We run the risk of going “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, it is almost certainly the only two satellites dedicated to observing the poles die before they can n replace .
And this may leave us unable to contemplate the major changes in the Arctic and Antarctic as the global climate warms.
The researchers have raised their concerns with the European Space Agency and the European Commission.
This week a letter detailing the problem and possible solutions was sent to the top officials of both entities and, although the issue has not been formally addressed, NASA is also aware of the scientists’ concern.
The fundamental problem is the longevity of the European CryoSat-2 and American IceSat-2 missions .
These ships carry instruments called altimeters that measure the shape and elevation of ice surfaces.
They have been instrumental in recording sea ice volume loss and glacier mass decline in recent years.
What is unique about both satellites are their orbits around the Earth.
Their path allows them to see all the Arctic and Antarctic regions , except 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 floes.
The concern is that CryoSat-2 and IceSat-2 may be decommissioned long before satellites are launched that keep track of the poles.
The two satellites
CryoSat-2 has already exceeded the useful life limit with which it was designed.
It was put into the space in 2010 with the expectation that it would operate 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 wo n’t survive much longer.
IceSat-2 was launched in 2018 with a three-year design life and fuel through 2025 .
Its altimeter also uses laser technology, a complex technology to maintain in space.
“Without successful mitigation, there will be a gap of between two and five years in the altimetric capabilities of our polar satellites,” says the scientists’ letter.
“This gap will introduce a decisive break in the 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 projected replacement is known as Cristal.
It is estimated that it will be like Cryosat, although with much greater capacity thanks to a dual-frequency radar altimeter.
Industry is already working on the spacecraft, 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 concern , we recognize it,” he told the BBC.
“We have put in place plans to build Cristal as quickly as possible. Despite covid-19, despite heavy workloads and video conferencing,” he said.
Concern
Just over 10% of the nearly 600 signatories to the letter are American scientists.
Thomas Zurbuchen, NASA’s science director, did not receive the letter because it is addressed primarily to European funders, and most of the signatories are from that continent.
However, the US officer knows about the letter and its contents.
Zurbuchen said he was hopeful that any polar gap could be plugged or minimized.
“I think there are multiple options right now that we can implement to that end, in partnership or in any other way,” he said.
One such solution would be to run a version of NASA’s IceBridge project .
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 data sets that could eventually be used to link the two IceSat missions .
But there are many who think that the European project “CryoBridge” is the most affordable and short-term option to mitigate the gap years that are anticipated between the retirement of CryoSat-2 and the launch of Cristal.
Manufacturing the airborne radar altimeter could take two years and cost more than $ 6 million .
Therefore, such a project would have 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 Society of Glaciology, and lead authors of the United Nations Intergovernmental Panel on Climate Change.
