At the risk of sounding like Chicken Little, the sky is falling …. again! Well strictly speaking, I am not referring to the actual sky falling but the ROSAT German X-ray satellite. According to the US Military website Spacetrack, it is expected to re-enter around Wednesday 12 October 2011.
You may think this sounds very familiar and you would be correct. We have almost a repeat of the situation that occured when NASA’s UARS satellite re-entered the Earth’s atmosphere on Saturday 24 September 2011. There are a couple of differences. The first is that the ROSAT orbit is not quite as inclined to the equator as UARS’s was. It still means however that the satellite could potentially land on any of the inhabited continents of the Earth. The second difference is more interesting if debris from the satellite happens to land on your head at around 400 kilometers an hour! More of the satellite is expected to survive re-entry. (From the ROSAT website) When the spacecraft re-enters the atmosphere at a speed of approximately 28,000 kilometres per hour, the X-ray observatory will break up into fragments, some of which will burn up by the extreme heat. The latest studies reveal that it is possible that up to 30 individual pieces weighing a total of 1.6 tons may reach the surface of the Earth. The largest single fragment will probably be the telescope’s mirror, which is very heat resistant.
However, as the UARS re-entry proved, most of the Earth is in fact ocean, and the chances of debris from ROSAT landing on solid Earth, let alone hitting someone are quite small (1 in 2,000 is the official figure). You might like to look for ROSAT before it does de-orbit. Information on how to do that can be found here on this site. Note that to get information on ROSAT visibility for your location, you will need to click on the ‘Select another satellite from the database’ link once you are at the appropriate Heavens-Above.com page for your location.
