First Webb Space Telescope Images of Red Planet
NASA’s James Webb Space Telescope has captured its first images and spectra of Mars that show a region of the planet’s eastern hemisphere at two different wavelengths or colors of infrared light. Astronomers will analyze the features of the spectrum to gather additional information about the surface and atmosphere of the planet. In the future, the Mars team will use this imaging and spectroscopic data to explore regional differences across the planet and to search for trace gases in the atmosphere, including methane and hydrogen chloride. Because it is so close to Earth, the Red Planet is one of the brightest objects in the night sky in terms of both visible light (which human eyes can see) and the infrared light that Webb is designed to detect. This poses special challenges to the observatory, because it was built to detect the extremely faint light of the most distant galaxies in the universe. In fact, Webb’s instruments are so sensitive that without special observing techniques, the bright infrared light from Mars is blinding, causing a phenomenon known as “detector saturation.” Astronomers adjusted for Mars’ extreme brightness by measuring only some of the light that hit the detectors, using very short exposures, and applying special data analysis techniques.