations,” said Ted Molczan, a respected satellite observer....With the 100-pound-thrust main engine now out of commission, ground controllers will look to the satellite’s small thrusters for saving the mission.The craft is equipped with 18 monopropellant hydrazine thrusters designed for attitude control — a dozen 0.2-pound thrusters and six 5-pound thrusters....The situation is reminiscent of the Air Force’s first Advanced Extremely High Frequency satellite that experienced a main propulsion system failure after launch due to a clogged fuel line. It was able to achieve geosynchronous orbit using its xenon-fed electric thrusters with no reduction to mission life.But the MUOS satellites do not have a xenon propulsion system, only hydrazine.
Do the RCS thrusters share a common fuel tank with the main engine? Or would they have to sacrifice station-keeping propellent to get it to a usable orbit?