Massive clock breakdowns on Galileo satellites
The on-board atomic clocks responsible for the navigation-satellite signal are rejecting the Galileo satellite network at an alarming rate.
On 18 satellites that are already in orbit, 9 timekeeping devices have stopped working.
Three of them are traditional rubidium atomic clocks; the six remaining more accurate hydrogen masers that were developed to give the Galileo system improved accuracy compared to the American GPS system.
The Galileo project was announced fully launched in December. However, there are still not enough satellites to form a fully working satellite constellation and now a decision has to be made: whether to launch launches while working on this problem.
Professor Johann-Dietrich Werner, director of the European Space Agency, spoke at a meeting with reporters: “Everyone is now asking the question: should we postpone the next launch until the causes of this problem are clarified, or should we launch it? You can answer both questions at the same time. You can say that we wait until we find a solution, but this means that if the rest of the clock starts to fail, we will reduce the possibilities of Galileo. But if we start launches, we will at least keep, if we do not increase the possibilities, but then we take the risk that the systematic problem will not be taken into account. Now we are discussing our next steps. ”
Each Galileo satellite carries two rubidium clocks and two clocks on hydrogen masers . This set of hours allows the satellite to work even after the failure of one of them. All 18 satellites continue to work in orbit, but one of them already has only 2 working hours. Most of the masers (5) refused on satellites that were sent to orbits to confirm the system, while all three failures of rubidium clocks were on satellites that were sent later to fill the constellation.
In the message of the agency, which was made later on Wednesday, additional facts were stated.
A possible reason for the failure of the rubidium clock was named “all problems have the same scenario, which was associated with a possible short circuit in the circuit, and possibly one of the testing procedures that was carried out on the ground.”
It also says that the failures of the maser clock better investigated, and named the two most likely causes, the second of which caused the greatest regret. ESA reported that the second scenario was “in the fact that when some hydrogen masers are off for a long time, they do not start due to changes in the system parameters.”
Measures have been taken to prevent future problems. They include a change in how the clock will work in orbit. Watches that are being prepared for launch are likely to be remade and the following orders for watches will include design changes.
Passive maser clocks in “Galileo” have an error of one billionth of a second per day or one second of three million years. Such accuracy will allow users to get measurement errors on the ground of less than one meter — much better than standard open GPS services.
The development of the “European GPS” is very thorny. The project is late in terms of years, and the price at the end of the project is expected to be around 7 billion euros for 2020. This is much higher than originally planned by EU members.
Original article in BBC English .
On 18 satellites that are already in orbit, 9 timekeeping devices have stopped working.
Three of them are traditional rubidium atomic clocks; the six remaining more accurate hydrogen masers that were developed to give the Galileo system improved accuracy compared to the American GPS system.
The Galileo project was announced fully launched in December. However, there are still not enough satellites to form a fully working satellite constellation and now a decision has to be made: whether to launch launches while working on this problem.
Professor Johann-Dietrich Werner, director of the European Space Agency, spoke at a meeting with reporters: “Everyone is now asking the question: should we postpone the next launch until the causes of this problem are clarified, or should we launch it? You can answer both questions at the same time. You can say that we wait until we find a solution, but this means that if the rest of the clock starts to fail, we will reduce the possibilities of Galileo. But if we start launches, we will at least keep, if we do not increase the possibilities, but then we take the risk that the systematic problem will not be taken into account. Now we are discussing our next steps. ”
Still act
Each Galileo satellite carries two rubidium clocks and two clocks on hydrogen masers . This set of hours allows the satellite to work even after the failure of one of them. All 18 satellites continue to work in orbit, but one of them already has only 2 working hours. Most of the masers (5) refused on satellites that were sent to orbits to confirm the system, while all three failures of rubidium clocks were on satellites that were sent later to fill the constellation.
In the message of the agency, which was made later on Wednesday, additional facts were stated.
A possible reason for the failure of the rubidium clock was named “all problems have the same scenario, which was associated with a possible short circuit in the circuit, and possibly one of the testing procedures that was carried out on the ground.”
It also says that the failures of the maser clock better investigated, and named the two most likely causes, the second of which caused the greatest regret. ESA reported that the second scenario was “in the fact that when some hydrogen masers are off for a long time, they do not start due to changes in the system parameters.”
Measures have been taken to prevent future problems. They include a change in how the clock will work in orbit. Watches that are being prepared for launch are likely to be remade and the following orders for watches will include design changes.
Passive maser clocks in “Galileo” have an error of one billionth of a second per day or one second of three million years. Such accuracy will allow users to get measurement errors on the ground of less than one meter — much better than standard open GPS services.
The development of the “European GPS” is very thorny. The project is late in terms of years, and the price at the end of the project is expected to be around 7 billion euros for 2020. This is much higher than originally planned by EU members.
Original article in BBC English .