WSU Program

WSU Program

Status as of October 2024

The Wideband Sensitivity Upgrade (WSU) is well underway, with key subsystems under development, including new receivers, digitizers, other parts of the wideband IF processor, a data transmission system, and a correlator. At the same time, the observatory is developing a detailed implementation plan through a careful project management and systems engineering approach based on an integrated Conceptual System Design, which outlines the upgrade's hardware, computing, and science operations aspects. The substantial improvements in the observing efficiency enabled by the WSU will further enhance ALMA as the world-leading facility for millimeter/submillimeter astronomy.

Definition of the WSU System and Program Plan

The WSU program began with an initiation phase (2019-2022), during which the observatory and the community evaluated enabling technologies and established top-level goals based on the achievements of previous scientific and technical research. This phase concluded with an initial Conceptual System Design Description (CoSDD), which focused on hardware and updates of the ALMA System Technical Requirements (STR). These efforts laid the groundwork for subsystem development. 

From 2022 to 2024, in parallel with hardware development, efforts focused on assessing the WSU's impact on software, computing infrastructure, and science operations. An updated design was proposed, incorporating these elements to provide the first integrated description of the full WSU system. This update also includes a deployment strategy designed to minimize disruptions to scientific observations. These efforts led to further refinement of the ALMA system-level requirements and the creation of an Initial Program Plan, which was positively reviewed by an external panel in July 2024.

The remainder of 2024 will focus on defining the initial plan for the Assembly, Integration, Verification, and Commissioning (AIVC), preparing the transition plan to WSU operations, and refining the WSU System Design. Key upcoming milestones include a System & Program Plan Review in July 2025.

A staged approach

The WSU System will offer improvements even during the deployment phase. As such, ALMA has set initial scientific priorities for early WSU observations and defined an initial WSU user release, which will implement high-priority observing modes with the 12m array as soon as at least 36 antennas have been upgraded. The goal is to offer initial WSU scientific observations by the end of the decade.

Implementation efforts will continue until the capabilities to meet the WSU goals are in place as early as possible in the 2030s. Based on priorities, additional capabilities, such as additional receiver upgrades, will be introduced through the ALMA Development Program in subsequent years. These plans will be shared with the scientific community as they become available.

Progress toward implementation

WSU Signal Chain and related infrastructure

Most ALMA Development Projects for the various parts of the WSU signal chain, which connect the receivers with the Advanced Technology ALMA Correlator (ATAC) and the new Total Power GPU Spectrometer (TPGS), are advancing through the design process.

  • Wideband IF Processor (WIFP): The WIFP includes the new IF switch, other IF components, digitizers, and the digital signal processing / optical transmission (DSP/OT) subsystem. The design is advancing towards a Preliminary Design Review.
  • Data Transmission System (DTS): This subsystem transmits data from each antenna to the new OSF Correlator Room. The design has passed its Preliminary Design Review and is proceeding toward the Critical Design Phase.
  • New AOS-OSF Fiber Optic infrastructure: This project is in the final stages of definition and will commence soon.
  • OSF Correlator Room (OCRO): The design has passed its Preliminary Design Review and is proceeding toward the Critical Design Phase.
  • Advanced Technology ALMA Correlator (ATAC): The 2nd Generation Correlator design has passed its Preliminary Design Review and is now in the Critical Design Phase.
  • Total Power GPU Spectrometer (TPGS): The design of the 2nd Generation Spectrometer for the ALMA Total Power array is in the final stages of definition and will soon undergo a Conceptual Design Review and Requirement Review.

Receivers

Band 2 (67-116 GHz): The first wideband receiver (2-18 GHz) is currently under construction phase, and the first receivers are being integrated into the telescope.

Band 6 version 2 (209-281 GHz): The receiver design is proceeding towards PDR in 2025.

Band 8 version 2 (385-500 GHz): The receiver design is proceeding towards PDR in 2025.