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17-Year-Old Radio Astronomy Mystery Traced Back To Kitchen Microwave
New submitter Bo'Bob'O writes: The BBC reports that the scientists at the Parkes and Bleien Radio Observatories in New South Wales, Australia, have tracked down earth-based signals that had been eluding observation for 17 years. These signals, which came to be called Perytons "occurred only during office hours and predominantly on weekdays." The source, as it turned out, was located right inside the antenna's tower where impatient scientists had been opening the kitchen microwave door before its cycle had finished. As the linked paper concludes, this, and a worn magnetron caused a condition that allowed the microwaves to emit a burst of frequencies not expected by the scientists, only compounding the original mystery.
I'd like to know which brand of microwave lasts 17 years?
Thar she blows! Typo off the starboard bow! Give it the trusty nitpick, er, harpoon...
I'm surprised that the paper (http://arxiv.org/pdf/1504.02165v1.pdf) required 15 co-authors. It seems like the sort of thing I'd give to an undergrad to write once somebody figured it out...
...and it takes a finite amount of time for the capacitors to discharge and the transformer fields to collapse.
"National Security is the chief cause of national insecurity." - Celine's First Law
An 8ms (falling phase of the 60hz power cycle) broad-spectrum burst of microwaves from a tired old oven won't cause even the slightest bit of damage to you.
It's my observation that many who become masters of one field are usually below average in several others. I've even known people with PhD degrees in work that requires a field component (paleo, anthro, geo, archeo) that have trouble actually operating in the field, like maintaining a safe distance driving off-road and not ditching the truck.
The best practice is to assume that they're experts in only their field, and to simply not judge in others. Though in this instance, you'd think that since they work with equipment that receives microwaves, and they're using a consumer appliance that emits microwaves that's even called a microwave, that they'd have figured that putting a microwave appliance in any proximity to the microwave receiver would be a bad idea.
Do not look into laser with remaining eye.
I told you the Burrito Nebula wasn't real
Table-ized A.I.
I worked at Jodrell Bank (the largest radio telescope in the UK) for a summer almost 10 years ago, and their on-site kitchen microwave was surrounded by a Faraday cage to prevent the microwave from interferring with signals picked up by the telescope.
To imply that astronomers had no idea that the microwave could be responsible is just a lie, this is a well-known problem that was solved a long time ago.
A professor once told the class he was tasked with finding the source of intermittent "garbage" characters emanating from a data entry work-station. After checking and swapping all the hardware, IT staff couldn't find the cause. So he sat to observe the work-station in action. Turns out the data entry lady had large bosoms that occasionally bumped the keyboard.
Table-ized A.I.
Power is killed, but the magnetron keeps spinning and some microwaves can escape.
Magnetrons don't spin. The electrons in a magnetron spin (all electrons have spin) and they circulate in a cylindrical chamber. The magnetron itself doesn't move and it has no moving parts to "keep spinning".
The frequency is determined for the most part by the physical dimensions of the magnetron (effectively forming an LC circuit), but the frequency will "chirp" as the voltage on the tube changes. That's the source of the "FRB" (fast radio burst) they were seeing.
An interesting comment in the reference is that the cavity looks like the rotating part of a revolver, and was first manufactured by using a revolver die.
Best to hit the stop button and wait a second before opening the door.
The door button on all the microwaves I've used unlatches the door and triggers the interlock, but you still have to pull the door open. If you're so impatient that you can get the door open after hitting the button before the supply voltage to the magnetron drops below operating levels, you maybe ought to eat the raviolis or chili cold out of the can.
I had a friend who was bemoaning how his "crappy" AT&T DSL service would flake out every evening at about the same time, and he'd had techs out to replace his DSL modem twice, re-do the wiring to his house, everything! He asked me whether I was happy with TWC (I wasn't), because he was fed up and was going to switch.
We got talking in general. I asked him whether he'd also done any renovating around his house, no matter what type. He admitted that he'd recently replaced all of his exterior house lights with CFL equivalents, and I asked him whether any were on timers, sensors, etc. He admitted that there was an exterior flood light on a light sensor.
I asked him if that sensor turned on that lamp about the same time of day his DSL service flaked out. His expression dropped. He replaced that one light with an incandescent, and the problem went away.
I'll go shoot myself now.
"To those who are overly cautious, everything is impossible. "
well it's basically the better versed someone is in a specific domain, they get hit with the double whammy of getting out of practice in everything else, while maintaining the delusion that they are masters in anything they attempt.
Linus Pauling later in his career is a /fantastic/ example of this.
They did not spend millions of dollars looking for the microwave oven,
Time on a radio telescope and the associated equipment (including supercomputer time) is not free. Perhaps a bit of hyperbole, but not excessive considering the venue of my comment.
and they knew all along that the signal was man-made.
I'll yield on that one. The paper says the properties of the signal "suggested" it was in the near field. It was only TFA (BBC) that says:
Figuring out precisely which item made it is the kind of thing that gets you in the newspapers,
Figuring out that a microwave oven generated microwave signals picked up by a microwave antenna at the same building may make the newspapers in Australia, but in advanced countries it wouldn't. OTH, we do have to own the idea that people in the US don't seem to understand that cell phones use radio waves, so nobody is completely innocent. The difference is that these are radio astronomy scientists and the cell-phone ignoramii are mostly Joe Sixpack and his cousin Bubba types.
Can you begrudge them their 15 minutes of fame?
You think someone becomes famous because they discover the obvious? You ought to read the paper. It's a hoot.
First, they used a communications receiver with a directional antenna that made a full circle every 20 minutes and obtained 0.1 sec of data at any given frequency. That they thought this receiver would observe RFI that lasts for 200ms and occurs rarely (three events during Jan-Mar 2015) is, well, not flattering to their experiment design qualifications.
Then they tested three microwaves at three locations by looking for emissions while heating a cup of water for 10 - 60s. Interestingly, they found perytons during this test. What they couldn't figure out is how the microwave they were testing at the time could have gotten a signal to the antenna -- it was blocked. A real puzzler. Then they found out that they had forgotten their control protocol for the experiment. Someone was using one of the other two microwave ovens while they were testing the third. Basic science: if you want to test object A for causality, you don't allow object B to be used at the same time. Corollary 1: if you're just going to come up with reasons why the observations were impossible, why bother making them in the first place?
Long story short: a facility that needs to avoid RFI at microwave frequencies took no precautions to avoid RFI at microwave frequencies and spent a lot of time (where the Beeb comes up with 17 years I can't determine) trying to figure out where the RFI they were seeing came from, and quite a bit of time analyzing what they knew was RFI so they could distinguish what they already knew was RFI from signals they already know are galactic in origin.
Anyone who knows that radio waves aren't magic and that microwave ovens are called microwave ovens because they use microwave radiation is scratching his head wondering why they didn't just get rid of the microwave ovens 17 years ago and not put 17 years worth of scientific research into galactic radio phenomena in jeopardy. The fact that they now have to defend the observations of FRB as real could have been prevented by one simple rule: no sources of RF on site. That they've publicly admitted they didn't take this obvious, basic preventative measure isn't "fame".
us geeks typically have insufficient exposure to the subject matter to perfect those sorts of details
Table-ized A.I.
Older than that perhaps.
Some ~20 years ago we visited the Tidbinbilla tracking station near Canberra, Australia. At that time they had a small snack-bar outside and not too far from the main entrance. Black Cat comes to mind as the name of the snack-bar but it was a long time ago! The snack bar had the usual foods and a customer-use microwave oven for warming them.
Before using the oven I glanced inside, looking particularly at the roof of the oven. I was not at all surprised to see the oven roof was rusted out and had a gaping hole the size of my palm where there should have been a perforated grating as an RF shield. I knew that oven well - We had one exactly like it and it too had also rusted out in the roof and been repaired under warranty.
The absurdity of a largely unshielded 650 watt microwave source operating in close proximity to super sensitive space tracking equipment was not lost on me and as soon as we returned home to Melbourne I telephoned the site and finally spoke to someone technical that realised the gravity of the situation. They never called me back, which was disappointing, but I can guess the Sharp oven hit the garbage pile the same day.
For the benefit of those that seek more detail, the oven was a Sharp model R8320 microwave/convection oven and was a popular model of the period. The cooking cavity was stainless steel except for the roof. Why that was made of mild steel is anyone's guess but it must have cost Sharp a pretty penny to replace those cavities
Perytons are just bursts, this oven could have caused minutes long tracking equipment wipe-outs.