Tag: China

The reentry window for Tiangong-1 has now been narrowed to 24 hours, centered on April 1st. It is still too soon, however, to determine where it will land. The map on the right shows the likeliest regions in yellow, the next likeliest in green, and areas with no chance of impact in blue.

The focus so far has been on where the surviving pieces of Tiangong-1 might land. The summary at the link notes that it also will provide an interesting fireworks display.

It may be possible to see Tiangong-1 reentering depending on your location, the time of day, and visibility during reentry which will not be known until a few days prior to the event…. Visibly incandescent objects from this reentry will likely last tens of seconds (up to a minute or more) in contrast with the vast majority of natural meteors which last mere seconds.

…Depending on the time of day and cloud visibility, the reentry may appear as multiple bright streaks moving across the sky in the same direction. Due to the relatively large size of the object, it is expected that there will be many pieces reentering together, some of which may survive reentry and land on the Earth’s surface.

The spacecraft does carry toxic hydrazine fuel, so if by some miracle a piece falls near you don’t touch it.

China’s first space station, Tiangong-1, is now predicted to crash to Earth in a window that has been narrowed to four days centered on April 1. The map to the right shows the station’s most likely landing areas, with yellow the most likely, green less likely, and blue not at all. Essentially, there is about a 50-50 chance the station will come down in the north mid-latitudes, with about a 70 percent chance it will land in water if it does so.

Thus, the odds of the station hitting a populated area is not large, but it definitely exists. We will not know the exact area of impact until very close to the moment the station finally comes down.

New estimates by the European Space Agency of when China’s Tiangong-1 space station prototype will re-enter the atmosphere have now been narrowed to one week, centered on around April 4.

The map on the right, created by the Aerospace Corporation, indicates the latitudes where the module is most likely to fall. Yellow is the more likely, green is less likely, and blue is no chance at all. Note that Aerospace has not yet narrowed its re-entry window, still holding it at two weeks centered on April 4.

Link here. Right now the de-orbit window of the dead Chinese space station suggests it will come down to Earth sometime around April 3, plus or minus a week. As we get closer this will get refined somewhat, but the uncertainties are always going to be great, until the actual moment it hits the atmosphere.

The map on the right, reduced to post here, comes from the link and was produced by the Aerospace Corporation and indicates the relative possibilities of debris falling in a given region.

Yellow indicates locations that have a higher probability while green indicates areas of lower probability. Blue areas have zero probability of debris reentry since Tiangong-1 does not fly over these areas (north of 42.7° N latitude or south of 42.7° S latitude). These zero probability areas constitute about a third of the total Earth’s surface area.

Depending on orbit, and whether the station is heading north or south in its orbital inclination, the odds of it crashing in populated areas changes significantly. If it is moving north the odds of coming down in the populated mid-latitudes of the northern hemisphere go up considerably. Of course, it could just as well come down in the northern mid-latitudes above the Pacific.

Regardless, the risks remain tiny, no matter what. Tiangong-1 is a small module, just large enough for some of it to survive reentry.