GIOVE
Encyclopedia
GIOVE, or Galileo In-Orbit Validation Element, is the name for each satellite
in a series being built for the European Space Agency
(ESA) to test technology in orbit for the Galileo positioning system.
Giove is the Italian
word for "Jupiter". The name was chosen as a tribute to Galileo Galilei
, who discovered the first four natural satellite
s of Jupiter
, and later discovered that they could be used as a universal clock
to obtain the longitude
of a point on the Earth
's surface.
The GIOVE satellites are exploited by the GIOVE Mission
(GIOVE-M
) segment in the frame of the risk mitigation for the In Orbit Validation (IOV) of the Galileo positioning system
.
, has provided industry with fundamental knowledge to develop the mission segment of the Galileo positioning system.
GIOVE satellites are transmitting multifrequency ranging signals equivalent to the signals of future Galileo
: L1BC, L1A, E6BC, E6A, E5a, E5b. The main purpose of the GIOVE mission is to test and validate the reception and performance of novel code modulations designed for Galileo
including new signals based on the use of the BOC (Binary Offset Carrier) technique, in particular the high-performance E5AltBOC signal.
It should be stressed that the role of GIOVE is purely to test transmission and reception of the new signals: these satellites can not be used for navigation even for testing.
(SSTL).
Its mission has the main goal of claiming the frequencies allocated to Galileo
by the ITU
. It has two independently-developed Galileo signal generation chains and also tests the design of two on-board rubidium
atomic clock
s and the orbital characteristics of the intermediate circular orbit for future satellites.
GIOVE-A is the first spacecraft whose design is based upon SSTL's new Geostationary Minisatellite Platform (GMP) satellite bus, intended for geostationary orbit
. GIOVE-A is also SSTL's first satellite outside low Earth orbit
, operating in medium Earth orbit
), and is SSTL's first satellite to use deployable sun-tracking solar arrays. Previous SSTL satellites use body-mounted solar arrays, which generate less power per unit area as they do not face the sun directly.
/Fregat
from the Baikonur Cosmodrome
in Kazakhstan
.
in Hampshire
, UK and the ESA Station at Redu
in Belgium
. Teams from SSTL and ESA have measured the signal generated by GIOVE-A to ensure it meets the frequency-filing allocation and reservation requirements for the International Telecommunication Union
(ITU), a process that was required to be complete by June 2006.
signal from the point of view of frequencies and modulations, chip rates, and data rates. However, GIOVE-A can only transmit at two frequency bands at a time (i.e., L1+E5 or L1+E6).
GIOVE-A codes are different from Galileo
codes. The GIOVE-A navigation message is not representative from the structure and contents viewpoint (demonstration only purpose). The generation of pseudorange
measurements and detailed analysis of the tracking noise and multipath performance of GIOVE-A ranging signals have been performed with the use of the GETR (Galileo Experimental Test Receiver) designed by Septentrio
.
There has been some public controversy about the open source nature of some of the Pseudo-Random Noise (PRN) codes. In the early part of 2006, researchers at Cornell monitored the GIOVE-A signal and extracted the PRN codes. The methods used and the codes which were found were published in the June 2006 issue of GPS World. ESA has now made the codes public.
It was originally built by satellite consortium European Satellite Navigation Industries
, but following re-organization of the project in 2007, the satellite prime contractor responsibility was passed to Astrium.
GIOVE-B also has MEO environment characterization objectives, as well as signal-in-space and receiver experimentation objectives. GIOVE-B carries three atomic clock
s: two rubidium standard
s and the first space-qualified passive hydrogen maser
.
/Fregat
rocket provided by Starsem
. The Fregat stage was ignited three times to place the satellite into orbit. Giove-B reached its projected orbit after 02:00 UTC and successfully deployed its solar panels.
(multiplexed binary offset carrier), in accordance with the agreement drawn up in July 2007 by the EU and the US for their respective systems, Galileo and the future GPS III".
“Now with GIOVE-B broadcasting its highly accurate signal in space we have a true representation of what Galileo will offer to provide the most advanced satellite positioning services, while ensuring compatibility and interoperability with GPS”, said ESA Galileo Project Manager, Javier Benedicto.
After launch, early orbit operations and platform commissioning, GIOVE-B's navigation payload was switched on and signal transmission commenced on May 7 and the quality of these signals is now being checked. Several facilities are involved in this process, including the GIOVE-B Control Centre at Telespazio's facilities in Fucino, Italy, the Galileo Processing Centre at ESA's European Space Research and Technology Centre (ESTEC), in the Netherlands, the ESA ground station at Redu, Belgium, and the Rutherford Appleton Laboratory (RAL) Chilbolton Observatory in the United Kingdom.
Chilbolton's 25-metre antenna makes it possible to analyse the characteristics of GIOVE-B signals with great accuracy and verify that they conform to the Galileo system's design specification. Each time the satellite is visible from Redu and Chilbolton, the large antennas are activated and track the satellite. GIOVE-B is orbiting at an altitude of 23 173 kilometres, making a complete journey around the Earth in 14 hours and 3 minutes.
The quality of the signals transmitted by GIOVE-B will have an important influence on the accuracy of the positioning information that will be provided by the user receivers on the ground. Onboard, GIOVE-B carries a passive hydrogen maser atomic clock, which is expected to deliver unprecedented stability performance.
The signal quality can be affected by the environment of the satellite in its orbit and by the propagation path of the signals travelling from space to ground. Additionally, the satellite signals must not create interference with services operating in adjacent frequency bands, and this is also being checked.
Galileo teams within ESA and industry have the means to observe and record the spectrum of the signals transmitted by GIOVE-B in real time. Several measurements are performed relating to transmitted signal power, centre frequency and bandwidth, as well as the format of the navigation signals generated on board. This allows the analysis of the satellite transmissions in the three frequency bands reserved for it.
The GIOVE-B mission also represents an opportunity for validating in-orbit critical satellite technologies, characterising the Medium Earth Orbit (MEO) radiation environment, and to test a key element of the future Galileo system - the user receivers.
for a second satellite, to ensure that the Galileo programme continues without any interruptions that could lead to loss of frequency allocations. Construction of GIOVE-A2 was terminated due to the successful launch and in-orbit operation of GIOVE-B.
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
in a series being built for the European Space Agency
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...
(ESA) to test technology in orbit for the Galileo positioning system.
Giove is the Italian
Italian language
Italian is a Romance language spoken mainly in Europe: Italy, Switzerland, San Marino, Vatican City, by minorities in Malta, Monaco, Croatia, Slovenia, France, Libya, Eritrea, and Somalia, and by immigrant communities in the Americas and Australia...
word for "Jupiter". The name was chosen as a tribute to Galileo Galilei
Galileo Galilei
Galileo Galilei , was an Italian physicist, mathematician, astronomer, and philosopher who played a major role in the Scientific Revolution. His achievements include improvements to the telescope and consequent astronomical observations and support for Copernicanism...
, who discovered the first four natural satellite
Natural satellite
A natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called its primary. The two terms are used synonymously for non-artificial satellites of planets, of dwarf planets, and of minor planets....
s of Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
, and later discovered that they could be used as a universal clock
Clock
A clock is an instrument used to indicate, keep, and co-ordinate time. The word clock is derived ultimately from the Celtic words clagan and clocca meaning "bell". A silent instrument missing such a mechanism has traditionally been known as a timepiece...
to obtain the longitude
Longitude
Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....
of a point on the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
's surface.
The GIOVE satellites are exploited by the GIOVE Mission
GIOVE Mission
The GIOVE Mission segment, or GIOVE-M, is the name of a project dedicated to the exploitation and experimentation of the GIOVE satellites. The GIOVE Mission is intended to ensure risk mitigation of the In Orbit Validation phase of the Galileo positioning system.-GIOVE Mission history:The GIOVE...
(GIOVE-M
GIOVE Mission
The GIOVE Mission segment, or GIOVE-M, is the name of a project dedicated to the exploitation and experimentation of the GIOVE satellites. The GIOVE Mission is intended to ensure risk mitigation of the In Orbit Validation phase of the Galileo positioning system.-GIOVE Mission history:The GIOVE...
) segment in the frame of the risk mitigation for the In Orbit Validation (IOV) of the Galileo positioning system
Galileo positioning system
Galileo is a global navigation satellite system currently being built by the European Union and European Space Agency . The €20 billion project is named after the famous Italian astronomer Galileo Galilei...
.
Purpose
These validation satellites were previously known as the Galileo System Testbed (GSTB) version 2 (GSTB-V2). In 2004 the Galileo System Test Bed Version 1 (GSTB-V1) project validated the on-ground algorithms for Orbit Determination and Time Synchronization (OD&TS). This project, led by ESA and European Satellite Navigation IndustriesEuropean Satellite Navigation Industries
European Satellite Navigation Industries, formerly called Galileo Industries until legal action prompted a name change, was a joint venture of the companies Alcatel Alenia Space and Thales , Finmeccanica , EADS Astrium and Galileo Sistemas y Servicios .The company was the primary construction...
, has provided industry with fundamental knowledge to develop the mission segment of the Galileo positioning system.
GIOVE satellites are transmitting multifrequency ranging signals equivalent to the signals of future Galileo
Galileo positioning system
Galileo is a global navigation satellite system currently being built by the European Union and European Space Agency . The €20 billion project is named after the famous Italian astronomer Galileo Galilei...
: L1BC, L1A, E6BC, E6A, E5a, E5b. The main purpose of the GIOVE mission is to test and validate the reception and performance of novel code modulations designed for Galileo
Galileo positioning system
Galileo is a global navigation satellite system currently being built by the European Union and European Space Agency . The €20 billion project is named after the famous Italian astronomer Galileo Galilei...
including new signals based on the use of the BOC (Binary Offset Carrier) technique, in particular the high-performance E5AltBOC signal.
It should be stressed that the role of GIOVE is purely to test transmission and reception of the new signals: these satellites can not be used for navigation even for testing.
GIOVE-A
Previously known as GSTB-V2/A, this satellite was constructed by Surrey Satellite Technology LtdSurrey Satellite Technology Ltd
Surrey Satellite Technology Ltd, or SSTL, is a spin-off company of the University of Surrey, now fully owned by EADS Astrium, that builds and operates small satellites. Its satellites began as amateur radio satellites known by the UoSAT name or by an OSCAR designation...
(SSTL).
Its mission has the main goal of claiming the frequencies allocated to Galileo
Galileo positioning system
Galileo is a global navigation satellite system currently being built by the European Union and European Space Agency . The €20 billion project is named after the famous Italian astronomer Galileo Galilei...
by the ITU
International Telecommunication Union
The International Telecommunication Union is the specialized agency of the United Nations which is responsible for information and communication technologies...
. It has two independently-developed Galileo signal generation chains and also tests the design of two on-board rubidium
Rubidium
Rubidium is a chemical element with the symbol Rb and atomic number 37. Rubidium is a soft, silvery-white metallic element of the alkali metal group. Its atomic mass is 85.4678. Elemental rubidium is highly reactive, with properties similar to those of other elements in group 1, such as very rapid...
atomic clock
Atomic clock
An atomic clock is a clock that uses an electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element...
s and the orbital characteristics of the intermediate circular orbit for future satellites.
GIOVE-A is the first spacecraft whose design is based upon SSTL's new Geostationary Minisatellite Platform (GMP) satellite bus, intended for geostationary orbit
Geostationary orbit
A geostationary orbit is a geosynchronous orbit directly above the Earth's equator , with a period equal to the Earth's rotational period and an orbital eccentricity of approximately zero. An object in a geostationary orbit appears motionless, at a fixed position in the sky, to ground observers...
. GIOVE-A is also SSTL's first satellite outside low Earth orbit
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...
, operating in medium Earth orbit
Medium Earth Orbit
Medium Earth orbit , sometimes called intermediate circular orbit , is the region of space around the Earth above low Earth orbit and below geostationary orbit ....
), and is SSTL's first satellite to use deployable sun-tracking solar arrays. Previous SSTL satellites use body-mounted solar arrays, which generate less power per unit area as they do not face the sun directly.
Launched on 28 December 2005
It was launched at 05:19 UTC on December 28, 2005 on a Soyuz-FGSoyuz-FG
The Soyuz-FG launch vehicle is an improved version of the Soyuz-U, from the R-7 family of rockets, designed and constructed by TsSKB-Progress in Samara...
/Fregat
Fregat
Fregat is a type of rocket stage developed by NPO Lavochkin in the 1990s. Its main engine is a liquid propellant rocket that uses UDMH and N2O4 as propellants.- Specifications :...
from the Baikonur Cosmodrome
Baikonur Cosmodrome
The Baikonur Cosmodrome , also called Tyuratam, is the world's first and largest operational space launch facility. It is located in the desert steppe of Kazakhstan, about east of the Aral Sea, north of the Syr Darya river, near Tyuratam railway station, at 90 meters above sea level...
in Kazakhstan
Kazakhstan
Kazakhstan , officially the Republic of Kazakhstan, is a transcontinental country in Central Asia and Eastern Europe. Ranked as the ninth largest country in the world, it is also the world's largest landlocked country; its territory of is greater than Western Europe...
.
First Galileo transmissions
It began communicating as planned at 09:01 UTC while circling the Earth at a height of 23,222 km. The satellite successfully transmitted its first navigation signals at 17:25 GMT on 12 January 2006. These signals were received at Chilbolton ObservatoryChilbolton Observatory
The Chilbolton Observatory is a facility for atmospheric and radio research located on the edge of the village of Chilbolton near Stockbridge in Hampshire, England...
in Hampshire
Hampshire
Hampshire is a county on the southern coast of England in the United Kingdom. The county town of Hampshire is Winchester, a historic cathedral city that was once the capital of England. Hampshire is notable for housing the original birthplaces of the Royal Navy, British Army, and Royal Air Force...
, UK and the ESA Station at Redu
Libin
Libin is a Walloon municipality of Belgium located in the province of Luxembourg.On 1 January 2007 the municipality, which covers 139.72 km², had 4,655 inhabitants, giving a population density of 33.3 inhabitants per km²....
in Belgium
Belgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...
. Teams from SSTL and ESA have measured the signal generated by GIOVE-A to ensure it meets the frequency-filing allocation and reservation requirements for the International Telecommunication Union
International Telecommunication Union
The International Telecommunication Union is the specialized agency of the United Nations which is responsible for information and communication technologies...
(ITU), a process that was required to be complete by June 2006.
Technical details
The GIOVE-A signal in space is fully representative of the GalileoGalileo positioning system
Galileo is a global navigation satellite system currently being built by the European Union and European Space Agency . The €20 billion project is named after the famous Italian astronomer Galileo Galilei...
signal from the point of view of frequencies and modulations, chip rates, and data rates. However, GIOVE-A can only transmit at two frequency bands at a time (i.e., L1+E5 or L1+E6).
GIOVE-A codes are different from Galileo
Galileo positioning system
Galileo is a global navigation satellite system currently being built by the European Union and European Space Agency . The €20 billion project is named after the famous Italian astronomer Galileo Galilei...
codes. The GIOVE-A navigation message is not representative from the structure and contents viewpoint (demonstration only purpose). The generation of pseudorange
Pseudorange
The pseudorange is the pseudo distance between a satellite and a navigation satellite receiver —for instance Global Positioning System receivers....
measurements and detailed analysis of the tracking noise and multipath performance of GIOVE-A ranging signals have been performed with the use of the GETR (Galileo Experimental Test Receiver) designed by Septentrio
Septentrio
Septentrio is a designer and manufacturer of high-end multi-frequency GNSS receivers. Its main target is to provide GNSS receiver boards for further system integration by Original Equipment Manufacturers...
.
There has been some public controversy about the open source nature of some of the Pseudo-Random Noise (PRN) codes. In the early part of 2006, researchers at Cornell monitored the GIOVE-A signal and extracted the PRN codes. The methods used and the codes which were found were published in the June 2006 issue of GPS World. ESA has now made the codes public.
GIOVE-B
GIOVE-B (previously called GSTB-V2/B), has a similar mission, but has greatly improved signal generation hardware.It was originally built by satellite consortium European Satellite Navigation Industries
European Satellite Navigation Industries
European Satellite Navigation Industries, formerly called Galileo Industries until legal action prompted a name change, was a joint venture of the companies Alcatel Alenia Space and Thales , Finmeccanica , EADS Astrium and Galileo Sistemas y Servicios .The company was the primary construction...
, but following re-organization of the project in 2007, the satellite prime contractor responsibility was passed to Astrium.
GIOVE-B also has MEO environment characterization objectives, as well as signal-in-space and receiver experimentation objectives. GIOVE-B carries three atomic clock
Atomic clock
An atomic clock is a clock that uses an electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element...
s: two rubidium standard
Rubidium standard
A rubidium standard or rubidium atomic clock is a frequency standard in which a specified hyperfine transition of electrons in rubidium-87 atoms is used to control the output frequency...
s and the first space-qualified passive hydrogen maser
Hydrogen maser
A Hydrogen maser, also known as hydrogen frequency standard, is a specific type of maser that uses the intrinsic properties of the hydrogen atom to serve as a precision frequency reference....
.
Launched on 27 April 2008
The launch was delayed due to various technical problems, and took place on 27 April 2008 at 04:16 Baikonur time (22:16 UTC Saturday) aboard a Soyuz-FGSoyuz-FG
The Soyuz-FG launch vehicle is an improved version of the Soyuz-U, from the R-7 family of rockets, designed and constructed by TsSKB-Progress in Samara...
/Fregat
Fregat
Fregat is a type of rocket stage developed by NPO Lavochkin in the 1990s. Its main engine is a liquid propellant rocket that uses UDMH and N2O4 as propellants.- Specifications :...
rocket provided by Starsem
Starsem
Starsem is a European-Russian company that was created in 1996 to commercialise the Soyuz launcher. Starsem is headquartered in Évry, France and has the following shareholders:* Russian Federal Space Agency...
. The Fregat stage was ignited three times to place the satellite into orbit. Giove-B reached its projected orbit after 02:00 UTC and successfully deployed its solar panels.
First Galileo navigation transmissions
GIOVE-B started transmitting navigation signals on May 7, 2008. The reception of the signals by GETR receivers and other means has been confirmed at a few ESA facilities.Technical details
According to ESA, this is "a truly historic step for satellite navigation since GIOVE-B is now, for the first time, transmitting the GPS-Galileo common signal using a specific optimised waveform, MBOCMBOC
Multiplexed binary offset carrier modulation is a modulation proposed for Galileo and modernized GPS signals, which combines a sine binary offset carrier SinBOC signal with a SinBOC signal, either via weighted sum/difference or via time-multiplexing...
(multiplexed binary offset carrier), in accordance with the agreement drawn up in July 2007 by the EU and the US for their respective systems, Galileo and the future GPS III".
“Now with GIOVE-B broadcasting its highly accurate signal in space we have a true representation of what Galileo will offer to provide the most advanced satellite positioning services, while ensuring compatibility and interoperability with GPS”, said ESA Galileo Project Manager, Javier Benedicto.
After launch, early orbit operations and platform commissioning, GIOVE-B's navigation payload was switched on and signal transmission commenced on May 7 and the quality of these signals is now being checked. Several facilities are involved in this process, including the GIOVE-B Control Centre at Telespazio's facilities in Fucino, Italy, the Galileo Processing Centre at ESA's European Space Research and Technology Centre (ESTEC), in the Netherlands, the ESA ground station at Redu, Belgium, and the Rutherford Appleton Laboratory (RAL) Chilbolton Observatory in the United Kingdom.
Chilbolton's 25-metre antenna makes it possible to analyse the characteristics of GIOVE-B signals with great accuracy and verify that they conform to the Galileo system's design specification. Each time the satellite is visible from Redu and Chilbolton, the large antennas are activated and track the satellite. GIOVE-B is orbiting at an altitude of 23 173 kilometres, making a complete journey around the Earth in 14 hours and 3 minutes.
The quality of the signals transmitted by GIOVE-B will have an important influence on the accuracy of the positioning information that will be provided by the user receivers on the ground. Onboard, GIOVE-B carries a passive hydrogen maser atomic clock, which is expected to deliver unprecedented stability performance.
The signal quality can be affected by the environment of the satellite in its orbit and by the propagation path of the signals travelling from space to ground. Additionally, the satellite signals must not create interference with services operating in adjacent frequency bands, and this is also being checked.
Galileo teams within ESA and industry have the means to observe and record the spectrum of the signals transmitted by GIOVE-B in real time. Several measurements are performed relating to transmitted signal power, centre frequency and bandwidth, as well as the format of the navigation signals generated on board. This allows the analysis of the satellite transmissions in the three frequency bands reserved for it.
The GIOVE-B mission also represents an opportunity for validating in-orbit critical satellite technologies, characterising the Medium Earth Orbit (MEO) radiation environment, and to test a key element of the future Galileo system - the user receivers.
GIOVE-A2
With the delays of GIOVE-B, the European Space Agency again contracted with SSTLSurrey Satellite Technology Ltd
Surrey Satellite Technology Ltd, or SSTL, is a spin-off company of the University of Surrey, now fully owned by EADS Astrium, that builds and operates small satellites. Its satellites began as amateur radio satellites known by the UoSAT name or by an OSCAR designation...
for a second satellite, to ensure that the Galileo programme continues without any interruptions that could lead to loss of frequency allocations. Construction of GIOVE-A2 was terminated due to the successful launch and in-orbit operation of GIOVE-B.
External links
- ESA GIOVE-B launch pages
- GIOVE Mission Processing Centre website
- eoPortal description of GIOVE
- blog of GIOVE-A launch and press releases from Ballard Communications Management, used by SSTL.
- Technical papers on GIOVE-A and B missions