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IF it were not for the precision measurement of

ALL the THINGS - which need to be measured


- that Professor Marcus du Sautoy has so eloquently elucidated in the first

episode of the BBC television series: Precision: The Measure of All Things

entitled - the story of the metre and the second - and  HOW an

astonishing journey across revolutionary France gave birth to the metre

and HOW scientists today are continuing to redefine the measurement of 

time and lengthwith extraordinary results - the complimentary creation  

of the  Galileo Satellite Navigation System - a European version of the  

US Global Positioning System (GPS) - would not have got off the ground -

because its success is entirely due to the fact that the Galileo system

is driven by the most accurate atomic clocks  thus far invented,

manufactured and launched into space.


Galileo services will come with quality and integrity guarantees which mark

the key difference of this first complete civil positioning system from the

military systems that have come before.


The skies above Europe are becoming increasingly congested, as are

Europe’s major airports. This growth in air traffic means smaller airports

also need to be safely accessible at all times, which cannot be achieved by

relying solely on non-precision approaches.



Air Traffic management technologies also need to evolve from costly and

rigid ground based infrastructures to more advanced systems, based on

new technology. EGNOS already acts as an overlay to the US Global

Positioning System (GPS) and once it is integrated with the fully operational

capability of Galileo, pilots will be able to monitor hands-off fully

automatic landings with centi-metric accuracy.



EGNOS, the European Geostationary navigation Overlay Service, will offer

enhanced vertical precision and integrity, improving safety, accessibility

and efficiency to operators, pilots and airports all over Europe - and

provide yet another tool in the evolving battle to challenge the effects

and consequences of climate change.  



Galileo's range of services will be extended as the system is built up from 

initial operational capability to reach Full Operational Capability (FOC)

by this decade’s end. The fully deployed Galileo system consists of 30

satellites (27 operational + 3 active spares), positioned in three circular

Medium Earth Orbit (MEO) planes at 23 222 km altitude above the Earth,

and at an inclination of the orbital planes of 56 degrees to the equator.


The four operational satellites launched so far - the basic minimum for

satellite navigation in principle - serve to validate the Galileo concept with

both segments: space and related ground infrastructure.


At this stage, The Open Service, Search and Rescue and Public Regulated

Service will be available with initial performances. Then as the constellation

is built-up beyond that, new services will be tested and made available to

reach Full Operational Capability (FOC).


Once this is achieved, the Galileo navigation signals will provide good

coverage even at latitudes up to 75 degrees north, which corresponds to

Norway's North Cape - the most northerly tip of Europe - and beyond.

The large number of satellites together with the carefully-optimised

constellation design, plus the availability of the three active spare satellites,

will ensure that the loss of one satellite has no discernible effect on the


Experimental satellites GIOVE-A and GIOVE-B were launched in 2005 

and 2008 respectively, serving to test critical Galileo technologies, while 

at the same time securing all of the Galileo frequencies within the

International Telecommunications Union.


Over the course of the test period, scientific instruments also measured

various aspects of the space environment around the orbital plane, in

particular the level of radiation, which is greater than in low Earth or

geostationary orbits.


The four operational Galileo satellites launched in 2011 and 2012 built

upon this effort to become the operational nucleus of the full Galileo








Views: 134

Comment by Michael Grove on November 25, 2013 at 10:14

TIME waits for no man/woman and any farmer, gardener, horticulturist or allotmenteer, will

confirm that NATURE only gives back that which HumanKIND puts in, in the very first place.

Homo sapiens sapiens has sought to establish its geophysical position, wherever that might be,

within the confines of the biosphere of planet earth - which we have in more recent times, come

to refer to as "the pale blue dot" within our cosmos - since the very beginning of our species

TIME on Planet Earth. In geographylatitude (φ) is a geographic coordinate that specifies the

north–south position of a point on the Earth's surface. Latitude is an angle which ranges from

0° at the Equator to 90° (North or South) at the poles. Lines of constant latitude, or parallels,

run east–west as circles parallel to the equator. Measurement of latitude requires an

understanding of the gravitational field of the Earth, either for setting up theodolites or for

determination of GPS satellite orbits.  

The notion of longitude was developed by the Greek Eratosthenes (c.276 BC – c.195 BC) in 

Alexandria and Hipparchus (c.190 BC – c.120 BC) in Rhodes and applied to a large number of

cities by the geographer Strabo (63 BC – c.24 AD). But it was Ptolemy (c. AD 90 – c. AD 168)

who first used a consistent meridian for a world map in his Geographia. Longitude is an angular

measurement, usually expressed in degrees and denoted by the Greek letter lambda (λ).

Meridians (lines running from the North to South poles connect points with the same longitude.

By convention, one of these, the Prime Meridian, which passes through the Royal Observatory,

Greenwich, England, was allocated the position of zero degrees longitude and subsequently

TIME at that point, has become known as Greenwich Mean Time (GMT) or ZULU TIME in accordance

with the Z of zero being pronounced as ZULU during the phonetic AlphaBET process of Air

Transport Trafic-Communications. The longitude of other places is measured as the angle east

or west from the Prime Meridian, ranging from 0° at the Prime Meridian to +180° eastward and

−180° westward. Specifically, it is the angle between a plane containing the Prime Meridian and

a plane containing the North Pole, South Pole and the location in question. [This then forms a 

right-handed coordinate system with the z axis (right hand thumb) pointing from the Earth's

center toward the North Pole and the x axis (right hand index finger) extending from Earth's

center through the equator at the Prime Meridian.] If the Earth were perfectly spherical and

homogeneous, then the longitude at a point would be equal to the angle between a vertical

north–south plane through that point and the plane of the Greenwich meridian. Everywhere on

Earth the vertical north–south plane would contain the Earth's axis. But the Earth is not

homogeneous, and has mountains - which have gravity and so can shift the vertical plane away

from the Earth's axis. The vertical north–south plane still intersects the plane of the Greenwich

meridian at some angle; that angle is the astronomical longitude, calculated from star

observations. The longitude shown on maps and GPS devices is the angle between the Greenwich

plane and a not-quite-vertical plane through the point; the not-quite-vertical plane is

perpendicular to the surface of the spheroid chosen to approximate the Earth's sea-level surface,

rather than perpendicular to the sea-level surface itself. 

GPS is operated and owned by the US and the EU has decided that being completely reliant on

another country's GPS system would leave them vulnerable if they and the US ever fell out.

That's why they're currently launching the first few of what will, when completed by 2019, be a

30-strong swarm of satellites. Collectively, they're known as Galileo - Europe's answer to the GPS.

But while Galileo has emerged largely due to politics, it will offer tangible benefits for you and

your pocket, too. Simply put, it will mean stronger signals and better coverage, leading to

a more accurate and more reliable service.

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