Tag Archives: Galileo GPS

Failed GPS satellites to test Einstein’s theory

Making lemonade from lemons: Scientists are going to repurpose two GPS satellites — launched into wrong orbits and thus useless for GPS — to conduct a test of Einstein’s theory of general relativity.

The satellites, operated by the European Space Agency (ESA), were mislaunched last year by a Russian Soyuz rocket that put them into elliptical, rather than circular, orbits. This left them unfit for their intended use as part of a European global-navigation system called Galileo.

But the two crafts still have atomic clocks on board. According to general relativity, the clocks’ ‘ticking’ should slow down as the satellites move closer to Earth in their wonky orbits, because the heavy planet’s gravity bends the fabric of space-time. The clocks should then speed up as the crafts recede.

On 9 November, ESA announced that teams at Germany’s Center of Applied Space Technology and Microgravity (ZARM) in Bremen and the department of Time–Space Reference Systems at the Paris Observatory will now track this rise and fall. By comparing the speed of the clocks’ ticking with the crafts’ known altitudes — pinpointed within a few centimetres by monitoring stations on the ground, which bounce lasers off the satellites — the teams can test the accuracy of Einstein’s theory.

There actually is little uncertainty here. No one expects this experiment to disprove Einstein’s theory, but the failed spacecraft provide a great opportunity to measure things at an accuracy never previously attempted, which in turn will help improve future GPS design.

Europe’s Galileo GPS constellation reaches 10 satellites

The competition heats up: A Soyus rocket today launched from French Guiana the 9th and 10th satellites in Europe’s competing GPS system.

This launch enhances competition in two ways. First it is a success of the Russian Soyuz rocket, launched from the European spaceport in South America, Second, it establishes a competing GPS system to the American system, which is great for everyone. Expect future GPS units to provide the capability to use both the systems, as well as the Russian Glonass system.

Europe’s continuing problems with Galileo GPS

A look at this week’s failed Soyuz launch and the continuing problems Europe has had building its Galileo GPS satellite constellation.

The program has had a series of problems and failures, which this most recent launch only helps highlight.

Soyuz puts two satellites in wrong orbit

A Russian-made Soyuz rocket launched from French Guiana for Arianespace has placed two European Galileo GPS satellites into the wrong orbit.

Russianspaceweb suggests that the problem was caused by the rocket’s Russian Fregat upper stage. (Scroll down about halfway to read their report on this launch.)

Multiple independent sources analyzing the situation suggested that the Fregat upper stage had fired its engine for the right duration, however the stage’s orientation in space during the second or both maneuvers had probably been wrong. According to Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics and a veteran space historian, the Fregat’s angular orientation error during engine firing could reach as much as 145 degrees.

This failure is a triple whammy. It hits both Arianespace and Russia since the Soyuz was part of a partnership between the two. It also hits Europe’s Galileo GPS satellite, which after many years of development was beginning to move towards full operation.

A successful first launch of a Russian rocket outside of the old Soviet Union

For the first time, the Russians today successfully launched a Russian rocket from a spaceport outside of the old Soviet Union.

The Soyuz also put into orbit the first two satellites of the European Galileo GPS constellation.