James Webb Space Telescope Sees Mars in a New Light

This story is part of Welcome to Marsour series exploring the red planet.

We have a standard view of what Mars looks like as a reddish rocky planet, As in this Hubble image. But the James Webb Space Telescope sees the universe in infrared. His first observations of Mars show how he will be able to explore the Red Planet in new and exciting ways.

Mars in infrared

JWST is designed to look into the depths of the universe, using infrared radiation to penetrate dust and see objects that are hiding from other telescopes. But it’s also useful for learning more about our planetary neighbors. On September 5, Webb looked at Mars and collected data using the Near Infrared Camera, also known as NIRCam.

Webb was able to see the side of Mars that was facing the telescope, called the visible disk. “As a result, Webb can capture images and spectra with the spectral resolution needed to study short-term phenomena such as dust storms, weather patterns, seasonal variations, and, on a single note, processes that occur at different times (day, sunset and night) for a Martian day,” NASA said In a statement Monday.

The image of Mars on the left is a reference map. At the top right is Webb’s NIRCam image showing reflected sunlight with a label for surface features. At the bottom right is a web view of emitted light that shows differences in temperature with latitude and time of day. The Hellas Basin appears darker due to atmospheric influences.


NASA has released a graphic showing what Webb can see in two different wavelengths of infrared light. It brings Webb’s versatility and shows how shorter and longer infrared wavelengths can generate different sets of data. Here is a crash course in How does infrared web imaging work?.

The brown view of Mars on the left is a reference map. Trace to the right of what Webb saw. The top image is a shorter wavelength view (2.1 microns) showing a portion of the planet that includes the surface features of Huygens Crater, Hellas Basin and Syrtis Major, a region that appears as a dark spot in visible light images.

Looks like the bottom web image”heat map. “This is what appears when Webb uses a longer wavelength view (4.3 microns). The brightest part is where the sun is overhead, which warms that region.” The brightness decreases toward the polar regions, which receive less sunlight and less light from the cooler Northern Hemisphere, which experiences winter at this time of year.”

Look closely at that yellow and purple note and you’ll see where NASA is referring to the Hellas Basin, which appears darker than the surrounding area. So what is going on there? It’s the atmosphere of Mars in action. Carbon dioxide molecules absorb some of the infrared light before it reaches Webb, giving the massive impact structure – 1,200 miles (2,000 km) across – a darker colour.

“The Hellas Basin is of lower elevation, and therefore is subjected to higher air pressure,” explained lead researcher Jeronimo Villanueva. “High pressure suppresses heat emission at this particular wavelength range [4.1-4.4 microns] Because of an effect called pressure expansion.”

Examining the atmosphere of Mars

On top of all that NIRCam’s infrared has to offer, Webb also used the Near Infrared Spectrophotometer (NIRSpec) instrument to collect data on water, carbon dioxide, and carbon monoxide in the planet’s atmosphere. “Initial analysis of the spectrum shows a rich set of spectral features that contain information about dust, ice clouds, the type of rock on the planet’s surface, and the composition of the atmosphere,” NASA said.

Webb’s near-infrared spectrometer has collected data on the composition of the Martian atmosphere.

NASA, ESA, CSA, STScI, and Mars JWST/GTO . Team

Webb is jointly operated by NASA, the European Space Agency and the Canadian Space Agency. NASA has confirmed that the telescope’s Mars data is meant to shed light on ongoing science. Scientists are still analyzing the NIRSpec information to learn more about the Red Planet’s surface and atmosphere. The results will be written into a study and submitted for peer review.

Observing Mars has been difficult for Webb because the planet is so close that it risks “blinding” the telescope with its bright infrared light. The JWST team has done this using short exposures and special data analysis techniques.

These early results show how Webb is more than just a long-range telescope. It promises to help scientists build a more complete picture of nearby Mars.