Near Earth Objects

[LaurieAG]

Reentry is down to 133 days and 9 hours now so we'll have a better idea of actual reentry in a couple of days. I can vaguely recall that the original orbit wasn't exactly polar or equatorial but more like an offset polar orbit so they may not be compatible. 

[Deepwater6]

https://www.space.com/38798-first-interstellar-object-name-oumuamua.html

 

Oumuamua? That's a mouthful of a name, but hey it's the first interstellar one found so we'll give the name some latitude.

[Deepwater6]

I'm losing it, this is the first I'm hearing about this one. Not only that, it supposedly was (until recently) once thought to have impact possibilities. Fairly large one too, It's not the more usual school bus size passing, but is 3 miles wide.

 

Oumuamua continues to be really interesting, I don't think I remember anything shaped close to it going through our solar system. I wish we had more information and a better view.

 

https://www.msn.com/en-us/video/wonder/asteroid-nasa-once-called-‘potentially-hazardous’-will-fly-past-earth-in-december/vi-BBFBoTv

[LaurieAG]

We've been getting very mild weather with rain lately in the north of Australia and are expecting a wet summer while Victoria and Tasmania are having another heat wave. I have also noticed that the TIANGONG I forecasts have ranged between 84 and 116 days til reentry in the past 6 days which means it should be coming in during our southern hemisphere cyclone season.

 

This map shows the location of the reentry predicted by USstratcom (United States Strategic Command).

When it gets closer to reentry it will impact the atmosphere around its path. The map should update when you refresh this page (currently March 25 2018 at 4:23pm over Australia).

Edited December 25, 2017 by LaurieAG

[LaurieAG]

Tiangong I has just changed it's descent rate from around 0.3 of a km per day to around 0.5 of a km per day. 

 

The Solar Maximum mission reentry showed a similar change in descent per day at a similar altitude although its mass is around 0.25 of the mass of Tiangong I.

 

Edited December 25, 2017 by LaurieAG

[Deepwater6]

https://www.universetoday.com/138179/mid-march-chinese-tiangong-1-space-station-going-come-crashing-back-earth-somewhere/

 

Not long now LG, hopefully it just lands in the ocean somewhere out of the way. Maybe we'll get lucky and have coverage of it's path somehow, it would be cool to see.

[Deepwater6]

https://www.space.com/39442-michigan-meteor-fireball-meteorites-found.html

 

This one woke a few people up.

[Deepwater6]

http://bleacherreport.com/articles/2756289-asteroid-reportedly-may-pass-by-earth-during-eagles-vs-patriots-super-bowl?utm_source=cnn.com&utm_medium=referral&utm_campaign=editorial

 

Well that sounds about right for my luck, my Philadelphia Eagles finally make it to the super bowl and an asteroid hits us to plunge us into a mini ice age. It's tough to be an Eagles fan for many reasons. It seems we have been having a lot of pass-by asteroids lately.

[LaurieAG]

https://www.universetoday.com/138179/mid-march-chinese-tiangong-1-space-station-going-come-crashing-back-earth-somewhere/

 

Not long now LG, hopefully it just lands in the ocean somewhere out of the way. Maybe we'll get lucky and have coverage of it's path somehow, it would be cool to see.

 

That's strange, there must have been some sort of a bit of a blip 6 weeks ago as the drop in altitude of Tiangong I is now finally but firmly 0.5k per day.  

 

I must be missing something here as the current forecast is for 75 days and 23 hours at a 255 km altitude of nominal burst but the current altitude is 267.5 so 267.5 - 255 = 12.5 which should take 25 days at 0.5km per day yet the forecast is 3 times more. 

 

[LaurieAG]

They have changed the altitude of nominal burst to 238 km from 255 km so the figures make more sense now. 

[Deepwater6]

Do you think China still has enough capability to maneuver the craft into the ocean or are they just spreading good PR and hoping for the best?

[LaurieAG]

The Chinese announced that they had lost control of it over a year ago so they have been straight about it. 

 

http://www.spacedaily.com/reports/Has_Tiangong_1_gone_rogue_999.html

 

The altitude of nominal burst has jumped from 238 to 264, the current altitude is 264.99km and the forecast reentry is 99days and 11 hours so the data still isn't straight.

[LaurieAG]

The altitude drop is almost 1km per day, the current altitude is 260.38km, the altitude of nominal burst is 223 and the forecast is currently 44d and 6hrs.

 

This forecast would be ok if it continued to drop at 1k per day but that's not going to happen so I'll put my head out and say it will come down sometime around 16-21 March 2018, or in 25-30 days.

[LaurieAG]

I have been recording 3 pieces of data once a day just to get a rough idea on how fast TIANGONG I is dropping and the data over the past couple of days makes me suspect that TIANGONG I may have just had a "bounce". 

Date           Time  (AEST)   Altitude     Difference
18/2/2018      5:00pm         261.37km     
19/2/2018      6:30pm         260.38km     0.99km
20/2/2018      3:30pm         260.16km     0.22km
21/2/2018      3:30pm         259.30km     0.86km

[LaurieAG]

While it's dropped nearly 1.0 km per day over 3 days on average it seems to be wobbling around quite a bit. 

Date           Time  (AEST)   Altitude     Difference    ANB
 
22/2/2018      5:00pm         258.61km     0.69km        221
23/2/2018      5:00pm         258.04km     0.57km        240
24/2/2018      9:00pm         256.79km     1.25km        229
25/2/2018      9:00pm         255.89km     0.90km        207

I know it actually orbits 16 times in a day so you can probably consider this rough as guts analysis equivalent to crossing your eyes and making things 'fuzzy' to see who's face was being obscured on tv. ;)

 

 

[LaurieAG]

Date           Time  (AEST)   Altitude     Difference ANB 

26/2/2018      9:00pm         255.18km     0.70km     211
27/2/2018      7:00pm         254.42km     0.76km     220
28/2/2018      7:00pm         253.97km     0.45km     217
01/3/2018      7:00pm         252.50km     1.47km     217

That's interesting, despite the wobbles the object drops 6km over 8 days making the plot (on a km/day scale) a 3,4,5 right angled triangle with the wobble going from trough to peak in 4 days.

 

I can even see a little sub wobble within the main wobble so It leads me to wonder if these changes in drop rate/altitude reflect an increasingly elongated orbit (time per rotation wouldn't change much) or the rotation (skewed?) of the object and any subsequent friction and surface area changes. 

 

Regardless US StratCom had it coming down at 217km in 41 days (at my last data point) which is a linear 0.82 km/day to (my rough plot is 0.80 km/day) so I'll change my forecast to April 2 just after midnight because 1km per day is a more reasonable average. 

 

 

 

[Deepwater6]

https://www.space.com/39845-bus-size-asteroid-2018-dv1-earth-flyby.html#?utm_source=sdc-newsletter&utm_medium=email&utm_campaign=03012018-sdc

 

LaurieAG, I'm taking it for granted the sinking ship has no heat tiles of any kind on it as the space shuttle did. How much of it do you believe will make it through?

 

The above article has 3 NEO's in it. One of them is the size of a school bus, but may be visible as it is predicted to pass just 70,000m. from Earth.

 

Another is a lot larger, thought to be (150-to-470m) and labeled "potentially dangerous" by NASA. A consequence of its size combined with its distance earns this NEO that dark title.