NASA’s SPHEREx Space Telescope begins capturing entire sky.

After weeks of preparation, the space observatory has begun its science mission, taking about 3,600 unique images per day to create a map of the cosmos like no other.

Launched on March 11, NASA’s SPHEREx space observatory has spent the last six weeks undergoing checkouts, calibrations, and other activities to ensure it is working as it should. Now it’s mapping the entire sky — not just a large part of it — to chart the positions of hundreds of millions of galaxies in 3D to answer some big questions about the universe. On May 1, the spacecraft began regular science operations, which consist of taking about 3,600 images per day for the next two years to provide new insights about the origins of the universe, galaxies, and the ingredients for life in the Milky Way.

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 14½ 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.

Source: www.nasa.gov

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