New re-entry forecasts by the European Space Agency and Aerospace Corp. have shifted the time of Tiangong-1's expected crash to between Sunday evening and early Monday (April 2). ESA officials are targeting 7:25 p.m. EDT (2325 GMT) Sunday as the likely time. An update this afternoon from the Aerospace Corp. forecasts a 7:53 p.m. EDT (2353 GMT) crash, give or take 7 hours.

on the ascending node on the last orbit its altitude was 159.8 km and over the past 7 hours its low point has been decreasing by about 1km per hour

that rate will rapidly increase as it comes in contact with the upper atmosphere but the sun has been quiet so that's not helping much in increasing the drag

latest prediction is 2200Z +/- 6 hours

quote:

Originally posted by jhe888:
The sky is falling - the sky is falling!

While it is certainly fun to panic, almost all of the space station, if not all of it, will burn up in the atmosphere. Anything toxic will be greatly diluted, and not add measurably to pollution. The path of where debris will enter the atmosphere is highly unpredictable, and if any pieces do make it to earth, the chances that they hit anyone are pretty damn small. Much of the possible "danger zone" is ocean.

There isn't actually much to worry about.

Well it couldn't hurt to make sure your rifle is clean, JIC Zombie Apocalypse.

Where is the expected reentry path?

TIANGONG-1: POSSIBLE DEBRIS PATH
PROBABLE NATURE OF CRASHED DEBRIS: CHUNKS OF DEBRIS AS LARGE AS 100 KG (220 LB) FROM DENSER PARTS OF SPACE STATION NOT LIKELY TO BE COMPETELY INCINERATED IN ATMOSHERE.

UPDATED TIME OF REENTRY: SUNDAY 4/1/2018 2200 ET ±7 HOURS

This message has been edited. Last edited by: kkina, April 01, 2018 06:47 AM

CHINESE SATELLITE TIANGONG-1 LIVE TRACKING

NOTE: This is one of the few truly realtime and embedable video feeds, but you may have to disable the audio if the backround music somehow detracts from your live experience. Or, perhaps you like to track and shred....

4.1 0554 ET -ALTITUDE JUST ABOVE 100 MILES. STATION CAN BEGIN FINAL DECAY (REENTRY) AT ANY TIME BELOW THIS ALTITUDE.
4.1 0700 ET -ALTITUDE IS JUST UNDER 100 MILES WITH STATION CROSSING BAJA CALIFORNIA.

This message has been edited. Last edited by: kkina, April 01, 2018 06:02 AM

Live track:

http://www.heavens-above.com/GroundTrack.aspx

^^That's a good feed but it can't be embedded into the forum (as far as I know).

Looks to me like it will probably go down some time soon, if the less than 100 mile altitude suggested above is correct. Either southern Africa or the southern Indian ocean.

Oops.. I was looking at it wrong... headed straight for us in the U.S. I wonder if the Chinese planned it that way.

quote:

Originally posted by Blume9mm:
Looks to me like it will probably go down some time soon, if the less than 100 mile altitude suggested above is correct. Either southern Africa or the southern Indian ocean.

Trouble is it keeps floating above and below 100 miles. It is literally floating, skimming the very edge of our atmosphere. Pretty cool.

I've started noticing that too... wonder if they have a way to give it a little boost until it is back over an ocean?
edit at 8:09 edt: looks like it missed us this time around.

quote:

Originally posted by Blume9mm:
I've started noticing that too... wonder if they have a way to give it a little boost until it is back over an ocean?

As far as anyone knows, the Chinese have lost all control of the spacecraft. This will be an uncontrolled reentry.

The next trajectory is well north of the last one. Hmmm, I could be under the reentry path in a few minutes. Altitude has dropped to 96 miles.

0833 ET Looks like it passed to the south of me. Altitude is back up to 99 as well. Wonder what the next pass will be like, though.

The point of no return is 100 kilometers, which is the Karman Line generally used to describe the lower boundary of outer space. Above this altitude, the speed required to keep a vehicle aloft though aerodynamic lift exceeds that required to maintain orbit; below it, atmospheric resistance will quickly brake an unpowered vehicle below orbital speed. As of now, the station is still following an orbital path with perigee and apogee (closest and farthest points from Earth) around 160 kilometers (100 miles). It's still being braked by the atmosphere of course, which gradually peters out somewhere between 1,000 and 10,000 kilometers, so will eventually drop below the Karman Line.

How come the charts I've seen show the final decay at 100 miles (160 kilometers)?

In the end it all depends upon your definition of "re-entry". Per the above, most satellites never really leave atmosphere, which is why they eventually de-orbit from residual atmospheric drag. Early manned missions like Vostok and Mercury had orbits between 100 and 200 miles, but they only needed to last a couple turns before return. In fact I guess the low orbits were a safety factor ensuring a quick landing even without a re-entry burn.

Well, I've got to get some sleep. Someone else will have to watch the space station.

Doesn't look like much has changed all morning.

I'm starting to see some change in altitude since last night. It's dropped below 92 mi.

ETA: False alarm.
Now it's going back up in altitude just as fast.
It had gotten down to as low as 91.7mi.

DailyMail:

“The station was due to [dis]appear as early as midday Saturday but has slowed down [i.e., demise delayed] due to changes in the weather conditions in space, according to the European Space Agency.

The agency said calmer space weather was now expected as a high-speed stream of solar particles did not cause an increase in the density of the upper atmosphere, as previously expected…”

https://dailym.ai/2Iic3Dj