The infrared planet: James Webb turns its gaze to Mars

21 Sep 2022

Image: © dimazel/

The powerful space observatory has captured new images of Mars, which could provide information about the surface and atmosphere of the planet.

The James Webb Space Telescope has used its powerful instruments to get a closer look at our planetary neighbour Mars.

The space observatory has been able to capture images of the red planet that can be used to study short-term phenomena such as dust storms, weather patterns and seasonal changes.

The first images shared from the telescope’s Near-Infrared Camera (NIRCam) show a region of Mars at two different wavelengths, or colours of infrared light.

Three images of Mars, with the left showing base maps and the images on the right taken from the James Webb Space Telescope.

Images of Mars captured by the James Webb Space Telescope’s NIRCam (right), with a reference map from NASA (left). Image: NASA/ESA/CSA/ STScI/Mars JWST/GTO team

The shorter wavelength image (top right) shows surface features such as craters and dust layers. The longer wavelength image (bottom right) shows thermal emission, or the light given off by the planet as it loses heat.

Since it is so close to Earth, Mars is one of the brightest objects in the night sky in terms of both visible light – that humans can see – and the infrared light that can be detected by James Webb.

This presents a challenge for the space telescope, however, which was designed to detect the extremely faint light of distant galaxies. James Webb’s instruments are so sensitive that the infrared light of Mars is “blinding” for the space observatory, according to NASA.

Astronomers had to adjust for the extreme brightness by using very short exposures and applying special data analysis techniques.

Despite the challenge, James Webb was able to capture unique photos of Mars, along with new details of the surface and atmosphere of the red planet. These details come from spectroscopy, which is the scientific method of studying objects and materials based on colour.

Webb provided a near-infrared spectrum of Mars by combining measurements from all six of the high-resolution spectroscopy modes of Webb’s Near-Infrared Spectrograph (NIRSpec).

A graph with an infrared image of Mars in the background.

A near-infrared spectrum of Mars, using data from James Webb’s NIRSpec. Image: NASA/ESA/CSA/STScI/Mars JWST/GTO team

This spectrum shows the subtle variations in brightness between hundreds of different wavelengths, representative of the planet as a whole.

A preliminary analysis suggests this shows information about dust, icy clouds, the kind of rocks on the planet’s surface and the composition of the atmosphere. The research team analysing the data is preparing a paper to be submitted for peer review and publication.

In the future, the team behind these James Webb observations plans to use the imaging and spectroscopic data to explore regional differences across Mars and search for trace gases in the atmosphere, including methane and hydrogen chloride.

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Leigh Mc Gowran is a journalist with Silicon Republic