Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

CryoSat-2 on the road to recovery

12.03.2007
Building a satellite in just three years is without doubt an ambitious undertaking. Nevertheless, the decision to rebuild CryoSat and recover the mission includes just that goal. A year on and the mission is now well on the way to recovery, with a design that incorporates no less than 85 separate improvements.

The CryoSat-2 satellite replaces CryoSat, which was lost as a result of launch failure in October 2005. With the threat of receding ice cover in the polar regions, thought to be due to climate change, the need to understand the extent to which this may be happening is even more relevant today than it was when the first CryoSat was selected for development in 1999. The International Polar Year 2007-2008 (IPY) will focus resources on making measurements of our polar environments. The loss of the original CryoSat prevented it contributing to this effort but the exploitation of CryoSat-2 will benefit from the IPY.


CryoSat can distinguish between altimetry signals returned from sea ice and open water - the difference between the two is known as the 'freeboard', and can be used to derive ice thickness. Over topographic surfaces, the first radar echo comes from the nearest point to the satellite. CryoSat can measure the angle from which this echo originates, so that the source point can be located on the ground. This, in turn, allows the height of that point to be determined. Credits: ESA - AOES Medialab

Although the impact of climate change is expected to be amplified at the poles, it is extremely difficult to determine what effect this is having on the polar ice cover. Recent reports of receding sea ice in the Arctic and the break-up of the edges of the massive Antarctic ice sheet are much in the public eye. On the other hand, there have also been reports of the ice at the North Pole being thicker than usual.

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 realise.

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 scrutinised. 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.

Richard Francis, ESA CryoSat-2 Project Manager said, “We hit the ground running with CryoSat-2. After the launch failure we managed to get ourselves organised 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.”

In addition to building the new satellite, a number of field experiments to support the mission are getting underway in the Arctic. First is the Arctic Arc Expedition, part of the International Polar Year. The expedition’s two Belgian explorers, Alain Hubert and Dixie Dansercoer, have just left for a punishing 110-day trek across the Arctic. Each pulling a 130-kg sledge holding supplies and equipment, the two intrepid explorers will 'walk' from an island off the coast of Siberia to southern Greenland – a route never before considered. In support of the CryoSat-2 Project they will be taking valuable measurements of snow depth throughout their journey. Regular updates are posted on the expedition web-site http://www.arcticarc.org

These measurements are extremely useful for helping to validate the technique which will be used to convert CryoSat-2’s radar measurements into accurate ice thickness data. Since direct measurements of snow lying on Arctic sea ice are hard to come by, ESA is very pleased to benefit from this opportunity.

The weight of overlying snow forces sea ice to float lower in the water than it otherwise would. CryoSat-2’s determination of sea-ice thickness depends on measuring its freeboard, or how high above the sea-surface it floats. Everybody knows that 7/8 of an iceberg is under the surface so if knowing how much is above the surface it’s easy to calculate the rest. So overlying snow, which the radar waves go right through, reduces the measured freeboard and so the derived thickness measurement is compromised. The kind of data that Hubert and Dansercoer will gather during their trek will contribute to the validation of the schemes that will be used to estimate the amount of snow during CryoSat-2’s lifetime.

As part of the CryoSat-2 validation campaign, scientists will also be heading out to the ice on Svalbard in mid-April to carry out the 2007 component of the CryoSat-2 Validation Experiment (CryoVEx-2007). This campaign will use ASIRAS, an airborne version of the SIRAL instrument, to make measurements over teams of glaciologists who will be making comprehensive in-situ measurements of snow and ice properties. This campaign continues a series started for CryoSat and which will also be complemented by further experiments as the remaining complexities in the exploitation of CryoSat data are explored.

Mariangela D'Acunto | alfa
Further information:
http://www.esa.int/esaEO/SEMAD0Q11ZE_planet_0.html

More articles from Earth Sciences:

nachricht Early organic carbon got deep burial in mantle
25.04.2017 | Rice University

nachricht New atlas provides highest-resolution imagery of the Polar Regions seafloor
25.04.2017 | British Antarctic Survey

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

NASA's Fermi catches gamma-ray flashes from tropical storms

25.04.2017 | Physics and Astronomy

Researchers invent process to make sustainable rubber, plastics

25.04.2017 | Materials Sciences

Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017

25.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>