On Thursday, December 2 (CET) another two Galileo navigation satellites will be launched from Kourou in French Guiana aboard a Soyuz rocket. This will raise the number of Galileo satellites in orbit from currently 26 to 28. All Galileo satellites use products from RUAG Space, a leading supplier to the space industry.

RUAG Space supplied the onboard computer that controls and monitors the payload of the Galileo satellites and many other subsystems. The computer also monitors the satellite status, such as temperature, to ensure that the satellites are fully functional. Furthermore, RUAG Space delivered the mission antenna for the Galileo satellites. The antenna is used to upload mission data for the onboard signal generators.

Once in orbit the Galileo satellites are protected from the 400 degrees Celsius temperature-differences it would experience on their hot sun-facing side and cold space-looking side by a thermal insulation from RUAG Space. This highly efficient insulation consists of several layers of metal-evaporated polyimide film. The sun is also the main power source of the satellites in orbit. To optimally align the solar array panels towards the sun rotating drive mechanisms are necessary. RUAG Space produced these mechanisms for the Galileo satellites.

RUAG Space dispenser places Galileo satellites in orbit

The European Galileo satellites will be sent to space with a Sojuz rocket. The dispenser from RUAG Space is a supporting structure that will hold the twin satellites firmly in place under the Soyuz fairing during launch. Then, some four hours into flight at an altitude of 23000 km, the dispenser will deploy the satellites into orbit by firing a pyrotechnic separation system. A distancing system ensures their release in opposing directions from the dispenser. The dispenser has a structural mass of 150 kg. It carries and separates two Galileo satellites - each one weighing 700 kg - into orbit. Since around 40 years RUAG Space develops and produces separation systems at its site in Linköping, Sweden. Dispenser systems from RUAG Space are especially suitable for spacecraft constellations, where a large number of spacecraft need to be placed in orbit in a short time frame.

Galileo provides global positioning, navigation and timing

The European Navigation System Galileo, also dubbed the European GPS, is created by the European Union through the European Space Agency (ESA) and operated by the European Union Agency for the Space Program. Galileo is a civil satellite navigation system that provides global positioning, navigation and timing. With at least four satellites constantly visible to the user, positioning becomes much more accurate than with previous systems, down to a meter.

Finding lost persons within 10 minutes

The Galileo system also provides a new global search and rescue service, which will be used for locating distressed people, e.g. a person lost in the desert, which needs to be located. RUAG Space contributes electronics to this Galileo search and rescue service. When Galileo search and rescue is in full operation, the time to detect a person who has disappeared at sea or in the mountains will be shortened from three hours to just ten minutes after activating an emergency transmitter.

Source:  RUAG
Associated URL: ruag.com

Additional testing was conducted this week to ensure the observatory’s health following an incident that occurred when the release of a clamp band caused a vibration throughout the observatory.

On Wednesday, Nov. 24, engineering teams completed these tests, and a NASA-led anomaly review board concluded no observatory components were damaged in the incident. A "consent to fuel" review was held, and NASA gave approval to begin fueling the observatory. Fueling operations will begin Thursday, Nov. 25, and will take about 10 days.

The Webb Space Telescope is an international partnership with the European and Canadian space agencies. It will explore every phase of cosmic history - from within our solar system to the most distant observable galaxies in the early universe, and everything in between. Webb will reveal new and unexpected discoveries, and help humanity understand the origins of the universe and our place in it.

Source:  Arianespace
Associated URL: arianespace.com

GIOVE-A was designed, built and tested by SSTL in only 30 months for the European Space Agency (ESA) and was launched on 28 December 2005 with a mission to secure vital frequency filings, generate the first Galileo navigation signals in space, characterize a prototype rubidium atomic clock, and model the radiation environment of MEO for future Galileo spacecraft. GIOVE-A was the first European satellite launched into the demanding MEO radiation environment, where it greatly out-performed its 27 month design lifetime.

After completion of its mission for ESA, GIOVE-A was maneuvered into a higher "graveyard" orbit at 23,300km above the Earth to make way for the first fully operational capability Galileo satellites. In 2012 SSTL took over operations from ESA and GIOVE-A continued to provide valuable in-orbit data on the MEO environment. The Merlin radiation monitor on-board GIOVE-A collected a unique 10+ year record for the MEO orbit and data analysis at the Surrey Space Centre, supported by ESA, showed some interesting features such as the "electron desert" in 2008/9 during what was the lowest solar minimum of the space era, and one of the largest electron storm events on record in April 2010. Several scientific journal papers have been published from the radiation data generated by GIOVE-A and a new model of the outer Van Allen belt electron fluxes, ‘MOBE-DIC’, has been produced to help improve future satellite designs. Monitoring of the rubidium clocks on board GIOVE-A, key data for the Galileo constellation that followed, revealed no issues during the 6.5 years that the navigation payload was operational.

Also onboard GIOVE-A was an experimental SSTL GPS receiver, the SGR-GEO, which in 2012 achieved a GPS position fix at 23,300km altitude - the first position fix above the GPS constellation on a civilian satellite. This demonstrated a new timing and orbital positioning solution for satellites operating in orbits higher than 20,000km which can only receive a few of the weaker GPS signals that "spill over" from the far side of the Earth.

The SGR-GEO was subsequently used to track many signals from GPS satellites, including the sidelobes not normally visible to ground-based systems. The performance of GNSS receivers at high altitudes is very sensitive to sidelobe strength, and data from the SGR-GEO helped to map out the antenna patterns of GPS satellites for use in planning navigation systems for future high altitude missions in geostationary orbit , lunar orbit, and beyond into deep space. In 2010 SSTL was awarded a contract to assemble, integrate and test the first navigation payloads for the full operational capability Galileo spacecraft, and over a period of 10 years SSTL supplied a total of 34 navigation payloads for Galileo, Europe’s global navigation positioning constellation.

GIOVE-A carries an engraved plaque in tribute to SSTL engineer, Tom Fairburn, who tragically lost his life in the 2004 Indian Ocean Boxing Day Tsunami. Tom worked as a payload mechanical engineer on GIOVE-A and is warmly remembered by colleagues at SSTL.

Source:  SSTL
Associated URL: sstl.co.uk