Multiple orbiters above Mars and the land-connected rovers Curiosity and Perseverance orbit the surface and regularly send back information. Webb’s infrared capabilities contribute another perspective that could reveal details about the Martian surface and atmosphere. Webb, located a million miles (1.6 million kilometers) from Earth, can spot the sunny side of Mars that the space telescope sees, which puts the observatory in the perfect position to spy on seasonal changes, storms dust and the planet’s weather simultaneously. The telescope is so sensitive that astronomers had to make adjustments to prevent Martian blinding infrared light from saturating Webb’s detectors. Instead, Webb observed Mars using very short exposures. The new images show the eastern hemisphere of Mars in different wavelengths of infrared light. On the left is a reference map of the hemisphere recorded by the Mars Global Surveyor mission, which completed in 2006. The top right image from Webb shows reflected sunlight on the surface of Mars, showing Martian features such as Huygens Crater, dark volcanic rock, and Hellas Planitia, a massive impact crater on the red planet that spans more than 1,200 miles (2,000 kilometers). . The bottom right image shows Mars’ thermal emission, or the light emitted by the planet as it loses heat. Brighter areas show the hottest spots. In addition, the astronomers spotted something else in the thermal emission image. When this thermal light passes through the Martian atmosphere, some of it is absorbed by carbon dioxide molecules. This phenomenon has made Hellas Planitia appear darker. “This is actually not a thermal phenomenon in Greece,” Geronimo Villanueva, a planetary scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said in a statement. “The Hellas basin is at a lower elevation and therefore experiences higher atmospheric pressure,” said Villanueva, who is also the principal investigator of the Mars and Ocean Worlds studies for Webb. “This higher pressure leads to a suppression of the thermal emission in this particular wavelength range due to a phenomenon called pressure broadening. It will be very interesting to disentangle these competing effects in this data.” With Webb’s powerful capabilities, Villanueva and his team also captured the first near-infrared spectrum of Mars. The spectrum indicates subtler differences in brightness across the planet, which could highlight aspects of the Martian surface and atmosphere. An initial analysis revealed information about the icy clouds, dust, rock types on the surface and the composition of the atmosphere contained in the spectrum. There are also water, carbon dioxide and carbon monoxide signatures. The NASA research team will share more about Webb’s Mars observations in a study that will be submitted for peer review and publication in the future. And the Mars team is looking forward to using Webb’s capabilities to spot differences between regions on the red planet and look for gases like methane and hydrogen in the atmosphere.
