![]() Villanueva and his team also released Webb’s first near-infrared spectrum of Mars, demonstrating Webb’s power to study the Red Planet with spectroscopy. It will be very interesting to tease apart these competing effects in these data.” That higher pressure leads to a suppression of the thermal emission at this particular wavelength range due to an effect called pressure broadening. “The Hellas Basin is a lower altitude, and thus experiences higher air pressure. “This is actually not a thermal effect at Hellas,” explained the principal investigator, Geronimo Villanueva of NASA’s Goddard Space Flight Center, who designed these Webb observations. The Hellas Basin – which is the largest well-preserved impact structure on Mars, spanning more than 1,200 miles (2,000 kilometers) – appears darker than the surroundings because of this effect. As light emitted by the planet passes through Mars’ atmosphere, some gets absorbed by carbon dioxide (CO 2) molecules. However, temperature is not the only factor affecting the amount of 4.3-micron light reaching Webb with this filter. The brightness decreases toward the polar regions, which receive less sunlight, and less light is emitted from the cooler northern hemisphere, which is experiencing winter at this time of year. The brightest region on the planet is where the Sun is nearly overhead, because it is generally warmest. The brightness of 4.3-micron light is related to the temperature of the surface and the atmosphere. The NIRCam longer-wavelength (4.3 microns) image shows thermal emission – light given off by the planet as it loses heat. The rings of the Huygens Crater, the dark volcanic rock of Syrtis Major, and brightening in the Hellas Basin are all apparent in this image. Credit: NASA, ESA, CSA, STScI, Mars JWST/GTO teamThe NIRCam shorter-wavelength (2.1 microns) image is dominated by reflected sunlight, and thus reveals surface details similar to those apparent in visible-light images. The bright yellow area is just at the saturation limit of the detector. Bottom right: Simultaneous NIRCam image showing ~4.3-micron (F430M filter) emitted light that reveals temperature differences with latitude and time of day, as well as darkening of the Hellas Basin caused by atmospheric effects. Top right: NIRCam image showing 2.1-micron (F212 filter) reflected sunlight, revealing surface features such as craters and dust layers. Left: Reference map of the observed hemisphere of Mars from NASA and the Mars Orbiter Laser Altimeter (MOLA). Webb’s first images of Mars, captured by its NIRCam instrument Sept. The near-infrared images from Webb are on shown on the right. This image shows a surface reference map from NASA and the Mars Orbiter Laser Altimeter (MOLA) on the left, with the two Webb NIRCam instrument field of views overlaid. Webb’s first images of Mars, captured by the Near-Infrared Camera (NIRCam), show a region of the planet’s eastern hemisphere at two different wavelengths, or colors of infrared light. 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 using very short exposures, measuring only some of the light that hit the detectors, and applying special data analysis techniques. This poses special challenges to the observatory, which was built to detect the extremely faint light of the most distant galaxies in the universe. As a result, Webb can capture images and spectra with the spectral resolution needed to study short-term phenomena like dust storms, weather patterns, seasonal changes, and, in a single observation, processes that occur at different times (daytime, sunset, and nighttime) of a Martian day.īecause it is so close, 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. Webb’s unique observation post nearly a million miles away at the Sun-Earth Lagrange point 2 (L2) provides a view of Mars’ observable disk (the portion of the sunlit side that is facing the telescope). The telescope, an international collaboration with ESA (European Space Agency) and CSA (Canadian Space Agency), provides a unique perspective with its infrared sensitivity on our neighboring planet, complementing data being collected by orbiters, rovers, and other telescopes. NASA’s James Webb Space Telescope captured its first images and spectra of Mars Sept. Editor’s Note: This post highlights data from Webb science in progress, which has not yet been through the peer-review process.
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