Mars Express

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Animation: Phobos and Jupiter in alignment (conjunction)
Credit: ESA/DLR/FU Berlin (G. Neukum).
20. December 2011

Phobos und Jupiter in einer Linie (Konjunktion)

On 1 June 2011, Mars Express carried out a special manoeuvre to observe a conjunction between Phobos and Jupiter. The animation shows Phobos moving from right to left through the camera’s field of view, then – outside this sequence of images – disappearing behind Mars. At the same time, Mars Express was approaching apoapsis – the furthest point from Mars in its orbit. At the moment that Mars Express, Phobos and Jupiter were aligned, the distance between Mars Express and Phobos was 11,389 kilometres, and another 529 million kilometres to Jupiter. This means that Jupiter was almost 50,000 times as far from Mars Express as Phobos, which is the reason why in this foreshortened perspective the largest planet in the Solar System, with a diameter of 140,000 kilometres, appears significantly smaller than the Martian moon located almost directly in front of the camera lens. While Mars Express and Phobos were continually moving forwards, the Super Resolution Channel (SRC) in the High Resolution Stereo Camera (HRSC) remained fixed on Jupiter. The image sequence contains a total of 104 separate images, taken within 68 seconds.

The observation and simultaneous determination of the exact time at which Jupiter moved behind the Martian moon were used to improve the orbital data for Phobos.

A motion de-blurring algorithm from the Chinese University of Hong Kong was used to improve the image quality (subtract the motion blurring). These improved SRC images were used for the animation. However, the images were moved horizontally by one pixel to fill in the gaps. Furthermore, the contrast was altered slightly.

The shown animation was generated at the Institute for Geological Sciences at the Freie Universität Berlin and published there as 'Highlights of the Month' in 2011. They present special Mars products obtained using the HRSC camera on board Mars Express.