Two more satellites join Galileo working constellation

June 8, 2017
Galileo satellites are placed in medium orbits, at 23 222 km altitude along three orbital planes so that a minimum of four satellites will be visible to user receivers at any point on Earth once the constellation is complete. The fifth and sixth Galileo satellites, launched together on 22 August 2014, ended up in an elongated orbit travelling out to 25 900 km above Earth and back down to 13 713 km. In addition, the orbits are angled relative to the equator less than originally planned. Credit: ESA-P. Carril

Two further satellites have formally become part of Europe's Galileo satnav system, broadcasting timing and navigation signals worldwide while also picking up distress calls across the planet.

These are the 15th and 16th satellites to join the network, two of the four Galileos that were launched together by Ariane 5 on 17 November, and the first additions to the working constellation since the start of Galileo Initial Services on 15 December.

The growing number of Galileo users around the world will draw immediate benefit from the enhanced service availability and accuracy brought by these extra satellites.

The launch into space and the manoeuvres to reach their final orbits still left a lot of rigorous testing before the satellites could join the operational constellation.

Their and search and rescue payloads had to be switched on, checked and the performance of the different Galileo signals assessed methodically in relation to the rest of the worldwide system.

This lengthy testing saw the satellites being run from the second Galileo Control Centre in Oberpfaffenhofen, Germany, while their signals were assessed from ESA's Redu centre in Belgium, with its specialised antennas.

The tests measured the accuracy and stability of the satellites' atomic clocks – essential for the timing precision to within a billionth of a second as the basis of navigation – as well as assessing the quality of the navigation signals.

Liftoff of Ariane flight VA233, carrying four Galileo satellites, from Europe's Spaceport in Kourou, French Guiana, on 17 November 2016. Credit: ESA–Stephane Corvaja, 2016

Oberpfaffenhofen and Redu were linked for the entire campaign, allowing the team to compare Galileo signals with satellite telemetry in near-real time.

Making the tests even more complicated, the satellites were visible for only three to nine hours a day from each site.

The satellites are now broadcasting working navigation signals and are ready to relay any Cospas–Sarsat distress calls to regional emergency services.

Now that these two satellites are part of the constellation, the remaining pair from the Ariane 5 launch is similarly being checked to prepare them for service.

Explore further: Satellites 11 and 12 join working Galileo fleet

Related Stories

Satellites 11 and 12 join working Galileo fleet

April 29, 2016

Europe's latest navigation satellites, launched last December, have been officially commissioned into the Galileo constellation, and are now broadcasting working navigation signals.

Galileo's search and rescue service in the spotlight

April 7, 2017

Europe's Galileo satnav network does more than let us find our way – it is also helping to save lives. Today sees a spotlight cast on Galileo's Search and Rescue service, which pinpoints people in distress on land or sea.

Recommended for you

A new virtual approach to science in space

June 21, 2017

When Apollo astronauts on the Moon spoke with Mission Control on Earth, there was a noticeable time gap between a statement from Tranquility Base and its immediate acknowledgment from Houston. The gap lasted almost three ...

NASA completes study of future 'ice giant' mission concepts

June 21, 2017

A NASA-led and NASA-sponsored study of potential future missions to the mysterious "ice giant" planets Uranus and Neptune has been released—the first in a series of mission studies NASA will conduct in support of the next ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.