Unlocking thermal remote sensing: a vital technology for sustainable resource management from space

One of the most crucial questions is: How does thermal remote sensing actually work?

In simple terms, thermal remote sensing is the process of measuring temperature by using sensors. These sensors can be mounted on various platforms, such as satellites, while their acquired data can have a variety of applications, for example monitoring the temperature of materials and surfaces.  

Still, we have to dig a little deeper here.  

Infrared data and the electromagnetic spectrum

Satellite imagery is typically associated with beautiful satellite photos made using sensors offering true color capabilities. True color aims to display the Earth as we often see with our eyes. In the visible part of the spectrum, different light wavelengths are often referred to as colors and can be well observed in a rainbow. On the other hand, the true advantage of this technology lies in its ability to capture what's not visible with the naked eye. In fact, many remote sensing techniques primarily rely on "sensing” non-visible wave lengths, of light that are reflected or emitted from the Earth's surface (Figure 1).  

Thus, Light is composed of various parts, including those that the human eye cannot sense. Some parts of the infrared spectrum give us a sensation of warmth when they reach our skin, while ultraviolet (UV) light can damage our cells with excessive exposure. The full range of light is described as an electromagnetic spectrum that ranges from short wavelengths (e.g UV) to long wavelengths (e.g Infrared). For example, radio waves and microwaves have less energy, whereas Infrared light is used for physiotherapy, night vision devices, and, in our case, to make sense of the surface temperature of Earth.

The portion of the light that is reflected by the Earth’s surface travels back towards space, carrying information specific to the surface it interacted with. By observing this light, we can gain valuable insights into the properties of the surface. On the other hand, longwave thermal infrared data that is captured by the sensor is the radiation that is emitted from the surface we are looking at on earth.

What is thermal imaging?

Thermal imaging provides valuable insights into temperature patterns and heat-related phenomena by utilizing the "thermal infrared" part of the electromagnetic spectrum. This incldes 3-5 μm (Mid-wave) and 8-14 μm (Long-wave) portions of this spectrum. Constellr captures long-wave thermal data emitted by objects on the Earth’s surface. The good news is that any object or material with a temperature above absolute zero (0 Kelvin or -273.15°C) will emit some thermal radiation in the form of infrared waves.

Operating in the infrared region allows for the measurement of Earth's temperature. Unlike local sensors, which are limited to specific locations, spaceborne thermal imagery provides continuous temperature information across larger areas and in an integrated manner. This capability enables us to monitor temperature changes and trends over time and space for various applications, such as assessing plant health earlier than traditional methods.

Why is monitoring temperature so important?

Companies and institutions in industry and agriculture are in dire need of sustainable solutions to save freshwater, comprehend urban infrastructure, and enhance supply chain efficiency.

Consider temperature as a critical proxy for agriculture and infrastructure. It plays a key role in guiding decisions related to, for example, urban planning, heat management or irrigation practices. By consistently and reliably monitoring temperature over time, we can gather valuable insights, painting a clearer picture than a single data point ever could. The advantages of temperature monitoring ripple out to numerous areas, impacting livelihood, health, food production, consumption, and essential survival needs.

The 2030 Agenda for Sustainable Development, adopted by all United Nations Member States in 2015, offers a shared blueprint for peace and prosperity for people and the planet, now and into the future. At its core are the 17 Sustainable Development Goals (SDGs), which are an urgent call to action for all countries, both developed and developing, to engage in a global partnership. Temperature monitoring is crucial for 12 of them.  

Through consistently delivering data over time, it is possible to make more intelligent decisions for the environment and their business. Surface Temperature data empowers actionable intelligence for the sustainable management of agricultural and infrastructure assets, for example monitoring agricultural fields at scale or gathering precise data on Urban Heat Islands.

Currently, there's no existing solution that offers such a timely, precise, and field-scale plant temperature measurements needed for understanding the health of our planet.

This is going to change.

Current remote sensing technologies have limitations in capturing thermal infrared data quickly and accurately. While missions like Sentinel-3 provide frequent data (several times a day), their spatial resolution (1,000 meters) is too low for understanding the field-level status of the crops, studying urban heat island precisely, or using the data for practical agricultural use.  
On the other hand, missions with higher spatial resolution, like ECOSTRESS (70 meters) and Landsat 9 (100 meters), are not ideal for monitoring due to infrequent revisit times, cloud cover, or inconsistent operation.

constellr is at the forefront of precise thermal monitoring from space. Our technology delivers the market's most accurate and dependable thermal data, specifically surface temperature (LST). LST is measured from space using the thermal, visible, and near-infrared data acquired by constellr.

Our space journey begins with the deployment of the High-precision Versatile Ecosphere (HiVE) monitoring constellation. With the first satellite going up to space in Q4 2024, our smallsat will create a digital twin of earth based on temperature data and enable thermal intelligence globally and at scale.  

This technological leap promises to revolutionize agriculture and infrastructure supply chains, promoting more efficient and sustainable practices.  

However, the concepts we've discussed are just the beginning of understanding thermal remote sensing and constellr's role in this field. Many questions remain unanswered:

• What are constellr's sensors and what do they capture? (VNIR, thermal, emissivity)

• What is LST data and how is it obtained by constellr?

• What role do ground stations play, and how do they retrieve data from the satellite to deliver it to us?

.. the list goes on. These questions, along with what makes constellr’s satellite unique, are just the tip of the iceberg. We will explore these and other topics in a series of upcoming articles. Stay tuned for more insights!

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