How to repair a dented carbon fiber dish

Canada’s National Research Council (NRC, Penticton, British Columbia, Canada) took a big step on May 7 when it successfully mounted the DVA-1 Primary Dish onto its telescope pier. DVA-1 is a prototype antenna for the international Square Kilometre Array (SKA) radio telescope project.

Built just outside of Penticton, the giant radio dish (or reflector), measures 15m/49.2 ft in diameter and weighs in at 8.7 metric tons (with metallic support structure) and is the first of its kind to be made with a single carbon fiber composite structure.

However, it was by luck and composites resiliance that the dish was mounted at all. In October 2013, the dish was being transported to Penticton by helicopter when a sudden gust of wind lifted the dish, causing it to buckle under its weight (see video, above). Gordon Lacy, NRC's lead engineer for the dish, called the accident a "blessing in disguise" as it helped NRC "demonstrate that it could be repaired." The repair occurred in two steps. The first involved the use of industrial bags placed under the dish and inflated to pop the dish back into its original shape. NRC then followed that with a scarfing and bagging process to fix 21 cracks left in the composite structure. In the end, NRC was able to bring the dish back into its specified dimensions, leading to the May 7 installation.

The installation of the dish onto its pedestal is a major step forward for NRC’s SKA prototype antenna. Three prototype antennas are being built by the SKA’s Dish Consortium: DVA-1 in Canada, DVA-C in China, and MeerKAT-1 in South Africa.

The SKA Dish Consortium is responsible for the design and verification of the final SKA dish antenna. The other prototypes have also been moving forward in the past few months. In March, the first MeerKAT antenna was inaugurated in South Africa, and in January, the Chinese partners also made progress by successfully completing the sub-reflector part of their antenna.

In June this year, the Dish Consortium will make a recommendation on the design of the SKA dish configuration. Over the next two years, the three prototypes will be used to test various subcomponents of the dishes. These tests will be fed into the design of the final SKA prototype known as SKA-P, to be ready by the end of 2016.

In its first phase of construction, the SKA will see 190 SKA antennas built in the Karoo (South Africa) alongside the 64 MeerKAT antennas, and 60 antennas will be built in Australia alongside the 36 ASKAP antennas. When the SKA is complete, around 2,000 dishes will spread across Africa.