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Calling all interested in #citizenscience projects! Join hundreds of contributors from at least 20 countries providing data for the Global Meteor Network (GMN). As the small patches of red on this map show, there is a lot more of the planet that we could cover.

Right now, in Aotearoa New Zealand we have only two GMN Raspberry Pi Meteor Stations (RMS), covering a volume of space above the Top of the South. More stations are needed over the rest of the entire country to provide decent coverage of the southern skies over Oceania. In Australia there is even more of a need for keen citizen science astronomers, because there are currently only two stations, and neither has any neighbouring station monitoring an overlapping volume of space, needed to triangulate meteor paths. 

To observe rare or unexpected meteor shower outbursts, we need monitoring equipment in as many places as possible to give as much longitudinal coverage of the planet as is possible. There are cameras everywhere now, right? Well, as recently as 2012 there was an unexpected draconid outburst for which there are no useful optical observations at all, because we simply do not have enough equipment pointed in the right direction, collecting data. We also need accurate data to be able to track and find meteorites dropped by significant fireballs, and that means more sky-pointed cameras are required. High-precision data is required in order to produce accurate models that can be used to predict meteoroid impact risk on spacecraft. In the last ten years steady progress has been made, and now the #GMN network is ready to expand rapidly as all the parts are in play to make it possible to widely deploy meteor monitoring cameras around the world.

For anyone interested in projects related to astronomy, this is a really neat one, because it is a set-and-forget type of effort. There is an up-front equipment cost of about NZ$350 (which, let’s face it, in a world of telescopes and eyepieces and equatorial mounts and cameras and electronic focusers and filter wheels and guidescopes and so on is actually a fairly modest cost for a whole functional system). But once installed and connected to your home WiFi network, it quietly chugs away, producing about 20GB of data each clear (or even partially clear) night, then number-crunching that down to about 1GB of processed information which is shared with the GMN server at the University of Western Ontario. You do not need to drag equipment out into the cold and dark. You don’t need to manually record any data. It is also a long-running project you can be part of on an on-going basis, instead of being something that you do only once in a while. 

But you could help recover a meteorite dropped by a big fireball, as happened in the UK in February 2021. It was captured on enough recording equipment – including both actual meteor cameras and even people’s home video-doorbells – that there was enough information to calculate quite reliable trajectories and estimate where meteorites dropped by this fireball might have landed. Almost 600g of meteorite material was quickly recovered, so it was not even rained on.

If you don’t wish to be totally passive, but would like to keep an eye on what your meteor camera is achieving, there are handy dashboards that will show you image stacks that overlay all the detected meteors from the previous night, radiant charts that show which part of the sky the meteors came from, maps that combine your data with those of others nearby to show the direction of travel of detected meteors, and equipment calibration plots that demonstrate your equipment is tuning itself to produce good quality datasets. 

You can expect to be credited for your data in any scientific papers published that draw on data you contributed.If you would like to be part of the project, head over to globalmeteornetwork.org and check out the wiki which has information on how to get started and build your own RMS meteor camera, and sign up for the newsgroup forum on groups.io.

Chicken Little got bonked on the noggin by an acorn and thought the sky was falling. As if.

Except there really is stuff falling from the sky, from way higher up than a big old oak tree. It is estimated that 29 to 57 tonnes of rock rain down on earth from space every day.

Most people know of the potential threat to the planet posed by a large asteroid. Besides being the thing that resulted in the demise of the dinosaurs, it has been the subject of movies starring Bruce Willis. But while we know that these big asteroids are a potential threat, few people realise that we are routinely running into space rocks that don’t quite measure up to that planet-killer status.

Most people are, however, quite excited to see a star streak across the sky. They squeal. They point. Wishes get made.

If there is a ‘well, actually’ type person present, they will let you know that these are not, in fact, shooting stars, but meteors. 

What we are seeing is a bit of space rock that has gotten in our way. Travelling merrily on its way minding its own business , unimpeded by the vacuum of space, it suddenly finds itself plowing into our atmosphere, which slows it down suddenly, and friction from the air makes it heat up A LOT making it glow very brightly, producing the streak of light we see. Most of these bits of space rock are small enough that they completely vapourise in the atmosphere, but some are large enough that bits will fall to the ground, and at this point we call them meteorites.

Don’t panic though, because to date there is only a single account of a meteorite actually hitting someone. Her name was Henny Penny Ann Hodges, the date was November 30, 1954, and she was having a nap when a meteorite crashed through the roof of her house, into a radio, and then onto her leg where it left a sizable bruise. 

Other notable meteors have caused damage to property. Back in 2013, a very large meteor shattered the skies above Chelyabinsk, the fireball it produced creating shockwaves that shattered windows over a large area, resulting in 1200 people being injured. The bright flash and detonation made people think a nuclear weapon had exploded, and indeed it is estimated that the energy released was equivalent to between 20- and 30-times the Hiroshima explosion. About 600kg of meteorite was recovered, and it is estimated that the rock was about 19m across with a mass of 12,000,000 kg before it crashed into our atmosphere. 99.995% burned up in the atmospheric explosion.

So with these dramatic events being part of our historical record, perhaps it is surprising that the amount of space rock entering the atmosphere is estimated to be somewhere between 29,000 and 53,000 kg per day. That seems like a pretty rough estimate, right? There is a good reason for that. We simply do not have enough data to make a half-decent estimate. 

There are sky surveys making concerted efforts to map the sky and find all the Potentially Hazardous Near Earth Objects, but these are focussed on the largest and most dangerous stuff, the pretty rare big chunks of space rock from about the Chelyabinsk-sized meteoroids up to asteroids hundreds of metres or kilometres in size. The stuff smaller than that is way more common, but much harder to see until we actually run into it.

We can also learn a lot about our local solar system environment if we study this smaller stuff too. Until recently, there have only been sporadic efforts to monitor the sky for meteors so these can also be studied. Developments in camera sensors and small single-board-computers have made it feasible to deploy a planet-wide meteor monitoring system, to collect much more data and expand our understanding of meteors. We can also use this data to track down and locate meteorites!

In February 2021, a search was undertaken to find meteorite material after a large fireball was caught on meteor cameras across the UK. In total, about 548g of meteorite material was recovered in the village of Winchcombe, Gloucestershire, by people who searched areas suggested by people triangulating the course of the meteor on the meteor camera network and from footage captured on people’s doorbell-cameras. This was the first bit of meteorite recovered in the UK since 1991, but some believe that good coverage of the night skies using meteor-detection cameras could result in recovering a meteorite annually from a land area the size of the UK or NZ. Check out how excited these searchers were:

The cool thing is, just about anyone can be involved in this project. Getting a meteor camera set up costs about NZ$350 and once set up it chugs away collecting data for this citizen science project, without your active involvement. Whenever you like, you can connect to your camera and see what meteors it was able to detect the previous night.

Dashboards share cool information that the network has been able to derive from your camera and those around nearby. 

When a fireball big enough to actually drop a meteorite is seen, the data on your meteor camera can be used to figure out where it came from, which direction it was heading and how fast, and where any meteor might be able to be located – down to as small as a 15m target!

This fireball meteor was captured by GMN RMS station CA0011 in January 2020. Overlaid over the whole stream is a frame-by-frame capture of the meteor streaking across the sky, with the brightness adjusted in the moving box to see better. Note how it flares and flickers as bits disintegrate off the rock.

Would you like to know more about how you can start collecting and contributing meteor data as part of this science project? Head over to globalmeteornetwork.org and check out the wiki which has information on how to get started and build your own RMS meteor camera, and sign up for the newsgroup forum on groups.io. 

As of 25 July 2021, my meteor camera is live and operational, fixed to the south wall of my garage and taking video of the sky every night.

To be clear, this involved next-to-no actual complex study on my part, just the purchase of a few items off the internet, downloading some software that someone else wrote and following the assembly instructions provided by people who had already done it before. It was easy, just big-kid-lego, really.

In fact, I was following a recipe for a meteor cam created by a group of enthusiasts called the Global Meteor Network (GMN). Damir Segon, Pete Gural, Denis Vida, Dario Zubovic, Mike Mazur and Patrik Kukic (with assistance from others also) have all had a hand developing the equipment configuration and software over a number of years, culminating in the Raspberry Pi Meteor Station (RMS) design. The GMN is the collection of installed RMSs and the centralised server at the University of Western Ontario they connect to.

There have been, and are, other interconnected meteor monitoring efforts, notably Cameras for All-Sky Meteor Surveillance (CAMS) but GMN has an advantage in the whole project being open-source, so the analysis methods are reviewable by anyone, the captured data is shared using an Open Data CC-BY-4.0 license so the data is accessible to any researcher, the ability to compute orbits is not limited to a single individual, and the station equipment cost is significantly less. 

I discovered this project one day when it was mentioned by Hamish Barker, an astronomer who is the Convenor of the region’s astronomy club, the Nelson Science Society’s Astronomy Section. He had established the first GMN RMS in Aotearoa New Zealand, and wondered if I would be interested in setting up another camera with overlapping coverage of the sky so it would be possible to triangulate the trajectories of any observed meteors. It’s a global citizen science project, it is astronomy that I can do every night with zero effort, and if we are lucky we might be able to track down a fallen meteor — uh, yeah, I’m interested. In fact, it was precisely the sort of project I think is really cool, because it involves a very modest set-up cost, an afternoon’s fiddling with electronic components, an evening or two of installation, setup and configuration, and after that it is continuously in action, collecting Real Usable Data whenever it can peak through the clouds. 

If you want to give it a go too, here is where you start.

While it might be possible to free-wheel a meteor camera setup of your own design, GMN recommends a specific set of hardware to enable the global collaboration and integration and to ease support issues as all involved are volunteers. So, for instance, the ‘brains’ in the RMS is a Raspberry Pi, and if you do not have one, you need to buy one. I know. I know, you might have an old laptop lying around that you could use instead, BUT a Raspberry Pi is incredibly inexpensive and you’ll save both yourself and others time and wasted effort if you just follow the tried and tested recipe.

Here are the main components that were required as at the time I was assembling my RMS:

• A Raspberry Pi 4 with 2GB RAM (a Raspberry Pi 3B+ with 1GB is actually sufficient, but the trend is toward the added capabilities of the Model 4), with 5V/3A power supply, 128GB micro SD card, and a specific recommended case/housing
• A Real Time Clock accessory for the Raspberry Pi
• A specific recommended security camera housing which includes a bracket needed to mount the camera
• A specific bare-board IP security camera sporting a Sony IMX291 sensor with a supplied Power over Ethernet power-and-communication cable
• One of four recommended lenses; for dark sky sites like mine a 4mm f/0.95 lens providing a 88°x45° field of view is recommended (in light polluted urban areas, an 8mm f/0.9 lens with a 40°x20° field of view is recommended)
• A Power over Ethernet Injector to supply power to the camera using a network cable into the camera’s PoE cable

Note that the official and up-to-date, full and complete recommended parts list is found on the GMN website, here. Don’t rely on my list above (which is also why I am not linking to specific items from this page – use the official parts list if you do this yourself).

The GMN provides a Raspberry Pi operating system image to put on your micro SD card; it is based on Raspberry Pi OS, configured for RMS operation and connection to the GMN, with all necessary software pre-installed. There are deployment instructions that need to be stepped through but even if you don’t understand what is going on they are trivial to do and before long you will be able to capture meteors just like me.

Because the cameras are continuously recalibrating, they can do quite detailed photometry measurements, and from those measurements some quite interesting estimates can be made, such as the initial mass of the meteoroid and it’s bulk density.

Why bother? Because right now we don’t even properly understand the scale of this area of study. We believe 43+/- 14 t of meteoroids enter earth’s atmosphere every day – although some estimates have been made of over 250t/day. Getting better data, with high-precision measurements means it is possible to produce accurate models that can be used for very important things such as predicting meteoroid impact risk on spacecraft.

Back in 2013 the Chelyabinsk fireball produced a bright flash, an atmospheric explosion with an air blast and shock wave, causing many initially to think it was a nuclear attack. It caused widespread damage, especially with blown out windows, and something like 1200 were injured as a result. It could have been a lot worse – the energy released has been estimated to be equivalent to between 400,000,000 and 600,000,000 kg of TNT (which is about 20x to 30x Hiroshima explosions). This was produced by a meteoroid that was possibly just 19m in size, and maybe 12,000,000 kg in mass. The meteorite that was recovered ended up being about 600kg, so 99.995% of the meteor vapourised in the atmosphere. We actually only know of about 1% of all Chelyabinsk-sized meteoroids. This sort of meteoroid is right on the limits of our Near Earth Object detection capability, and in this case it came at us from the sunlit side of the earth, so it was as if it was coming at us while we were blinded by sun-strike on the windscreen. 

Sky-survey projects are scanning the skies for large and potentially hazardous objects like this and bigger. But there is also a lot to learn from the smaller objects that are harder to see until they interact with our atmosphere.

Some meteor showers are unexpected, and because there hasn’t been any real global monitoring effort until now, some events are missed entirely – eg there are no recorded observations of the 2012 draconid outburst.

How can we improve our understanding and reduce uncertainties? Well, that is why we now have  a citizen science project to monitor meteor activity in the atmosphere.

With multiple cameras observing a meteor, the trajectory can be calculated to determine its initial position and direction of travel and initial velocity. From there a meteor’s orbit can be calculated. When this is done for lots of meteors an overall picture can be constructed of where the meteoroids are and perhaps what the parent body was can be inferred from that data. The GMN RMS network can provide the high-precision data required in order to produce accurate models that can be used to predict meteoroid impact risk on spacecraft.

Right now there are hundreds of contributors to the project in at least 20 countries – but mostly in Europe, Canada, the UK and the USA. We need a lot more GMN RMS stations in all longitudes, but we especially need more stations in southern hemisphere latitudes. If you would like to be part of the project, head over to globalmeteornetwork.org and check out the wiki which has information on how to get started and build your own RMS meteor camera, and sign up for the newsgroup forum on groups.io.