Slung Low, Sweet Satellites: Galileo Anomaly Update

August 28, 2014  - By and 0 Comments
Galileo mission logos have been applied to the payload fairing, which encapsulates the two-satellite payload and their dispenser system.

The satellite payload fairing pre-launch.

The wording is terse, the intent clear.

“Following the failure on Friday August 22nd to inject Galileo satellites 5 and 6 into the correct orbit, the European Commission has requested Arianespace and the European Space Agency (ESA) to provide full details of the incident, together with a schedule and an action plan to rectify the problem.”

This is the only official face showing, but extremely high levels of activity take place behind the curtain, studying what might have caused several million Euros of hardware to end up much lower above the Earth than desired. Meanwhile, active speculation in the satnav blogosphere provides glimpses of possible outcomes from the latest satellite disaster — not exclusive to Galileo, by any means — created in all likelihood by a malfunction aboard its Soyuz launcher and/or the Fregat upper stage thereof.

The full official EC announcement is available here.

The satellites are under the control of the European Space Operations Centre (ESOC), ESA’s main mission control center in Darmstadt, Germany. But they are far out off position — more than 3,500 kilometers of space away, so far as to make their eventual use as part of the Galileo constellation very unlikely. Discussions continue with ESA and Arianespace regarding whether or not the satellites are likely to be of use, but odds are against it.

Their onboard fuel is not enough to compensate for the launch shortfall to reach higher orbits under their own power. ESA scientists are studying how they might still possibly  be used, far from their optimum position,s within the Galileo constellation.

According to an Arianespace press release on August 23, the target orbit was circular, inclined at 55 degrees with a semi-major axis of 29,900 kilometers, but what they got was an elliptical orbit, eccentricity of 0.23, semi-major axis of 26,200 kilometers and inclined at 49.8 degrees.

On August 28, the Russian newspaper Izvestia reported that “The failure of the European Union’s Galileo satellites to reach their intended orbital position was likely caused by software errors in the Fregat-MT rocket’s upper-stage.”

“The nonstandard operation of the integrated management system was likely caused by an error in the embedded software. As a result, the upper stage received an incorrect flight assignment, and, operating in full accordance with the embedded software, it has delivered the units to the wrong destination,” an unnamed source from Russian space Agency Roscosmos was quoted as saying by the newspaper.

An independent inquiry panel has been set up by Ariane. It is headed by former ESA Inspector General Peter Dubock. It starts work on August 28. The panel includes a couple of academics and a majority of ESA and EC figures.

Ferdinando Nelli Feroci, the new EC Commissioner for Industry and Entrepreneurship.

Ferdinando Nelli Feroci,
the new EC Commissioner for Industry and Entrepreneurship.

The new EC commissioner in this area, Ferdinando Nelli Feroci has invited ESA and Arianespace to his study during the first week of September to present the initial results of the inquiry.

The commissioner commented, “The problem with the launch of the two Galileo satellites is very unfortunate. The European Commission will participate in an inquiry with ESA to understand the causes of the incident and to verify the extent to which the two satellites could be used for the Galileo programme. I remain convinced of the strategic importance of Galileo and I am confident that the deployment of the constellation of satellites will continue as planned.”

The commissioner expects that the Galileo constellation will be fully deployed by the end of this decade. This may qualify as optimism because system planners had envisioned for six spares – and three are already blown.

Ariane and ESA did not insure the satellites.

According to back-of-the-envelope calculations, system operators are now one short of the minimum 24 needed for full 24/7 global coverage, as they have 4 IOVs up (1 broken) and 22 FOCs on order (2 launched and now in what could be called a junk orbit) which makes a potential maximum 23 sats that have actually been ordered – one short of the target.

The Satellites Are Alright

Satellite manufacturer OHB Systems of Bremen, Germany, issued a release stating that “Controllers at ESA’s ESOC control centre in Darmstadt, Germany, confirm the good health and the nominal behaviour of both satellites. They are in a safe configuration, are thermally stable, have stable pointing to the sun and sufficient power production. All platform subsystems have been checked and they work properly. Also the procedures to deploy the solar arrays are successfully performed and all solar arrays are properly unfolded.”

Further, “The orbit anomaly has no impact on the production and delivery of the in total further 20 satellites. Two FOC*-satellites are currently at ESTEC test facilities in Noordwijk, the remaining are in various status of integration. ”

Blogging the Boondoggle

The chairman of the Executive Board of the German Aerospace Center, Johann-Dietrich ‘Jan’ Wörner, writes an interesting blog. The current installment opens with a quote from Elon Musk: “Rockets are tricky.”

Wörner goes on to say, “The Soyuz launcher lifted off from the European Spaceport in French Guiana. Initially, all of the measurements suggested a perfect mission; the launcher took off at the scheduled time, followed the prescribed trajectory, and the stage separation was carried out correctly. However, the first problem became apparent when the two satellites proved unable to deploy their solar arrays as intended. A more detailed analysis then revealed that the eccentricity, the altitude and the inclination of the satellites’ orbits with respect to Earth’s equator did not meet the specifications. The upper stage had also evidently failed to induce the planned rotation around the longitudinal axis of the spacecraft (known as ‘barbeque’ mode, designed to maintain favourable thermal conditions during exposure to the Sun).”

Further discussion of the possible causes of the anomaly can be found on a Russian site, which focuses on the Fregat stage thrusters and indicates that the Russians think the barbeque maneuver was completed, and thus not the problem.

The other big issue is how the telemetry didn’t pick up the issue straight away.

There is avid speculation and a number of interesting theories being aired on the Canadian Space Geodesy Forum. For subscriptions to this vital listserv, visit here.

Alan Cameron

About the Author:

Alan Cameron is editor-in-chief and publisher of GPS World magazine, where he has worked since 2000. He also writes the monthly GNSS System Design e-mail newsletter and the Wide Awake blog.

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