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- Jonathan Amos
- BBC Science Correspondent
Image source, Rob Larter / BAS
Satellites have monitored ice loss in Antarctica and the Arctic.
We run the risk of becoming “blind”.
Scientists warn that there will be a gap of a few years in our ability to measure the thickness of the ice at the top and bottom of the planet.
In fact the only two satellites dedicated to the observation of the poles are almost certainly die before you cann replace.
And that may leave us unable to contemplate major changes in the Arctic and Antarctic as the global climate warms.
Researchers they expressed their concerns before the European Space Agency and the European Commission.
This week a letter describing the problem and possible solutions was sent to senior officials of both entities, and while the problem has not been formally addressed, NASA is also aware of the scientists’ concern.
The fundamental problem is the longevity of the European missions CryoSat-2 is American IceSat-2.
These ships carry instruments called altimeters that measure the shape and elevation of frozen surfaces.
I have been fundamental in recording sea ice volume loss and the decrease in the mass of glaciers in recent years.
Image source, ESA / NASA
Artist Impression: CryoSat-2 (top) and IceSat-2 (bottom) are expected to last until the middle of this decade.
What makes both satellites unique are their orbits around the Earth.
Their journey view all arctic and antarctic regionsexcept for a small circle of about 430 km in diameter at the poles themselves.
In contrast, most other satellites miss a large swath of the central Arctic Ocean and its ice shelves.
The concern is that CryoSat-2 and IceSat-2 may be downloaded long before satellites are launched to track the poles.
The two satellites
CryoSat-2 ya has exceeded the life limit with which it was designed.
It was introduced into space in 2010 with the expectation that it would run for at least three and a half years.
Engineers believe they can keep it running until 2024, but battery degradation and a fuel leak suggest it it won’t survive long.
Image source, THAT
There is a small circle of about 430 km in diameter which cannot be measured due to the orbit of the satellites.
IceSat-2 was launched in 2018 with a duration of three years and fuel until 2025.
His altimeter also uses laser technology, a technology that is complex to maintain in space.
“Without successful mitigation, there will be a two to five year gap in the altimetric capabilities of our polar satellites,” says the scientists’ letter.
“This gap will usher in a decisive break in long-term records of sea ice and ice sheet thickness change and polar oceanography, and this in turn will degrade our ability to assess and improve. climate model projections“, they point out.
The only replacement intended is known as Cristal.
It is estimated that it will be like Cryosat, albeit with much greater capacity thanks to a dual frequency radar altimeter.
The industry is already working on the spaceship, but it won’t launch until 2027 or 2028, perhaps even later because full funding is not yet available.
Josef Aschbacher, director of Earth observation for the European Space Agency, says the entity is working as quickly as possible to close the gap.
“This is a concernWe recognize that, “he told the BBC.
“We have plans in place to build Cristal as quickly as possible. Despite covid-19, despite heavy workloads and video conferencing,” he said.
Image source, NASA
The Americans brought a laser altimeter aboard a plane as a temporary measure.
Concern
Just over 10% of the nearly 600 signatories of the letter are American scientists.
Thomas Zurbuchen, scientific director of NASA, did not receive the letter because it is mainly aimed at European lenders and most of the signatories come from that continent.
However, the US officer knows the letter and its contents.
Zurbuchen stated that he hoped any polar gap it could be covered or minimized.
“I think at the moment there are more options that we can implement to that end, in collaboration or in any other way,” he said.
One such solution would be to run a version of IceBridge project from NASA.
It is an aerial platform that the US agency operated in the eight years between the end of the first IceSat mission in 2010 and the launch of IceSat-2 in 2018.
A plane flew a laser altimeter over the Arctic and Antarctic to collect some limited datasets that would eventually be could be used to link the two IceSat missions.
But there are many who think that the European “CryoBridge” project is the most convenient and short-term option to mitigate the years of pause that lie ahead between the withdrawal of CryoSat-2 and the launch of Cristal.
The manufacture of the airborne radar altimeter could they take two years and cost more than $ 6 million.
Therefore, such a project is expected to be launched relatively soon.
Signatories to the letter sent to European entities include leading scientists using data from CryoSat and IceSat, the president of the International Glaciology Society and lead authors of the United Nations Intergovernmental Panel on Climate Change.
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