December 7, 2010, 10:20
Why the Proton could not make it
One extra tonne of fuels: specialists now regard an error made during tanking a most probable version of the accident that send Proton-M rocket off-course.
Moscow, Dec 7, INTERFAX.RU - Specialists have determined that during tanking a Proton was filled with an excessive tonne of fuel. As an informed source told INTERFAX, this version becomes primary in the committee's investigation. "We have an assumption that DM-03 upper stage was filled with one tonne of fuel more than necessary during tanking at Baikonur" - told us the source.
He also noted that this explains well the telemetry information the specialists now study, which tells that by the moment of the upper composite (the upper stage plus triple GLONASS satellites) separation, velocity of the rocket was short by 100 m/s off nominal. They have simulated a situation with extra load of fuel and obtained a failure scenario identical to what has actually happened last Sunday.
At present moment, Roscosmos officially disallowed launching Proton rockets until the final assessment on the failure is made.
Nothing could save the satellites
A Proton-M LV's flight program does not allow a separation of the upper composite ahead of the preset time. "The rocket guidance system is nonadjustable when already in flight, so we could not order separation of the upper composite from the third stage ahead of time" - told us the person.
It was his comment on assumptions made by some mass media yesterday that the GLONASS satellited could have been saved, if a timely command to separate the upper composite was sent up.
He explained, that "the guidance system just does not respond to commands from Earth, it simply follows the onboard computer's program to deliver the upper stage and satellites at a specific point in space and separate them by reaching a preset speed and preset altitude."
Moreover, he added, even if the upper stage had been separated shortly after the rocket wandering off-course, it had no chance of compensating for the change of velocity lost with the remainder of the 3rd stage's intended work. "Such abnormal mode is not programmed into memory of the upper stage's onboard computer, and also, it would have run short of fuel".