ESA SARAS: Catching signals faster - Video

SARAS – a Spanish acronym for ‘Fast Acquisition of Satellites and Launchers’ – enables ground stations to acquire signals from new satellites faster and more accurately than ever before. 

A circular array of eight small radio-frequency sensors are mounted around the rim of an existing dish antenna. 

It was fitted to the 15 m-diameter dish at ESA’s ESAC Establishment in Spain, seen here during upgrade work, in 2013.

Since then, it has been extensively tested, receiving signals from missions including CryoSat, XMM, and Swarm. 

It also helps the station to acquire signals from multisatellite missions, such as the three-craft Swarm.

ESA Cryosat: Arctic sea ice volume increased

Measurements from ESA’s CryoSat satellite show that the volume of Arctic sea ice has significantly increased this autumn.

The volume of ice measured this autumn is about 50% higher compared to last year.

In October 2013, CryoSat measured about 9000 cubic km of sea ice – a notable increase compared to 6000 cubic km in October 2012.

Over the last few decades, satellites have shown a downward trend in the area of Arctic Ocean covered by ice.

However, the actual volume of sea ice has proven difficult to determine because it moves around and so its thickness can change.

CryoSat was designed to measure sea-ice thickness across the entire Arctic Ocean, and has allowed scientists, for the first time, to monitor the overall change in volume accurately.

About 90% of the increase is due to growth of multiyear ice – which survives through more than one summer without melting – with only 10% growth of first year ice.

Thick, multiyear ice indicates healthy Arctic sea-ice cover.

This year’s multiyear ice is now on average about 20%, or around 30 cm, thicker than last year.

ESA Cryosat: West Antarctica continues to lose ice

West Antarctica continues to lose ice to the ocean and this loss appears to be accelerating, according to new data from Europe's Cryosat spacecraft.

The dedicated polar mission finds the region now to be dumping over 150 cubic km of ice into the sea every year.

It equates to a 15% increase in West Antarctica's contribution to global sea level rise.

Cryosat was launched in 2010 with a radar specifically designed to measure the shape of ice surfaces.

And the instrument's novel design, scientists believe, is enabling the European Space Agency satellite to observe features beyond the capability of previous missions.

The new study, presented here in San Francisco to the American Geophysical Union (AGU) Fall Meeting, confirms the usual suspects to be involved in the increased ice loss.

They are Pine Island, Thwaites and Smith Glaciers.

These major glaciers and their associated tributaries drain the interior of West Antarctica, taking its mass into the Amundsen Sea.

The ice near to their grounding lines - the places where the ice streams lift up off the land and begin to float out over the ocean - is now thinning by between four and eight metres per year.

"Interestingly, Smith Glacier is thinning fastest," said study leader Dr Malcolm McMillan from the UK's Nerc Centre for Polar Observation and Modelling (CPOM).

"It's smaller but its thinning rate is roughly double that of Pine Island or Thwaites, which tend to get all the headlines because they have such huge catchments," he told reporters.

In a recent major review of all satellite data, scientists concluded that ice losses from West Antarctica pushed up global sea levels by some 0.28mm a year between 2005 and 2010.

The new Cryosat data picks up from the end of that period, and suggests the contribution has risen still further.

Professor Andrew Shepherd from the University of Leeds, who led the West Antarctica study, said that part of the increase of ice loss could be due to faster thinning, but that part of it may also be down to CryoSat’s capacity to observe previously unseen terrain.

“Thanks to its novel instrument design and to its near-polar orbit, CryoSat allows us to survey coastal and high-latitude regions of Antarctica that were beyond the capability of previous altimeter missions, and it seems that these regions are crucial for determining the overall imbalance,” he said.

ESA’s CryoSat mission observes continuing Arctic winter ice decline

Offering new insights into our fragile polar regions, ESA’s CryoSat mission has provided three consecutive years of Arctic sea-ice thickness measurements, which show that the ice continues to thin.

Although satellites have witnessed a downward trend in the extent of sea ice over the last two decades, it is essential to have accurate information on the mass or volume of ice being lost. This is a more accurate measure of the changes taking place.

Along with observations of ice extent, CryoSat’s measurements of thickness now span from October 2010 to April 2013, allowing scientists to work out the real loss of ice, monitor seasonal change and identify trends.

Speaking today at the Living Planet Symposium in Edinburgh, UK, Prof. Andrew Shepherd from the University of Leeds, UK, said, “CryoSat continues to provide clear evidence of diminishing Arctic sea ice.

“From the satellite’s measurements we can see that some parts of the ice pack ice have thinned more rapidly than others, but there has been a decrease in the volume of winter and summer ice over the past three years.

“The volume of the sea ice at the end of last winter was less than 15 000 cubic km, which is lower than any other year going into summer and indicates less winter growth than usual.”

While it seems unlikely that a record minimum of sea-ice extent will be set this September, the thinner ice at the start of summer could mean that the actual volume of ice may reach a new low.

Rachel Tilling, PhD student at University College London, who is working with the CryoSat data stated, “Readings from CryoSat in October, when the ice starts to refreeze, will confirm this either way.”

Moreover, scientists can look forward to a continued stream of this vital information from CryoSat for some time.

“CryoSat has been in orbit since 2010 and with the satellite still in excellent health it is now set to continue providing precision measurements until 2017,” said ESA’s Tommaso Parrinello, who is responsible for the mission.

Much of the success in the way the mission’s radar height measurements are exploited to understand ice change is thanks to Prof. Seymour Laxon from University College London who passed away in January as the result of an accident.

ESA CryoSat maps largest-ever flood beneath Antarctica

Location of the crater in Victoria Land, East Antarctica at about 73ºS and 156ºE. The colour scale shows height derived from CryoSat data. The crater is located within the white box. Credit: ESA/M. McMillan

ESA's CryoSat satellite has found a vast crater in Antarctica's icy surface. Scientists believe the crater was left behind when a lake lying under about 3 km of ice suddenly drained.

Far below the thick ice sheet that covers Antarctica, there are lakes of fresh water without a direct connection to the ocean.

These lakes are of great interest to scientists who are trying to understand water transport and ice dynamics beneath the frozen Antarctic surface – but this information is not easy to obtain.

One method is to drill holes through kilometres of ice to the water – a difficult endeavour in the harsh conditions of the polar regions.

But instead of looking down towards the ice, a team of European scientists is looking to the sky to improve our understanding of subglacial water and its transport.

By combining new measurements acquired by CryoSat with older data from NASA's ICESat satellite, the team has mapped the large crater left behind by a lake, and even determined the scale of the flood that formed it.

From 2007 to 2008, six cubic kilometres of water – about the same amount that is stored in Scotland's Loch Ness – drained from the lake, making it the largest event of its kind ever recorded.

That amount of water equals a tenth of the melting that occurs beneath Antarctica each year.

Since the end of 2008, the lake appears to be refilling but six times slower than it drained. It could take decades to reform.