Opening the CryoSat Workshop Appreciating the CryoSat challenge – Guy Ratier, Project Manager

6 September 2005 Guy Ratier has overall responsibility for ESA’s first Earth Explorer mission. With a background in optical engineering he has a long record of providing observing tools to astronomers – experience he has now turned to delivering the ice science community the most detailed picture ever of how Earth’s Polar Regions are changing.

How did you begin working for ESA?

I joined the Agency in 1982, when I was the optical engineer on Hipparcos, a science satellite to measure the position of stars. After this I joined the then-new division of the Earth Observation Preparatory Programme, preparing for ESA’s new missions, in particular the well-known Envisat satellite.

I left four years later to return to stars, back to the Centre National de la Recherche Scientifique (CNRS) astronomy site in Toulouse, then the European Southern Observatory (ESO) headquarters in Garching, Germany, where I was responsible for the optics of the four Very Large Telescopes (VLT), with 8.2-metre diameter mirrors.

From there I was asked back to ESA to oversee the optical payload on Envisat, namely, the MERIS, GOMOS and MIPAS instruments. Now after Envisat comes the Earth Explorer missions – CryoSat being the first of many.  

Hipparcos Is it a big change to work on a non-optical mission like CryoSat?

We are working here with microwaves instead of visible light – it’s only a change of wavelength really! The CryoSat sensor is not so different in approach from a lidar, such as ESA is developing for the forthcoming Earth Explorer mission ADM-Aeolus, which works at optical wavelengths. In fact the American counterpart of CryoSat is a satellite named ICESat which is based on lasers!

Technically the technology is different but the operating philosophy is the same, and in terms of project management, it is not so different.

CryoSat What does being CryoSat Project Manager for ESA involve?

As Project Manager I am nominally in charge right the way through up to the commissioning phase, which is scheduled for six months after launch, when I hand over to the Mission Manager Pascal Gilles at ESRIN.

CryoSat, as a project, is a much smaller scale than Envisat – which is obviously a big success; but with ten instruments on board it needed a complex interface and took 14 years to be developed. So it became clear in the late 1990s that there would be an interest in a faster approach to give answers to specific scientific issues, which resulted in the Earth Explorer missions.

CryoSat has been selected to measure trends in the evolution of ice thickness, an interesting subject – one that we can’t afford to wait 14 years to get the results! So it is a good example of this new line.

CryoSat in the acoustic chamber How many people are working on the project?

The CryoSat core team in ESTEC is no more than about eight people, plus there are operations people in ESOC and a small team in ESRIN. We are also getting complementary support from the Technical Directorate engineers at ESTEC. Working in a small team is very pleasant and motivating for all staff members, the only drawback being the high load of work, especially as we approach launch.

The ‘faster, better, cheaper’ approach has not always been successful in the past, so even though we have similar constraint of a small team and a limited budget, we have put a lot of effort into the testing. Additionally, to further reduce risks, components have recently been exchanged on the main spacecraft while it was still in Germany, and also the SIRAL instrument when in Toulouse. The penalty is that we are not as ‘fast’ as anticipated.

Unloading CryoSat in the Integration Facility hall in Plesetsk, Russia Our team also has synergy with other ESA projects, for example we share our onboard computer and ground segment approach with the follow-on Earth Explorer mission GOCE, and – being part of the family of Earth Explorers – we are the first new ESA satellite to be launched from Plesetsk in Russia by a Rockot launcher.

Our team has had reviews there on many occasions, and is quite confident the Russian Krunichev team will carry out a smooth launch campaign.

How did it feel to see the CryoSat spacecraft coming together?

The surprise has been it looks just like a normal satellite, with all the complexity of a normal satellite – such as attitude control system, antennas, various instruments and so on – despite its small budget. It weighs in at only 700 kilograms, but still, all the technology is here. It makes you appreciate what a challenge it has been.

From here, not only the engineers but also scientific people hope CryoSat will make its current launch date of early October 2005, because the scientists want to make cross measurements with Envisat and especially ICESat – CryoSat’s optical brother – which has a limited lifetime. So there is a lot of interest in launching the flight as soon as possible.

Where will you be for the launch?

In Plesetsk, close to the satellite – as close as possible! Then, I will come back as soon as possible to ESOC, to attend partially the launch and early operations phase (LEOP) as the satellite starts to work.