By | September 20, 2022
Mars Is Mighty: First Webb Space Telescope Images of the Red Planet

Web March

Webb’s first images of Mars, taken by its NIRCam instrument on September 5, 2022 [Guaranteed Time Observation Program 1415]. Left: Reference map of the observed hemisphere of Mars from NASA and the Mars Orbiter Laser Altimeter (MOLA). Top right: NIRCam image showing 2.1 micron (F212 filter) reflected sunlight and revealing surface features such as craters and dust layers. Bottom right: Simultaneous NIRCam image showing ~4.3-micron (F430M filter) emitted light revealing temperature differences with latitude and time of day, as well as darkening of Hellas Basin caused by atmospheric effects. The light yellow area is right at the saturation limit of the detector. Credit: NASA, ESA, CSA, STScI, Mars JWST/GTO team

The 5th of September NASA’s James Webb Space Telescope captured its first images and spectra of

Mars is the second smallest planet in our solar system and the fourth planet from the sun. It is a dusty, cold desert world with a very thin atmosphere. Iron oxide is widespread in the surface of Mars resulting in its reddish color and its nickname "The red planet." Mars’ name comes from the Roman god of war.

” data-gt-translate-attributes=”[{” attribute=””>Mars. The powerful telescope provides a unique perspective with its infrared sensitivity on our neighboring planet, complementing data being collected by orbiters, rovers, and other telescopes. Webb is an international collaboration with ESA (European Space Agency) and CSA (Canadian Space Agency).

Webb’s unique observation post is nearly a million miles away from Earth at the Sun-Earth Lagrange point 2 (L2). It provides a view of Mars’ observable disk (the portion of the sunlit side that is facing the telescope). 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.

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.

Webb's Orbit

Webb orbits the Sun near the second Sun-Earth Lagrange point (L2), which lies approximately 1.5 million kilometers (1 million miles) from Earth on the far side of Earth from the Sun. Webb is not located precisely at L2, but moves in a halo orbit around L2 as it orbits the Sun. In this orbit, Webb can maintain a safe distance from the bright light of the Sun, Earth, and Moon, while also maintaining its position relative to Earth. Credit: STScI

Webb’s first images of Mars [top image on page]caught by Near-infrared camera (NIRCam), shows a region of the planet’s eastern hemisphere at two different wavelengths, or colors, of infrared light. This image shows a surface reference map from

Founded in 1958, the National Aeronautics and Space Administration (NASA) is an independent agency of the United States federal government that succeeded the National Advisory Committee for Aeronautics (NACA). It is responsible for the civil space program, as well as aeronautical and space research. Its vision is "To discover and expand knowledge for the good of mankind." Its core values ​​are "safety, integrity, teamwork, excellence and inclusion."

” data-gt-translate-attributes=”[{” attribute=””>NASA and the Mars Orbiter Laser Altimeter (MOLA) on the left, with the two Webb NIRCam instrument field of views overlaid. The near-infrared images from Webb are on shown on the right.

The NIRCam shorter-wavelength (2.1 microns) image [top right] dominated by reflected sunlight, thereby revealing surface details similar to those seen in visible light images [left]. The rings in Huygens Crater, the dark volcanic rock Syrtis Major, and the brightening of the Hellas Basin are all evident in this image.

The longer wavelength (4.3 micron) NIRCam image. [lower right] shows thermal emission – light given off by the planet as it loses heat. The brightness of 4.3 micron light is related to the temperature of the surface and atmosphere. The brightest region on the planet is where the sun is almost overhead, as it is generally the warmest. Brightness decreases toward the polar regions, which receive less sunlight, and less light is emitted from the cooler northern hemisphere, which experiences winter at this time of year.

James Webb Space Telescope L2

The James Webb Space Telescope. Credit: NASA’s Goddard Space Flight Center

However, temperature is not the only factor that affects the amount of 4.3 micron light that reaches Webb with this filter. When light emitted by the planet passes through the Martian atmosphere, some of the carbon dioxide (CO) is absorbed2) molecules. 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 its surroundings because of this effect.

“This is actually not a thermal effect on Hellas,” explained the principal investigator, Geronimo Villanueva of the NASA’s Goddard Space Flight Center, who designed these Webb observations. “The Hellas Basin is a lower elevation and thus experiences higher air pressure. The higher pressure leads to a suppression of the thermal emission at this specific wavelength range [4.1-4.4 microns] due to an effect called pressure broadening. It will be very interesting to tease apart these competing effects in these data.”

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.

Web The composition of Mars' atmosphere

Webb’s first near-infrared spectrum of Mars, captured by the Near-Infrared Spectrograph (NIRSpec) on September 5, 2022, as part of the Guaranteed Time Observation Program 1415, over 3 slit gratings (G140H, G235H, G395H). The spectrum is dominated by reflected sunlight at wavelengths shorter than 3 microns and thermal emission at longer wavelengths. Preliminary analysis reveals that the spectral dips occur at specific wavelengths where light is absorbed by molecules in the Martian atmosphere, particularly carbon dioxide, carbon monoxide and water. Other details reveal information about dust, clouds, and surface properties. By constructing a best-fit model of the spectrum, using for example the Planetary Spectrum Generator, the abundance of given molecules in the atmosphere can be derived. Credit: NASA, ESA, CSA, STScI, Mars JWST/GTO team

While the images show differences in brightness integrated over a large number of wavelengths from place to place across the planet at a given day and time, the spectrum shows the subtle variations in brightness between hundreds of different wavelengths that are representative of the planet as a whole. Astronomers will analyze the characteristics of the spectrum to gather additional information about the planet’s surface and atmosphere.

This infrared spectrum was obtained by combining measurements from all six high-resolution spectroscopy modes at Webb Near-infrared spectrograph (NIRSpec). Preliminary analysis of the spectrum shows a rich set of spectral features that contain information about dust, icy clouds, the type of rocks found on the planet’s surface and the composition of the atmosphere. The spectral signatures – including deep valleys called absorption features – of water, carbon dioxide and carbon monoxide can be easily detected with Webb. The researchers have analyzed the spectral data from these observations and are preparing a paper that they will submit to a scientific journal for peer review and publication.

In the future, the Mars team will use these images and spectroscopic data to explore regional differences across the planet and to search for trace gases in the atmosphere, including methane and hydrogen chloride.

These NIRCam and NIRSpec observations of Mars was conducted as part of Webb’s Cycle 1 Guaranteed Time Observation (GTO) solar system program led by Heidi Hammel of AURA.

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