WASHINGTON -- A Russian government report on last October's explosion of a Proton space booster is blaming shoddy workmanship at a rocket engine manufacturing plant as the likely cause of the mishap.
An English translation of the report was released in the United States on Friday by International Launch Services (ILS), a commercial company that markets the rockets for a Lockheed Martin consortium.
"The most likely cause of the Proton failure on October 27, 1999 was the presence of metallic or mineral particulate matter inside the [upper-stage] engine," the report said. The material caused the turbopump of the rocket engine to ignite and explosively fail.
"The most likely cause of the particulate matter to find its way into the engine is poor workmanship at the Voronezh Mechanical Plant in 1992 and 1993," it added. The engines that failed on the October launch as well as an earlier failure of a Proton booster last July were both made from the same batch at the plant in 1992 and 1993.
The foreign matter was identified as either "a piece of asbestos fabric, traces of aluminum or sand," the report said. Rocket expert Charles P. Vick of the Federation of American Scientists told space.com in early December that he had heard sand might have contaminated the rocket, causing the failure.
"At the [Baikonur] Cosmodrome there have been some discussions of sand having gotten into the propellants," Vick said at the time. (See "Proton Rocket Down But Not Out," space.com, December 6, 1999)
The report cleared the rocket's fuel and propellant as potential sources of the contamination but suggested that the materials entered the doomed engine "through the fuel line downstream of the starter valve." According to Russian investigators, that meant that the material got into the fuel line during the manufacture of the engine and its related components.
During 1992-93, the number of engines built at the rocket engine plant had dropped to just 19 percent of the earlier, higher 1986 levels. As a result, incidents of failure to follow proper assembly and production procedures had escalated as the work had slumped.
"Thus a gross neglect of requirements was committed in the course of fabrication of the turbopump" aboard the rocket, which eventually failed, the investigators said.
The review cleared workers at the Proton's launching site and said that all countdown and fueling operations had followed the correct procedures. Only the engines used in the third stages of the failed rockets remained suspect.
Some engineers had suggested that the turbopumps in batches of the rocket engines built in the early 1990s had manufacturing flaws. Officials had ordered extensive test firings of other engine units from the same production batch as those that failed during the launches on July 5 and October 27 of last year.
The testing pointed to problems with those engines as the likely cause of the disasters, which set back the Proton launch schedule in late 1999 and threatened the big rocket's return to flight in early 2000.
ILS indicated that their assessment of the review panel's report, as well as coordination with the Russian government and the Krunichev design bureau -- the Proton's builder -- would lead to corrective actions to speed the rocket back into service.
Minimal disruption of the Proton launch schedule was expected if the rocket could resume flights this spring.
The service module for the International Space Station (called Zvezda), as well as other Russian and commercial payloads, are awaiting clearance of the rocket to get their missions underway.
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