U.S. chance of Tiangong-1 sighting now less than 2%

March 31st, 2018 by Roy W. Spencer, Ph. D.

The latest Aerospace Corp. prediction of the reentry time for the Chinese Space Station Tiangong-1 is now 3:30 p.m. CDT (plus or minus 8 hours) on Sunday, April 1. As reentry approaches, the predictions will get better, and the potential paths of the satellite will be narrowing.

The latest potential paths of reentry look like this:

Potential Tiangong-1 reentry orbital paths on April 1 2018 (Aerospace Corp.)

The paths over the U.S. are morning paths, and would be quite early in the time window of reentry. The total time these orbits are visible from the contiguous U.S. is only about 25 minutes (you could see the satellite burning up as far as 400 miles away from these paths, assuming no clouds are in the way). That is only 2.6 percent of the total time of the reentry window (16 hours), so given the the fact the U.S. paths are quite early in the window (and thus lower probability), I’d say the chances of anyone in the U.S. getting to see the fireworks show is less than 2%. Once you factor in cloud cover, it’s probably more like 1%.

Of course, we always knew the probability was very small.

And I think Michigan can now deactivate their Emergency Operations Center.

But, if you are feeling lucky and live within a few hundred miles of one of the paths show in the above graphic, I suggest visiting heavens-above.com, (1) enter your location (or nearest city), (2) click on “Tiangong-1”, and (3) change from “Visible only” to “All”, to see exactly what time(s) the satellite will be passing near you. Click on one of those times to see the path it will be making across the sky.

18 Responses to “U.S. chance of Tiangong-1 sighting now less than 2%”

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  1. Svante says:


    DR says:
    March 31, 2018 at 11:44 AM
    Dr. Spencer, I would very much like you to comment on this:


    Modeling the Earths climate is one of the most daunting, complicated tasks out there. If only we were more like the Moon, things would be easy. The Moon has no atmosphere, no oceans, no icecaps, no seasons, and no complicated flora and fauna to get in the way of simple radiative physics. No wonder its so challenging to model! In fact, if you google climate models wrong, eight of the first ten results showcase failure. But headlines are never as reliable as going to the scientific source itself, and the ultimate source, in this case, is the first accurate climate model ever: by Syukuro Manabe and Richard T. Wetherald. 50 years after their groundbreaking 1967 paper, the science can be robustly evaluated, and they got almost everything exactly right.

    • AaronS says:

      Im confused how this relates to topic of the post about seeing a space station?

      Plus its obviously wrong to stop temperature measurement at the peak of a major 2016 El Nino to compare to a model. El Nino warming is major and can not be factored in. So using a 2016 number is not accurate for comparison.

      • Svante says:

        No relation to the space station, sorry. I just wanted to save DR’s post from oblivion.

        The article says 1 C, but the 2016 peak seems to be 1.5 C in that diagram.

    • An Inquirer says:

      From a scientific view, we are a long ways away from saying that “they got almost everything exactly right.”

      First, there is the issue of when to measure. Taking the ending measurement point when there were secular deviations would raise concern.

      Second, Although some may feel that we have the world temperature nailed down, that is more of a leap of faith than science. In the article, it seems like they use NASA’s temperature estimate which is quite a hodgepodge of estimation techniques and yields results that are internally inconsistent.

      Third, quite a few analysts says that if temperature goes up only 2 degrees from doubling CO2, will be okay. And it far from certain that human emissions would ever cause a doubling of CO2 concentration.

  2. PpEntropic man says:

    I notice that Tiangong-1 will be passing over China around the predicted time.

    Still poor odds of landing on its country of origin, but perhaps the universe will take this opportunity for irony.

  3. Erik Aamot says:

    this could land near my family’s farm in southwest Uganda :-O

  4. g*e*r*a*n says:

    The thing weighs close to 19,000 pounds. That could do some serious damage, if not for the fact that it will be mostly burned up by friction from the atmosphere..

    It’s times like this it would be nice to have some more CO2 in the air.

  5. It’s times like this it would be nice to have some more idiotic comments in the blog.

  6. Darwin Wyatt says:

    It’s times like this we should target practice on it with Patriot missiles.

  7. AaronS says:

    Well I am in China now and will keep my eyes open. However I believe the haze needs factored into the likelihood I will see it.

  8. Those wanting the time should keep a close eye on the source. It’s no longer “3:30 p.m. CDT (plus or minus 8 hours) on Sunday, April 1.”

    Tiangong-1 is currently predicted to reenter the Earths atmosphere around April 2nd, 2018 02:00 UTC 7 hours.

    Daylight savings always confuses me, but the time is now centered on Sunday evening in the U.S.

    Check out their map with the orbital paths, keeping in mind the craft is moving from left to right. The map is now less cluttered and more readable. There’s now only one path in the predicted range that passes over the U.S. and that’s over north Florida and south Georgia. That is also at the very end of the predicted range.

  9. Mike Flynn says:

    Should be a snap for climatologists. Basic physics.

    One object, known trajectory.

    How hard can it be?


  10. E. Swanson says:

    I did some analytical work calculating the atmospheric drag on a large satellite way back when. I was able use a digital simulation to show how to reduce the usage of control gas, the result being that the satellite series exhibited double the lifetime on orbit compared to the original projection.

    With this one, there’s the known unknowns which complicate the question. For example, is the attitude control system still working or is the satellite tumbling as it descends? Not an easy problem at all.

    But, Mikie insists on making a snide comment anyway, comparing this computational problem to that of estimating the impact of increasing Green House Gases being added to the atmosphere. An April Fool, as usual…

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