Iridium Satellites

Heads up

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 Polar regions).

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.

source

Iridium Home

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.

source





more pix


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.
source

* When "flareing" an Iridium sat could go to magnitude -8, as much as the half lit Moon!
source

* 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.
source





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]

Great post quadricle, very informative. I agree that satellites in general account for a lot of "sightings".

It's amazing that something that small can be seen 780km up!

I see the Iridium flashes very often.
If I am with someone, I will usually say:

Hey, what the heck is THAT!?
Reactions are varied, but most people at least think it's cool.

Here is a place that allows you to "predict" when flashes should occur in your area. It's not completely accurate, but hey, you could make yourself seem awfully powerful by pointing to the sky, at Just the right time!
Don't forget to make a laser-gun sound with your mouth when pointing!

Iridium predictions

I have fantastic luck using Chris Peat's Heavens-Above site for predicting Iridium as well as other orbiting goodies. When you catch a -8 magnitude flare you will be slack-jawed.

Spectre,

Have you tried, you know, the laser-gun idea?

Not exactly, spacedoubt, but I am guilty of having people observe with me and telling them I am watching for the ISS and pretending something awful must have happened. That has seemed in bad taste since the shuttle disaster, so I change my story to the Hubble Space Telescope and let them sweat that for a second.

Wow, in print, that seems pretty evil of me.

Thanks spacedoubt, great site information.

zero lift

No, not evil.
Sick, yes, in a good sense of the word sick.
Face it Spec, you're a good guy, and I am sure you don't
Let it go on TOO long.

Since the Meteor shower last week was, weak.
Maybe I should try to capture some flares on digital.
That would be a fun project.

Originally posted by spacedoubt
Since the Meteor shower last week was, weak.
Maybe I should try to capture some flares on digital.
That would be a fun project.

thanks for the comments and info guys, great prediction sites -

I'll be sure to make the laser gun sound when pointing at it

spacedoubt, it would be amazing to see some first hand pix of these flares, looking forward to seeing some.

BTW

the Iridium "constellation" isn't the only one hanging above our heads, at about 1300km up - the Geostar network of approx 48 sats races around a 113 minute orbit.... (the Iridium's orbit is 100min)

FYI

Here near Mesa Arizona I see one flare every so often. It looks pretty cool.

I remember one time I was prospecting in the Goldfield Mts. outside of Apache Junction, Arizona and I saw a huge fuzzy light rise magestically into the sky about nine at night. I swore to God that I had just witnessed a ufo. Later when I got home I found out that there had been a Minuteman missile launch from Vandenberg AFB in California.

Originally posted by quadricle
....races around a 113 minute orbit.... (the Iridium's orbit is 100min)

can someone care to explain how all these objects and some (there are probably thousands more)
can all race around our orbit at break-neck speeds without colliding with each other?

How about space debris?

or how do shuttle/rocket (or aliens ) launches deal with all this crazy traffic?




LEO images
----------------
LEO stands for Low Earth Orbit, and is the region of space below the altitude of 2000 km from the earth. It is the most concentrated area for orbital debris......
source






[edit on 2-7-2004 by quadricle]

that last pic is cool makes me wonder if we will find a planet with that
munch stuff floating around it. with the descovery of new planets all the time it would be great to descover a planet with evin 1 satalite let alone a bunch. what is your take.

Originally posted by quadricle
can someone care to explain how all these objects and some (there are probably thousands more) can all race around our orbit at break-neck speeds without colliding with each other?

There's so much room for them.

Originally posted by quadricle
can someone care to explain how all these objects and some (there are probably thousands more)
can all race around our orbit at break-neck speeds without colliding with each other?

How about space debris?

or how do shuttle/rocket (or aliens

) launches deal with all this crazy traffic?

ok, seems I found the answer to my own question

from NASA FAQ

Is it possible for two orbiting satellites to collide?

Possible, certainly. The real question is, how likely such collisions are.

Many things are possible (e.g. you getting hit by a falling meteorite) but are ignored as too unlikely.

Collisions between satellites are indeed unlikely, but their likelihood increases rapidly with the number of satellites: increase the number of satellites 10 times and, other things being equal, the likelihood of collision grows 100-fold.

It all depends on the orbits of course.

Most satellites move in low-altitude Earth orbit, 600-1000 kilometer above the ground. At any times, this space is filled by thousands of pieces of matter--satellites, rocket stages, cast-off pieces of hardware (like weights used to slow down satellite spin), etc., about 100,000 pieces, most of them fragments from exploding rockets, but also including some 7500 larger accountable pieces of space hardware.

Space is huge, but all these are moving rapidly. Luckily, all motions are essentially in the same direction (west to east, chosen to take advantage of the Earth's rotation) with almost the same speed.

Even so, that speed is enormous, and collisions still may occur, since the orbits make different angles with the Earth's equator.

One definite collision has been recorded in July 1996. The French satellite Cerise, launched in 1995, collided with debris from a 1986 launch, and broke off a stabilizing boom. In this case it was soon noted that the satellite had lost orientation and control was reestablished.

Fine grains of debris occasionally hit the space shuttle, leaving impact marks in the heat tiles and even in the windows; to avoid damage to the sensitive front of the shuttle, at times when no reason exists to do otherwise, it flies tail-first.

A "ding" 1/16 inch across, in a window of the shuttle.

So it was solar flares. That explains what I saw the other night while I was looking up at the sky.

Originally posted by quadricle
spacedoubt, it would be amazing to see some first hand pix of these flares, looking forward to seeing some.

You asked, you recieve!

This was my FIRST attempt. Capturing an Iridium Flare, based on a prediction
From the Heavens Above website.
This was a low elevation pass from my perspective, about 12 degrees from
the Horizon, out of the Northeast. The prediction was a magnitude -5.
That was probably pretty close to what I saw.
Taken with a Sony DSC-F707 Digital.
ISO400
30 second exposure.






So there
Is your Flare

Originally posted by spacedoubt
You asked, you recieve!

wicked spacedoubt!

thanks for that, much appreciated

YOu're welcome!

The Flare was RIGHT ON TIME.
I was a split second late, I was fiddling with camera settings..
So I didn't get the entire thing.
When I capture more, I'll post 'em.
Do you know a good place for some free webspace, by the way?
Something that will allow linking from here?


Space out.

That looks great, SD! I can hardly wait to see what else you grab. About webspace, are you looking for a place to put photos? If so, i am still using Photobucket even though they were having problems lately. Some folks have switched to Imageshack.