Darkness has descended upon the star-tracking spacecraft of the European Space Agency (ESA), Gaia. The initiative, which has been surveying the Milky Way for the past 12 years, ceased its scientific operations on Wednesday (January 15).
The conclusion of the mission’s data-gathering period was prompted by Gaia’s depletion of the cold gas propellant used for its rotation. The top-hat-shaped vehicle has consumed approximately 12 grams of this propellant daily since its launch from Europe’s Spaceport in French Guiana aboard a Soyuz-Fregat rocket on December 19, 2013.
Nevertheless, despite Gaia shutting its eyes to the universe, this does not signify the end of the spacecraft’s impact on astrophysics.
“In my opinion, the Gaia mission is not concluding — only the data collection,” stated Kareem El-Badry, a researcher at the Harvard and Smithsonian Center for Astrophysics (CfA) and a frequent user of Gaia data, to Space.com. “I anticipate that Gaia’s most significant discoveries are yet to unfold, particularly in the domains I am most passionate about — binary stars and black holes.”
Gaia: Departed but Not Forgotten
During its operational span, Gaia examined nearly 2 billion stars and various entities within and surrounding the Milky Way. This extensive stellar survey encompasses information regarding stellar motions, luminosities, temperatures, and chemical compositions.
The objective is to create the largest and most accurate three-dimensional map of our local cosmos. The spacecraft’s initial data release occurred on September 14, 2016; the second took place on April 25, 2018, and the third (most recent) was released on June 13, 2022.
The scientific team working on Gaia will not have time to mourn its absence; they are gearing up for Gaia Data Release 4 (GR4), anticipated before mid-2026. According to five and a half years of collected observations, ESA stated that GR4 will not offer “more of the same,” but is expected to surpass GR3 in terms of data quality and quantity.
Once all of Gaia’s data has been transmitted to Earth, efforts will commence on GR5, the final data release from the spacecraft. This will be a massive data deposit comprising stellar observations accrued over 10.5 years. GR5 is not anticipated to be published before the end of the 2020s.
“Fewer than one-third of all Gaia data sets have been released thus far, and the ultimate data will not be ready for scientific use until the 2030s,” El-Badry remarked. “Processing the data requires considerable human and computational resources.”
This indicates that we will continue to provide updates on Gaia-related research for the foreseeable future.
Moreover, Gaia will now serve as a test platform for researchers aiming to enhance spacecraft and instrument handling in space.
These experiments will take place over several weeks while Gaia remains at a gravitationally stable position between Earth and the sun, known as Lagrange point 2, or L2.
Upon departing L2 and its present orbit, Gaia will be positioned into an orbit that keeps it clear of the Earth-moon system for the foreseeable future. In March or April 2025, the Gaia spacecraft will transition to its final orbit beyond Earth’s sphere of influence, ensuring it does not disrupt operations of other spacecraft.
ESA indicated that further information regarding the “passivation” of Gaia and the commemoration of this groundbreaking space mission’s conclusion will be released shortly.