UPDATE-2: A re-selection session of frames from the November 29 imaging session provided another useful color image and an interesting comparison of images obtained with 10 seconds time difference. This comparison shows the shift in observing angle of the different details. Also it shows the stability of the spacecraft by then.
UPDATE – 1: Maybe the best image of the November 29 imaging session shows a good resolved view of the modules, both employed solar panels and confirmation of the interpretations in the previous images.
UPDATE: A new image from the same session, taken about 20 seconds preceding the image below, shows a well-resolved view of the modules, and a further confirmation of earlier interpretations.
This is an improved resolution version of my best Phobos-Grunt image, obtained during the imaging session on November 29. Note the clear color difference between the visible solar panel and the main body. The other – less visible – solar panel can be seen on the other side. This image has improved color clearness and is color corrected. The other ‘unexplainable’ colors visible in the image are caused mainly by external influences, like reflections from Earth.
This picture was taken on November 29, when I first had a chance to observe the stranded Russian probe in the second day of visible observing window over the Netherlands. A previous attempt, a day earlier failed due to bright twilight and no visual orientation. Since I track objects manually with the telescope, I need to be able to track the object visually. On the second day of the observing window, Phobos-Grunt was passing close to Altair, the brightest star in the constellation Aquila. After a couple of clear sunny days, the edge of a front was approaching very fast from the West. I was afraid it would cover the sky just a few minutes before the greatly awaited pass of the probe. But it didn’t. Phobos-Grunt roared across the sky as bright as a star. It had an obvious reddish color visible in the tracking scope, or at least that was my impression in the few seconds of the pass, while I was concentrated at aligning the crosshairs of my viewfinder with an object passing by with an angular velocity of 1.68 degrees per second.
The probe passed by from West-Southwest, moving into Eastern direction with a 56 degrees elevation. To locate the spacecraft in what was still a considerably bright sky with the sun at -6 degrees elevation, I used a technique which recently enabled me to obtain images of the fallen satellite ROSAT, during a favorable pass in its last days before reentry. For ROSAT, the situation presented a comparable difficulty: bright twilight. The technique consists in picking up an object while it passes in front of a bright star. This time the great ‘helper’ was Altair.
The best color image coming from this imaging session shows clearly the difference between the solar panels and the main body of Phobos-Grunt. Comparison of more images with different viewing angle during the pass, quickly cleared up the best plausible interpretation of the visible elements. Space-journalist Anatoly Zak was the first who provided any interpretation on this site. The propulsion module makes out a big part of the entire object and appears in the images as a reasonably bright element, separated in all frames by some dark structures. We see what may be a sign of the globular fuel tanks, visible in the image below. Many frames show a striking yellow color of the main body, which probably caused the impression of a the reddish color while I was tracking the spacecraft.
Leave a Reply