"5,000 tiny robot arms": How a humble telescope created the largest 3D map of the universe to help unlock dark energy's secrets

Date:
Tue, 21 Apr 2026 03:30:00 +0000

Description:
The DESI project recorded data from 47 million galaxies and quasars and built
a 3D map of the universe to help unlock dark energy's secrets.

FULL STORY
Astronomers have completed the largest high-resolution 3D map of the
universe ever recorded, after a five-year observing campaign that tracked
tens of millions of galaxies.

The project, known as the Dark Energy Spectroscopic Instrument, or DESI , focuses on understanding dark energy, the mysterious force driving the universes accelerating expansion. The survey exceeded its original targets, recording data from more than 47 million galaxies and quasars instead of the planned 34 million. Researchers also gathered observations from more than 20 million nearby stars to study the structure of the Milky Way.

Tiny robot arms -- At the center of the
project is a system of 5,000 robotic fiber-optic positioners mounted on a telescope in Arizona. These tiny robot arms move into position roughly every
20 minutes, aligning optical fibers to capture faint light from distant galaxies.

That light is then fed into spectrographs that split it into its component colors, allowing scientists to calculate how far away each galaxy lies from Earth. By combining distance measurements with sky positions, the system
builds a layered 3D map showing how matter is spread across the universe.

The telescope used for the project is the 4-meter Nicholas U. Mayall
Telescope at Kitt Peak National Observatory. Engineers replaced its original camera with DESIs fiber-based system, allowing it to measure thousands of galaxies at once.

DESI was built to study how galaxies cluster across different distances and times. Those patterns act as markers of how quickly the universe expanded in the past, revealing how dark energy influenced cosmic growth over billions of years.

Earlier results from the project suggested that dark energy might not behave
as a steady force. Instead of remaining constant, early data hinted that its influence could change over time, although researchers caution that
additional data could still alter that conclusion.

Completing the planned map doesn't mark the end of the project. Scientists
plan to cover additional regions of the sky and to capture more distant galaxies.

Future observations will also revisit existing areas to gather denser data
and improve the precision of recorded measurements to help researchers test whether earlier hints about changing dark energy persist in the larger
dataset.

Via Science.org

Link to news story: https://www.techradar.com/pro/5-000-tiny-robot-arms-how-a-humble-telescope-cre ated-the-largest-3d-map-of-the-universe-to-help-unlock-dark-energys-secrets

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