Engineering in Neuchâtel at the heart of the Rosetta space mission

Neuchâtel inside

As part of the Rosetta mission, on 12 November 2014, the European Space Agency (ESA) outdid its American counterpart NASA for the first time, by achieving the feat of landing on a comet.

Thanks to an unprecedented marketing campaign, the whole world held its breath and watched live as the Philae robot touched down. This visual feed came thanks in particular to miniature cameras… from Neuchâtel. Neuchâtel, alongside 25 Swiss companies and 14 European countries, contributed to this major project.

Europe takes the lead 

It all began in 1991, when the international scientific community suggested launching a mission dedicated to comets. Two years later, an ESA project commenced. Its aim was to travel into space and bring a comet sample back to Earth. Given the scale of the challenge, the space agency had to curtail its ambitions. It abandoned the idea of a partnership with NASA, decided to land on a comet rather than take a sample from it, and renounced its plan to bring two landers on the trip in order to focus on one single robot, known as Philae. 

After an initial failed rocket launch in 2002, the Rosetta mission was once again recalibrated. Departure was deferred until 2004 and the destination was changed. The target now became the 67P/Churyumov–Gerasimenko, comet, aka “Chury”. In the course of its voyage, which would last ten years, the Rosetta probe carrying the Philae robot would fly past the asteroids Steins in 2008 and Lutetia in 2010 (on its secondary mission). It would then enter hibernation for 31 months in order to conserve energy. 

The crucial final stage

Upon reawakening, the probe was just seven months’ flying time from the comet, or 9 million kilometres. The mission was monitored via images taken by cameras from Neuchâtel. On 25 August 2014, high-resolution images taken from a distance of around one hundred km from the comet made it possible to identify five potential landing sites for Philae, as the highlight of the mission. On 29 September, the chosen location was announced and the date set for 12 November.

On that day, the Philae lander was ejected from the Rosetta probe and descended for 7 hours and 2 minutes. It was an agonising wait for the 2000 people who had worked on this mission for 20 years. Despite a few nail-biting moments when the robot bounced several times due to low gravity, Philae ended its journey over a kilometre from the location originally targeted. From this new site, data was gathered for three days. The cameras captured a 360° panoramic view and showed a surface which appeared harder and rockier than expected.

Satisfied by these findings and with 80% of objectives met, the space agency brought an end to the mission on 30 September 2016, after the probe in turn had reached the surface of the comet. Rosetta and Philae, now inert, were set to accompany “Chury” until it disintegrated or collided with another celestial body, at some unknown date in the future.

 

 

 

Neuchâtel as a key player

This unprecedented project, which cost around 1.3 billion euros, comparable to the cost of three Airbus 380s, owes its success in part to Swiss know-how. Among the twenty or so Swiss companies involved, APCO Technologies in Aigle was responsible for the ROSINA spectrometer mechanism, the role of which was to analyse gas and dust emitted by the comet. This instrument was primarily designed by the Physics Institute at the University of Berne.

The company RUAG Space in Zürich developed, among other things, a “sleeping bag” used to protect the probe from cold and meteorite impacts during its flight. Electrical installations on the ground benefited from the expertise of Basel company Clemessy. And with regard to the landing craft, its two engines were provided by Obwalden firm Maxon Motor AG.

Yet one contribution to the project really stands out: that of the CSEM, the Space Exploration Institute (Space-X), led by Jean-Luc Josset. Based in Neuchâtel, the latter provided the “eyes” of the mission. Commissioned by the European Space Agency in the early 1990s, the CSEM developed the world’s smallest digital cameras. This was a real technological breakthrough at the time.

People thought such an invention was impossible, it was difficult to convince them, especially because they did not know us. But they were persuaded by Swiss quality and by our proposal.

recalls Dr Ivar Kjelberg, a member of the CSEM team

An engineering challenge for the CSEM

The team at the institute, composed of around ten specialists, worked from 1992 to 1997 to design seven entirely unique micro-cameras. These lenses were vital pieces in the puzzle, a key aspect of the project, and would represent a significant success for the CSEM. But it was a risky challenge, according to Dr Ivar Kjelberg.

All spaces voyages are dangerous, he stresses. The difference is that in Switzerland we’re more expensive than other countries, so we have to stand out by undertaking special high-risk projects.

Caméra miniature CSEM
Caméra miniature développée par le CSEM

Several prototypes emerged from these years of research. The first ones measured 35 mm high, 21 mm wide and 1 mm thick, not much larger than a postage stamp. Months of testing made it possible, in 1998, to propose a totally autonomous and energy-efficient camera. One shot now required just two watts, similar to the consumption of a torch. The end products were finally delivered in 2001, meeting all the demands of the mission’s specifications.

Based on Flextec technology, a titanium component and a bulk-machined internal spring, all parts of the camera came together perfectly and were prepared for all kinds of difficulties anticipated during their voyage. For the Philae landing robot, two cameras were designed to look in the same direction, providing stereo vision for greater depth. The five others were to be placed on all sides of the lander to obtain a 360° panoramic view.

The advantage of our cameras is that they are minuscule, with a high-quality lens (1 million pixels) and very light, which avoids overloading the robot,

states Dr Kjelberg. By way of comparison, the device weighs just 100 grams, about the same weight as an apple.

Problems surmounted

Developing a device of this kind for an unknown environment certainly poses real challenges.

We had to overcome numerous obstacles in designing our cameras. In particular, these included extreme temperature variations (-150°C to +150°C), vacuum conditions and cosmic radiation, requiring great precaution in terms of the choice of materials. We knew about the difficult flight conditions, but the rest of the mission was based on assumption, which complicated our analysis and testing,

the CSEM researcher recalls.

Fortunately, the Neuchâtel-based institute was able to find solutions. And two fundamental factors were to thank for this, according to Dr Ivar Kjelberg. Firstly, the diverse qualifications of the CSEM team offered a wide range of options. While they all had a background in systems engineering, each person provided their own area of experience and expertise.

Secondly, there was the aspect of long service with the organisation. Ivar Kjelberg, for example, has been bringing his know-how to the CSEM for over 30 years.

This is a real advantage in a mission,” he observes. “If one person works from the beginning to the end of a project, they know all its ins and outs, whereas changing an operator along the way can mean precious time being lost.

This is an advantage for the Neuchâtel institute, thanks to its relatively modest size.

Post-Rosetta in the canton

Three years after the end of the Rosetta mission, the CSEM is delighted with its participation.

This project did not make us millionaires. On the contrary, we lost money, but we gained expertise, boosted our international reputation, and found new sub-contractor partners.

smiles Dr Kjelberg

Indeed, local companies who contributed to production of the cameras, such as Fisba Optik AG in Saint-Gall, were able to benefit, through the CSEM, from good publicity abroad. More globally, Neuchâtel’s participation in this project highlighted the micromechanics sector as a further speciality of the canton in addition to watchmaking. 

This space experience demonstrated what Neuchâtel is capable of, showing that the institute’s engineers could easily collaborate with big companies and achieve real advances in micromechanics. This set the CSEM on the path towards major new projects in space engineering, such as the current European project, Remove Debris.


Key dates:

1993 : Rosetta project approved by the European Space Agency.

2001 : Delivery of seven miniature cameras developed in Neuchâtel.

2004 : Probe launched into space from Kourou in French Guiana.

2008 : Flight past Steins asteroid.

2010 : Flight past Lutetia asteroid.

2011 : Mise en sommeil de la sonde. Probe placed in hibernation mode.

2014 : Probe reactivated and put into orbit around the comet. Philae robot lands on “Chury”.

2016 : End of the Rosetta mission.

 

Main information:

Mission objective: The aim of the Rosetta mission was to study, using the 21 instruments onboard the lander and orbiter, the link between comets and interstellar matter. It also looked at the role played by comets in the formation of the solar system.

Profile of the comet: 67P/Churyumov-Gerasimenko was discovered in 1969 by two Soviet scientists after whom it was named. It has a diameter of approximately 4 kilometres and completes its orbit in six and a half years. Mainly composed of ice, its surface is grey and uneven.

Profile of Philae: This 1.3-metre robot weighs 100 kilos on Earth but just 1 gram on the comet. For the mission, it carried ten scientific instruments (including the Neuchâtel cameras).

Profile of Rosetta: Equipped with eleven instruments for its mission, the main role of this three-tonne probe was to transport the Philae robot which was to land on the comet.

 

Main findings :

  • The theory that water present on Earth was brought here by comets was not confirmed by the analyses.
  • However, the comet does possess elements which may have contributed to the formation of life on Earth.
  • The shape of the comet was ultimately unexpected.
  • This shape has an influence on the seasons, the movement of dust on the surface of the comet, as well as on the composition of its atmosphere.
  • The gasses emitted by the comet were unexpected.
  • Numerous organic elements were detected on it.
  • The surface turned out not to be soft but as hard as ice.

 

Videos and photos of the mission:

 

ESA     CSEM     DLR     CNES     Final images from ESA

Article written by Julie Müller

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