“Resuming scientific observations was our top priority after the attack,” ALMA Director Sean Dougherty said.
The Oct. 29 attack on ALMA's computer systems affected various servers and critical operational computers, the observatory said in a statement posted Wednesday on a provisional website.
It forced the suspension of astronomical observations, limited its messaging services and took its website offline.
The incident is under investigation by the Chilean police.
Mr Dougherty explained that all of the observatory's critical systems, such as telescope control, archives and the data processor, were repeatedly tested before observations could resume.
"After the recovery of the computer systems, it took a tremendous amount of work to carry out the complete tests," he pointed out.
The Atacama Large Millimeter/submillimeter Array (ALMA), the world's most powerful telescope for observing molecular gases and dust, studies the building blocks of stars, planetary systems, galaxies, and life itself.
It has 66 antennas, located at more than 5,000 meters above sea level, on the Chajnantor plateau, in the Atacama desert, one of the driest places on the planet.
The complex, which began exploring the Universe in 2011, collaborated last April to discover the most distant candidate galaxy ever detected, located 13.5 billion light-years away.
ALMA employs around 300 experts, including 40 computer engineers and technicians in charge of its powerful computers, servers, data storage systems and displays.
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