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The European Space Agency (ESA) has released the first images and infrared spectrum of Mars from the James Webb Space Telescope (JWST). The Webb telescope took its first images and spectra of the red planet on September 5, 2022.
Webb is located approximately 1.5 million kilometers from our planet at the second Sun-Earth Lagrangian point (L2). From the telescope’s point of view, he gets a view of the observable disk of Mars, which is the part of the illuminated side facing the telescope. This allows JWST to capture images and spectra with the specific resolution needed to study short-term phenomena. These phenomena include dust storms, weather and seasonal changes.
While this may not sound impressive for a telescope designed to detect distant faint objects, it actually is. Mars is very close to Earth and is one of the brightest objects in the night sky in both visible and infrared light. But because Webb’s instruments are so sensitive, the bright infrared light from Mars is almost blinding, causing something known as “detector saturation.”
Scientists must use special detection techniques to overcome this, including using very short exposures and measuring only the fraction of light that hits the detectors. They then used special data analysis techniques to arrive at the picture.
JWST’s first images of Mars were taken by the Near-Infrared Camera (NIRCam) and show part of the planet’s eastern hemisphere at two different wavelengths. The image above includes a surface reference map taken by NASA’s Mars Global Surveyor on the left and two Webb NIRCam fields overlaid on the right.
Spectral data of Mars captured by the James Webb Space Telescope. (Image credit: NASA, ESA, CSA, STScI, Mars JWST/GTO team)
Webb’s images of Mars show differences in brightness at a large number of wavelengths from place to place across the planet at a given date and time. But the spectrum illustrates the subtle variations in brightness among the hundreds of different wavelengths that represent the planet as a whole. Astronomers will analyze the properties of the spectrum to gain more information about the planet’s surface and atmosphere.
