Space in Images - 2016 - 07 - Mars navigation
http://www.esa.int/spaceinimages/Images/2016/07/Mars_navigation
In order to precisely deliver the Schiaparelli landing demonstrator module to the martian surface and then insert
ExoMars/TGO into orbit around the Red Planet, it’s necessary to pin down the spacecraft’s location to within just
a few hundred metres at a distance of more than 150 million km.
To achieve this amazing level of accuracy, ESA experts are making use of ‘quasars’ – the most luminous objects
in the Universe – as ‘calibrators’ in a technique known as Delta-Differential One-Way Ranging, or delta-DOR.
On Wednesday this week, ESA ground stations began the first of many delta-DOR observations that will be used to
precisely locate ExoMars/TGO, using quasar P1514-24, seen inset in an image of ESA's deep-space tracking station
at Malargüe, Argentina, above.
![](http://pbs.twimg.com/media/Cn5bUg6WAAEaPKz.jpg)