ALMA is approaching completion of its originally envisaged capabilities and, within the first five years of operations, the original fundamental science goals of ALMA have been essentially achieved. The ALMA Board established a Working Group to develop a strategic vision and prioritize new capabilities for the Observatory out to 2030 as part of the ALMA Development Program. The ALMA Board approved the resulting ALMA Development Roadmap in November 2017. The document is a summary of the Roadmap, approved by the Board in June 2018 for broad distribution.
According to the vision in the Board-approved Roadmap, the current development priorities as based on scientific merit and technical feasibility, are:
• To broaden the receiver IF bandwidth by at least a factor two, and
• To upgrade the associated electronics and correlator.
These developments will advance a wide range of scientific studies by significantly reducing the time required for blind redshift surveys, spectral scans, and deep continuum surveys. In order of scientific priority, receiver upgrades are recommended for intermediate (200-425 GHz), low (< 200 GHz), and high (> 425 GHz) frequencies.
The Board acknowledges that there are other potential development areas for the future for which the science cases and technical feasibility need to be further demonstrated. These areas include:
• To extend the maximum baseline length by a factor of 2-3
• To enhance the wide-field mapping speed by developing focal plane arrays.
