Damage To Arecibo Leaves Gaping Hole In Astronomy

In the early morning hours of August 10th, a support cable at the Arecibo Observatory pulled lose from its mount and crashed through the face of the primary reflector below. Images taken from below the iconic 305 meter dish, made famous by films such as Contact and GoldenEye, show an incredible amount of damage. The section of thick cable, estimated to weigh in at around 6,000 kilograms (13,000 pounds), had little difficulty tearing through the reflector’s thin mesh construction.

Worse still, the cable also struck the so-called “Gregorian dome”, the structure suspended over the dish where the sensitive instruments are mounted. At the time of this writing it’s still unclear as to whether or not any of that instrumentation has been damaged, though NASA at least has said that the equipment they operate inside the dome appears to have survived unscathed. At the very least, the damage to the dome structure itself will need to be addressed before the Observatory can resume normal operations.

The Arecibo Observatory by JidoBG [CC-BY-SA 4.0]
But how long will the repairs take, and who’s going to pay for them? It’s no secret that funding for the 60 year old telescope has been difficult to come by since at least the early 2000s. The cost of repairing the relatively minor damage to the telescope sustained during Hurricane Maria in 2017 may have been enough to shutter the installation permanently if it hadn’t been for a consortium led by the University of Central Florida. They agreed to share the burden of operating the Observatory with the National Science Foundation and put up several million dollars of additional funding.

It’s far too early to know how much time and money it will take to get Arecibo Observatory back up to operational status, but with the current world situation, it seems likely the telescope will be out of commission for at least the rest of the year. Given the fact that repairs from the 2017 damage still haven’t been completed, perhaps even longer than that. In the meantime, astronomers around the globe are left without this wholly unique resource.

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Faux Radar Uses Ultrasound & Python

Radars are simply cool, and their portrayal in movies and TV has a lot to do with that. You get a sweet glowing screen that shows you where the bad guys are, and a visual representation of your missiles on their way to blow them up. Sadly, or perhaps thankfully, day to day life for most of us is a little less exhilarating. We can make do with a facsimile of the experience instead.

The project consists of an Arduino Uno outfitted with an ultrasound module that can do basic range measurements on the order of tens of centimeters. The module is then placed on a servo and scanned through a 180 degree rotation. This data is passed back to a computer running a Python application, which plots the results on a Plan Position Indicator, or PPI – the sweeping display we’re all so familiar with.

While it’s unlikely you’ll be using such a setup to engage bandits, it could prove as a useful module for robot navigation or similar applications. We’ve seen ultrasonic transducers used for exactly that. Video after the break.

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Wind Farms In The Night: On-Demand Warning Lights Are Coming

There appears to be no shortage of reasons to hate on wind farms. That’s especially the case if you live close by one, and as studies have shown, their general acceptance indeed grows with their distance. Whatever your favorite flavor of renewable energy might be, that’s at least something it has in common with nuclear or fossil power plants: not in my back yard. The difference is of course that it requires a lot more wind turbines to achieve the same output, therefore affecting a lot more back yards in total — in constantly increasing numbers globally.

Personally, as someone who encounters them occasionally from the distance, I find wind turbines mostly to be an eyesore, particularly in scenic mountainous landscapes. They can add a futuristic vibe to some otherwise boring flatlands. In other words, I can not judge the claims actual residents have on their impact on humans or the environment. So let’s leave opinions and emotions out of it and look at the facts and tech of one issue in particular: light pollution.

This might not be the first issue that comes to mind when thinking about wind farms. But wind turbines are tall enough to require warning lights for air traffic safety, and can be seen for miles, blinking away in the night sky. From a pure efficiency standpoint, this doesn’t seem reasonable, considering how often an aircraft is actually passing by on average. Most of the time, those lights simply blink for nothing, lighting up the countryside. Can we change this?

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Teardown: Cobra XRS 9740 Radar Detector

Drivers with a lead foot more often than not have Waze open on their phone so they can see if other drivers have spotted cops up ahead. But avoiding a speeding ticket used to involve a lot more hardware than software. Back before the smartphone revolution, that same driver would have had a radar detector on their dashboard. That’s not to say the gadgets are completely unused today, but between their relatively high cost (one of the top rated models on Amazon as of this writing costs over $300) and the inevitable false positives from so many vehicles on the road having their own radar and LIDAR systems, they’ve certainly become a less common sight over the years

The subject of today’s teardown is a perfect example of “Peak Radar Detector”. Manufactured back in 2007, the Cobra XRS 9740 would have been a fairly mid-range entry offering the sort of features that would have been desirable at the time. Over a decade ago, having an alphanumeric display, voice alerts, and a digital compass were all things worth shouting about on the box the thing was sold in. Though looking like some kind of Cardassian warship was apparently just an added bonus.

As the name implies these devices are primarily for detecting radar activity, but by this point they’d also been expanded to pick up infrared lasers and the strobe beacons on emergency vehicles. But false positives were always a problem, so the device allows the user to select which signals it should be on the lookout for. If you were getting some kind of interference that convinced the detector it was being bombarded with IR lasers, you could just turn that function off without having to pull the plug entirely.

But it’s important to remember that this device was built back when people were still unironically carrying around flip phones. Detecting laser and multi-band radars might sound like something pulled from the spec sheet of a stealth fighter jet, but this is still a piece of consumer electronics from more than a decade in the past. So let’s crack it open and take a look at what goes on inside a radar detector that’s only a few years away from being old enough to get its own driver’s license.

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Just How Can You Lose Something The Size Of A Cargo Ship?

I’m writing from a cozy farmhouse just outside of Oxford, UK where we are slowly emerging from a particularly intense Atlantic storm. Some areas have widespread flooding, while fallen tree branches and damaged roofs are countrywide. Our neighbours in the Irish Republic are first in the path of these storms, and receive an especially strong pasting.

In the news following the storm is a merchant ship that was washed up by this storm on the coast of County Cork. The MV Alta  is a nearly 2300t and 77m (just over 253 ft) freighter that had been abandoned in 2018 south of Bermuda after a mechanical failure had rendered it incapable of navigation. Its crew had been rescued by the US Coast Guard, and since then — apart from a brief sighting in mid-Atlantic by a Royal Navy polar research vessel — it had passed unseen as a drifting ghost ship before appearing on the Irish coast.

In a very literal sense it had dropped off the radar, but the question for us is how? With the huge array of technological advances in both navigation aids and global sensing available at the end of the 21st century’s second decade, should that even be possible? It’s worth taking a while as land-lubbers to look at how ships are tracked, to try to make sense of the seeming invisibility of something that is after all pretty large and difficult to hide.

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Keep An Eye On The Neighborhood With This Passive Radar

If your neighborhood is anything like ours, walking across the street is like taking your life in your own hands. Drivers are increasingly unconcerned by such trivialities as speed limits or staying under control, and anything goes when they need to connect Point A to Point B in the least amount of time possible. Monitoring traffic with this passive radar will not do a thing to slow drivers down, but it’s a pretty cool hack that will at least yield some insights into traffic patterns.

The principle behind active radar – the kind police use to catch speeders in every neighborhood but yours – is simple: send a microwave signal towards a moving object, measure the frequency shift in the reflected signal, and do a little math to calculate the relative velocity. A passive radar like the one described in the RTL-SDR.com article linked above is quite different. Rather than painting a target with an RF signal, it relies on signals from other transmitters, such as terrestrial TV or radio outlets in the area. Two different receivers are used, both with directional antennas. One points to the area to be monitored, while the other points directly to the transmitter. By comparing signals reflected off moving objects received by the former against the reference signal from the latter, information about the distance and velocity of objects in the target area can be obtained.

The RTL-SDR test used a pair of cheap Yagi antennas for a nearby DVB-T channel to feed their KerberosSDR four-channel coherent SDR, a device we last looked at when it was still in beta. Essentially four SDR dongles on a common board, it’s available now for $149. Using it to build a passive radar might not save the neighborhood, but it could be a lot of fun to try.

Quantum Radar Hides In Plain Sight

Radar was a great invention that made air travel much safer and weather prediction more accurate, indeed it is even credited with winning the Battle of Britain. However, it carries a little problem with it during times of war. Painting a target with radar (or even sonar) is equivalent to standing up and wildly waving a red flag in front of your enemy, which is why for example submarines often run silent and only listen, or why fighter aircraft often rely on guidance from another aircraft. However, researchers in Italy, the UK, the US, and Austria have built a proof-of-concept radar that is very difficult to detect which relies upon quantum entanglement.

Despite quantum physics being hard to follow, the concept for the radar is pretty easy to understand. First, they generate an entangled pair of microwave photons, a task they perform with a Josephson phase converter. Then they store an “idle” photon while sending the “signal” photon out into the world. Detecting a single photon coming back is prone to noise, but in this case detecting the signal photon disturbs the idle photon and is reasonably easy to detect. It is likely that the entanglement will no longer be intact by the time of the return, but the correlation between the two photons remains detectable.

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