Last weekend, for a few seconds — seven to be precise — my two young sons thought I was a modern day prophet.  And for a fleeting moment, I felt like one too.  It was 7pm and I hustled my boys outside where we had an uninterrupted view of the dark sky above South Canberra.  “Quiet,” I commanded, “look into the sky where I am pointing and you will see a sign.”
“But it’s dark,” stated the oldest one matter-of-factly.  I was about to shush him again, when we all gasped.  Just where I had pointed, exactly as I predicted, a dazzling white flash appeared, swiftly turned into a line, and then faded away to a little zooming dot.
“Wow, Dad!” said the youngest.

I thought “Wow!” as well, and for a moment I too was amazed at the beauty of the heavens and the brilliance of science that had allowed me, ever so briefly, to predict a heavenly sign.  For what I had predicted wasn’t spiritual guidance, a UFO, or even a meteor.  It was a satellite, or more accurately, one of a constellation of sixty-six small satellites.  I had the opportunity to show my boys what has become known in astronomical circles as an “Iridium Flare.”

The story of the Iridium Flare is both as exciting and as improbable as the stories that spawned the use of hand held communication devices many years ago.  Maxwell Smart had his shoe phone, Buck Rogers his interstellar communicator and James Bond his ‘Q’ inspired inventions.  But now, thanks to Iridium, we are all able to communicate with each other, regardless of where we are on this planet.  We could be on top of Mt Everest, kayaking across the Tasman, or even lost in a valley in Namadgi National Park.

Rewind to 1987.  While satellite phones were available in the ‘80s, they had limited global coverage and, owing to the height the satellites orbited, the transmission and receiving delay made a conversation sound as though you was speaking down a long tunnel.  The large US electronics company Motorola thought that the world was ready for something better, and proposed creating a massive network of satellites that would provide global coverage.  These satellites would orbit at a much lower altitude than their competitors and so the quality of transmissions would improve dramatically.  The cost of the project was astronomical.  Over A$7 billion was required to put 77 satellites into low earth orbit.  Compare that cost to building the Titanic today — which is estimated at a mere A$580 million.  And just like the Titanic, Iridium hit an ‘iceberg’ — but more of that later.

Because of the number of satellites required, the project was called ‘Iridium’ after element 77 in the periodic table — the hard, platinum-like metal iridium.  However, cost-cutting by the accountants led to the scientists to redesign the project and it was agreed to reduce the number of satellites to 66.  The marketers kept the name Iridium, rather than change the project name to element 66 — dysprosium.  Probably a wise choice as ‘dysprosium’ comes from the Greek meaning “hard to get.”

The first group of Iridium satellites were launched from the US Vandenberg Airforce Base by a Delta 7000 rocket built by McDonnell-Douglas (now Boeing).  The first five satellites were sent to a height of 780 km above earth.  A Russian Proton rocket at Baikonur in Kazakhstan launched the next group of seven satellites.  And in December 1997, Iridium 42 and 44 were launched from Taiyuan in China on a Long March rocket, proving that in the world of commerce there is no ‘loyalty’ to a particular nation.

The full Iridium service commenced in December 1998.  Unfortunately, despite the brilliance of the technology, people’s expectations had changed since 1987.  People expected their phone to be lightweight, usable inside buildings and the calls to be relatively cheap.  Iridium phones were heavy — as they needed powerful batteries — they didn’t work inside buildings and call costs were around A$10 per minute.  Saying “Hello, it’s John Smith,” cost A$1, and you spent your time hoping that you didn’t get an answering machine with a long message!

At the cost of construction of A$7 billion, Iridium needed over one million subscribers to break even.  By mid 1999 it had gained 55,000 subscribers and was rapidly running out of money.  In August 1999 the Iridium was bankrupt and subscribers found themselves without a dial tone.  There were several attempts at selling Iridium, but no company could afford it. 

By early 2000 the only employees left at Iridium were those employed to ‘de-orbit’ the satellites.  It may not look like it, but our sky is littered with satellites, rocket debris and other space junk.  According to the US Space Command Centre, there are 8,120 pieces of space junk orbiting the earth, including an astronaut’s glove from a Gemini mission in the 1960s.  All these pieces of junk pose a danger to operating satellites, the International Space Station, and of course other space vehicles, such as the Space Shuttle.  Therefore, Iridium was required to burn them up in the atmosphere.  This spectacular end to a A$7 billion dollar dream was planned to start in late 2000 and would take two years to destroy all the satellites.

Then in November 2000 over the hill galloped the US Cavalry — literally.  The US Defence Department teamed up with a little company called ‘Iridium Satellite’ which bought the whole system from Motorola for a bargain price of A$35 million.  The Defence Department contracted Iridium Satellite to provide communications services to the value of A$100 million over two years.  Iridium was saved.  Under the new structure, the company only needed 60,000 subscribers to break even.  It currently has 169,000 subscribers and the numbers are growing, despite the fact that the phone requires a line-of-sight with a satellite and thus can’t work inside buildings.

Flying above our heads is an array of over 66 Iridium satellites (there are a few spare satellites as well as a few damaged ones) travelling at over 17,000 kph, providing communication to every part of our planet.  It may have been a disastrous financial project, but it is a remarkable technological achievement, and all of us can view these satellites and predict to the second when any given satellite in the network can be seen.

The brightness of objects in the sky, whether they are planets, comets, satellites or stars, is described by how much light they reflect or emit.  This brightness is called ‘magnitude’.  The brighter an object, the lower is its magnitude.  Thus the sun has a magnitude of -26.7.  The magnitude scale is logarithmic to base 2.5.  That is, an object with a magnitude of -1 is 2.5 times brighter than an object with a magnitude of 0.  The full moon has a magnitude of -12.7.  The dimmest object that the human eye can perceive is about magnitude +6.  The brightest Iridium flares are quite spectacular with a magnitude of -8, especially when viewed against a dark sky.

The sun reflecting off the satellite’s antennae causes the ‘flare’.  Each satellite has three antennae that are made from brightly polished aluminium covered by silver-coated Teflon (for heat control), giving a total area of 4.8m2 of reflective surface.  When the satellite is at the right angle the sun catches the antenna and we are treated with a spectacular white flare, which lasts between four and twenty seconds.

So, you too can be a prophet and predict where in the night sky an Iridium flare will appear.  There are a number of flare prediction sites available on the internet.  I used “Heavens-Above” and it can be found at: http://www.heavens-above.com/

The next excellent sighting for Canberra is on Thursday 22 February when from Red Hill Lookout the flare will reach a magnitude of -8, which is very bright.  Iridium 19 will create a flare at an altitude of 62° (the horizon is 0° and directly overhead is 90°) and azimuth of 61°, which is East-north-east.  Happy flare-hunting!

© 2007, David Vernon

This article was first published in The Canberra Times on 19 Feb 2007 in Times2, p6

David Vernon is a freelance writer.  Based in Canberra he writes about science, parenting, health and history.  In mid-2006 he completed his third book, an anthology of birth stories told by men, called Men at Birth.  He is the father of two boys and is their fulltime carer.

Website: http://web.mac.com/david.vernon
Email: dvbooks@mac.com