ISS, Tiangong, Satellites Over Puna

[TomK]

Nothing much has been happening recently. There have been some ISS passes and Iridium flares, but the ISS passes have occurred during bad weather and the Iridium flares are now becoming quite rare.

Anyway, some might know about the Chinese space station (Tiangong-1) that is now out of control and will soon re-enter the Earth's atmosphere. There's a fair chance a lot of it will survive re-entry and crash somewhere on the Earth's surface.

I don't think Hawaii is at risk as the current orbit doesn't have it going overhead before it re-enters, but there are a couple of opportunities to see it beforehand. It'll be around mag 0 which means it will be easily visible if the weather cooperates.

March 16th at 18:51 - around 58 degrees above the horizon in the NE.

March 26th at 05:18 - almost overhead and heading to the NE.

I'm not giving precise details because the orbit is unstable and will likely change very quickly as it starts hitting more of the atmosphere, so even the times above might change.

It's supposed to burn up in the atmosphere around 3rd April (just when I'm flying across the Pacific!) but that date is extremely uncertain and it could happen a week before or after that date. There's a very slight chance the re-entry will be visible from Puna, but it's too early to predict.

[PaulW]

Looking forward to it!

[HereOnThePrimalEdge]

the Chinese space station (Tiangong-1)... will soon re-enter the Earth's atmosphere.

Thanks for the reminder TomK. I checked regularly in early February when I had guests visiting, but there were no visible overhead passes at that time. We did see Tiangong-2 though.

Although we may only have a couple of chances to see the Tiangong-1 before it returns to earth, the good news is that because it seldom passes over Hawaii there's little chance it will reenter the atmosphere over our islands and scatter debris here.

Here's a good article (link below) with a map showing the areas with a slightly higher probability for reentry. In the US it's a thin band that stretches from Northern California/Oregon to New York/New Jersey. Best estimate right now as TomK noted is is April 3rd, +- one week.
http://www.aerospace.org/cords/reentry-p...1-reentry/

Declare yourself a success: you'll be admired by those who've declared themselves failures. - Last Aphorisms

[PaulW]

Thank HOTPE. TomK, any idea why that yellow band has a higher probability than the rest? As a complete layman I thought maybe the atmosphere would be thicker at the Equator and there was more chance of re-entry there.

Not much chance of it hitting Hawaii but that's a lot of North America in the way.

[TomK]

Paul - it's due to the geometry of the orbit, not so much the thickness of the atmosphere. It's in a near-circular orbit which is inclined to the equator. The result of this is that it spends a little more time at the edges of the latitude band, hence a slightly higher probability that's where it'll re-enter.

[PaulW]

Thanks Tom

[TomK]

All - from a very cold 8,000 miles away...

The Tiangong-1 orbit has changed so much that the evening opportunity to see it this evening (March 16th) will no longer happen. Apologies for those who hoped to see it, but nature is taking over. This also means the 26th March date is canceled for now.

The current prediction for re-entry is now April 4th but still +/- one week.

[HereOnThePrimalEdge]

Almost time for reentry of the Tiangong-1 Chinese space station.
The estimated return window is down to April 1st +- 2 days, so possibly as early as this Friday.

There are no predicted visible passes over Puna at dawn or dusk, but a fair number occur in the daytime or nighttime (unlit).
http://heavens-above.com/PassSummary.aspx?satid=37820&lat=0&lng=0&loc=Unspecified&alt=0&tz=UCT

Here's detailed info on the space station and the latest on reentry:
http://www.aerospace.org/cords/reentry-p...1-reentry/

If you want to combine the dual pleasures of insanity and social acceptance, religion is your only choice. - Last Aphorisms

[HereOnThePrimalEdge]

Here's a photo of the Chinese Long March rocket breaking up over Hawaii. It's not the Tiangong-1, but the space station might put on a similar show if reentry happens on a night pass:
https://www.universetoday.com/wp-content...129963.jpg


Radar image of Tiangong-1:
https://www.space.com/40089-china-space-...mages.html

If you want to combine the dual pleasures of insanity and social acceptance, religion is your only choice. - Last Aphorisms

[HereOnThePrimalEdge]

Live Ground Track of Tiangong-1
Tiangong-1 is currently predicted to reenter the Earth’s atmosphere around April 1st, 2018 23:30 UTC ± 7 hours.

http://heavens-above.com/GroundTrack.aspx?lat=19.6012&lng=-154.9466&loc=Keaau%2c+HI+96749%2c+USA&alt=13&tz=UCT10

If you want to combine the dual pleasures of insanity and social acceptance, religion is your only choice. - Last Aphorisms