We Can Rebuild It. We Can Make It Better...

Building a satellite in just three years is without doubt an ambitious undertaking. Nevertheless, the decision to rebuild CryoSat -- which, as ANN reported, was lost in a launch failure in October 2005 -- and recover the mission includes just that goal for the European Space Agency.

ESA representatives tell ANN the mission is now well on the way to recovery, with a design that incorporates no less than 85 separate improvements over the original. Scheduled for launch in 2009, CryoSat-2 will measure fluctuations in the thickness of ice on both land and sea to provide conclusive evidence as to whether there is indeed a trend towards diminishing ice cover.

Moreover, since ice plays such an important role in the Earth system, predicting future climate and sea level depends on the data that CryoSat-2 will realize.

In the year since the go-ahead to build CryoSat-2, much has been achieved and the project has just passed an important milestone, that being the Critical Design Review during which all the changes to the design were scrutinized. Notable among the changes, is the decision to have the satellite carry a back-up for the main payload, the SAR/Interferometric Radar Altimeter (SIRAL). This means fitting in a complete second set of electronics.

Radar altimeters have been flown in space before, but the SIRAL is a radar with a difference. Its sophisticated design encompasses enhanced resolution and observing capabilities to meet the challenges of acquiring accurate measurements of the thickness of floating sea ice, whilst also being able to survey the surface of vast ice sheets accurately enough to detect small changes.

As a result of the dual SIRAL payload and associated interfaces, and other improvements to reliability, there has been a knock-on effect to the design of the satellite. For example, the back-up SIRAL has to be kept warm while it is switched off -- the additional heater power is provided by increasing the size of the satellite's battery. Some minor shortcomings found in the original design have been fixed and other changes were needed to replace obsolete equipment and parts. Overall 85 separate improvements were specified of which 30-40% have been small software changes that make the satellite much easier to operate.

"We hit the ground running with CryoSat-2," said Richard Francis, ESA CryoSat-2 Project Manager. "After the launch failure we managed to get ourselves organized pretty quickly so that when we got the go-ahead for CryoSat-2 we knew exactly what to do. Our industrial team has made astonishing progress in the last year with some flight hardware already delivered. So far everything's on track and we expect that to continue, so that by the end of 2007 our beloved CryoSat will be almost completely reassembled."

FMI: www.esa.int, www.arcticarc.org