Your Own 11.2 GHz Radio Telescope

Modern life has its conveniences. Often, those conveniences lead to easier hacks. A great example of that is the rise of satellite television and the impact it has had on amateur radio telescopes. There was a time when building a dish and a suitable low noise amplifier was a big deal. Now they are commodity parts you can get anywhere.

The antenna in use is a 1.2-meter prime focus dish. Some TV dishes use an offset feed, but that makes it harder to aim for use in a radio telescope. In addition to off-the-shelf antenna and RF components, an AirSpy software-defined radio picks up the frequency-shifted output from the antenna. There is more about the software side of the build in a follow-up post. We liked that this was a pretty meaty example of using GNU Radio.

Continue reading “Your Own 11.2 GHz Radio Telescope”

SpaceAusScope Team Listens To The Galaxy

Australia has always had a reputation for astronomy. It is a great site low in the Southern hemisphere and there are lots of sparsely inhabited areas free from light and radio interference. Some of the first video from the Apollo 11 landing, for example, came in from “the dish” — a very large radio telescope down under. Australian hobbyists have formed a group, SpaceAusScope, where teams across Australia are building radio telescopes with the plan — which has been delayed by the pandemic — of collecting data and providing it for public analysis.

A secondary goal of the group is to provide better documentation for amateur radio telescope builders. So even if you don’t live in Australia, you might want to check out their website. It looks as thoughthe documentation will arrive in the future, but there is a very informative blog post from one team member about the helical antenna design most of the teams are using to eavesdrop on the hydrogen line.

Continue reading “SpaceAusScope Team Listens To The Galaxy”

The Wow! Signal And The Search For Extraterrestrial Intelligence

On a balmy August evening in 1977, an enormous radio telescope in a field in the middle of Ohio sat silently listening to the radio universe. Shortly after 10:00 PM, the Earth’s rotation slewed the telescope through a powerful radio signal whose passage was noted only by the slight change in tone in the song sung every twelve seconds by the line printer recording that evening’s data.

When the data was analyzed later, an astronomer’s marginal exclamation of the extraordinarily powerful by vanishingly brief blip would give the signal its forever name: the Wow! Signal. How we came to hear this signal, what it could possibly mean, and where it might have come from are all interesting details of an event that left a mystery in its wake, one that citizen scientists are now looking into with a fresh perspective. If it was sent from a region of space with habitable planets, it’s at least worth a listen.

Continue reading “The Wow! Signal And The Search For Extraterrestrial Intelligence”

Eulogy To Arecibo: With Demise Of A Unique Scientific Facility, Who Will Carry The Torch?

Few telescopes will get an emotional response from the general public when it is ultimately announced that they will be decommissioned. In the case of the Arecibo Observatory in Arecibo, Puerto Rico, the past months has seen not only astronomers but also countless people across the world wait with bated breath after initial reports of damage to the radio telescope’s gigantic dish.

When the National Science Foundation announced that they would be decommissioning the telescope, there was an understandable outpouring of grief and shock. Not only is Arecibo a landmark in Puerto Rico, it is the telescope from iconic movies such as GoldenEye (1995) and Contact (1997). Its data fed public programs such as the Seti@Home and Einstein@Home projects.

Was Arecibo’s demise truly unavoidable, and what does this mean for the scientific community?

Continue reading “Eulogy To Arecibo: With Demise Of A Unique Scientific Facility, Who Will Carry The Torch?”

Hackaday Links: October 18, 2020

Remember subliminal advertising? The idea was that a movie theater operator would splice a single frame showing a bucket of hot buttered popcorn into a movie, which moviegoers would see and process on a subconcious level and rush to the concession stand to buy the tub o’ petrochemical-glazed starch they suddenly craved. It may or may not work on humans, but it appears to work on cars with advanced driver assistance, which can be spoofed by “phantom street signs” flashed on electronic billboards. Security researchers at Ben Gurion University stuck an image of a stop sign into a McDonald’s ad displayed on a large LCD screen by the side of the road. That was enough to convince a Tesla Model X to put on the brakes as it passed by the sign. The phantom images were on the screen anywhere from an eighth of a second to a quarter second, so these aren’t exactly subliminal messages, but it’s still an interesting attack that bears looking into. And while we’re skeptical about the whole subliminal advertising thing in the first place, for some reason we really want a bacon cheeseburger right now.

Score one for the good guys in the battle against patent trolls. Mycroft AI, makers of open-source voice assistants, proudly announced their latest victory against what they claim are patent trolls. This appears to be one of those deals where a bunch of investors get together and buy random patents, and then claim that a company that actually built something infringes on their intellectual property. Mycroft got a letter from one such entity and decided to fight it; they’ve won two battles so far against the alleged trolls and it looks pretty good going forward. They’re not pulling their punches, either, since Mycroft is planning to go after the other parties for legal expenses and punitive damages under the State of Missouri’s patent troll legislation. Here’s hoping this sends a message to IP squatters that it may not be worth the effort and that their time and money are better spent actually creating useful things.

Good news from Mars — The Mole is finally completely buried! We’ve been following the saga of the HP³, or “Heat Flow and Physical Properties Package” aboard NASA’s Mars InSight lander for quite a while. The self-drilling “Mole”, which is essentially the guts of an impact screwdriver inside a streamlined case, has been having trouble dealing with the Martian regolith, which is simultaneously too soft to offer the friction needed to keep the penetrator in its hole, but also too hard to pierce in places where there is a “duricrust” of chemically amalgamated material below the surface. It took a lot of delicate maneuvers with the lander’s robotic arm to get the Mole back on track, and it’s clearly not out of the woods yet — it needs to get down to three meters depth or so to do the full program of science it was designed for.

If watching Martian soil experiments proceed doesn’t scratch your itch for space science, why not try running your own radio astronomy experiments? Sure, you could build your own radio telescope to do that, but you don’t even have to go that far — just log into PICTOR, the free-to-use radio telescope. It’s a 3.2-m parabolic dish antenna located near Athens, Greece that’s geared toward hydrogen line measurements of the galaxy. You can set up an observation run and have the results mailed back to you for later analysis.

Here’s a fun, quick hack for anyone who hates the constant drone of white noise coming from fans. Build Comics apparently numbers themselves among that crowd, and decided to rig up a switch to turn on their fume extractor only when the soldering iron is removed from its holder. This hack was executed on a classic old Weller soldering station, but could easily be adapted to Hakko or other irons

And finally, if you’ve never listened to a Nobel laureate give a lecture, here’s your chance. Andrea Ghez, co-winner of the 2020 Nobel Prize in physics for her work on supermassive black holes, will be giving the annual Maria Goeppert Mayer lecture at the University of Chicago. She’ll be talking about exactly what she won the Nobel for: “The Monster at the Heart of Our Galaxy”, the supermassive black hole Sagittarius A*. We suspect the talk was booked before the Nobel announcement, so in normal times the room would likely be packed. But one advantage to the age of social distancing is that everything is online, so you can tune into a livestream of the lecture on October 22.

DIY Radio Telescopes Hack Chat

Join us on Wednesday, February 12 at noon Pacific for the DIY Radio Telescopes Hack Chat with James Aguirre!

For most of history, astronomers were privy to the goings-on in the universe only in a very narrow slice of the electromagnetic spectrum. We had no idea that a vibrant and wondrous picture was being painted up and down the wavelengths, a portrait in radio waves of everything from nearly the moment of creation to the movement of galaxies. And all it took to listen in was an antenna and a radio receiver.

Over the years, radio telescopes have gotten more and more sophisticated and sensitive, and consequently bigger and bigger. We’re even to the point where one radio telescope often won’t cut it, and astronomers build arrays of telescopes spread over miles and miles, some with antennas that move around on rails. In the search for signals, radio astronomy has become the very definition of “Big Science.”

But radio astronomy doesn’t have to be big to be useful. James Aguirre, an astronomer at the University of Pennsylvania, spends his days (and nights) studying the radio universe with those big instruments. But he’s also passionate about down-scaling things and teaching everyone that small radio telescopes can be built on the cheap. His Mini Radio Telescope project uses a cast-off satellite TV dish and a couple of hundred bucks worth of readily available gear to scan the skies for all sorts of interesting phenomena.

Dr. Aguirre will join us on the Hack Chat to discuss all things radio astronomy, and how you can get in on the radio action on the cheap. Chances are good your junk pile — or your neighbor’s roof — has everything you need, and you might be surprised how approachable and engaging DIY radio astronomy can be.

join-hack-chatOur Hack Chats are live community events in the Hack Chat group messaging. This week we’ll be sitting down on Wednesday, February 12 at 12:00 PM Pacific time. If time zones have got you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about. Continue reading “DIY Radio Telescopes Hack Chat”

Roofing Radio Telescope Sees The Galaxy

[David Schneider] asked himself, “How big a radio antenna would you need to observe anything interesting?” The answer turns out to be a $150 build of a half meter antenna. He uses it to detect the motions of the spiral arms of the Milky Way. The first attempt was a satellite TV dish and a cantenna feed, which didn’t work as the can wasn’t big enough to pick up signals at the 21cm wavelength of hydrogen emissions. Interstellar gas clouds are known to emit radio energy at this frequency.

Looking online, [David] tried aluminized foam board insulation, but was worried that the material didn’t seem to actually be conductive. A quick thrown-together Faraday cage with a cell phone didn’t seem to block any calls. Abandoning that approach, he settled on aluminum flashing used for roofing.

Continue reading “Roofing Radio Telescope Sees The Galaxy”