September 21, 2017

AstroEvent of the Week: Spotting Iridium Flares.

 An Iridium Flare graces the dusk. (Photo by Author).

Photo by Author.  

   Looking up at the dawn or dusk skies, it’s not uncommon to see a satellite brighten, flare up, and the abruptly disappear from view. What you’ve just seen is an Iridium flare, a glint of sunlight off of a refrigerator sized satellite panel. Motorola launched this series of 66 communications satellites in 1997 through 1998 and they are currently owned and operated by Iridium Communications, Inc. [Read more...]

Satellite Spotting: A Quick How-to Guide.

Two objects you can see tonite; the Hubble Space Telescope & (if it's in orbit) the Space Shuttle! (Credit: Art Explosion).
Two objects you can see tonite; the Hubble Space Telescope & (if it’s in orbit) the Space Shuttle! (Credit: Art Explosion).

Go out any reasonably clear night around dawn or dusk and look up. Chances are, after a few minutes, a moving “star” will drift silently by. What you’ve just seen is a satellite in low Earth orbit, a symbol of our modern technological age. Many are truly surprised by this sight when I point it out at star parties; I always check for bright passes before I load the ‘scope in the car. Some are active; many are space junk or discarded boosters. A very few, like the Space Shuttle or the International Space Station, may have human eyes staring back at you; and an occasional rare spy satellite may even have electronic eyes of a more sinister nature.  This week, we’re going to discuss the astronomical sub-pursuit of “satellite spotting,” a pastime that anyone can quickly engage in with a minimum of gear and know how. All you really need is a set of eyes, patience, and knowledge of when and where to look. A good Internet connection (hey, you’re reading this, right?) and a pair of binoculars can up your game a notch, as you’ll soon see.

          Satellite spotting used to be a matter of national security. As recounted in Patrick McCray’s Keep Watching the Skies! Operation Moonwatch  recruited amateur spotters to keep tabs on the Russians, as our country found itself woefully unprepared for a potential “red menace from space”. This had its roots in pre-space age aircraft spotters placed along the U.S. coasts by the Civil Air Patrol. Moonwatch officially ended in 1975, but many aficionados liked what they saw, and kept up their skills via ham radio, home stapled newsletters, and various other pre-Internet modes of communiqué. Some can even still get the political goat of a space faring nation or two. For instance, in 1990 satellite spotters reported the classified shuttle deployed payload MISTY as alive and well, much to the chagrin of the U.S. government who had hoped to perhaps use the cover story of a failed launch to put the new breed of spy satellite in orbit.  Conversely, amateurs have been able to quickly confirm and/or deny such recent space age hopefuls as Iran and North Korea in their fortrays into space.

And of course, satellites have been the source of a good many UFO sightings over the years. Some, such as the ever-growing International Space Station, can appear brighter than Venus! Iridium flares are also splendid sights, often brightening up to magnitude -8 before fading out of sight.

Depiction of a Satellite Pass. (Created by Author).

Depiction of a Satellite Pass. (Created by Author).

So, you ask, how can I see these splendid sights? The best time is local dawn or dusk; even after the Sun has set on the Earth’s surface, it’s still shining and reflecting off of objects high over head. Anything that’s visible to the naked eye will be at least several meters across and in low Earth orbit about 50-200 miles up. At that height, things move around the Earth about once every 90 minutes. Fun fact: did you know that Sputnik I was invisible to the naked eye? The vision of folks gathering on their porches to witness this silent messenger of the Space Age now persists in our collective mythos; such a depiction was even shown in the movie October Sky. What most people saw was, in fact, the spent but much larger booster that put it there!

In any event, like much of astronomy, knowing what that moving dot is adds to the moment. At very least, it might help explain grandpa Jeb’s most current UFO sighting…. Here’s where ye ole Internet comes into play. Basically, you’ll need three pieces of information for a successful identification. What time an object is passing over, what’s its max altitude or elevation, and its position, or azimuth along the horizon. Match these up, and you’ve got yourself a successful sighting. Visual characteristics are handy; satellites do not blink (that’s a plane) or leave a fiery trail (that’s a meteor) unless, of course, the satellite itself is re-entering. Anyhow, when Astroguyz wants to know what’s up in the man-made sky, here’s where we turn;

Heavens-Above : This is the ultimate clearing house for online local astronomy; once you’ve got your local latitude, longitude and elevation preset in, it’ll predict passes in an easy to read format. This is a fine starting point and introduction to satellite tracking. The only drawback it has is they can be a bit slow on updates for recent launches.

Orbitron: this is an uber-cool applet that installs onto your computer; once configured, it’ll operate in the field, sans internet connection, a huge plus. The trick is to occasionally update the Two-Line Elements from time to time, as new stuff gets launched and old stuff decays; I find once a month is adequate or more frequently if it’s a rapidly evolving situation, like a recent Shuttle launch. Orbitron is the only true stand-alone, satellite simulation free-ware out there; you can even set it to chirp when a satellite enters or leaves the local sky! It’ll even take hand-loaded TLE’s with a little skill; the only objection would be the need for a possible addition of local constellations in overhead mode.   

Space Weather: If you want dirt simple, Space Weather’s simple satellite tracker is it; simply plug in your zip code for Canadian and US users, or  locale for international, and out comes the local flybys in a no fuss format. Even grampy Jeb could use it!

Spaceflight Now: A good place to track goings on in terms of recent and upcoming launches; Spaceflight Now publishes all worldwide launches right down to the communication satellite that currently brings such trailer park opuses as “Wife Swap” and “Monster Truck Mania” into your house. And their live chat and twitter feed  is indispensible for real time updates.

NASA: It can take some digging, but NASA publishes ground tracks for shuttle re-entries which can be copied and overlaid on Google Earth to aid with possible sightings.

So, what strange beasties are there in the satellite world? While not all inclusive, here’s a short list of what to look out for;

Manned missions: these are the ones that really stir the Buck Rodgers in all of us. It’s just plain neat to think that someone’s chasing zero-g M & Ms around the cabin, right over head. These days, most manned missions revolve around the International Space Station, but expect that to change as we return to the Moon later this decade.

Iridium and other flares: In the mid-90’s, Motorola launched a constellation of communications satellites designed for Sat-phone linkups. These sport three each solar panels that are refrigerator-sized and highly reflective, and if they catch the Sun just right, a brilliant flare will occur, sometimes up to -8 magnitude! Heavens-Above is a great site for predicting these, and you seldom have to wait more than a week to sight a flare from your locale.   

Space junk: After monitoring satellites a bit, you begin to realize just how crowded it’s getting up there. A great many objects in orbit are derelict, mostly boosters used to put satellites in odd or highly inclined orbits. And some can be downright unique, like the tool kit “dropped” by astronaut Heidi Stefanyshyn-Piper last year while working outside of the ISS!

Spy and satellite constellations: Yes, there is some strange goings on in Earth orbit; satellite constellations, such as the NOSS series, are some of the weirdest (and rarest) things you’ll see in the manmade sky. These will look like a group of satellites moving in formation. I’ve seen this only once from North Pole, Alaska, and believe me, it’s a bizarre sight!     

Dumps, dockings and re-entries: If you’re persistent (and lucky) you may be able to witness a docking/undocking of the Shuttle or Soyuz with the ISS. Generally, these happen either two days before launch or landing… following the missions via streaming NASA TV  can come in handy to catch this. Does the Shuttle or ISS look a bit of a fuzzy halo or trail? You might have been lucky enough to catch a fluid dump, which can look pretty cool if you catch it just right. Re-entries of the Shuttle used to be common place, but after the Columbia disaster in 2003, are now less frequent. The shuttle now almost exclusively supports the ISS, which means it must match orbits with the station. Reentry now generally comes in over Central and South America. And of course, unscheduled reentries can happen any time!

So, you’ve seen the pretty moving dots and you want more? The sub genre of satellite spotting is always open to expansion and innovation;

Binocular spotting: A good many objects are out of naked eye visual grasp; a good pair of binocs will aid you in this task. To be effective, it’s helpful to know when a satellite is whizzing by a bright star. Simply aim at the star at the appointed time, and watch the object zip by. I successfully spotted the aforementioned errant tool bag this way! Wide field imaging around the Orion Nebula region some times of year can even turn up geosynchronous satellites, which give themselves away by their slow up and down nodding motion.  

Tracking and photography: A simple way to photograph a satellite pass or flare is to lock the shutter open as your quarry drifts by; a more difficult method is to video or photograph the target at higher magnification through the telescope. Setups can range from sophisticated computer tracking mounts to low tech manual setups; simply aim, keep the satellite in the crosshairs, and hope you nabbed a frame or two for later extraction. Both the Shuttle and the ISS are large enough to show telescopic detail. Another tried and true method is to fix on an object such as the Sun (with proper filter in place!) or Moon and let the satellite come to you. This has the advantage of being possible in the daylight, or when the satellite is not illuminated, although the object moves quick, less than ½ a second across the solar or lunar disk! CALsky can be configured to give you local e-mail alerts for transits in your area.  

Reporting: sure, these days, everybody’s got a blog; but it can also be a great way to get your sightings out. Also, Spaceweather is very approachable for amateur photography submissions, and their Spaceweather Flash routinely posts all things astronomical.

So there you have it, the wonderful and sometimes wacky world of satellite spotting. And unlike some exotic fields of amateur astronomy-dom, this is something you can do tonight with very little startup! Remember, the sky is waiting… and tracking the comings and goings of human and technological activity in orbit can be fun for the whole family to enjoy.

Drama in low Earth orbit! (Credit: STS-51A/NASA).

Drama in low Earth orbit! (Credit: STS-51A/NASA).