Radio antennas at the Atacama Large Millimeter/submillimeter Array have stopped gathering data because of a workers' strike. Credit: ALMA (ESO/NAOJ/NRAO), C. Padilla

Less than half a year after the inauguration of a US$1.4-billion radio telescope array in Chile, astronomical observations have ceased because of a labour strike.

Work at the Atacama Large Millimeter/submillimeter Array (ALMA) ground to a halt on 22 August after contract negotiations broke down with the local workers’ union. Many of the 195 striking employees remain at the operations-support facility, a hub more than halfway up the 5,000-metre-high Chajnantor plateau in Chile’s Atacama Desert. Most staff astronomers, who are not part of the union, have left.

Science observations have stopped, although data analysis continues off site. In an e-mail to ALMA users, observatory director Pierre Cox warned that the strike poses “challenges” for ALMA’s current set of scheduled observations, known as cycle 1. Cycle 1 began in January using about half of the array’s planned 66 telescope dishes. “I do not anticipate and will do my utmost to prevent the delay of Cycle 2,” Cox wrote. Cycle 2 observations were to begin in June 2014 and use more of the array’s dishes.

The dispute is over how to replace a three-year collective contract that expired on 13 August. On 1 July, a union representing nearly 80% of the Chileans who work at ALMA proposed terms for the new contract that asked for pay rises, bonuses and shorter work shifts. The employees on strike include engineers, data managers and administrative staff.

 “What we attempted to put into the collective contract was similar working conditions to the other international observatories located here in Chile,” says Victor Gonzalez, a software engineer at ALMA and president of the union. For instance, Gonzalez says, ALMA has 12-hour shifts and 45-hour weeks, whereas other observatories have 11-hour shifts and 40-hour weeks.

On the other side of the bargaining table is Associated Universities Incorporated (AUI), a corporation based in Washington DC that is the legal employer of ALMA’s Chilean staff. The AUI says that it has commissioned surveys on salaries in Chile and that ALMA’s are well within the local market. Several rounds of negotiation and mediation have failed.

The strike came just as ALMA workers were poised to complete the installation of the last few telescope dishes, expected by the end of 2013. Already the observatory is generating powerful results. By studying the faint glow of cool gas, astronomers are using ALMA to discover the birthplaces of giant stars and show how winds associated with stellar nurseries affect the evolution of galaxies.

In May the observatory announced that array testing was going so well that the call for cycle 2 proposals would go out in October, with a submission deadline of December. Ethan Schreier, president of the AUI, says that plans for those observations should move forward in spite of the strike. “Astronomers should continue to prepare for using ALMA,” he says.

But no observations will be made until the impasse is broken. Striking workers are camping out in their rooms at the ALMA operations building, and the mood is said to be extremely tense. Although the AUI is directly responsible for the labour contracts, ALMA has a complex management structure that involves three primary partners: the European Southern Observatory, the US National Radio Astronomy Observatory and the National Astronomical Observatory of Japan.

The labour union and the AUI are likely to return to the bargaining table soon, driven by the workers’ need to be paid and the AUI’s need to get ALMA up and running again. Gonzalez says that everyone will benefit from improvements in working conditions. “It should be possible to fix this,” he says.