An “epidemic” mysterious continues to spread in the Galileo constellation. In November 2016, there were two atomic clocks down, had finally admitted to the european space Agency (ESA) after the revelations of The Tribune, and then, in January, it was nine. Finally, according to our information, today it is a score of clocks, which would have malfunctions, of which ten would be already out of service. A twenty clocks on the 72 in the orbit (four satellites). Which makes a lot. Too much? Not for the ESA, which considers that the problem is under control even if nobody at the european space Agency does not know yet with accuracy the sickness of the clocks. This poses a problem…
“It’s a sensitive issue” because the atomic clocks are elements of a “very important” for the proper functioning of the system of satellite navigation, competitor of the american GPS, had stated in January the director general of ESA, Jan Woerner.
The renewed assurances of the ESA, responsible for the project management of the satellite navigation system european, have convinced the european Union, which had been very worried and disgusted by these problems, to make a new start from this year, the four satellites of the constellation european on board Ariane 5. This will make a total of 22 satellites put into orbit by Arianespace. All satellite clocks are affected by this epidemic, are functional, are assured to La Tribune. “Politically, it is important for Europe to launch by the end of the year,” says one. A launch is being targeted by the ESA to December.
The ESA recommends HBOT for the final installment
In spite of the problems of the atomic clocks, the european commission, on the insistence of the ESA, has renewed its trust in OHB-System by signing on the occasion of the salon du Bourget, the contract for the last tranche of the Galileo constellation. Eight satellites to 324 million euros. Not surprisingly, the european space Agency (ESA), under the influence of the German (?), had selected the end of April the German manufacturer for this new order even as the issue of clocks was not set. Is this clock manufactured by the group Orolia, which is faulty, or the environment of the satellite, which would cause this failure? In any case, the clocks fail the were after an intensive use for testing, ” says one to The Tribune. To preserve the other, the ESA uses the least possible…
“This will allow us to complete the Galileo constellation and the satellites in reserve both in orbit and on the ground,” had said Paul Verhoef, head of Galileo programme at ESA, quoted in a press release.
Three manufacturers were in the fight for a call for tenders issued last spring by the Commission for the construction of eight new satellites. OHB-System has already won three competitions for the construction of the first 22 satellites for Galileo-operational configuration (FOC, Full operational capability). The German group OHB, who won in 2010 and then in 2012 the first two tenders of the satellites FOC (14 and 8), had been chosen twice to the general surprise, in the face of Airbus. The issue of dual source was already laid in 2012.
Four clocks on board a satellite Galileo
The satellites of the Galileo constellation will be loaded with two types of clocks : masers hydrogen passive and rubidium atomic clocks. More precisely, each of them will be equipped with two masers hydrogen which serves as the main reference for the generation of the navigation signals while the second will be used redundancy passive. This type of clock ensures a precision of the order of the nanosecond (a billionth of a second) per 24 hours. What is to lose or gain a second every 2.7 million years, according to ESA. “This means that the clocks masers hydrogen liability of Galileo will be about a billion times more accurate than a regular watch,” says the european space Agency.
Each operational satellite also carries two clocks, rubidium. The first, used in active redundancy (which means that it runs constantly) immediately takes over from the hydrogen maser in the event of a failure. This allows to avoid any interruption in the generation of the signal. The second clock to the rubidium will be used redundancy passive. The clocks rubidium provide a precision of 10 nanoseconds per day. By comparison, a wrist-watch ordinary digital has an accuracy of about a second per day.