; ), or Galileo In-Orbit Validation Element, is the name for two

satellite A satellite or an artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. They have a variety of uses, including communication relay, weather forecasting, navigation ( GPS), broadcasting, scient ...

s built for the

European Space Agency The European Space Agency (ESA) is a 23-member International organization, international organization devoted to space exploration. With its headquarters in Paris and a staff of around 2,547 people globally as of 2023, ESA was founded in 1975 ...

(ESA) to test technology in orbit for the

Galileo positioning system Galileo is a satellite navigation, global navigation satellite system (GNSS) created by the European Union through the European Space Agency (ESA) and operated by the European Union Agency for the Space Programme (EUSPA). It is headquartered ...

. The name was chosen as a tribute to

Galileo Galilei Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642), commonly referred to as Galileo Galilei ( , , ) or mononymously as Galileo, was an Italian astronomer, physicist and engineer, sometimes described as a poly ...

, who discovered the first four

natural satellite A natural satellite is, in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small Solar System body (or sometimes another natural satellite). Natural satellites are colloquially referred to as moons, a deriv ...

s of

Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...

, and later discovered that they could be used as a universal

clock A clock or chronometer is a device that measures and displays time. The clock is one of the oldest Invention, human inventions, meeting the need to measure intervals of time shorter than the natural units such as the day, the lunar month, a ...

to obtain the

longitude Longitude (, ) is a geographic coordinate that specifies the east- west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek lett ...

of a point on the

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

's surface. The GIOVE satellites are operated by the

GIOVE Mission ; ), or Galileo In-Orbit Validation Element, is the name for two satellites built for the European Space Agency (ESA) to test technology in orbit for the Galileo (satellite navigation), Galileo positioning system. The name was chosen as a tribut ...

GIOVE mission core infrastructure
ESA press release, 26 February 2007. ( GIOVE-M) segment in the frame of the risk mitigation for the In Orbit Validation (IOV) of the

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 Industries, has provided industry with fundamental knowledge to develop the mission segment of the

. GIOVE satellites transmitted multifrequency ranging signals equivalent to the signals of future

Galileo Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642), commonly referred to as Galileo Galilei ( , , ) or mononymously as Galileo, was an Italian astronomer, physicist and engineer, sometimes described as a poly ...

: L1BC, L1A, E6BC, E6A, E5a, E5b. The main purpose of the GIOVE mission was to test and validate the reception and performance of novel code modulations designed for

including new signals based on the use of the BOC (

Binary Offset Carrier Binary offset carrier modulation (BOC modulation) was developed by John Betz in order to allow interoperability of satellite navigation systems. It is currently used in the US GPS system, Indian IRNSS system and in Galileo and is a square sub-carr ...

) technique, in particular the high-performance E5AltBOC signal.

Satellites

GIOVE-A

Previously known as ''GSTB-V2/A'', this satellite was constructed by

Surrey Satellite Technology Ltd Surrey Satellite Technology Ltd, or SSTL, is a company involved in the manufacture and operation of small satellites. A spin-off company of the University of Surrey, it is presently wholly owned by Airbus Defence and Space. The company began o ...

(SSTL). Its mission has the main goal of claiming the frequencies allocated to

by the

ITU The International Telecommunication Union (ITU)In the other common languages of the ITU: * * is a specialized agency of the United Nations responsible for many matters related to information and communication technologies. It was established ...

. It has two independently developed Galileo signal generation chains and also tests the design of two on-board

rubidium Rubidium is a chemical element; it has Symbol (chemistry), symbol Rb and atomic number 37. It is a very soft, whitish-grey solid in the alkali metal group, similar to potassium and caesium. Rubidium is the first alkali metal in the group to have ...

atomic clock An atomic clock is a clock that measures time by monitoring the resonant frequency of atoms. It is based on atoms having different energy levels. Electron states in an atom are associated with different energy levels, and in transitions betwee ...

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 A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular orbit, circular geosynchronous or ...

. GIOVE-A is also SSTL's first satellite outside

low Earth orbit A low Earth orbit (LEO) is an geocentric orbit, orbit around Earth with a orbital period, period of 128 minutes or less (making at least 11.25 orbits per day) and an orbital eccentricity, eccentricity less than 0.25. Most of the artificial object ...

, operating in

medium Earth orbit A medium Earth orbit (MEO) is an geocentric orbit, Earth-centered orbit with an altitude above a low Earth orbit (LEO) and below a high Earth orbit (HEO) – between above sea level.

), 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-FG The Soyuz-FG was an improved variant of the Soyuz-U launch vehicle from the R-7 (rocket family), R-7 rocket family, developed by the Progress Rocket Space Centre in Samara, Russia. It featured upgraded first and second stage engines, RD-107A and ...

Fregat Fregat () is an upper stage developed by NPO Lavochkin for universal compatibility with a wide range of medium- and heavy-lift launch vehicles. Fregat has been used primarily with Soyuz and Zenit rockets, and entered operational service in ...

from the

Baikonur Cosmodrome The Baikonur Cosmodrome is a spaceport operated by Russia within Kazakhstan. Located in the Kazakh city of Baikonur, it is the largest operational space launch facility in terms of area. All Russian Human spaceflight, crewed spaceflights are l ...

Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to th ...

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 Observatory in

Hampshire Hampshire (, ; abbreviated to Hants.) is a Ceremonial counties of England, ceremonial county in South East England. It is bordered by Berkshire to the north, Surrey and West Sussex to the east, the Isle of Wight across the Solent to the south, ...

, UK and the ESA Station at

Redu Redu () is a village of Wallonia and district of the municipality of Libin, located in the province of Luxembourg, Belgium. The village is twinned with Hay-on-Wye in the United Kingdom and was one of the first book towns. The village was giv ...

Belgium Belgium, officially the Kingdom of Belgium, is a country in Northwestern Europe. Situated in a coastal lowland region known as the Low Countries, it is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeas ...

. 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 The International Telecommunication Union (ITU)In the other common languages of the ITU: * * is a list of specialized agencies of the United Nations, specialized agency of the United Nations responsible for many matters related to information ...

(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

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

codes. The GIOVE-A navigation message is not representative from the structure and contents viewpoint (demonstration only purpose). The generation of

pseudorange The pseudorange (from pseudo- and range) is the ''pseudo'' distance between a satellite and a navigation satellite receiver (see GNSS positioning calculation), for instance Global Positioning System (GPS) receivers. To determine its position, ...

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.

Retirement

GIOVE-A was retired (but not decommissioned) on 30 June 2012, after being raised in altitude to make way for an operational satellite. It remained under command by SSTL until 24 November 2021, when it was officially decommissioned.

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, but following re-organization of the project in 2007, the satellite prime contractor responsibility was passed to

Astrium Astrium was a European aerospace company and subsidiary of the European Aeronautic Defence and Space Company (EADS), headquartered in Paris. It designed, developed and manufactured civil and military space systems and provided related services ...

. GIOVE-B also has MEO environment characterization objectives, as well as signal-in-space and receiver experimentation objectives. GIOVE-B carries three

s: two

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. Synopsis The Rb standard is the most inexpensive, compact ...

s and the first space-qualified passive

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. Overview Both the proton and electron of a hydrogen ato ...

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

rocket provided by

Starsem Starsem is a French-Russian company that was created in 1996 to commercialise the Soyuz launcher internationally. Starsem is headquartered in Évry, France (near Paris) and has the following shareholders: * ArianeGroup (35%) * Arianespace (15% ...

. 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, MBOC (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. On board, 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.

Retirement

GIOVE B was retired (but not decommissioned) on 23 July 2012.

GIOVE-A2

With the delays of GIOVE-B, the European Space Agency again contracted with SSTL 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.

Mission segment

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 was intended to ensure risk mitigation of the In Orbit Validation (IOV) phase of the

GIOVE Mission history

The GIOVE Mission Segment began in October 2005 with the purpose of providing experimental results based on real data to be used for risk mitigation throughout the overall Galileo In Orbit Validation (IOV) phase of the

. The GIOVE Mission segment infrastructure was based on evolution of the Galileo System Test Bed Version 1 (GSTB-V1) infrastructure conceived to process data from the GIOVE-A and GIOVE-B satellites.GIOVE System Architecture
, GIOVE website. The GIOVE Mission segment was composed of a central processing facility called the Giove Processing Center (GPC) and a network of thirteen experimental Giove Sensor Stations (GESS). The main objectives of the GIOVE Mission Segment experimentation were in the areas of: * On-board clock characterisation * Navigation message generation * Orbit modelling

References

External links

GIOVE Mission Processing Centre websiteblog of GIOVE-A launch
an
press releases
from Ballard Communications Management, used by SSTL.
Technical papers on GIOVE-A and B missionsGIOVE Mission Processing Centre - Website
{{DEFAULTSORT:Giove European Space Agency satellites Galileo satellites Satellites orbiting Earth Aerospace engineering Twin satellites