NASA's SPHEREx Space Telescope Begins Skyward Mission After Shedding Protective Shield

NASA's SPHEREx mission, newly launched into low Earth orbit on March 11, has taken a major step toward beginning its cosmic survey by discarding its dust cover. On March 18, mission controllers successfully directed the observatory to jettison the shield that safeguarded the telescope's aperture from particles and moisture.

This crucial component, which measured roughly 25 inches by 16 inches (64 cm by 40 cm), was designed to protect sensitive elements, including the trio of mirrors central to SPHEREx's optical system. Engineers at NASA's Jet Propulsion Laboratory in Southern California issued commands activating two mechanical releases, allowing built-in springs to propel the cover away from the spacecraft. After separation, the cover drifted away and is expected to disintegrate upon re-entry into Earth's atmosphere.

The SPHEREx team has not yet powered up the telescope's camera, as it must first cool to its operational temperature of below minus 300 degrees Fahrenheit (around minus 190 degrees Celsius). Instead of relying on direct imaging, mission specialists verified the dust cover's detachment by observing a subtle shift in the spacecraft's positioning - a brief motion detected after each release mechanism triggered. Following the second motion, SPHEREx's sensors noted a temperature decrease, confirming exposure to the vacuum of space.

Compact in design, the spacecraft approximates the dimensions of a subcompact car, while its telescope, about the size of a washing machine, is housed within three conical photon shields. These layers guard the instrument from heat and light originating from both the Sun and Earth.

Over the course of its two-year initial mission, SPHEREx will employ spectroscopy to construct four full-sky maps, each capturing data across 102 infrared wavelengths. This detailed spectral information will allow scientists to gauge the distances of remote galaxies, analyze the composition of interstellar gas clouds, and explore a range of other astronomical phenomena.