Tag: ESTEC

How Galileo satellites are tested before launch

A Galileo satellite in the Maxwell chamber

Each Galileo satellite must go through a rigorous test campaign to assure its readiness for the violence of launch, the vacuum of space, and temperature extremes of Earth orbit, reported the European Space Agency.

Each one is despatched to a unique location in Europe to ensure its readiness before launch: a 3,000-square-meter cleanroom complex nestled in sandy dunes along the Dutch coast, filled with test equipment to simulate all aspects of spaceflight.

The test centre in Noordwijk — Europe’s largest satellite test site — is part of ESA’s main technical centre, but it is maintained and operated on a commercial basis on behalf of the Agency by a private company created for the purpose: European Test Services (ETS) B.V.

“Our company was founded 2000 as a joint venture between two of Europe’s leading satellite environmental test companies, Intespace in France and IABG in Germany,” said Pierre Destaing, ETS test programme support manager for Galileo. “That business setup is a source of flexibility: there are 30–35 people working here throughout the year, but if extra specialists are needed for a given campaign, we can call on our parent companies.”

ETS has been responsible for supporting many historic test campaigns – including space-certifying Europe’s 20-tonne ATV space truck and Envisat, the world’s largest civilian Earth-observing mission. But in terms of scale alone, its work with Galileo is the company’s greatest challenge.

ETS is about to complete its contracts with OHB System AG, covering the environmental test of 22 ‘Full Operational Capability’ Galileo satellites, preceded by the testing of the very first of the first-generation ‘In-Orbit Validation’ Galileo satellites on a previous, separate contract.

A Galileo FOC satellite is slid out of its transport container into the clean room at ESTEC. (Photo: ESA)

The pressure has been steady to ensure satellites are available in time to meet Galileo’s launch schedule.

“Traffic management is a big part of the job – it’s like a game of Tetris,” Pierre said. “We have a steady stream of Galileo satellites to accommodate, along with other missions such as the BepiColombo Mercury orbiter, Solar Orbiter, the Cheops exoplanet detector and currently the latest MetOp weather satellite, with a fixed set of test facilities. The biggest challenge is definitely ensuring that every project can have the access to the facility they need at the right time, which demands complicated logistics and security adherence.”

ETS has built up to a steady rhythm with the OHB System team, typically accommodating multiple satellites in storage on site, at the same time as others undergo further active testing.

“When each new satellite arrives, it is first unpacked within the carefully filtered and air conditioned Test Centre environment,” Pierre said.

Moving a Galileo Full Operational Capability satellite between test facilities at ESA’s Test Centre in Noordwijk, the Netherlands. (Photo: ESA)

July 31, 2017
Four Galileo Satellites Now at ESTEC

Weeks of testing simulated the airlessness and temperature extremes of orbital space, taking place at the ESTEC Test Centre in Noordwijk, the Netherlands during May 2015. (Photo: ESA)

News by the European Space Agency

Europe’s latest Galileo was unboxed at ESA’s technical centre in the Netherlands in May, bringing the total number of satellites at the site to four.

ESTEC in Noordwijk is the largest satellite test facility in Europe, with all the equipment needed to simulate every aspect of the launch and space environment under a single roof. It is an essential stop on the way to space for Europe’s Galileo satellites, built by OHB in Bremen, Germany, with navigation payloads from Surrey Satellite Technology Ltd. in Guildford, UK.

The 12th Galileo arrived by lorry from Bremen on May 13, in a custom-built environmentally controlled container. The satellite will begin with a thermal vacuum test in a 4.5-meter-diameter stainless steel chamber, subjected to about five weeks of hard vacuum and the temperature extremes of space.

Galileo-11 recently completed the same trial before moving on to final system testing, including a compatibility run with the ground network.

Meanwhile, the ninth and tenth satellites are in storage at ESTEC, having passed their own checks. They will be flown to Europe’s Spaceport in French Guiana in late July for launch by Soyuz in September, which will bring the total in orbit into double figures.

The 12th Galileo satellite, FOC FM-08, arrived at the ESTEC Test Centre on May 13. It was transported by lorry from Bremen in a protective air-conditioned container.

The first four Galileos, launched in 2011 and 2012, were in-orbit validation satellites, built by prime contractor Airbus Defence & Space. They confirmed that the overall system worked as planned, while also serving as the foundation of the full constellation to follow.

The follow-up Full Operational Capability satellites are now being launched regularly to increase the size of the constellation to the point where early Galileo services can begin next year.

European Partners. Galileo is a collaboration between ESA and the European Commission (EC). The validation phase was co-funded by ESA and the EC, while the full operational phase is funded by the EC. Under a delegation agreement, ESA acts as design and procurement agent on behalf of the commission.

June 10, 2015
Satnav Augmentation Systems Settle on Common Channels Post-2020

EGNOS is Europe’s first venture into satellite navigation. EGNOS broadcasts augmented information through a trio of geostationary satellites linked to a network of monitoring ground stations, to sharpen the accuracy and reliability of GPS signals across the continent. (artist’s concept: ESA)

News from the European Space Agency

The next decade’s aircraft pilots will be able to rely on enhanced, reliable satellite navigation signals on a seamless basis across much of the world, thanks to decisions made at the latest gathering of worldwide satnav augmentation system providers and experts.

The U.S. Wide Area Augmentation System (WAAS) and European Geostationary Navigation Overlay Service (EGNOS) are leading examples of satellite-based augmentation systems (SBAS) that apply additional ground stations and satellite transponders to sharpen the accuracy and reliability of existing satnav services across given geographical regions.

These performance enhancements permit satnav to be employed for safety-of-life services, especially aviation. Such systems are based on the U.S. GPS for now, but plans are being laid to move to a multi-constellation design employing Europe’s Galileo, China’s Beidou and Russia’s GLONASS satnav systems beyond 2020.

The 28th Satellite-based Augmentation Systems Interoperability Working Group (IWG), planning standardization of SBAS systems to come, was hosted at ESA’s ESTEC technical centre at Noordwijk, the Netherlands, on April 1-3.

The ESTEC facility in Noordwijk, The Netherlands. (Photo: ESA)

All participants unanimously endorsed the “message definition” for a new secondary SBAS channel — to be known as L5, along with the current L1 — for the planned second-generation SBAS systems, which will utilize dual-frequency multi-constellation signals.

Using dual frequencies greatly increases the accuracy of navigation systems, by allowing interference from the ionosphere — an electrically active outer layer of Earth’s atmosphere — to be largely subtracted from the final result.

“This definition is presented in what is called the Dual Frequency Multi-Constellation Definition document,” explained Didier Flament, representing ESA. “It represents the outcome of a four-year activity, which started at IWG 19 in Japan, back in 2010, coordinated between all IWG members under the technical leadership of ESA and French space agency CNES on the European side, and the Federal Aviation Authority (FAA) and Stanford University on the U.S. side.

“The formal IWG review loop for the document took six months to conclude, with this IWG 28 then allowing endorsements to be gathered by SBAS project managers, culminating in formal signatures to the document,” Flament said.

SBAS coverage for 2020: Comparing current worldwide SBAS coverage — based on WAAS, EGNOS and MSAS — to the situation envisaged for 2020–25: near-global coverage based on WAAS, EGNOS, MAAS, SDCM and GAGAN, with an expanded network of stations in the southern hemisphere, all based on a common dual-frequency/dual satnav standard being finalized by the SBAS Interoperability Working Group. (Image: ESA)

IWG members now intend to have this document accepted by the official international SBAS standardization bodies: the International Civil Aviation Organisation, the U.S. Radio Technical Commission for Aeronautics (RTCA) and the European Organisation for Civil Aviation Equipment.

“This next step is very important,” added Didier. “Not only for the coming 2016-22 implementation of the European EGNOS v3 but for implementation of other second generation SBAS in other regions of the world.”

The meeting also reported on the state of development of the other global SBAS systems. Along with the four operational systems — the U.S. WAAS, European EGNOS, Japan’s Multi-functional Satellite Augmentation System (MSAS) and India’s GPS-aided geo-augmented navigation or GPS and geo-augmented navigation system (GAGAN) — these comprise South Korea’s KASS, China’s Beidou SBAS, Russia’s System for Differential Corrections and Monitoring (SDCM) and the West African Agency for Aerial Navigation Safety in Africa and Madagascar (ASECNA) SBAS.

The follow-up IWG meeting will take place in October, hosted by the FAA in Washington, D.C., in conjunction with the next RTCA meeting.

May 7, 2015
Four Galileo Satellites Now at ESTEC, Production Continues

News courtesy of the European Space Agency.

The latest Galileo satellite, formally known as FOC FM06, arrived at the ESTEC Test Centre in its protective container on Dec. 18, after traveling from OHB in Bremen, Germany. Photo: European Space Agency

The latest Galileo satellite has arrived at ESTEC, in the Netherlands, and is undergoing a full checkout to prove its readiness for space.

The satellite was carried by lorry from its manufacturer in Germany, cocooned within an environmentally controlled container. It arrived inside ESTEC’s cleanroom environment on Dec. 18. The container was then opened up to begin preparations for testing.

The first six Galileo satellites are already in orbit, launched in pairs in 2011, 2012 and August this year.

The last pair was delivered into the wrong orbit by a faulty upper stage, but the fifth satellite’s orbit has since been changed to allow checking of its navigation payload, which began at the end of November.

The sides and top of the Galileo satellite container were sprayed clean before it was taken inside the bay of the ESTEC Test Centre to keep any contamination from entering the pristine cleanroom. Photo: European Space Agency

Meanwhile, down on the ground, production of further satellites continues steadily, taking the Galileo series into double figures overall.

Following on from the first four In-Orbit Validation satellites, 22 of these Full Operational Capability satellites are being built by OHB in Bremen, Germany, with navigation payloads from SSTL in Guildford, UK.

Numbered Flight Model 6, or FM06 for short, this latest of the newer satellites is now reunited under the test centre’s roof with three others. FM03 and FM04 have completed their acceptance testing, culminating in the weeks-long thermal-vacuum test. Each satellite was subjected to the same vacuum and extreme temperature conditions experienced in orbit, as well as radio-frequency testing of their navigation payloads and antennas inside an anechoic chamber isolated from the external universe. This pair is now in storage in the centre pending the results of their concluding acceptance review.

The other satellite, FM05, recently ended its own thermal-vacuum trial. It is now being reconfigured for radio-frequency testing, planned to take place after the Christmas break. The latest unboxed Galileo satellite will undergo its own thermal–vacuum test in January.

ESTEC is an essential stop on the way to space for Galileo. It is equipped with all the facilities needed to simulate space conditions under a single roof, including an acoustic chamber, earthquake-strength shaker tables, and anechoic and vacuum chambers, along with a range of specialised measuring equipment.

Once ESTEC gives the satellites its stamp of quality then they are in principle ready to be flown to Europe’s Spaceport in Kourou, French Guiana. ESA and the European Commission are currently deciding on the launch schedule for these next Galileos.

The container containing the latest Galileo satellite, FOC FM06, was carefully hoisted off the lorry that carried it from OHB in Bremen, Germany. Its underside was then carefully cleaned before it was taken out of the bay into the cleanroom environment. Photo: European Space Agency

January 2, 2015
Salvaged Galileo Performs Its First Navigation Fix

Scatter plot of the Galileo fix performed in ESA’s Navigation Laboratory at its ESTEC technical centre on 9 December 2014. The plot was calculated by the Lab’s Septentrio Test User Receiver, with dispersion of less than 2 m.

News from the European Space Agency

Galileo’s fifth satellite — recently salvaged from the wrong orbit to begin navigation testing — has been combined with three predecessors to provide its first position fix.

Test receivers at ESA’s technical centre in Noordwijk, the Netherlands, and at the Galileo In-Orbit Test station at Redu in Belgium received the signals at 12:48 GMT on December 9 from the quartet of satellites and fixed their horizontal positions to better than 2 meters.

This achievement is particularly significant because the fifth satellite is the first of a new design of 22 Galileo satellites set to be launched over the next few years.

Further position fixes were then made by France’s CNES space agency in Toulouse, France, as noted by Bernard Bonhoure: “The results are as good as those for the first Galileo fixes in 2013 with the initial four satellites.”

The following day, fixes were performed using Galileo’s Public Regulated Service, the encrypted highest-precision class of signal.

“The very good geometry of the satellites in the sky relative to the receivers helped us to achieve this result, plus the signal strength of the fifth satellite,” explained Gustavo Lopez Risueno, coordinating the receiver team at the Navigation Laboratory in ESA’s ESTEC technical centre.

“This is a significant milestone for the Galileo program because it marks the very first time that a Full Operational Capability satellite has performed a fix together with its In-Orbit Validation predecessors — which were the first four satellites launched into orbit, in 2011 and 2012. This establishes they work together well.

“While it is not yet possible to make routine use of the fifth Galileo, this shows such an outcome is within our reach.

Galileo satellite geometry and received signal strength for the December 9 fix using the first Galileo FOC satellite. The first Galileo FOC satellite corresponds to E19 on the left display; IOV PFM to E11, FM2 to E12 and FM3 to E19.

“In particular, it opens the door to its immediate use in combination with additional navigation message information provided through ground networks, which is a standard mode of operation for mass market receivers, such as those found in our smartphones.”

The fifth and sixth satellites were delivered into the wrong orbit by their Soyuz–Fregat rocket in August. Their elongated orbit took them out to 25,900 km above Earth and back down to 13,713 km, rather than the planned circular path at 23,222 km. The angle of the orbit to the equator was also wrong.

The satellites’ shifting altitude left them unable to lock onto Earth for part of each orbit, preventing them from being used for navigation purposes.

But, last month, a series of 11 maneuvers took the fifth satellite into a more circular orbit, some 3500 km higher, allowing its navigation payload to be switched on for testing. A similar salvage operation is planned soon for its companion.

The main hurdle in using the fifth (and subsequently sixth) satellite operationally is that mass market receivers in particular might take longer to find it. Their orbits fall outside the almanacs satellite-locating standard broadcast within navigation messages.

Utilizing navigation-assistance information would be a way of shortening acquisition times — and ESTEC’s Navigation Laboratory has already demonstrated it with mass market receivers.

Working in conjunction with the European Commission and Europe’s Global Navigation Satellite Systems Agency, the Lab performed position fixes with both Galileo and GPS satellites using only navigation-assistance information.

Test position fix in the grounds of ESTEC, performed with a mass-market receiver using navigation-assistance information, based on signals from the fifth Galileo satellite plus GPS satellites. This satellite’s elliptical orbit means extra data are needed to speedily utilize its signals, which could be provided through ground networks. Navigation-assistance information is already employed by the mass market receivers found within smartphones. Source: European Space Agency

EDITOR’S NOTE: Researchers at the German Aerospace Center (DLR) report on their success in producing a pseudorange-based all-Galileo position fix using precisely determined satellite orbits and clocks from Technische Universität München (TUM) in the January issue of GPS World. Richard Langley reports that his team at the University of New Brunswick has managed to produce a Galileo-only carrier-phase-based precise-point-positioning solution with better than decimeter accuracy using TUM’s orbits and clocks.

Also, GMV performed a first Galileo-only PPP with IOV + FOC-1 satellite with data from December 6, obtaining centimetric accuracy. Read about their results on their blog.

December 17, 2014
Galileo Satellites Put to the Test

The main antenna of the second Galileo Full Operational Capability (FOC) satellite being inspected with a flashlight in advance of mass property testing during August 2013.

Europe’s next pair of Galileo satellites have been the focus of a busy autumn at the European Space Agency’s (ESA’s) technical centre in the Netherlands, continuing a full-scale campaign to ensure their readiness for space.

The first Galileo Full Operational Capability (FOC) satellite, FM1, seen beside the Phenix test chamber being readied for its five-week long thermal vacuum testing in October 2013.

With the first four Galileos already in orbit, these new versions are the first two of a total 22 Full Operational Capability (FOC) satellites being built by OHB in Germany with a payload from Surrey Satellite Technology Ltd. in the UK.

The second satellite joined its predecessor in mid-August at ESA’s European Space Research and Technology Centre in Noordwijk. This is the largest spacecraft testing site in Europe, with a full range of space simulation facilities under a single roof in cleanroom conditions. A wide range of tests have been performed on the two satellites.

The first of the two satellites is now midway through a five-week immersion in vacuum and temperature extremes that mimic the conditions it faces in space. This thermal-vacuum test takes place inside a 4.5-meter diameter stainless-steel vacuum chamber called Phenix. An inner box called the thermal tent has sides that are heated to simulate the Sun’s radiation or cooled down by liquid nitrogen to create the chill of Sunless space.

Second Galileo Full Operational Capability (FOC) satellite being prepared for acoustic testing, simulating the noise of a rocket launch, inside the Large European Acoustic Facility, LEAF, of the ESTEC Test Centre in early September 2013.

The newly arrived satellite first underwent a mass property test — measured to check its center of gravity and mass are aligned within design specifications. The more precisely these are known, the more efficiently the satellite’s orientation can be controlled with thruster firings in orbit, potentially elongating their working life by conserving propellant.

Meanwhile, its predecessor left the wider universe behind in the Maxwell Test Chamber. Shielded walls blocking out all external electrical signals and spiky, radio-absorbing anechoic material lining the chamber enable electromagnetic compatibility testing. Isolated within the chamber as though floating in infinite space, the satellite could be switched on to check all its systems can operate together without interference.

September saw the second satellite undergo acoustic testing in the Large European Acoustic Facility, LEAF, effectively the largest sound system in Europe. The first satellite submitted to this trial just a few weeks before. A quartet of noise horns are embedded in one wall of this 11-meter-wide, 9-meter-deep and 16.4-meter-high chamber, generating sound by passing nitrogen gas through the horns, surpassing 140 decibels.

Galileo Full Operational Capability (FOC) satellite first flight model, FM1, being prepared for ‘passive intermodulation testing’ within the Maxwell electromagnetic test facility inside the ESTEC Test Centre at the end of August 2013.

Accelerometers placed within the satellite checked for potentially hazardous internal vibration during this trial by sound. Then the spacecraft was vibrated on the shaker tables, simulating the violent forces of a rocket launch.

Up-and-down vibration on the QUAD shaker followed by side-to-side shaking on the horizontal shaker, with data gathered across hundreds of channels.

The satellite was then connected to the dispenser that will hold it during launch to simulate the separation at the end of its climb to orbit. This separation is triggered by firing a pyro device which then pushes the satellite away from the dispenser. This demonstration took place last month.

“There will always be two Galileo satellites being tested at the ESTEC Test Centre for the next few years,” explains Giuliano Gatti, the head of the Galileo Space Segment Procurement Office.

“As the Galileo constellation takes shape, ESTEC will remain an essential part of each satellite’s pathway to space, between the end of manufacturing in Germany and UK and the launch by Soyuz ST-B or Ariane-5 from Europe’s Spaceport in French Guiana.

“Of course, the testing on these initial FOC satellites is especially rigorous because we are validating the overall design. The Galileo satellites to follow will undergo more streamlined ‘acceptance’ testing instead.”

The next two satellites are in final assembly at OHB in Germany, scheduled to reach ESTEC early next year, as these first two satellites head off to French Guiana for launch.

Galileo Full Operational Capability Flight Model 2, FM2, satellite’s main L-band antenna used for broadcasting navigation messages, seen during preparation for a mass property test at the ESTEC Test Centre at the end of August 2013.

November 11, 2013