Peering into the most distant parts of the universe will become considerably cheaper, with the development of a low-cost way to connect widely separated instruments. The success is good news for the giant Square Kilometre Array (SKA) telescopes whose construction will start in Australia and South Africa this year, which are intended to eventually be connected to sites the width of a continent away.
Radio astronomy has made major advances by linking up multiple telescopes into arrays, such as the famous Very Large Array that featured in Contact. When operated together, Professor Ken Baldwin of the Australian National University explained to IFLScience, these provide as much angular resolution as if they were a single giant telescope, with a dish as large as the distance between the most distant elements.
However, Baldwin noted, this only works if the telescopes are perfectly synchronized so that as electromagnetic waves arrive at each we can see how they are changing in real time, relative to each other.
With multiple telescopes located at a single site, synchronization is a solved problem. However, as astronomers have got more ambitious they have sought to link telescopes hundreds or thousands of kilometers apart. The SKA telescopes will initially consist of hundreds of low and medium frequency telescopes located together at sites in Western Australia and South Africa's Karoo respectively.
However, the intention is to subsequently dot dozens of mid-frequency telescopes across southern Africa and low-frequency devices over Australia, possibly as far as New Zealand, which will be linked to the primary site, creating telescopes Baldwin described as being able to “Detect faint radio waves from deep space with a sensitivity about 50 times greater than that of the Hubble telescope.” The capacity will be put to use seeking dark matter, dark energy, and extraterrestrial intelligence among other great mysteries.
To achieve synchronization, however, it was anticipated that each site would need an atomic clock. At a cost of around $200,000 each, the need to put a clock at the site of every telescope would make a non-trivial contribution to the cost of this project. The savings will increase the chance of making even more powerful instruments.
However, in Optica, Baldwin has announced the success of a project to send stable frequency signals by laser through a fiber optic network allowing the receiver to keep time as accurately as if it was next to the source. Most importantly, the signal can be carried over ordinary telecommunications fibers. “By running the experiment on optical fibers also carrying normal traffic, we showed that transmitting the stable frequency standard doesn’t affect the data or telephone calls on the other channels,” Baldwin said in a statement.