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WASHINGTON — Since July, the James Webb Space Telescope has been wowing the world with its stunning images from space including incredible peeks of the Cartwheel Galaxy, 13 billion-year-old galaxies, the Tarantula Nebula and the planet Jupiter.
Now, Webb has turned its high-tech cameras on Mars, a target much closer to home and a body that stands out in the night sky of Earth thanks to its sheer brightness.
Why is Webb observing Mars?
In its latest released shots, Webb's near-infrared camera has captured two views of the red planet. But it has the capability of recording a host of short-term phenomena on the planet 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.
NASA reports that because Mars 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.
NASA says the brightness of Mars poses special challenges for Webb, which was built to detect the extremely faint light of the most distant galaxies in the universe. 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."
According to NASA, 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.
What's so great about infrared imaging?
While the Hubble Space Telescope "sees" objects in the optical and ultraviolet spectrums, with some limited infrared capabilities, the Webb telescope is optimized for looking at the universe via the infrared spectrum. The Webb telescope also has a much larger mirror than the Hubble, which collects more light and is able to peer farther back in time than the Hubble is capable of doing.
Fun facts about NASA's space telescopes
The $10 billion Webb telescope is an international collaboration that includes NASA, the European Space Agency and the Canadian Space Agency. It launched into space last Christmas atop a European Ariane 5 rocket and traveled to a position 1 million miles from home, where it is orbiting the sun.
While the first Webb images were transmitted back to earth in July, where the data is picked up by ground-based antennas in Australia, California and Spain, the Hubble is still in operation and making observations from its position about 340 miles above earth. Hubble launched in 1990 with an expected lifespan of about 15 years, but NASA scientists say it could continue operating until the late 2020s.
