The end of Iridium flares? | Hacker News Reader

The end of Iridium flares?

heavens-above.com

201 pointsColinWright66 comments

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.

pared down

As in the thing you do with a paring knife.

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

I didn't get an offer.

Ya miss 100% of the shots you don’t take.

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

Didn't that company end up going out of business and getting bought out for pennies on the dollar by another company which is the one operating it now?

You might have dodged a bullet there.

Probably wouldn't want to work there if they couldn't take the joke!

And for completeness, the name of the element comes from the name of the Greek mythological personification of the rainbow. With rainbows being something of a "heavenly" phenomenon, the name was doubly appropriate.

Cambridge Consultants designs a lot of their subscriber equipment - modems, handsets etc. Their internal project name for the Iridium work is Dysprosium for exactly this reason.

Yes, original Motorola design called for 77 which drove the name, which stuck.

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.

I’d love to subscribe to this!

The Android app 'ISS detector' can alert your phone when there's a flare (or the ISS) about to assist.

trying to envision said parties

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

I'M IN

Then you put your phone back in your pocket, laugh dramatically, and close with "And that's the last time NASA messes with me."

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.

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.

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.

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

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.

Sounds like my experience in Melbourne. It was the plaid that really hit the spot.

I've wowed "normal" people at outdoor parties by "showing" them the ISS, they knew about the it but have never seen it. If I were more charming and better prepared I could also claim I'm an alien, and my spaceship is up there, here let me turn on the headlights, timing it to an Iridium flare.

But people usually say isn't that (the ISS) a plane? And you'd have to explain that plane lights blink.

— You want to see a party trick?

— Yeah!

— Let's see… hmm, not today.

The "Sky Guide" iPhone app will send you push alerts for Iridium flares, as well as when the ISS will be visible.

The app in Google's Play Store by the same name is apparently a different app by a different company.

The website that this HN post links to has their own app called Heavens-Above which is free and helps "identify lights in the night sky, predict Iridium flares, ISS and sat passes."

This is going to sound weird, but... One of the best nights of my life, I was on the beach at Bellows in the middle of the night with this Israeli chick the week after I got back from my last tour in Iraq. We were laying there in the sand, doing what people do on the beach at night and talking about the stars and the universe and smoking dope. I was just talking about the launch of one of the shuttles about half an hour before, and right there over our heads the ISS tracked across the sky with the shuttle right behind it, preparing to dock. I thought it was such an odd configuration and impossibly bright for anything smaller, so I checked my phone and sure enough, that's what it was. I'd give anything for more nights like that. Just the most incredible coincidence, perfect timing. Perfect night.

Really cool. My dad used to make me go around to teachers before a big meteor shower with documentation as to why this year's shower was "gonna be the big one" and me being out of school the next day should be an excused abcense.

That translates to at least ten summers of one night a year under the stars during a shower. Your story reminded me of a time when what must have been a school bus of space dust burned across the entire sky in front of our scout troop. Thanks Dad. Space is crazy.

I wonder if it was the 1998 Leonids. I got about 25 people from my college dorm to drive to the beach that night. It was the night of the fireballs. Another great memory.

That's a beautiful memory for me too! A lot of us gathered in the college ground and spent 1-2 hours watching the beautiful spectacle. I started to count, and then after sometime just gave up the counting. Never have got another chance after 1998 to see so many in one night.

We caught that with binocualrs. Mind-blowing that we could clearly see the shape of the Shuttle and the ISS. Those are big things.

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

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!

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

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.

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.

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.

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.

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

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.

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

https://www.youtube.com/watch?v=I_0GgKfwCSk

Which will not flare.

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?)

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

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

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

The original Iridium satellites had large metal panels (which contained the phased array antennae) that were at a bit of an angle to the ground, this made it possible for reflected sunlight to hit the Earth, causing a "flare" for whoever happened to be in that beam. The Iridium NEXT satellites have an antenna panel that is much closer to parallel to the surface of the Earth, so any reflected sunlight beams will pass at a glancing angle and won't intersect the Earth.

Why is this getting downvoted? These are the reason for the end of the Iridium flares, and they're being deployed live on that video feed right now.

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.

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

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.

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)

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.

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...

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

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

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.

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

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?

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.

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

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?

Why do you think they’re painted white? The flare itself is the result of reflections from the polished antennae which aren’t painted at all.

White and black are really the same colour, or lack of colour. The moon is actually like tyre rubber. But a tyre being lit by the sun at night is still brighter than anything else.

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

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

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

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