Construction of what NASA flagship space telescope, designed to map billions of galaxies, was completed in December 2025?

The NASA flagship space telescope whose construction was completed in December 2025, and is designed to map billions of galaxies, is the Nancy Grace Roman Space Telescope. This cutting-edge observatory is named in honor of Nancy Grace Roman, who served as NASA's first chief of astronomy (Deals) and is widely recognized as the "Mother of Hubble" for her pivotal role in advocating for new space-based tools that ultimately led to the Hubble Space Telescope's launch. Previously known as the Wide-Field Infrared Survey Telescope (WFIRST), the mission was renamed in 2020 to acknowledge Roman's significant contributions to the field of astronomy.

The Roman Space Telescope is poised to revolutionize our understanding of the cosmos, with its construction officially completed on November 25, 2025, and announced by NASA in early December 2025. Its primary mission objectives include investigating the mysteries of dark energy and dark matter, which are thought to be responsible for the universe's accelerating expansion, and discovering thousands of exoplanets. Equipped with a 2.4-meter primary mirror, identical in size to Hubble's, Roman's standout feature is its Wide-Field Instrument. This impressive 300.8-megapixel camera boasts a field of view 100 times larger than Hubble's infrared channel, enabling it to capture vast swathes of the sky in unprecedented detail and survey hundreds of millions of galaxies.

Operating in infrared light, the Roman Space Telescope will provide high-resolution images across a broad expanse of the universe, allowing scientists to create detailed maps of galaxy positions and study their evolution across cosmic time. This wide-field capability will be crucial for understanding the large-scale structure of the universe, including the arrangement of galaxies along the invisible strands of the "cosmic web." The telescope's ability to observe distant galaxies and detect exoplanets through gravitational microlensing will offer new insights into how planetary systems form and evolve, building upon the discoveries of previous missions and opening up new avenues for astronomical research for decades to come. The Roman Space Telescope is currently scheduled for launch in late 2026 or by May 2027 aboard a SpaceX Falcon Heavy rocket.