Galileo update

Galileo quartet successfully launched from Kourou

Four new Galileo satellites were successfully launched from the European spaceport in Kourou, French Guiana on July 25, bringing the constellation to a total of 26 satellites.

For the second time, the European GNSS Agency (GSA) is responsible for the Early Orbit Phase (EOP) of this mission, overseeing Spaceopal – a joint venture between Telespazio and DLR-GfR – in their role as Galileo Service Operator (GSOp) and EOP Mission Director, and CNES as EOP Operations Director. The EOP is one of the most important phases of a space mission during which the spacecraft is launched and put into the correct orbit and the first satellite elements are gradually switched on and tested.

“Today is an excellent opportunity to celebrate what Europe can achieve when resources, competences and commitments are brought together,” GSA Executive Director Carlo des Dorides said immediately after the launch. “Yet the success of Galileo is not measured by the number of satellites, but by the number of users, and here too we have achieved remarkable results. In the past 18 months, Galileo has moved from zero to 400 million users,” he said. www.gsa.europa.eu

Galileo satellites viewed in smartphone app

ESA ran an internal competition for its trainees to develop an app capable of making positioning fixes using only Galileo satellites.

“As part of our support for the competition, we developed our own app on a voluntary basis to serve as a benchmark,” explains Paolo Crosta of ESA’s Radio Navigation Systems and Technology section. “We included this augmented reality view, so users can ‘see’ the satellites their smartphone is using as they hold it up to the sky.”

The positioning calculations and assistance data functions for the app were developed by Paolo, with telecom engineer Tim Watterton contributing the main structure of the app, together with how it looks and its user interface.

Tim adds: “The satellites are overlaid in real time on the camera view in their predicted positions in the sky, based on ‘ephemeris’ information, assistance data that describes the current satellite orbits with high precision. “When a signal is being received, the satellite is shown in green, overlaying the predicted position. The satellite shown in red is one of the two placed in elongated orbits, but these satellites are expected to be used soon in the operational constellation. Satellites coloured orange are transmitting, but the signal is not detected, which may be due to obstruction by terrain or buildings.”

Panning the phone around to position the crosshair over a green coloured satellite adds additional information about it, such as its signal status, ‘pseudo-range’ (the uncorrected distance the signal has travelled to reach the receiver) plus the satellite’s manufacturer, launch date among other items. https://phys. org/news/2018-07-galileo-satellitesviewed- smartphone-app.html#jCp