An Iridium flare slices through the twilight sky. Image credit and copyright: Alan Dyer.
You never forget your first one. I remember reading about a curious new set of flaring satellites, known as Iridiums. This was waaaaay back in the late 1990s, when we still occasionally read things in something called magazines, which involved pressing ink into plant-flesh to convey information.
Fast-forward to 2019, and the age of the predictable Iridium flare may be coming to an end. Already, scrolling through Heavens-Above reveals very few Iridium flares for the coming months, and these familiar nighttime flashes may become a thing of the past come the end of the decade in 2020.
An artist's conception of an Iridium-NEXT satellite in low Earth orbit. Credit: Iridium Communications Inc.
The skies, they are uh changin’… I remember reading in Astronomy magazine waaaay back in the late 1990s (in those days, news was disseminated in actual paper magazines) about a hot new constellation of satellites that were said to flare in a predictable fashion.
This is the Iridium satellite constellation, a series of 66 active satellites and six in-orbit and nine ground spares. The ‘Iridium’ name comes from the element with atomic number 77 of the same name (the original project envisioned 77 satellites in low Earth orbit), and the satellites serve users with global satellite phone coverage.
A ‘double Iridium flare’ capture! Image credit: Mary Spicer
Over the years, Iridium satellite flares have become a common sight in the night sky… but that may change soon.
Known as Iridium-NEXT, the first launch is set for October of this year from Dombarovsky air base Russia atop a converted ICBM Dnepr rocket. The Dnepr can carry two satellites on each launch, and SpaceX has also recently agreed to deploy 70 satellites over the span of seven missions launching from Vandenberg Air Force Base in California later this year.
Both the initial Iridium satellites and Iridium NEXT are operated by Iridium Communications Incorporated. The original satellites were built by Motorola and Lockheed Martin, and the prime contract for Iridium NEXT construction went to Thales Alenia Space.
There are also several fascinating issues surrounding the history of the Iridium constellation, both past and present.
Originally fielded by Motorola in the 1990s, satellite phones were to be “the next big thing” until mobile phones took over. Conceived in the late 1980s, the concept of satellite phones was practically obsolete before the first Iridium satellite got off the ground. The high cost of satellite phone services assured they could never manage to compete with the explosive growth of the mobile phone industry, and satellite phones at best only found niche applications for remote operations worldwide. Iridium Communications declared bankruptcy in 1999, and the $6 billion US dollar project was bought by a group of private investors for only $35 million dollars.
Airmen using an Iridium satellite phone in Antarctica. Image credit: Robert Tingle/USAF
The original Iridium constellation employed a unique system of Inter-Satellite Links, enabling them to directly route signals from satellite to satellite. Iridium NEXT will use an innovative L-band phased array antenna, allowing for larger bandwidth and faster data transmission. The Iridium NEXT constellation is planned to eventually contain 81 satellites including spares, and the system will be much more robust and reliable.
The Iridium NEXT constellation will also face some stiff competition, as Google, SpaceX and OneWeb are also looking to get into the business of satellite Internet and communications. This will also place hundreds of new satellites—not to mention the growing flock of CubeSats—into an already very crowded region of low Earth orbit. The Iridium 33 satellite collision with the defunct Kosmos 2251 satellite in 2009 highlighted the ongoing issues surrounding space debris.
The company applied for a plan to deorbit the original Iridium constellation starting in 2017 as soon as the new Iridium NEXT satellites are in place.
Now, I know what the question of the hour is, as it’s one that we get frequently from other satellite spotters and lovers of artificial things that flash in the sky:
Will the Iridium NEXT satellites flare in manner similar to their predecessors?
Unfortunately, the prospects aren’t good. Missing on Iridium NEXT are the three large refrigerator-sized antennae which are the source of those brilliant -8 magnitude flares. And sure, while these flares weren’t Iridium’s sole mission purpose, they were sure fun to watch!
An ‘Iridium classic…’ note the trio of reflective antennae on the lower bus. Image credit: Iridium Communications inc.
David Cubbage, Associate Director of NEXT Spacecraft Development and Satellite Production recently told Universe Today:
“It was very exciting when we first discovered that the Iridium Block 1 satellite vehicles (SVs) reflected the sunlight into a concentrated “flare” that could be viewed in the night sky. The unique design of the Block 1 SV, with three highly reflective Main Mission Antennas (MMA) deployed at an angle from the SV body, is what caused that to happen. For the Iridium NEXT constellation, the SVs will be built under a different design with a single MMA that faces the Earth — a design that requires fewer parts that do not need to be as reflective. As a result, it will not likely produce the spectacular flares of the Block 1 design.”
But don’t despair. Though the two decade ‘Age of the Iridium flare’ may be coming to an end, lots of other satellites, including the Hubble Space Telescope, MetOp-A and B, and the COSMO-SkyMed series of satellites can ‘slow flare’ on occasion. We recently saw something similar during a pass of the U.S. Air Force’s super-secret ATV-4 space plane currently carrying out its OTV-4 mission, suggesting that a large reflective solar panel may be currently deployed.
An Iridium flare passing through the constellations Orion and Lepus. Image credit: David Dickinson
And though the path to commercial viability for satellite internet and communications is a tough one, we hope it does indeed take off soon… we personally love the idea of being able to stay connected from anywhere worldwide.
Be sure to catch those Iridium flares while you can… we’ll soon be telling future generations of amateur astronomers that we remember “back when…”
-Check out the chances for the next Iridium flare coming to a sky near you on Heavens-Above.
An Iridium Flare flashes over western Maine in this beautiful night sky image from June 2014. Credit and copyright: Mike Taylor/Taylor Photography.
Ever seen a flash in the night sky and wondered if you were seeing things? Iridium flares are often mistaken for meteors because of their notable bright flashes of light in the night sky but they are actually caused by a specific group of satellites that orbit our planet. The Iridium communication satellites are just in the right orbit that when sunlight reflects on their antennas, a flash — or flare — is visible down on Earth. There are currently about 66 Iridium satellites in orbit, so flares are a rather common occurrence.
This image from photographer Mike Taylor is one frame from a timelapse of the Milky Way and other features of the night sky in motion against a silhouetted foreground. “Photographed from western Maine, this shot includes quite a bit of light pollution and some fast moving cloud cover,” Mike told Universe Today via email. “Most of the light pollution in this image is coming from Farmington, Maine which is about 35 miles from this location.”
Mike added the footage from this timelapse will be featured in his upcoming short film “Shot In The Dark.”
He also provided this info about Iridium flares:
Iridium satellites are in near-polar orbits at an altitude of 485 miles. Their orbital period is approximately 100 minutes with a velocity of 16,800 miles per hour. The uniqueness of Iridium flares is that the spacecraft emits ‘flashes’ of very bright reflected light that sweep in narrow focused paths across the surface of the Earth. An Iridium communication satellite’s Main Mission Antenna is a silver-coated Teflon antenna array that mimics near-perfect mirrors and are angled at 40-degrees away from the axis of the body of the satellites. This can provide a specular reflection of the Sun’s disk, periodically causing a dazzling glint of reflected sunlight. At the Earth’s surface, the specular reflection is probably less than 50 miles wide, so each flare can only be viewed from a fairly small area. The flare duration can last from anywhere between 5 to 20 seconds and can easily be seen by the naked eye.
If you want to try and see an Iridum flare for yourself, check out Heavens Above for your location.
For this image Mike used:
Nikon D600 & 14-24 @ 14mm
f/2.8 – 30 secs – ISO 3200 – WB Kelvin 3570
06/23/14 – 11:07PM
Processed via Lightroom 5 & Photoshop CS5
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