I came accross this interesting information
about the massive amount of Iridium communication satellites
orbiting at approx 780 km above us.
Iridium was originally developed by Motorola funded by the pentagon.
The Iridium constellation was originally planned to have 77 active satellites, and named after the element with 77 electrons by a Motorola employee.
(count the electron shells to get 77 when the atom is not bonded. Iridium also has an atomic number of 77 resulting from its 77 protons; the idea of
electrons orbiting the nucleus being analogous to satellites orbiting the earth is tenuous, thanks to Heisenberg's uncertainty principle.)
Iridium was later redesigned to need fewer satellites - the 66 active satellites of today. (We're not counting in-orbit or ground spares.)
The Iridium Satellite System is a global, mobile satellite voice and data system with complete coverage of the Earth (including oceans, airways and
Through a constellation of 66 low-earth orbiting (LEO) satellites operated by Boeing, Iridium delivers essential communications services to and from
remote areas where terrestrial communications are not available. The service is ideally suited for industrial applications such as heavy construction,
defense/military, emergency services, maritime, mining, forestry, oil and gas and aviation.
Iridium currently provides services to the United States Department of Defense and launched commercial service in March 2001.
The sats usualy have a normal brightness of +6 magnitude (binoculars are useful to spot it), occasionally some of the Iridium satellites provide
reflective flares/glints of magnitude (-)8.
For comparison, Venus can be as bright as magnitude (-)4.9, thus reflections can be up to 30 times brighter than Venus.
The flares/glints can last anywhere from 5 to 20 seconds before the satellite once again becomes almost invisible to the naked eye.
Some flares have been observed during the daylight hours which is very unusual for reflective glares from satellites.
so far from what I understand:
* Originally developed by Motorola, funded by the military.
* Cost - $7 billion
* Pentagon awarded Iridium Satellite LLC a two-year, $72 million contract to provide service to the military.
* When "flareing" an Iridium sat could go to magnitude -8, as much as the half lit Moon!
* A study of the Iridium satellite reentries, show they are within a NASA and U.S. government standard of acceptable risk for falling space debris.
* There is a one-in-10,000 chance of anybody being hurt on the ground by a falling sat.
It's interesting to see that so many sats are floating above us to serve our cells, internet, gps and who knows what else.
They claim about 66 to 77 currently in orbit, the number varies...
Obviously their not built to last forever, so they burn up and re-enter....
Could they be the cause of some meteor reports?
How about amateur astronomers mistaking them for stars or novas?
any further info or views or comments from you guys?
[edit on 3-7-2004 by quadricle]