
The end of Iridium flares? - ColinWright
https://www.heavens-above.com/IridiumDemise.aspx
======
donarb
An interesting fact is why the name Iridium?

When they were in the planning stages for this set of satellites, they
estimated that they would need 77 of them to completely cover the Earth
(including the poles), evoking an image of 77 electrons circling the nucleus
of an atom. The atomic number for the element Iridium is 77. The number of
satellites needed was paired down to 66, so the satellites should actually be
named Dysprosium.

~~~
basementcat
I pointed this out when I interviewed for a job at Iridium.

I didn't get an offer.

~~~
codinghorror
You may not have gotten an offer, but you do get something else of
incalculable value: my upvote!

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kokey
I used to have a cron job that ran a little perl script that screen scraped
heavens-above once a day and then set up 'at' jobs to send me an SMS when a
visible pass of the ISS or an Iridium flare was going to show up over me in
the next 5 minutes. Was a great party trick at times and I got to see some
great flares and also saw the ISS and a space shuttle a few miles from each
other.

~~~
tomcam
trying to envision said parties

~~~
matte_black
Rooftop parties in the city, drinking beer from bottles, strings of vintage
lightbulbs, people wearing plaid, taking out your phone to say “Hey look at
this!” and pointing out a spot in the sky where an iridium flare streaks
across while everyone gasps “Wwwooww!!” High fives

~~~
dcfrdrklj
The University of Sydney Physics Society (physoc) used to have some great
rooftop parties (in the late 80s). Invariably someone would raid the dry ice
freezer and put it in the empty bottles and screw the lids on to make "depth
charges". These would get dropped over the edge and go off with a resounding
boom sometime later, scaring the wits out of anyone at ground level.
University Security would invariably arrive to find everything peaceful at
ground level and so sign of the party above.

~~~
toomanybeersies
That's one of those things that wouldn't fly at universities these days.

At least in NZ, all the traditional student events and activities have been
slowly neutered over the past decade or so, to ensure that nobody gets hurt,
and that everything is tame and hurts nobody's sensibilities.

~~~
abraae
I was about to prove you wrong by demonstrating that couch fires are still a
fun student tradition in NZ, but googling shows the very opposite.
[https://www.odt.co.nz/news/dunedin/heat-out-couch-
burning](https://www.odt.co.nz/news/dunedin/heat-out-couch-burning).

Only 11 fires in the first three months of last year, a massive 65% drop on
the previous low of 31 for the period.

~~~
toomanybeersies
Every time I saw a couch fire at Canterbury, the fire brigade arrived shortly
to put it out.

They were definitely frowned upon. Especially when the couches were stolen
from the halls of residence and burned on Ilam fields.

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sciurus
If, like me, you need context on what an Iridium flare is:
[https://en.wikipedia.org/wiki/Satellite_flare#Iridium_flares](https://en.wikipedia.org/wiki/Satellite_flare#Iridium_flares)

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macNchz
I used to keep close tabs on the brightest upcoming Iridium flares–it has long
been a great party trick of mine to point up at a section of the night sky and
tell a group of people sitting around a campfire to watch carefully just as a
bright flare lights up. It'll usually spark a bit of a sense of wonder and
some great conversations. Too bad they're going away!

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brunoTbear
I captured a series of still images of one passing through Orion with an old
dSLR a few years ago.

[https://www.youtube.com/watch?v=zd288ct92pk](https://www.youtube.com/watch?v=zd288ct92pk)

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rosser
I didn't know these were a thing until reading this, and now wonder if I'll
ever get to see one.

Ohai, wistfulness.

Thank you, HN, for expanding my world yet again.

~~~
macintux
Yeah, I’m wondering how I would have discovered these. I don’t have a TV, so I
miss a lot of cultural events, but this is something that should have crossed
my radar before it was too late.

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winkywooster
Crazy.. I've never seen a satellite flare until a couple of weeks ago. Camping
in New Mexico and I decided to sleep out in the open. As I kept waking up in
the night worrying about critters, I was watching the stars make their way
through the sky. I was surprised at the number of satellites I saw, including
one glint which I've never seen before. I had to look up if that was actually
a thing.

~~~
timdierks
You should seek out a flare if you can, it's much much brighter than seeing a
satellite or the ISS, as impressive as those are.

~~~
Bromskloss
Hmm, so an Iridium satellite is much brighter than a satellite or the ISS (a
satellite). Got it!

~~~
Stratoscope
An Iridium _flare_ can be much brighter than any other satellite including the
ISS.

The Iridium satellites are not very bright most of the time - you would be
lucky to see one with the naked eye. But when they flare, they can be the
brightest thing in the night sky for a few seconds.

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chinathrow
The launch of more Iridium Next sats is actually in progress over at Spacex.

[https://www.youtube.com/watch?v=I_0GgKfwCSk](https://www.youtube.com/watch?v=I_0GgKfwCSk)

~~~
garmaine
Which will not flare.

~~~
SimonPStevens
Whats the reason for this? What is it about a satellite that causes it to
produce flares that the new ones don't have.

(I always thought flares were sunlight reflections off solar panels. Is it
that the new ones have less panels? Or is it about positioning?)

~~~
ascorbic
Iridium flares are reflections from the antennas, not solar panels. The new
satellites have a different antenna arrangement which doesn't flare.

~~~
saagarjha
Having a solar panel that flares seems like an easy way to get an inefficient
solar panel…

~~~
garmaine
Not sure why you’re down voted. That’s a critical part of the answer.

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cup-of-tea
I've been telling people for a while that this year might be their last chance
to see an Iridium flare. Just today I had a predicted daytime flare but it did
not show up. Seems like maybe the chance has already gone.

You can still see other satellites and the ISS, but the Iridium flares were
special. I'm glad I showed my wife a good one last year.

~~~
askvictor
They might still be there for a while, just not predictable. Which might make
them a bit more special.

~~~
cup-of-tea
Apparently they will all be taken down by the end of the year. It was posted
on HN a while back. I'm not sure why this current article seems unaware of
these plans.

~~~
askvictor
According to Wikipedia there are a few in uncontrolled orbits, so they might
be around for a while yet. As for the ones still under control, it looks like
they'll drop 15-20km below their replacements as a contingency for a little
while, before finally being de-orbited (I can't find any details on the timing
for this)

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0xcafecafe
Thats a shame. Seeing Iridium flares was one of the highlights of my amateur
astronomy experience. The best one I remember was seeing one just randomly
when I was leaving a friend's house after a saturday night party. Just decided
to look up at the sky and there it was.

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azswcowboy
In fact most of the Iridium block 1 sats are being de-boosted so as to not
create space junk. Iridium actually has a Twitter campaign to mark the
occasion.

[https://mobile.twitter.com/IridiumBoss/status/99610389859420...](https://mobile.twitter.com/IridiumBoss/status/996103898594205696)

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accnumnplus1
Oh no! I've loved watching them. This calls for a petition to leave one in
place as a memorial.

~~~
John_KZ
Or, we can crowdfund a very large Mylar mirror. I'd pay at least $5 for this.

~~~
solarkraft
Humanity star was an attempt. We might be able to keep one in orbit for a few
years. I doubt astronomers would be happy about it, however. But I'd also
contribute money.

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owenversteeg
Anyone know the Iridiums that have been deorbited? Or, more specifically,
anyone know the status of 61, 10, 14, and 32? 32 is the most important to me
as it'll be giving a bright flare near where I am soon...

[edit] and 84, my girlfriend and I will be staying in a dark spot where we
should be able to see 84, hopefully it's still doing OK...

[edit 2] Decayed so far:

25, 72, 14 may

13, 29 april

94, 18 april

19, 7 april

Started to decay:

68, 10 may

21, 3 may

72, 27 april

25, 19 april

All decayed: 25, 72, 13, 94, 19, 23, 49, 43, 3, 34, 6, 8, 30, 77, 74.

It appears to take between two to four weeks for an Iridium satellite to decay
from the start of the deorbiting process.

I got all my information from this excellent page here:
[http://www.rod.sladen.org.uk/iridium.htm](http://www.rod.sladen.org.uk/iridium.htm)

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jcims
Does the tracker actually model the directed reflections or just the relative
angle of the viewer, the satellite and the sun and let chance take care of the
rest?

~~~
LVB
IIRC it is a fairly precise model. They know which antennas, and the directed
reflection. The width ground track is not all that wide, but if you're right
in the middle of it they're very bright. Years ago I drove to be in the center
of the path and could easily see the flare in broad daylight.

~~~
jcims
Thanks for the reply, that's pretty amazing!!!

------
CoolGuySteve
Is there a heat dissipation reason why satellites are painted white instead of
black? And if so, why are they white instead of a completely reflective
surface?

~~~
Sharlin
Satellites are not painted white. Satellite bodies are are typically covered
with reflective thermal blankets made of materials like Mylar or Kapton
[1][2][3]. However, what makes satellites reflect enough sunlight to be
visible in the sky is not the blankets but solar panels or antennas.

[1]
[https://en.wikipedia.org/wiki/Space_blanket](https://en.wikipedia.org/wiki/Space_blanket)

[2] [https://en.wikipedia.org/wiki/BoPET](https://en.wikipedia.org/wiki/BoPET)

[3]
[https://en.wikipedia.org/wiki/Kapton](https://en.wikipedia.org/wiki/Kapton)

