With the decision by the Russian authorities to de-orbit the 15 year old Mir space station, there has been much interest in when and where it will come down. To provide those interested with as much information as possible, we show above a new graph plotting the orbital height of Mir against time. Clearly visible are the re-boosts which have ocurred over the last year, and the gradual decay in between. The height is averaged over one orbit, and the gradual decrease is caused by atmospheric drag. As can be seen from the plot, the rate of descent is not constant and this variation is caused by changes in the density of the tenuous outer atmosphere due mainly to solar activity.

This graph is updated continuously as new orbital data is published by NASA, and re-entry will occur when the lowest point of the orbit descends to approximately 100 km. Close to the end, the drag will be much higher because of the increase in air density at lower altitudes and so Mir will descend very rapidly in the last few days.

It is notoriously difficult to predict exactly when and where a satellite will re-enter the atmosphere, especially when the expected re-entry is still several weeks away. Heavens-Above does not currently attempt to make such predictions, but Alan Pickup's excellent Decay Watch page is a good source. Please note that Alan's predictions assume an uncontrolled satellite, but the Russians intend to bring down Mir in a controlled manner in the South Pacific Ocean, so as to minimise risk of pieces landing on populated areas. Launch of a Progress vehicle to act as a "tug" is expected in the near future.

Other pages with Mir information:

Current position of Mir Visiblity predictions for your location