[DigitalToday reporter Jinju Hong (홍진주)] An international research team has completed the largest high-resolution 3D map of the universe in human history.

On April 21 local time, IT outlet TechRadar reported that the map was built by tracking tens of millions of galaxies over five years of observations. It will be used as key data to identify the nature of dark energy.

The project was carried out around the Dark Energy Spectroscopic Instrument (DESI). DESI focuses on identifying dark energy, which is cited as a cause of accelerating expansion of the universe. Researchers secured data on more than 47 million galaxies and quasars, exceeding the initial target of 34 million. They also observed more than 20 million nearby stars to study the structure of the Milky Way.

The key observational device is 5,000 robotic fiber-optic positioners mounted on a telescope in Arizona in the United States. These small robotic arms move about every 20 minutes, realigning fiber-optic positions to capture the faint light of distant galaxies. The presence of the 5,000 robotic fiber-optic positioners at the heart of DESI shows the map was created on a large-scale automated observation system.

Light collected by the device is sent to a spectrograph and split into its color components. Based on this, researchers calculated how far each galaxy is from Earth. By combining that with sky-position information, they created a 3D map that shows, layer by layer, how matter is distributed in space. DESI was designed to measure thousands of galaxies at a time.

The equipment used for the observations is the 4-metre-class Nicholas U. Mayall Telescope at Kitt Peak National Observatory. Engineers replaced the existing camera with DESI's fiber-optic-based system, greatly increasing the telescope's throughput. The system was designed to track how fast the universe expanded in the past by comparing the distribution of galaxy clusters at different distances and epochs.

Researchers are examining, through these patterns, how dark energy has affected the growth of the universe over billions of years. Earlier initial results raised the possibility that dark energy may not remain a constant force. The early data suggested its influence could change over time, but researchers warned that additional data could change that conclusion.

Completing the map does not mean the end of the project. Researchers plan to observe a wider area of the sky and capture more distant galaxies. They also plan to reobserve areas already surveyed to increase data density and improve measurement precision.

These follow-up observations will lead to a step that checks whether the possibility of time-varying dark energy raised in the initial data holds in a larger dataset. DESI has completed its target observations, but it is expected to focus on more precisely determining the history of cosmic expansion and the nature of dark energy through additional observations in the future.