NASA's SPHEREx Space Telescope Begins Capturing Entire Sky

NASA's SPHEREx space observatory has officially begun its two-year mission to map the entire sky in 102 infrared wavelengths, capturing about 3,600 images daily to create 3D maps of hundreds of millions of galaxies. Its goal is to unlock new insights into cosmic inflation, the origins of galaxies, and the building blocks of life in the Milky Way by using spectroscopy to analyze light and matter across the universe. From a press release: From its perch in Earth orbit, SPHEREx peers into the darkness, pointing away from the planet and the Sun. The observatory will complete more than 11,000 orbits over its 25 months of planned survey operations, circling Earth about 14.5 times a day. It orbits Earth from north to south, passing over the poles, and each day it takes images along one circular strip of the sky. As the days pass and the planet moves around the Sun, SPHEREx's field of view shifts as well so that after six months, the observatory will have looked out into space in every direction.

When SPHEREx takes a picture of the sky, the light is sent to six detectors that each produces a unique image capturing different wavelengths of light. These groups of six images are called an exposure, and SPHEREx takes about 600 exposures per day. When it's done with one exposure, the whole observatory shifts position -- the mirrors and detectors don't move as they do on some other telescopes. Rather than using thrusters, SPHEREx relies on a system of reaction wheels, which spin inside the spacecraft to control its orientation.

Hundreds of thousands of SPHEREx's images will be digitally woven together to create four all-sky maps in two years. By mapping the entire sky, the mission will provide new insights about what happened in the first fraction of a second after the big bang. In that brief instant, an event called cosmic inflation caused the universe to expand a trillion-trillionfold.

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