GIOVE

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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.^[1]

Giove is the Italian word for "Jupiter". The name was chosen as a tribute to Galileo Galilei, who discovered the first four natural satellites 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^[2] ^[3] (GIOVE-M) segment in the frame of the risk mitigation for the In Orbit Validation (IOV) of the Galileo positioning system.

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 Galileo positioning system.^[4]

GIOVE-A launch

1 GIOVE-A
2 GIOVE-B
3 GIOVE-A2
4 References
5 External links

[edit] GIOVE-A

Previously known as GSTB-V2/A, this satellite was constructed by Surrey Satellite Technology Ltd (SSTL), and was launched at 05:19 UTC on December 28, 2005 on a Soyuz rocket from Baikonur Cosmodrome in Kazakhstan. 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 clocks and the orbital characteristics of the intermediate circular orbit for future satellites. 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, 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.

There has been some public controversy about the open source nature of some of the Pseudo-Random Noise (PRN) codes.^[5] 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.^[6]

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, in medium Earth orbit.

[edit] GIOVE-B

This satellite (previously called GSTB-V2/B), built by European Satellite Navigation Industries, has a similar mission, but has improved signal transmission hardware. GIOVE-B also has MEO environment characterization objectives, as well as Signal-In-Space and receiver experiments. GIOVE-B will also carry two atomic clocks: a rubidium atomic clock and the first space-qualified passive hydrogen maser atomic clock. Launch has been delayed due to technical problems,^[7] and is now scheduled for late 2007.

[edit] GIOVE-A2

With the delays of GIOVE-B, the European Space Agency has 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.^[8]