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Space

CryoSat - Set for launch

Amsterdam, 05 October 2005

Cryosat, the first satellite designed to measure polar sea ice, is ready for launch. Developed and built by EADS Astrium for the European Space Agency (ESA), the satellite is due to be launched on 8 October from the Plesetsk cosmodrome by a Eurockot Rockot launch vehicle. Eurockot is a subsidiary of EADS.

Cryosat is the latest European satellite designed to measure climate change and the environment. Operating from a polar orbit, Cryosat will measure the variations in the thickness of the polar ice caps and floating sea ice with unprecedented accuracy. The satellite will also provide climate change scientists with new data on previously inaccessible regions.

CryoSat will enable us to determine whether, and to what extent global warming is causing a reduction in polar ice. Of special interest are the floating ice masses which greatly affect the radiation balance of the Earth as well as the ridges of the great land ice masses on Greenland and Antarctica. If these ridges melt, the runoff can influence the great ocean currents with unforeseen consequences for the climate of the world.

Data on global warming is increasingly available. The Intergovernmental Panel on Climate Change (an international board of climate experts) reports that the average global surface temperature rose by 0.6 degrees in the 20th century. Data also indicates that the 20th century was the warmest in the last thousand years. Since 1950 the concentration in the atmosphere of the greenhouse gases carbon dioxide and methane, has grown by 30 and 150 percent respectively as a result of human activities.

Current climate models offer only limited information on how these developments affect the climate. The predictions vary between a rise in temperatures of 1.4 to 5.8 degrees Centigrade in the next hundred years. As a consequence, experts expect some polar ice and glaciers to melt leading to sea levels rising by up to one metre.
Polar ice as a climate factor

Polar ice plays a key role in regulating the global climate. Despite being thousands of kilometres away from the most inhabited areas, the ice has a profound effect on the climate in Europe, Asia and the Americas. Three aspects are most important:

* Snow and ice reflect sunlight extremely well
* Sea-ice cover insulates the water underneath
* Large amounts of melted ice-water affect the large-scale ocean currents.

Polar ice reflects a large proportion of the sunlight and the absorbed and reflected light balance each other out. As polar ice melts, less sunlight is reflected leading to the polar regions becoming warmer. Consequently, more ice melts and the reflective capabilities are further reduced. Some experts predict this could result in a self-accelerating cycle of global warming.

During the night, open water radiates a large quantity of heat, about 90 Watts per square metre. Snow covered sea-ice floating on the ocean surface has a negative effect on this. To a certain extent, it acts as a thermal blanket and therefore plays a significant part in regulating the heat balance of the Earth. This effect is reduced as soon as the ice thins or decreases in area.

Ocean currents have a special influence on the climate. They act as heat pumps, distributing the energy stored in the oceans around the globe. The best known is the Gulf Stream, which transports warm water from the tropics diagonally over the Atlantic to northern Europe, providing Britain with a mild climate and ensuring ice-free ports up to northern Scandinavia. If the ice sheets and large areas of sea-ice melt, the larger quantities of fresh water could disrupt or even change these ocean currents – with unforeseeable effects on the climate.

Much of the uncertainty in the climate models today is due to a lack of precise information about polar ice and its development. Experts estimate that the sea ice has receded by 10 to 15 percent since 1950. The thickness of the Arctic ice is reported to have reduced by 40 percent in the last few decades. These statements, however, are largely speculative due to the lack of accurate information on sea-ice thickness. CryoSat will provide this data and fill an important information gap.

Radar altimeter measures ice thickness

CryoSat will circle the Earth in a polar orbit at an altitude of 720 km. Its radar will measure the thickness and circumference of the polar ice sheets and sea-ice cover. Earlier radar satellites, such as the European ERS 1 and 2 or Envisat, are only equipped with a single antenna which enables them to gather information about uniform ice surfaces over a large area. CryoSat, on the other hand, has two antennas. Similar to the way in which humans, with two eyes, can see in 3-D, CryoSat's double radar Siral will be able to scan the surface very precisely. Experts call this radar interferometry and an average accuracy of one to three centimetres is possible. It will also collect data on inhomogeneous ice structures with very steep walls in the polar seas, glaciers or ice sheets.

To achieve this extraordinary precision, knowing the orbit altitude of the satellite is crucial. To achieve this to within a few centimetres, ground stations emit signals, which are received and processed by an on-board instrument called DORIS. The altitude information produced is then conveyed via the normal data stream to the ground station.

CryoSat's outer surface also incorporates a laser retro-reflector. Similar to cats' eyes on a road, it reflects a ray of light. A laser beam transmitted from a ground station and reflected by CryoSat will enable the height of the satellite to be determined from the transit time.

CryoSat's radar altimeter works day or night and can also penetrate clouds. Therefore, it is particularly suited to the research of the large polar ice sheets, which rise up to 4000 metres above sea level and which are often covered by clouds. The data from the CryoSat mission will provide information about the rate of change of these huge ice sheets.

EADS Astrium and CryoSat

EADS Astrium, as the prime contractor for CryoSat, is responsible for a consortium of 31 companies. EADS Astrium (Friedrichshafen) has built the satellite platform and integrated all instruments. EADS Astrium is responsible for the reliability of the entire satellite. The industrial contract is valued at approximately €70 million.

The 4.6m long, 2.34m wide CryoSat continues the present, dominant trend of smaller and more economical satellite missions with narrowly defined scientific goals. With the CryoSat mission EADS Astrium, strengthens its leading position in this market, which the company took over with the construction of the geo-scientific satellites Champ and Grace.

A particular challenge for EADS Astrium engineers was the apparently contradictory requirements of high reliability, quick turn-around and low cost. In order to meet these demands, EADS Astrium developed a compact satellite architecture which was as simple as possible. For example, folding mechanisms such as retractable antennas or sun sails have not been used – eliminating the need for expensive electronic controls. In building CryoSat, components were used which as much as possible had already been used in space.

The so-called Nadir-Plate forms the “backbone” of CryoSat. Almost all the most important sub-systems like temperature and energy control and storage, data management, communications electronics and instrument and sensor electronics are located on it. The “nose” of the satellite is modularly coupled. Here is the main instrument, Siral. The compact and streamlined design ensures that forces including friction from the residual atmosphere and the influence of the sun affect the satellite in orbit as little as possible.

Attitude control of the satellite is achieved using 3 magnetic coils and 16 cold gas thrusters. Solar cells located on the upper side of the satellite provide electricity. In addition the satellite’s battery supplies electricity during the shadow phase behind the Earth and when the solar generator is poorly illuminated. The lithiumion battery is assembled from commercially available battery cells. These batteries are similar to those which were used on board the Rosetta space probe built by EADS Astrium.

The satellite is the first Earth Explorer Mission of ESA's "Living Planet" programme initiated in 1998. The aim of this research programme is to find answers to urgent scientific questions. The "Living Planet" programme is pursuing two strategies: First, the so-called Core Explorer Missions which are relatively complex and cost-intensive Earth observation missions for scientific purposes and second, the Opportunity Missions using established technology enabling fast and low-cost project implementation.

EADS SPACE and the Earth Explorer

EADS SPACE is also involved in other satellites of the Earth Explorer Missions currently under construction. EADS Astrium in the UK is the prime contractor for the ADM-Aeolus wind mission, with the Aladin instrument being developed by EADS Astrium in France. In addition to the lead on the CryoSat ice satellite, EADS Astrium, Friedrichshafen, is also responsible for the platform and the satellite integration of GOCE, the surfer of the gravitational field. EADS Astrium in Spain is developing and building the Miras payload of the SMOS mission for the acquisition of data on soil moisture and ocean salinity.

The launch provider Eurockot (Bremen), a unit of EADS SPACE, will carry out the launches of the satellites CryoSat, GOCE and SMOS on board its Rockot launchers from Plesetsk.

EADS Astrium is Europe's leading satellite specialist. Its activities cover complete civil and military telecommunications and Earth observation systems, science and navigation programmes, and all spacecraft avionics and equipment. EADS Astrium is a wholly owned subsidiary of EADS SPACE, which is dedicated to providing civil and defence space systems. In 2004, EADS SPACE had a turnover of €2.6 billion and 11,000 employees in France, Germany, the United Kingdom and Spain.

EADS is a global leader in aerospace, defence and related services. In 2004, EADS generated revenues of €31.8 billion and employed a workforce of more than 110,000.

CryoSat

Mass: 650 kg
Instruments: Radar altimeter (SIRAL)
Data receiver (DORIS)
Laser retro-reflector
> Height resolution: 1 to 3 cm
Horizontal resolution: approx. 300 m
Total finance value: approx. 140 million euros
of which industrial contract: approx. 70 million euros
Mission duration: at least 3 years
Orbit: 720 km altitude,
92 degrees inclination
Planned launch date: October 8th, 2005

 

Contacts for the Media:
Rémi ROLAND
EADS SPACE (FR)
Tel.: +33 (0) 1 42 24 27 34

Jeremy CLOSE
EADS SPACE (UK)
Tel.: +44 (0) 1 438 77 3872

Mathias PIKELJ
EADS SPACE (GER)
Tel.: +49 (0) 7545 8 91 23



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