PARIS — Europe’s Giove-A navigation satellite, which was built on a shoestring budget almost as an afterthought but ended up saving precious broadcast frequency rights for the coming Galileo constellation, is being retired, the 19-nation European Space Agency (ESA) announced July 3.

Launched in December 2005 on what was supposed to be a 27-month mission, Giove-A took on crucial importance when the larger Giove-B, built by a different industrial consortium, fell behind schedule. It was Giove-A that preserved Europe’s priority rights to use radio spectrum needed for what is intended to be a 30-satellite Galileo constellation.

The medium Earth orbiting Giove-A was built by Surrey Satellite Technology Ltd. (SSTL) of Britain, a company that had launched a couple of dozen small spacecraft for governments including China, the United States, France and Chile but whose smaller-faster credo was viewed skeptically by ESA and Europe’s space industrial base. Giove-A was viewed by some at the time as an unnecessary expenditure.

SSTL built and delivered the satellite under a 30-month contract valued at 28 million euros, or about $36 million at current exchange rates. Because of concerns about whether Giove-B would make it into orbit in time, ESA signed a second contract with SSTL for a Giove-A2 satellite that was never completed.

Giove-B, built by a consortium led by Astrium Satellites and Thales Alenia Space that had promised to finish the job before SSTL, eventually was launched in April 2008. Giove-B, which contains a backup atomic clock and resembles more closely the satellites that will form the operational Galileo constellation, remains operational.

In its statement, ESA said Giove-A will be shut down in a retirement orbit about 100 kilometers higher in altitude than its operating orbit of 23,222 kilometers.

The first two Galileo validation satellites were launched in October 2011, with the final pair set for launch next October. These four spacecraft were built by the same Astrium-Thales Alenia Space team that built Giove-B.

But in a decision that may have been influenced by SSTL’s performance on the Giove-A program, ESA and the European Union have selected a team led by OHB AG of Germany, with SSTL providing the payload electronics, to build the first 22 operational Galileo satellites, to be launched starting in 2013.

Giove-B will be used in the coming months for calibration tests with the Galileo validation satellites before being sent into retirement in September. Giove-B’s graveyard orbit will be 300 kilometers above its operating orbit, ESA said.

Peter B. de Selding was the Paris bureau chief for SpaceNews.