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by Mick the Ram
The pioneering European Remote Sensing (ERS-2) satellite, the second of two sent into space back in 1995, is expected to take an uncontrolled plunge back into earth’s atmosphere sometime in the next 24 hours, so the European Space Agency (ESA) revealed, early on Wednesday 21 February.
At the time of their launch, the two satellite’s were cutting-edge observation platforms, shaping technologies that are used routinely in this day and age, to monitor everything about our planet.
Weighing more than two tonnes, ERS-2 has been gradually descending since ending operations in 2011 and an agency spokesperson reported that the expectation is for most of it to burn up on its way down.
They say that there is a possibility that some of its more robust parts could withstand the heat intensity that will be generated on its rapid dive, but insist the prospect of any fragments striking populated areas are extremely slim.
Pinpointing any potential landing is seemingly very difficult, with much depending upon solar activity and in particular the density of the upper atmosphere. Nevertheless, they have said that the satellite is most likely begin breaking apart high above Africa and any debris would disappear into the ocean.
ERS-1 failed several years ago, before engineers could lower its altitude, meaning that it remains more than 700km above the Earth, with experts suggesting that at that height it may well be more than a century before any natural fall.
ERS-2 had specific technology fitted to assess the protective ozone layer, something that has gained in global interest markedly in the near 30 years since its launch.
Over time the two satellites have earned themselves the nickname “the grandfathers of Earth observation in Europe”.
Highly advanced capabilities
They were ahead of their time, incredibly sophisticated and had technical capabilities that were ground breaking. The two near-identical ERS satellites carried a suite of instruments that would track changes on the land, in the oceans and in the air.
They monitored floods, measured ocean-surface temperatures, traced the movement of ice fields, and sensed shifts and distortions during earthquakes.
Early detection of climate change
Dr Ruth Mottram, a glaciologist with Danish Meteorological Institute, recalled the revolution these satellites brought to her discipline when she was still a university student, explaining how at the time they were led to believe it would be decades before any kind of impact would be seen as a result of climate change.
“We were told that the ice sheets were very cold and stable, and they weren’t going to change much, but through the ERS project we were able to determine that this wasn’t true, and that there were big changes happening already.”
Two years ahead of estimated time
ERS-2 was originally placed 780km above the Earth, before engineers conducted more than 60 manoeuvres to get it to use up its final fuel reserves and lower its altitude to 570km, back in 2011.
They predicted at the time that it would remain in space for approximately 15 years, so they are a couple of years out on their initial calculation.
The ESA know for certain that the re-entry will occur between 82 degrees North and South, as this was the extent of the satellite’s orbit around the Earth, but apart from that, much of it will be guess work.
Antenna could make it through
Any fragments that do impact the Earth they say could include internal panelling and some metal parts, such as fuel and pressure tanks.
However, the element containing the highest probability of making it through the atmosphere in some form or another, is said to be the antenna for the synthetic aperture radar system, which has a carbon-fibre construction, meaning that it can tolerate extremely high temperatures.
Mirko Albani from Esa’s Earth Observation Ground Segment Department, tried to reassure anybody with grave concerns when he said: “It’s worth highlighting that NONE of the elements that might re-enter the atmosphere and reach the surface are radioactive or toxic.”
That however would matter little if anything or anybody actually were struck by a high-speed part.
Threat to other satellites
Only last week the Secure World Foundation, who are an advocacy group for the sustainable use of space, along with LeoLabs, a US company that tracks space debris, issued a joint statement calling for the removal of redundant orbital hardware.
They said: “Clusters of uncontrollable mass pose the greatest debris-generating potential to the thousands of newly deployed satellites that are fuelling the global space economy.”
Pride in its achievements
ESA’s own Zero Debris Charter recommends that a new disposal grace period now should not exceed five years and says that its future satellites will be launched with the necessary fuel and capability to “propulsively de-orbit themselves in short order.”
They proudly announced that data from the two satellites supported more than 5,000 projects, which have produced roughly 4,000 scientific publications.
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