Lancering Sirius 4 in augustus '07

[Trulli]

De eerder genoemde datum van 4 juni '07 wordt dus niet gehaald.

Onderstaand bericht geplukt van de SES Sirius pagina.

 

Super satellite almost ready.

 

In August SIRIUS 4 will be launched into space – if everything stays on schedule. SIRIUS 4 is SES SIRIUS’ major investment in a new satellite built by Lockheed Martin. Final assembly and testing are in full swing in Sunnyvale, California.

Lockheed Martin is currently integrating all subsystems for our new SIRIUS 4 satellite. These subsystems have been manufactured in different locations in the United States and have now been delivered to the Sunny-vale facility, where they are being assembled. All components are being tested extremely carefully at the time of assembly,” says Jan-Olof Alfredsson, Chief Technical Officer at SES SIRIUS, who is monitoring the work. “A modern satellite is incredibly complex. I would be amazed if all of the tests were carried out without any glitches. On the contrary, now is the time to find the problems.”

“The satellite will be tested under the conditions that will occur in space. For example, it will be exposed to vibrations that will match the worst conditions during the launch (with a margin). The satellite will also be tested in a vacuum chamber with substantial temperature variations, corresponding to the temperatures it will have in orbit, when exposed to sunlight and shadow. The external components suffer the greatest exposure. The solar panels are exposed to temperature variations between -170oC and + 133oC and the antennae from -165oC to +100oC. In the tests the strains are even greater in order to be sure that they work flawlessly up in orbit.”

“The payload – the part that receives, treats and broadcasts the signals that come from the ground (receivers, channel filters, amplifiers, frequency converters, etc.) – is mounted inside the satellite body and is more protected from temperature variations using heaters, etc. These parts are tested in the interval 0oC to +75oC.”

“We just finished the payload tests and discovered a few problems with two frequency converters for the Ka band (19-30 GHz) and a satellite gyro. Now these units are undergoing careful examination,” says Alfredsson.

Several of the components in the satellite have redundancy, which means there are “spare parts” that can be put in function if something breaks. This is the case for the transmitting tubes, which are the most important parts of the satellite. The satellite carries several spare tubes, as well as several spare receivers, which guarantees reliability of operation.

During the spring the antenna system will also be carefully tested to verify that the antennae still fulfill the specifications for coverage. These tests are called ranging tests. If all goes according to the schedule, the satellite will be ready for shipment to the cosmodrome in Baikonur, Kazakhstan, sometime this summer. The preparations in Baikonur will take about one month. The launch is expected to take place in August.