65th International Astronautical Congress | Fregat Plumbing Blamed for Soyuz Failure that Stranded Galileo Satellites in Wrong Orbit
UPDATED Oct. 1 at 2:45 p.m. EDT
TORONTO — A Europeanized version of Russia’s Soyuz rocket placed two European navigation satellites into the wrong orbit in August because its hydrazine fuel line was installed too close to a supercold helium line on the Fregat upper stage, European government officials said.
The installation caused the hydrazine to freeze long enough to upset the Fregat stage’s orientation and cause the two satellites’ release into an orbit that is both too low and in the wrong inclination, officials said.
One official said the Euro-Russian board of inquiry into the failure discovered that one in four Fregat upper stages at prime contractor Moscow-based NPO Lavochkin had the same fuel-line installation.
The board of inquiry is expected to release its findings the week of Oct. 6.
“We have to assume that this was a practice that had gone on in perhaps a quarter of the Fregat stages produced in the past decade, but that it had not affected our launches up to now because of mission-specific aspects like coast time between burns, the number of burns and so on, which can influence the effect of the helium on the hydrazine,” this official said. “In any case, we’d like, which currently has almost no inspection rights on the Soyuz, to be given more say in quality assurance.”
In the stages without the installation issue, the hydrazine and helium lines were separated so that the supercold helium could not freeze the hydrazine.
One industry official said the installation glitch was not a workmanship error insofar as the Fregat design manual did not recommend that the helium and hydrazine lines be separated. It was left to each installation team to do as it wished.
“In the context of all the Proton rocket issues, let’s not confuse workmanship and design,” this official said. “If the design does not foresee a problem in putting the lines together, and in fact that is a problem for some missions, you cannot blame the workers. This is not another story of Russian quality control gone wrong, and it is an easily addressable issue.”
The Galileo positioning, timing and navigation system is owned by the European Commission, which is the executive arm of the 28-nation European Union. The commission has charged the 20-nation European Space Agency with technical management of the program.
Government and officials said the commission is debating how to proceed now that it knows that, as expected, the Fregat failure was not one of design, but of assembly and quality control.
The options are to continue, as scheduled, with the December launch of two more Galileo satellites aboard a Soyuz Fregat rocket, or to wait until next spring or summer and launch four Galileo satellites on a heavy-lift Ariane 5 vehicle.
Officials fromand from OHB AG, the Bremen, Germany-based prime contractor, have said the two satellites are in good health, and like all 22 Galileo satellites being built by OHB were designed to carry more fuel than necessary to accomplish their missions.
One argument for waiting until mid-2015 for the next launch is that it would give ESA and OHB additional time to put the satellites through a rigorous in-orbit test regime to debug them before launching additional satellites.
The August failure placed the first two fully operational Galileo positioning, navigation and timing satellites into an orbit that, in addition to being badly off target, regularly sends them through the Van Allen radiation belts around Earth.
While these satellites were built to better withstand radiation than the four Galileo validation spacecraft already in orbit, and built by a different contractor, regular exposure to radiation will reduce their operational lives.
In a presentation here Sept. 30 to the 65th International Astronautical Congress, OHB’s Galileo deputy program manager, Kristian Pauly, said he was optimistic that once the satellites’ perigee is raised and their orbit made less eccentric, they can be fitted at least partially into the Galileo program and perform a navigation function.
The first priority, Pauly said, is to take them out of regular contact with the Van Allen belts and adjust their Earth sensors to their new, unplanned view of Earth — which is much closer given the lower altitude.
Pauly declined to speculate on what the Galileo launch schedule would be, saying that OHB’s delivery schedule will not change much. “We have a delivery schedule that is extremely challenging and we will keep to it,” he said.
Several government and industry officials said the European Commission may wish to spend extra time testing the satellites rather than place two more into orbit aboard a Soyuz-Fregat rocket, as had been planned. In this scenario, the commission, through ESA, would order an Ariane 5 rocket with its new, Galileo satellite dispenser, which launches four Galileo satellites at a time.