Unlocking Earth’s secrets from above: How antenna innovation is advancing climate monitoring

Climate change stands as an undeniable reality, commanding attention on both a scientific and political level. Amidst the urgency to gain a more accurate assessment of our environment, satellites in Low Earth Orbit (LEO) have emerged as a pivotal tool for monitoring and measuring Earth’s dynamics and their effects on fragile ecosystems.

In contrast to geostationary satellites, LEO satellites inherently move with respect to Earth and therefore offer an invaluable vantage point for detailed observations. Often referred to as Earth observation satellites, they are equipped with a variety of instruments, including in some cases microwave radiometers and radars that, via their built-in antennas, act as remote thermometers for unlocking crucial insights into our oceans, atmosphere, sea ice, forestation, and other critical areas.

The importance of Earth observation solutions for a sustainable Arctic to monitor and combat the effects of climate change in the Arctic environment is clearly recognized

Craig Donlon, Head of Earth Observation System Architecture at the European Space Agency (ESA), elaborates: “The Arctic region is changing more rapidly than anywhere else in the world due to the impact of global warming. The importance of Earth observation solutions for a sustainable Arctic to monitor and combat the effects of climate change in the Arctic environment is clearly recognized, and the urgent need for sustained operational multifrequency microwave imaging measurements is identified as a priority for Arctic policy needs”.

One such example is the Copernicus Imaging Microwave Radiometer (CIMR), a highly ambitious radiometer mission by the European Space Agency and the European Commission to measure sea-surface temperature, sea-ice concentration, and sea-surface salinity with unprecedented accuracy and spatial resolution.

While this is fuelling the advent of more innovative antennas and the verification methods that enable their development, it is also creating new challenges around their delivery and deployment.

However, an issue that has arisen alongside our need for more effective solutions to climate change, is our requirement for more accurate data to base them upon. While this is fuelling the advent of more innovative antennas and the verification methods that enable their development, it is also creating new challenges around their delivery and deployment.

Bespoke antennas essential for accurate climate data

The antenna is a crucial component of the instruments onboard an Earth observation satellite, featuring highly specialised characteristics and components designed to detect fluctuations in temperature, pressure, and many other parameters, down to a granular level.

Specific requirements for which frequencies to measure at, how finely resolved data needs to be, with what sensitivity the instrument should operate, among others, ultimately determine the antenna technology. As an example, larger antennas will provide a finer resolution of measured data. This, in turn, allows for more informed analysis of phenomena like glacial melting, deforestation rates, and urbanisation impacts on local climates, and enables scientists to better comprehend the nuances of climate change and its regional manifestations – ultimately aiding in more targeted interventions and policy formulations.

Earth observation satellites generally warrant bespoke antennas with special surface properties and structure, complex and custom-made antenna feeding elements, state-of-the-art array antennas, and more.

Because the antenna to a great extent determines the instrument performance, it is usually better to optimise the antenna to meet the mission performance requirements

Martin Suess, Head of Microwave Instruments Section at ESA, explains: “It may be possible to use an off-the-shelf antenna as a building block for an Earth observation satellite. However, then the instrument performance is determined by the antenna, and the rest of the instrument, the satellite, and the mission must be designed around the constraints of the antenna. Because the antenna to a great extent determines the instrument performance, it is usually better to optimise the antenna to meet the mission performance requirements”.

The ideation and development of such advanced antennas require, on one hand, highly specialised and skilled engineers with deep knowledge and creative ideas to meet stringent requirements of such missions and, on the other, dedicated and specialised antenna simulation tools to explore concepts and ideas.

Pushing the boundaries of design and application

Computer simulations and measurements are essential for the development of complicated and large antennas needed for Earth observation satellites, and both are playing a pivotal role in the evolution of next-generation technologies.

It is very difficult and takes a long time to characterise the antenna pattern in flight. Therefore, the most effective approach is to measure or model the antenna radiation pattern through an antenna model based on measurements on ground

“The knowledge and stability of the antenna pattern is a key requirement if you are interested in calibrated measurements. It is very difficult and takes a long time to characterise the antenna pattern in flight. Therefore, the most effective approach is to measure or model the antenna radiation pattern through an antenna model based on measurements on ground”, says Martin Suess.

The capabilities and scope of modelling tools are evolving at an exponential rate, and they are becoming highly specialised at specific tasks. While some simulation frameworks are general-purpose solvers that are ideal for generic antenna design, others are tailored to provide more advanced models and algorithms for the special types of antennas used in instruments on Earth observation satellites, such as reflectors, reflectarrays, complex feed horns, and array antennas.

SWOT and CIMR missions and their specialised antennas

With the aid of such specialist tools, designers are not only able to improve on existing designs but also create entirely new types of instruments.

The accuracy of the instrument’s measurements is due to the reflectarray antennas that were developed and designed using specialised antenna simulation tools.

As a recent example of this, the Surface Water and Ocean Topography (SWOT) instrument that was co-developed by NASA and the French space agency (CNES) and launched to space in 2022 features two large and deployable reflectarray antennas. This instrument performs global measurements of water surfaces across the globe, including how these vary over time, which may help to improve weather and climate models. The accuracy of the instrument’s measurements is due to the reflectarray antennas that were developed and designed using specialised antenna simulation tools.

Another example is the CIMR mission. The CIMR instrument will feature a custom-designed and umbrella-like deployable reflector antenna that can be folded into a small shape when onboard a rocket and then unfolded to full size once the instrument is in orbit. Design and validation of such an antenna likewise requires dedicated antenna simulation tools that may capture all details and aspects, which is not possible using general-purpose alternatives.

On the antenna technology developed for the CIMR mission, ESA’s Martin Suess adds: “It has evolved dramatically allowing European industry to address directly European needs for the most advanced Earth observation systems in the world. CIMR is a great challenge where low-frequency microwave-radiometer measurements are required at high spatial resolution”.

With advancements in antenna simulation tools, the application is broadening which is proving to be invaluable for businesses in other industries.

With advancements in antenna simulation tools, the application is broadening which is proving to be invaluable for businesses in other industries. For example, thanks to Earth observation satellites, the insurance sector is leveraging more timely and precise data around natural disasters to aid insurers in assessing and mitigating risks, thereby enabling more accurate pricing and policy issuance.

Better data for a brighter future

Earth observation satellites coupled with innovative antenna design represent a convergence of technological prowess and scientific inquiry. These advancements not only enhance our understanding of climate change but also permeate various industries, transforming the landscape of data-driven decision-making and risk assessment.

As the technology behind the instruments onboard these platforms continues to evolve, and likewise the sophistication of virtual simulation tools that enable their design and development, the synergy between satellite observation and antenna innovation promises a brighter, more informed future in tackling the challenges posed by climate change.

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