How do we know what we know?
Gemma Cirac-Claveras, associate professor and historian of science at the Universitat Autònoma de Barcelona, it trying to answer a great epistemological question on a very timely topic. More specifically, she and her team of researchers are conducting research towards writing a history of climate data.
“Satellite data are crucial in decision-making on climate policy,” she explains. And while some people may be vaguely aware that values for measured quantities such as land surface temperature, precipitation and global sea levels are derived from satellite data, the fact is that these data “have to be made”.
Discovering the processes and decision-making behind the transformation of satellite signals into usable information requires a look at the institutions behind the science. That is the main objective of Cirac-Claveras’ research project “The History of a Curve. Satellites, Sea Level Rise, and Climate Change,” for which she received a European Space Agency Postgraduate Research Grant at the HAEU. The project is an extension of the ERC-funded project “CLIMASAT. Remote-sensing satellite data and the making of global climate in Europe 1980-2000”, on which she is principal investigator.
ESA and earth observation
According to Dr Cirac-Claveras, the European Union’s role in space history remains “an untold story,” despite the importance of the European context. Research on the EU as a space actor provides a counter-narrative to the prevalent “space age” and “space race” stories, which focus almost exclusively on the US, China and the former Soviet Union, and provide insufficient detail on the practical achievements of space science.
Indeed, “The History of a Curve” zeroes in on the production of sea-level data, which for decades were extrapolated from signals sent from the European Space Agency’s European Remote-Sensing satellite (ERS-1), launched as ESA’s first mission in the area of earth observation.
“ERS-1 carried a radar altimeter, a sensor capable of measuring the height of ocean waves,” explains the historian. “These measurements, transmitted back to receivers on earth via radar signals, would then be transformed by scientists into graphs of rising sea levels.” Cirac-Claveras’ project aims to open the black box of this data production, revealing “how the ‘global mean sea level’ indicator was negotiated, produced, and made evident; how it gained impetus and status; how was it disseminated and shared, stored, owned, used, and re-used; and how, along these processes, it contributed to shaping climate knowledge”.
ESA fonds at the HAEU
Dr Cirac-Claveras’ archival research brings to light the myriad actors and entities involved in the production of usable satellite data, collected from signals by numerous antennae located in several European countries. While in many cases national space agencies receive the data from ground antennae, a variety of public and private data centres have processed and promoted the data for different purposes over the years, from the historical rise in sea levels, to the conditions of the oceans in real time.
In this regard, mentioned Cirac Claveras, “ESA had to develop a data policy to govern data distribution across this complicated web of satellite sensors, receivers and processors. The ESA archives in Florence provide information on the working group they assembled to do this.”
Professor Cirac-Calveras’ in-person sojourn at the HAEU enabled her to expand her selection of the archival files relevant to her work, and she appreciated the expert assistance of archivists Gherardo Bonini (now retired), and Andreja Casar, who helped her navigate the ESA holdings and were on hand to answer questions.
European Space Agency Postgraduate Research Grant Programme
The European Space Agency Postgraduate Research Grant Programme at the Historical Archives of the European Union aims to increase knowledge about the origins of the European Space Agency, the development of European space research, and the evolution of Europe’s activities in space. Up to two grants are awarded each year.