Carried into space from the Baikonur Cosmodrome in Kazakhstan by a Soyuz launch vehicle on 28 December 2005, GIOVE-A then successfully completed the initial tasks in its mission – orbit injection, deployment of its solar arrays and the commissioning and check-out of its various payload systems – before commencing the transmission of navigation signals.
This signal transmission has secured the use of the frequencies allocated to the Galileo system by the International Telecommunication Unit (ITU), achieving the primary mission for which the satellite was constructed.
The receivers that have been developed for Galileo were able to receive the first signals at ESA sites at Redu (Belgium) and Noordwijk (Netherlands), at the Chilbolton Observatory (UK) and at the Guildford (UK) mission control centre of Surrey Satellite Technology Ltd, the prime contractor for GIOVE-A.
The navigation signal has been broadcast continuously to fulfil the other important objectives of the GIOVE mission:
*verification of the critical technologies for the Galileo satellites, including the on-board Rubidium Atomic Frequency Standard (RAFS) clocks, the navigation signal generator and the chain of equipment that comprises the navigation payload
*characterisation of the novel features of the Galileo signal design, including the verification of user receivers and their resistance to interference and multi-path reception in realistic static and dynamic conditions, aiming to better estimate the effect on navigation services and future applications
*characterisation of the radiation environment of the Medium Earth Orbit (23 260 km altitude) planned for the Galileo constellation, to better understand this particular environment – particularly the radiation doses and electro-magnetic fields that could affect the design of the operational system
GIOVE Mission Segment
To complete the in-orbit validation mission, ESA has deployed the GIOVE Mission Segment, composed of a network of 13 monitoring stations located around the world and a GIOVE Processing Centre located at ESA’s European Space Research and Technology Centre (ESTEC), in Noordwijk, the Netherlands. The processing centre is currently receiving measurements for GIOVE-A, and will also receive data for the GIOVE-B satellite which will be launched by the end of 2007.
The GIOVE Processing Centre computes precise orbits and clock timings for the GIOVE satellites, based on the measurements made by the global network of Galileo Experimental Sensor Stations that collect Galileo and GPS observables once per second. In the future, navigation messages will be generated and up-linked to the satellites through their control centres.
The GIOVE Processing Centre is already started to provide fascinating, first-ever experimental results that will allow risk mitigation for the operational system development in the in-orbit validation phase.
In satellite navigation, the achievable positional accuracy is driven by, among other factors, the performance of the navigation message broadcast by the satellites, the satellite clock stability, and the user’s receiver and environment. The GIOVE mission is confirming the correctness of assumptions made at the early stages of the Galileo system design using actual measurements performed in orbit. This confirmation shows that the service performance requirements can be met and the overall Galileo system design is on track.
New web site
Information on the GIOVE mission is now accessible at www.giove.esa.int. This new web site provides general information to the public and measurement data and core products to registered external users who are collaborating with ESA on the mission experiments.
Galileo is a joint initiative of the European Commission (EC) and ESA. The EC is responsible for the political dimension and the high-level mission definition. ESA’s responsibility covers the technology development as well as design, development and in-orbit validation of the space and ground elements.
Dominique Detain | alfa
Goodbye, login. Hello, heart scan
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Stable magnetic bit of three atoms
21.09.2017 | Sonderforschungsbereich 668
Controlling electronic current is essential to modern electronics, as data and signals are transferred by streams of electrons which are controlled at high speed. Demands on transmission speeds are also increasing as technology develops. Scientists from the Chair of Laser Physics and the Chair of Applied Physics at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have succeeded in switching on a current with a desired direction in graphene using a single laser pulse within a femtosecond ¬¬ – a femtosecond corresponds to the millionth part of a billionth of a second. This is more than a thousand times faster compared to the most efficient transistors today.
Graphene is up to the job
At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.
Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
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