Space | 25. August 2014 | posted by Jan Wörner

'Rockets are tricky'

Die 30 Galileo%2dSatelliten
Credit: ESA-P. Carril
Artist's impression of the 30 Galileo satellites.

This is a quote from Elon Musk, a pioneer in the field of commercial space travel and founder of SpaceX. It expresses his feelings when, on 23 August 2014, SpaceX experienced an unsuccessful test launch. Equipment used for spaceflight is always very sophisticated technically, due to the complexity of the systems involved, the fact that they have to be deployed without much of a safety margin and the relative scarcity of options for real-time adjustments. Although rocket technology has been continuously and very successfully developed over the years, the aforementioned aspects imply that 'absolute certainty' is a pipe dream. This fact reared its head once again during the launch of two Galileo satellites on 22 August 2014.##markend##

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). It is still too early to make any conclusive statements about the causes and consequences. However, going back to the quote from Elon Musk, I am concerned that we should fall into the trap of mutual recriminations. Instead, we need to focus on identifying the causes and on taking the necessary steps to ensure the success of future launches.

Galileo is one of the flagships of Europe's space activities, created through cooperation between the European Commission, the European Space Agency (ESA), national space agencies and the aerospace industry. Our need for this system is not a result of European vanity; instead, the need stems from the urgent requirement to acquire the necessary redundancy to guarantee the safety level that independence provides in a series of applications of crucial importance to security – for instance, using satellite navigation to guide the final approach that aircraft make before landing.

It goes without saying that the events of 22 August are a setback for the Galileo programme. From its inception many years ago, the programme has suffered these repeatedly – although, to date, the issues have been mainly administrative rather than technical. Nevertheless, the need for it is undisputed among experts, and this must be the foundation for all future decisions and actions. Precise orbit insertion places extremely high demands on the systems involved, and hence it represents a particular challenge. Here, the technical side may have to accept certain consequences, for instance, in the selection of future European launch vehicles – to maximise the options for real-time corrections within the narrow scope defined by the laws of physics.


About the author

The ‘Jan Wörner’ blog was written by Johann-Dietrich ‘Jan’ Wörner during his time as the Chairman of the Executive Board of the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR). Jan Wörner wrote all the posts himself and then sent them to DLR Corporate Communications for editing, picture research and online publication. to authorpage