The SKA will need to store 300 to 1,500 petabytes (1.5 exabytes) of data per year, generating enough raw data to fill 15 million 64GB iPods every day. It wouldn't be cost effective to store that amount of data on hard disk drives, said Eleftheriou, who heads the Storage Technologies Group of IBM's Zurich Research Laboratory. Today, tape costs about $25 per terabyte of capacity.
"Eventually, you store [the data] in files that have to be accessible by scientists around the world. It's similar to what's happening in CERN, but even bigger," Eleftheriou said. "The tape will be used as a deep archive."
On average, the CERN hadron collider stores 15 petabytes of data per year.
The tape cartridges IBM is developing will hold up to 128TB of data each, significantly more than today's technology, which holds about 6TB. In order to increase the capacity, technologists in IBM's Zurich Research Laboratory must increase the areal density of today's tape cartridges by a factor of 10, which Eleftheriou said his team has already proved it can do.
Eleftheriou's team has already demonstrated it can store 29.6Gb of data per square inch of magnetic tape. The team is shooting for 100Gb per square inch in order to achieve the 128TB tape cartridges it is seeking. While latency would be a problem if tapes were stored offsite, tapes stored in a robotic library will be able to be read sequentially, once the beginning of a file is reached. Today's enterprise-class tape drives afford up to 250MBps throughput, more than enough for data hungry scientists.
Construction is expected to start in 2016 and take four years. The exascale supercomputer is expected to be completed by 2024, enabling SKA to be online by 2026, Eleftheriou said.
The actual radio telescope array will be far larger than 1 kilometer. The kilometer in the SKA's name refers to the total collecting area of the SKA, which will be 1 million square meters, according to the SKA website. To achieve this, the SKA will use 3,000 dish antennas, each about 15 meters in diameter as well as two other types of radio wave receptor, know as aperture array antennas. The antennas will be arranged in five spiral arms and the dishes will extend to distances of at least 3,000 kilometers from the center of the long baseline array.
Closeups of the SKA's radio telescope dishes (Source: ASTRON)