At the Paris Observatory, monitoring by the IMCCE in no way rivals the standard space surveillance, and in particular that carried out over the national territory by the State.
The exact point of re-entry over the Earth will be known only a few hours before the break-up of the station.
After having tested various orbit calculation methods, the Paris Observatory can now give an estimate of the regions involved in this re-entry.
Potential regions are :
- The extreme south of the metropolitan area, including Corsica,
- Guyana,
- New Caledonia.
During the next few days, Guadeloupe, Martinique, the Réunion are not under the path of the Chinese station, and so have nothing to fear from the possible fall of debris.
Status on Thursday, March 29th 2018
On the basis of publicly available data on path of the satellite to which the Paris Observatory and the Laboratoire de Météorologie Dynamique - LMD (CNRS / ENS / École Polytechnique / UPMC) have access, the trajectory of Tiangong-1 has been calculated with an accuracy on the order of a kilometer.
This determination has taken into account as much as possible observational data, but nevertheless does take into account the latest observations of the national units responsible for space surveillance.
On March 29th 2018, the altitude of the station was between 187 and 203 km (altitude calculated without taking into account the polar flattening of the Earth).
Its altitude is now decreasing by about 5 kilometers per day.
As the station passes through increasingly dense parts of the atmosphere, this decrease will become increasingly more important.
Trajectory details
Maps created in collaboration with the Laboratoire de Météorologie Dynamique have enable us to refine the path of the station over the Earth as it falls, between March 29th and April 2nd 2018.
Many inhabited zones, in particular in the Northern hemisphere, are below the path of the station.
One should nevertheless keep in mind that the speed of the flight is 7,22 km/s, so that the station orbits the Earth in about 90 minutes : as in the case of all atmospheric re-entries, the risks of ground based damage are as a consequence extremely small, as indeed have shown the increasingly frequent atmospheric re-entries of artificial bodies.
Nevertheless, because of the size of the station, it is possible that pieces of it will reach the terrestrial surface. Depending on the winds, it is quite likely that the debris will be spread over an ellipse of about :
- 500 meters wide over the trajectory ;
- and on the order of ten km long. (These figures are based on what
happens during meteorite showers).
French territories
Over metropolitan France, the flight lasts just a few seconds per day. Thus, the risks of fragments surviving over France are extremely small.
Map of metropolitan France
The French towns which could be involved are : Leucate, Bastia, Propriano, Kourou…
Map of the Antilles
Map of Guyana
Map of the Reunion
Other maps
Update
This information will be updated by the Paris Observatory if it turns out that fresh calculations change significantly the information given here.
It is unlikely that the Paris Observatory will be able to give an estimate of the location of the fall before it actually happens.