Since I’ve been away, a lot has been happening in the wide, wild world of radio astronomy. In particular, the location has been chosen for the next generation’s largest telescope, the Square Kilometer Array (or SKA). And, like a quantum cat, it seems that it’ll be in two places at once.
The idea for the SKA goes back to the early 1990s, and possibly even earlier, when astronomers thought it would be pretty sweet to literally have a square-kilometer worth of collecting area. The larger the collecting area, the more sensitive your telescope, thus the fainter the objects you can see. (You can think of it like using a wider bucket to collect more rainwater.)
It’s the 21st century, and technology is finally catching up to the dreams and whims of these astronomers. The SKA has been “The Next Big Thing” for as long as I’ve been kicking around the radio astronomy field, and many sites and constructions were proposed to achieve this goal. From alien-looking “Luneburg lenses” to a “field of Arecibos”, the choices were narrowed down until the somewhat familiar “dishes and dipoles” design would be landing in either South Africa or Australia in the coming decades.
Both countries are building pathfinder, or precursor, telescopes on their candidate sites, both in remote desert locations far, far from human-made radio signals. Both are also host to guest projects, and I was fortunate to spend a few weeks at the South Africa site working on my Ph.D. project. So you can imagine my surprise when it was announced last week that both sites would be chosen to host the project.
I hate to brag, but I called it in, oh, 2005? Okay, really, pretty much everyone in the field was presuming that a dual site would be the outcome. The SKA is a BIG project in terms of money and humanpower, and it’s going to take the full support of many international partners to really get it going. With both contenders having put so much money and effort into their sites and pathfinders so far, who would want to alienate a potentially important collaborator?
As telescopes get larger, it is taking more resources than ever before to get these observatories built. For example, the Atacama Large Millimeter Array has significant participation from the United States, the European Union, and Japan. So it surprised no one when antenna designs were accepted from all three nations to make the array. But would an international collaboration really split a telescope by location like this?
We have our answer now, as the SKA will be located both in Australia and in South Africa. Both sites are excellently suited to host the telescope. It was already becoming clear that two types of antenna design would be needed to cover the entire frequency range desired by SKA. So, naturally, the telescope will be split in this way, with the low frequency antennas at the Australian site and the higher-frequency dishes at the South Africa site.
So, The SKA is including everybody, so everybody wins, right? Well, there are some disadvantages. Most obvious to me would be the duplication of infrastructure costs. Part of the package when you pick a remote site is having to make the site somewhat habitable for the astronomers, engineers, and technicians who will spend at least some of their time there. The telescopes themselves need power and high-speed internet if they are going to do their thing. Putting infrastructure in the middle of the desert takes money, and this will be essentially doubling that particular cost to have two sites. However, I suspect that the rationale is that it is better to have a slightly more expensive telescope than none at all if the project implodes politically.
This isn’t the first time that a single “telescope” is geographically spread over a large area. The Very Long Baseline Array is a set of 10 identical radio dishes spread across North America. However, that particular array has all the data come together to a centralized computer in New Mexico to prepare it for processing. It remains to be seen if the SKA sites will be connected in this way at all, but I suspect not. So is it really one telescope, one single array, or two?
Frankly, I think you can call it whatever you want, as long as it gets people working together to get it built.
Image: Artist’s conception of the SKA dishes under the Milky Way at night. Having seen such a sight in person, it really is that amazing. Credit: SKA Organisation/TDP/DRAO/Swinburne Astronomy Productions.
Note: All opinions are solely my own and do not reflect upon any institutions or projects that I work with or have worked with. In case you forgot.