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Physics + MathPhysics & Math

Build Your Own Radio Telescope

ByTim De ChantNOVA NextNOVA Next
CARMA Radio Telescope
A DIY radio telescope won't have the power of the CARMA Radio Telescope seen here, but you'll have a view of the sky shared by few others.

In 2010, on the far northern part of New Zealand’s North Island, a satellite dish was unceremoniously decommissioned and scheduled for demolition. But thanks to pluck of a few scientists, the anticipated death of the dish ended up giving radio astronomy on the island new life.

Lewis Woodburn, who is in charge of maintenance for Auckland University of Technology’s radio telescope, and his colleagues smelled opportunity when they heard of the decommissioning and convinced Telcom New Zealand to transfer ownership of the dish over to their department. At 30 meters, Telcom New Zealand’s dish was substantially larger than the 12-meter dish already operated by the university. If they could successfully repurpose it, the new, larger dish would boost their capabilities in radio astronomy.

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It wasn’t easy, though. Technology Review details their struggles in getting the 30-meter dish operational:

What they inherited was a far cry from a state-of-the-art radio telescope. The dish is located near a remote township in the very north of New Zealand’s North Island. Being only five kilometers from the sea, salt corrosion was significant issue, particularly given the lack of recent maintenance.

So the team’s first task was to clean the dish service and replace rusty bolts and equipment. In particular, the motors that move the dish had become rusted and in any case were old and inefficient.

That’s not all; Technology Review’s Emerging Technology From the arXiv blog goes into more detail . After a series of refurbishment and upgrades, the new dish is finally a bonafide radio telescope, though it still needs a bit more work to give it the capabilities astronomers at Auckland University of Technology want.

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This clever repurposing of an old telecommunications dish led to an inevitable question: Can anyone build their own radio telescope? The answer, I discovered, is yes.

There are a few blog posts that detail people’s experiments with refitting old satellite TV dishes for radio telescope duty, but they vary in their level of detail. Fortunately, Jeff Lashley goes into great detail in a chapter titled “Microwave Radio Telescope Projects.” ( pdf ) He explains how to convert a compact satellite dish into a radio telescope and how to hook it up to software developed at MIT for a similar purpose. With all the parts in place, you can do things like observe radio waves emitted by the sun or study how the ionosphere affects those same emissions.

A home-built radio telescope may not be as sensitive as the Very Large Array, but you’ll still be able to study the stars in ways few people can.