On September 5th, the James Webb telescope performed its first observations of Mars, taking pictures and collecting spectral data of the Red Planet. The discovery, which was made public by NASA and the European Space Agency (ESA) on Monday (19), provides a novel view of our neighbouring planet thanks to the telescope’s great sensitivity to infrared light.
The Near-Infrared Camera (NIRCam) instrument took the first pictures of Mars, which depict a portion of the planet’s eastern hemisphere in shorter and longer wavelengths, respectively at 2.1 microns and 4.3 microns. The pictures are displayed next to a fictitious representation of Mars created using information from NASA and the Mars Orbiter Laser Altimeter (MOLA) instrument on the Mars Global Surveyor spacecraft.
The top image, which is dominated by reflected sunlight and shows details of the Martian surface similar to those in visible light photographs like those taken by MOLA, is the one with shorter wavelengths. Longer wavelengths were used to create the image at the bottom, which depicts light emanating from the planet as it dissipates heat.
Note that the brightness decreases toward the polar regions, which receive less light, and that the northern hemisphere emits less light because it is winter because there is where the Sun practically directly strikes Mars, making that area hotter. Some of the light released by Mars is absorbed by carbon dioxide molecules as it travels through the atmosphere.
At Hellas Basin, a significant impact feature on Mars, this effect is considerably more obvious. As a result of its lower altitude and higher atmospheric pressure, Hellas Basin, according to NASA’s Goddard Space Flight Center’s Geronimo Villanueva Due to a phenomenon known as “pressure amplification,” he continued, “this higher pressure causes a suppression of thermal emission in this wavelength region [4.1 to 4.4 microns]. Differentiating these competing effects in the data will be quite intriguing.