&lt;div class=&quot;track&quot;&gt;&lt;img alt=&quot;&quot; src=&quot;http://hits.guardian.co.uk/b/ss/guardiangu-feeds/1/H.22.2/83728?ns=guardian&amp;pageName=Spacewatch%3A+The+end+of+Rosat%3AArticle%3A1642227&amp;ch=Science&amp;c3=Guardian&amp;c4=Space+%28Science%29%2CScience%2CSatellites+%28science%29&amp;c5=Not+commercially+useful&amp;c6=Alan+Pickup&amp;c7=11-Oct-05&amp;c8=1642227&amp;c9=Article&amp;c10=Feature&amp;c11=Science&amp;c13=Spacewatch&amp;c25=&amp;c30=content&amp;h2=GU%2FScience%2FSpace&quot; width=&quot;1&quot; height=&quot;1&quot; /&gt;&lt;/div&gt;&lt;p&gt;If you thought that Nasa&#039;s odds of one in 3,200 that someone somewhere on the Earth would be struck by a piece of the falling UARS satellite were worrying, then the next major satellite decay poses even more of a risk. The German Aerospace Center puts the equivalent odds for Rosat, the Roentgen Satellite, at one in 2,000. In fact, your personal odds of being hit are more like 1 in 14 trillion, so it is probably safe to put away that tin hat. If you live north of the Wash, then you are out of the &quot;danger zone&quot; which extends to 53&deg; N and S of the equator.&lt;/p&gt;&lt;p&gt;Launched by a US rocket in 1990, Rosat was a joint venture between Germany, the US and the UK. Equipped with an 84cm mirror, it completed an X-ray survey of the sky, finding more than 150,000 objects. It followed up with targeted observations of interesting objects from galaxies, to neutron stars and even comets. It was switched off in 1999 and I calculate that it is now perhaps three weeks away from re-entry as its orbit decays, though it could survive into November.&lt;/p&gt;&lt;p&gt;At 2,400kg, Rosat is less than half as massive as UARS, but more than half of it is thought likely to survive re-entry, including much of its heavy mirror which was built from a glass-ceramic material with a high melting point. The expectation is that this will drop harmlessly into an ocean. The US tracking authorities took more than two days to confirm the details of UARS&#039;s plunge into the Pacific, so let us hope that they do better with Rosat.&lt;/p&gt;&lt;div class=&quot;related&quot; style=&quot;float: left; margin-right: 10px; margin-bottom: 10px;&quot;&gt;&lt;ul&gt;&lt;li&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/space&quot;&gt;Space&lt;/a&gt;&lt;/li&gt;&lt;li&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/satellites&quot;&gt;Satellites&lt;/a&gt;&lt;/li&gt;&lt;/ul&gt;&lt;/div&gt;&lt;div class=&quot;author&quot;&gt;&lt;a href=&quot;http://www.guardian.co.uk/profile/alanpickup&quot;&gt;Alan Pickup&lt;/a&gt;&lt;/div&gt;&lt;br/&gt;&lt;div class=&quot;terms&quot;&gt;&lt;a href=&quot;http://www.guardian.co.uk&quot;&gt;guardian.co.uk&lt;/a&gt; &amp;copy; 2011 Guardian News and Media Limited or its affiliated companies. All rights reserved. | Use of this content is subject to our &lt;a href=&quot;http://users.guardian.co.uk/help/article/0,,933909,00.html&quot;&gt;Terms &amp; Conditions&lt;/a&gt; | &lt;a href=&quot;http://www.guardian.co.uk/help/feeds&quot;&gt;More Feeds&lt;/a&gt;&lt;/div&gt;&lt;p style=&quot;clear:both&quot; /&gt;