Editing Envisat (section)

=== Space safety ===
[[File:Debris-GEO1280.jpg|thumb|[[Space debris]] populations seen from outside [[geosynchronous orbit]] (GEO). Note the two primary debris fields, the ring of objects in GEO, and the cloud of objects in [[low Earth orbit]] (LEO).]]
Envisat poses a hazard because of the risk of collisions with [[space debris]]. Given its orbit and its area-to-mass ratio, it will take about 150 years for the satellite to be gradually pulled into the Earth's atmosphere.<ref>[http://spacenews.com/envisat-pose-big-orbital-debris-threat-150-years-experts-say/ "Envisat To Pose Big Orbital Debris Threat for 150 Years, Experts Say."] ''SpaceNews''. Retrieved: 27 September 2015.</ref> Envisat is currently orbiting in an environment where two catalogued space debris objects can be expected to pass within about {{convert|200|m|ft|abbr=on}} of it every year, which would likely trigger the need for a manoeuvre to avoid a possible collision.<ref name=Kessler>{{cite news | first = Andrea | last = Gini | title = Don Kessler on Envisat and the Kessler Syndrome | date = 25 April 2012 | url = http://www.spacesafetymagazine.com/2012/04/25/don-kessler-envisat-kessler-syndrome/ | work = Space Safety Magazine | access-date = 9 May 2012}}</ref> A collision between a satellite the size of Envisat and an object as small as 10&nbsp;kg could produce a very large cloud of debris, initiating a self-sustaining chain-reaction of collisions and fragmentation with production of new debris, a phenomenon known as the [[Kessler Syndrome]].<ref name=Kessler/>

Envisat was a candidate for a mission to remove it from orbit, called [[e.Deorbit]]. The spacecraft sent to bring down Envisat would itself need to have a mass of approximately 1.6 tonnes.<ref name="ESAconference1">{{cite web|url=https://indico.esa.int/indico/event/46/|title=e.Deorbit Symposium|publisher=ESA|date=6 May 2014|access-date=2 June 2015|archive-date=1 July 2015|archive-url=https://web.archive.org/web/20150701150318/https://indico.esa.int/indico/event/46/|url-status=dead}}</ref>