If you have any astronomer friends you’ll soon discover that theirs is a world of specialist high-quality optical equipment far ahead of the everyday tinkerer, and for mere mortals the dream of those amazing deep space images remains out of reach. It’s not completely impossible for the night sky to deliver impressive imagery on a budget though, as [David Schneider] shows us with a Raspberry Pi powered whole sky camera.
The project was born of seeing a meteor and idly wondering whether meteorite landing sites could be triangulated from a network of cameras, something he quickly discovered had already been done with some success. Along the way though he found the allsky camera project, and decided to build his own. This took the form of a Raspberry Pi 3 and a Pi HQ camera with a wide-angle lens mounted pointing skywards under an acrylic dome. It’s not the Hubble Space Telescope by any means, but the results are nevertheless impressive particularly in a timelapse. We wish there were less light pollution where we live so we could try it for ourselves.
There was a time when putting an object into low Earth orbit was the absolute pinnacle of human achievement. It was such an outrageously expensive and complex undertaking that only a world superpower was capable of it, and even then, success wasn’t guaranteed. As the unforgiving physics involved are a constant, and the number of entities that could build space-capable vehicles remained low, this situation remained largely the same for the remainder of the 20th century.
Nathaniel Evry
But over the last couple of decades, the needle has finally started to move. Of course spaceflight is still just as unforgiving today as it was when Sputnik first streaked through the sky in 1957, but the vast technical improvements that have been made since then means space is increasingly becoming a public resource.
Thanks to increased commercial competition, putting a payload into orbit now costs a fraction of what it did even ten years ago, while at the same time, the general miniaturization of electronic components has dramatically changed what can be accomplished in even a meager amount of mass. The end result are launches that don’t just carry one or two large satellites into orbit, but dozens of small ones simultaneously.
Tuning into a GPS satellite is nothing new. Your phone and your car probably do that multiple times a day. But [dereksgc] has been listening to GPS voice traffic. The traffic originates from COSPAS-SARSAT, which is a decades-old international cooperative of 45 nations and agencies that operates a worldwide search and rescue program. You can watch a video about it below.
Nominally, a person in trouble activates a 406 MHz beacon, and any of the 66 satellites that host COSPAS-SARSAT receivers can pick it up and relay information to the appropriate authorities. These beacons are often attached to aircraft or ships, but there are an increasing number of personal beacons used by campers, hikers, and others who might be in danger and out of reach of a cell phone. The first rescue from this system was in 1982. By 2021, 3,632 people were rescued thanks to the system.
The satellites that listen to the beacon frequencies don’t process the signals. They use a transponder that re-transmits anything it hears on a much higher downlink frequency. These transponders are always payloads on other satellites like navigation or weather satellites. But because the transponder doesn’t care what it hears, it sometimes rebroadcasts signals from things other than beacons. We were unclear if these were rogue radios or radios with spurious emissions in the translator’s input range.
The video has practical tips on how to tune in several of the satellites that carry these transponders. Might be a fun weekend project with a software-defined radio.
Satellite internet used to be a woeful thing. Early networks relied on satellites in geostationary orbits, with high latency and minimal bandwidth keeping user demand low. That was until Starlink came along, and provided high-speed, low-latency internet access using a fleet of thousands of satellites in Low Earth orbit.
The simplest way to look for meteors is to go outside at night and look up — but it’s not terribly effective. Fortunately, there’s a better way: radio. With a software-defined radio and a little know-how from [Tech Minds], you can easily find them, as you can see in the video below.
This uses the UK meteor beacon we’ve looked at before. The beacon pushes an RF signal out so you can read the reflections from meteors. If you are too far from the beacon, you may need a special antenna or you might have to find another beacon altogether. We know of the Graves radar in France and we have to wonder if you couldn’t use some commercial transmitter with a little experimentation.
[Tech Minds] has some practical tips to share if you want to try doing it yourself. If you want to see what a detected meteor looks like, you can visit the UK beacon’s gallery page.
We saw another presentation on the UK beacon earlier this year. Using commercial transmitters sounds like it might be easy, but apparently, it isn’t.
We aren’t much into theories denying the moon landing around here, but [Dagomar Degroot], an associate professor at Georgetown University, asserts that the Apollo 11 quarantine efforts were bogus. Realistically, we think today that the chance of infection from the moon, of all places, is low. So claiming it was successful is like paying for a service that prevents elephants from falling through your chimney. Sure, it worked — there hasn’t been a single elephant!
According to [Degroot], the priority was to protect the astronauts and the mission, and most of the engineering money and effort went towards that risk reduction. The — admittedly low — danger of some alien plague wiping out life on Earth wasn’t given the same priority.
Although experimental verification is at the heart of the scientific method, there is quite a difficulty range when it comes to setting up such an experiment. Testing what underlies the formation of the fast solar winds that are ejected from coronal holes in the Sun’s corona is one of these tricky experimental setups. Yet it would seem that we now have our answer, with a newly published paper in Nature by S. D. Bale and colleagues detailing what we learned courtesy of the Parker Solar Probe (PSP), which has been on its way to the Sun since it was launched in August of 2018 from Earth.
Artist rendition of the Parker Solar Probe. (Credit: NASA)
The Sun’s solar wind is the name for a stream of charged particles which are ejected from the Sun’s corona, with generally two types being distinguished: slow and fast solar winds. The former type appears to originate from the Sun’s equatorial belt and gently saunters away from the Sun at a mere 300 – 500 km/s with a balmy temperature of 100 MK.
The fast solar wind originates from coronal holes, which are temporary regions of cooler, less dense plasma within the corona. These coronal holes are notable for being regions where the Sun’s magnetic field extends into interplanetary space as an open field, along which the charged particles of the corona can escape the Sun’s gravitational field.
These properties of coronal holes allow the resulting stream to travel at speeds around 750 km/s and a blistering 800 MK. What was unclear up till this point was exactly what powers the acceleration of the plasma. It was postulated that the source could be wave heating, as well as interchange reconnection, but with the PSP now close enough to perform the relevant measurements, the evidence points to the latter.
Essentially, interchange reconnection is the reestablishing of a coronal hole’s field lines after interaction with convection cells on the Sun’s photosphere. These convection cells draw the magnetic field into a kind of funnel after which the field lines reestablish themselves, which results in the ejection of hotter plasma than with the slow solar wind. Courtesy of the PSP’s measurements, measured fast solar winds could be matched with coronal holes, along with the magnetic fields. This gives us the clearest picture yet of how this phenomenon works, and how we might be able to predict it.
(Heading image: Diagram of the Sun. (Credit: Kelvinsong) )
