DISH has continued to make strong progress since last reporting in December and, at time of writing, all Detailed Design Reviews (DDRs) relevant for Bands 1 and 2 have been conducted although a few issues for resolution remain.
December was a busy month with Dish Consortium team members working hard to complete documentation required to closeout the Single Pixel Feed (SPF) Band 2 DDR held at the end of November (since closed out) and to prepare for three additional DDRs.
The Dish Fibre Network (DFN), a small but important subsystem, completed its DDR in early December. DFN passed without reservation and close out documentation has been finalised.
In mid-December, the team convened in China for the critical path subsystem Dish Structure (DS) DDR. The significantly more complicated DS DDR received some 700 OARs, most from non-review panel personnel. The review panel, chaired by Dr Richard Hill, was an extremely experienced group from the UK, Germany, South Africa and Chile and made many constructive recommendations. Although the panel did note that some areas of the design were less mature and identified some issues which were still to be resolved, its recommendation was for DS to commence manufacturing of the dish prototype as soon as possible while those outstanding issues were being resolved. Given the complexity of the DS subsystem and its fundamental importance to SKA-mid, the DDR outcome was very positive.
Since December, DS members have made great progress closing out many open design issues and, at the time of writing, the DS design is well resolved. A particular challenge faced by the DS team was the late resolution of design and cost responsibility for the composite sub-reflector. As Dish Consortium Leader, my deep thanks go to CETC-54 for yet again stepping to the fore and accepting the responsibility for cost, design and development of the sub-reflector, thankfully in concert with DS lead organisation, MT Mechatronics.
Prototype manufacture has begun on several fronts by various Dish subsystem (Sub Element) teams but probably the most striking example is the work done by CETC-54 to build the M1 main reflector moulds. The main dish reflector design will employ 66 fabricated aluminium panels, each requiring high precision vacuum forming. These, in turn, will require 66 moulds. By DS DDR in December 2016, 13 moulds had been built and members of the DS Review Panel and Dish Management team were invited to view the completed moulds as part of the DS DDR (see photo above). By March 2017, there were some 40 moulds built. Again this demonstrates the huge capital investment being made by Dish Structure team members, and CETC-54 especially, during the pre-construction phase.
January was a more relaxed month with most Dish Consortium team members taking some hard earned down time and particularly the Southern Hemisphere members in South Africa and Australia. One more DDR remained, being the Receivers subsystem (SPFRx DDR) for Bands 1 and 2, which was conducted in late January in Victoria, Canada. A stellar review panel team, chaired by Sias Malan from South Africa, performed a deeply constructive review of the design. Although the review panel found no major design problems, and despite the huge effort performed by the SPFRx team at NRC, a number of minor issues led the panel to the decision that a delta review should be held. The delta SPFRx review is nominally anticipated in the May timeframe. This will be preceded in April by a delta DDR for Band 1 feeds. Preparations are currently in progress for both delta reviews.
Also in January, Dish sub-elements submitted their revised construction phase capital cost estimates to Dish Consortium Management, so they could be aggregated and submitted to the SKAO. While it was evident that a fully compliant solution could not be delivered within the current cost cap, a positive side of this costing round was that only a small increase in estimated cost was made and this was accompanied by a small reduction in contingency. This is not surprising given the professionalism of the Dish team and its predominantly industrial makeup.
In February, the Dish Management team attended the SKA Consortium Leaders’ Meeting at SKA Headquarters and provided an update about the great progress being made. The Dish Structure remains on the critical path from a schedule perspective but it was evident that the DS team members were not holding back any effort to succeed. All dish Sub-Elements are working hard to commence construction of the prototype systems so that the SKA-MPI Dish System with see first light at the SKA site in South Africa in late 2017 or early 2018. The first SKA prototype dish, SKA-P, will be erected and mechanically tested in Shijiazhuang, China during Q3 of CY2017.
Overall, remarkable progress from a global and truly professional Dish Consortium Team. Now, where are the spanners?