This staggering performance is made possible through 189 sensors, known as charge-coupled devices (CCDs) that each measure 16 megapixels. The CCDs are packaged into units called “rafts,” which make up the camera’s focal plane. There are 21 rafts, plus four specialty rafts not used for imaging. Altogether, the focal plane contains 3.2 billion pixels. Each of the rafts, worth up to $3 million apiece, were inserted into a grid for the focal plane over six “nerve-wracking” months. 

Thankfully, the 3,200 megapixel images are the result of the sensors passing an important first test. While some higher-stakes phases of the project are behind them, the team still has challenging work to do in building the rest of the camera. Final testing is expected to start mid-2021.