First Webb Space Telescope images of the Red Planet

web mars

Webb’s first images of Mars, captured by its NIRCam instrument on September 5, 2022 [Guaranteed Time Observation Program 1415], Left: Reference map of the hemisphere of Mars as seen from NASA and the Mars Orbiter Laser Altimeter (MOLA). Top right: NIRCam image showing a 2.1-μm (F212 filter) reflectance of sunlight, revealing surface features such as craters and layers of dust. Bottom right: Simultaneous NIRCam image showing ~4.3-μm (F430M filter) emitted light that reveals temperature differences with latitude and time of day, as well as darkening of the Hellas Basin due to atmospheric effects. The bright yellow region occurs only at the saturation limit of the detector. Credits: NASA, ESA, CSA, STScI, Mars JWST/GTO Team

on 5th September, NASA’s James Webb Space Telescope captured its first images and spectra of[{” 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]captured by near-infrared camera (NIRCam), showing a region of the planet’s eastern hemisphere in two different wavelengths, or colors of infrared light. This image shows a surface reference map from[{” 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] is dominated by reflected sunlight, and thus reveals surface details similar to those seen in visible-light images [left], The rings of Huygens Crater, the deep volcanic rock of Syrtis Major, and the glowing Hellas Basin are all evident in this image.

NIRCam long-wavelength (4.3 µm) image [lower right] Reflects thermal emission – the light given off by the planet loses heat. The brightness of the 4.3 µm light is related to the surface temperature and the atmosphere. The brightest region on the planet is where the Sun is almost overhead, as it is usually the hottest. Brightness decreases toward the polar regions, which receive less sunlight, and less light is emitted from the colder Northern Hemisphere, which is experiencing winter at this time of year.

James Webb Space Telescope L2

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

However, temperature is not the only factor affecting the amount of 4.3-μm light reaching the web with this filter. As the light emitted by the planet passes through the atmosphere of Mars, some is absorbed by the carbon dioxide (CO.)2) molecules. The Hellas Basin – the largest well-preserved impact structure on Mars, extending over 1,200 miles (2,000 km) – appears deeper than the surroundings due to this impact.

“It’s not really a thermal effect in Hellas,” explained Geronimo Villanueva, the principal investigator of NASA’s Goddard Space Flight Center, who designed these web overviews. “The Hellas Basin is a low altitude, and thus experiences high air pressure. That high pressure leads to the suppression of thermal emissions over this particular wavelength range [4.1-4.4 microns] Because of an effect called pressure widening. It would be very interesting to separate 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. spectroscopy,

Webb Mars Atmosphere Structure

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 less than 3 µm and thermal emission at longer wavelengths. Preliminary analysis suggests spectral dips appear at specific wavelengths where light is absorbed by molecules in the Martian atmosphere, notably carbon dioxide, carbon monoxide and water. Other details reveal information about dust, clouds and surface features. By building the most appropriate model of the spectrum, for example, by using Planetary Spectrum Generators, the abundance of a given number of molecules in the atmosphere can be obtained. Credits: NASA, ESA, CSA, STScI, Mars JWST/GTO Team

While the images show differences in brightness integrated over a large number of wavelengths across the planet at a particular day and time, the spectrum as a whole shows subtle variations in brightness among hundreds of different wavelengths representative of the planet. 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 of Webb near-infrared spectrograph (NIRSPC). Preliminary analysis of the spectrum reveals a rich set of spectral features that contain information about dust, icy clouds, what kind of rocks are on the planet’s surface, and the composition of the atmosphere. The spectral signatures – including deep valleys known as absorption features of water, carbon dioxide and carbon monoxide – are easily detected along Webb. The researchers are analyzing the spectral data from these observations and preparing a paper they will submit to a scientific journal for peer review and publication.

In the future, the Mars team will use this imaging and spectroscopic data to detect 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 Webb’s Cycle 1 Guaranteed Time Observations (GTOs) were conducted as part of the Solar System program, led by Heidi Hamel of AURA.

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