The European Space Agency (ESA) has announced the successful launch of the 27th and 28th satellites in its Galileo satnav constellation on Sunday.
"With these satellites we are now increasing the robustness of the constellation so that a higher level of service guarantees can be provided," said ESA Director of Navigation Paul Verhoef.
The 715kg satellites were launched by Arianespace-operated Soyuz launcher VS-26 from Europe's Spaceport in French Guiana, as seen in this photo tweeted by the ESA:
Over the next few weeks their onboard thrusters will manoeuvre them into a 23,222km orbit while being monitored during the Launch and Early Operations Phase by prime contractor Spaceopal.
The monitoring will take place from Galileo's own control centre in Germany. Incidentally, this marks the first time ESA has had a contractor do such monitoring onsite. Usually an external mission control site is required.
Somewhat confusingly, the new satellites are the first of 12 Galileo first-generation satellites in the satnav system. Previous launches used a "Full Operational Capability" (FOC) design.
Second-gen satellites are already under development and scheduled for launch beginning in 2024. ESA has labelled those birds the "most advanced and powerful, and fully reconfigurable navigation satellites ever built".
The satellite constellation has provided satnav positioning to over 2.3 billion users since 2016, and ESA wants more signal-slingers for two main reasons. One, their kit and orbit are more suitable for coverage of northern Europe than their predecessors – US GPS and Russian Glonass satellites. Also prior to Galileo, European users were reliant on those predecessor constellations – a situation the EU recognized as problematic in the '90s on grounds that other nations' systems could be degraded or disabled at a moment's notice.
Galileo is interoperable with GPS and Glonass, and the use of basic (think lower-precision) services is free and open. ®