International Space Station (ISS)

                          
The ISS photographed in 2015 with a 10 inch Newtonian reflector and fully manually tracking through a 6x30 finderscope
 
Introduction


The International Space Station (ISS) is the biggest artificial satellite ever built and its complex structure makes it an interesting target to photograph. Many people are intrigued by the bright moving 'star' containing non-stop habitation.The ISS appears in the sky as an object with the angular size roughly comparable to that of the planet Jupiter which means that any magnification that shows the Jovian disk should resolve the ISS into more then a point of light. Observing visually at the eyepiece of a telescope with a magnification suited for planetary observing, it's a hard task to see any smaller detail on the ISS due to the high angular speed of roughly 1 degree per second when it is moving overhead. Starting around 2006 / 2007, I witnessed observationally from Earth the last construction years of the ISS. With every Space Shuttle mission, new elements were added and telescopic imaging sessions revealed the new additions like modules and trusses. Around 2008, I reached an image resolution of 1 to 2 meters on the ISS and smaller elements could be photographed successfully. Since then I captured relatively small details like the 2 meters wide crew lock of the Quest Airlock were astronauts prepare shortly before leaving the station for a spacewalk. Finally, I had the amazing privilege to capture for the first time in history astronauts during spacewalks, see page 'Astronauts in the Telescope'.


                             Left: Color video view of the ISS, still under construction, captured in February 2008. Note especially the absence of the Kibo and
                                Columbus modules. Note also the striking blue Earth light reflected by the white elements. Right: impressive color flare on the solar
                                  panels captured on August 10, 2011 when the ISS was approaching. All images tracked manually through a 10 inch telescope
                                   
 


                                                      Historic ISS Assembly View



                                                                                 Deployment of a Solar Array Documented


The images below show the ISS in June 2007 before and after a new solar panel was unfolded during the STS-117 mission. On the June 11 image and video on the left side, there was only 1 solar panel mounted (visible on the left side) on the ISS truss so far, while the S3/S4 truss segment for the new solar panel was just installed on the Starboard site (right side). In both images, some parts of the docked Space Shuttle Atlantis are recognizable. This may be one of the few or even the only captured ground-based view of this construction phase of the ISS. The S3/S4 truss segment with solar arrays was transported by the Atlantis to the ISS.


                



ISS as a Photo Object

The always different observing angle in combination with different illumination on each pass, makes the ISS a dynamic photo-object, even after completion. Because the space station is orbiting above the Earth's atmosphere, we need steady skies to obtain sharp images, comparable to planetary imaging. However, obtaining many frames to improve signal-to-noise ratio is much more challenging due to the high angular speed of the ISS and other satellites.
Sometimes it's useful to create an animated gif of several frames from an imaging session which displays the actual air turbulence and we see a realistic telescopic view. The four large solar panels of the space station feature often an impressive sight in any image of the ISS, but these are not always well visible in every occasion. Their visibility depends strongly on relation between sun-angle and observing-angle and therefore also related to seasons. In good seeing it is possible to see smaller detail such as the Robotic Arm Canadarm-2 or docked spacecraft capsules such as Soyuz, Progress or HTV. 


      This image taken on April 8, 2015 shows a good general view of the modules and solar panels mounted on the ISS, but also some smaller details like the Cupola window.
        The visible movement is only caused by seeing effects and is a good illustration of how atmospheric effects affect an image. Taken through 10 inch aperture telescope
       


                                                  
 The ISS can be a very varying photo-object. Here photographed on May 12, 2008 (left), and on March 17, 2015 (right). Both taken using a manually tracked 10 inch telescope

   


The Cupola as seen from Earth


In recent years, the ISS orbit was increased to an altitude of over 400 kilometers, making the photography of small detail more challenging. In good conditions it's still possible to capture small detail such as the Cupola, the 7-window observatory on the ISS that has an outer diameter of 2,95 meters and sometimes visible as a circular spot in the Tranquility node. Depending on the lighting conditions, it can appear as a dark spot or as a light spot or a combination of both. As the Cupola is a window to observe mainly the Earth, it located on the Earth facing side of the ISS and therefore it is possible to see the Cupola from a favorable angle from the ground, especially when it is passing high over the observing location. The Cupola was added the space station in February 2010 when it was carried to the ISS by the Space Shuttle Endeavour on mission STS-130. Since then, I had several times the opportunity to photograph a glimpse of it with the telescope.

Below are some of the best images I took that show the Cupola. All were taken through a manually tracked 10 inch relfector.


 
                                       The Cupola is clearly visible in this image as a light spot surrounded by a dark structure. The image was taken April 8, 2015
                                       The surrounding dark structure is better defined in the processing below, left and could be a sign of the shutters of the Cupola

                    

                                             The Cupola is a large window on the ISS. (marked). It can be seen as a dark spot in this image from August 6, 2014




The Cupola in the Tranquility node (the round dark spot circled in the image on the right) and many other details including a minor flare from an element on the port side of the
 truss can be seen in this video from September 2, 2010, the year that the Cupola was mounted to the ISS. These animated gif's were made from handtracked video through
  a 10 inch Newtonian telescope. The video provides also a good indication of the used telescopic imaging scale as the turbulence due to the Earth atmosphere is obvious.  

                                                                                                                                    


                                             Detailed image of the ISS with a very special illumination on June 23, 2010. Compare with the other 2010 image above
                                             The Cupola seems to be illuminated as well. Compare its location on the ISS with the images above and recognize it


                   

ISS Images through the Years

A gallery of images of the International Space Station taken over the years. All images were taken through a 10 inch F/4,8 aperture Newtonian telescope with a JVC color camcorder or Astrolumina ALccd 5L-11 mono CMOS camera. Tracking was fully manually through a 6x30 finderscope.



                                                          Very rare video capture of the Japanese HTV-1 cargo ship closing in to the ISS in 2009 and orbiting
                                                            a short distance below the station. Note also the special illumination visible on the solar panels.   
                                                                                                                                                


                            A rare good view of the 4 big solar panels of the ISS photographed on June 11, 2015. Image fully manually tracked  with a 10 inch telescope 
                           Note especially the brightening at the edges of the solar arrays on the left side, caused by white strips mounted at the tips of the solar panels                       
                                                     
                    
 
                            Beautiful colors on the ISS, captured on December 27, 2008. Note the blue Earth color reflected by different modules and radiators and the
                           yellow color at the tips of the solar panels caused by sunlight reflecting from a particular angle towards the observer that causes 'minor-flares'


                                  

   Sometimes much difference is present between the attitude of the 4 big solar panels, here photographed on August 1, 2014 (left) with a monochromatic ccd camera
     and on May 7, 2009 (right) with a color camcorder. Compare these views also with the images above were the solar panels are positioned in the same attitude.

                        
    


                                   The almost completed ISS photographed in August 2013. Marked are some visible main modules and the docked cargocraft ATV-4


                                                     

                                
              This early ISS image from November 4, 2008 shows an incredible amount of detail along the station's Truss including the Starboard Solar Alpha Rotary Joint 
              (SARJ). This is the element at the place were the solar panels rotate. Also is the Integrated Truss Structure over almost its full width visible in this image,
              apart from only over its full length. Due to shadow effects, it is not always possible to see the full truss width, illumination of the truss must be particularly good



Observing Minor Structures within the Solar Panels


The separation between each of the 4 large solar panels of the ISS can be visible as a contrasty dark space between each set of panels. Much harder to photograph are very thin lines that appear across the width of the solar panels.These stripes are often visible in close-up photo's of the ISS taken from space but there are very few images taken from the ground showing them clearly. Though, it is even possible to photograph the lines with a backyard telescope as succeeded in the image set below taken late 2008 when the altitude of the ISS was still much lower then nowadays is the case. These solar panel structures were especially well visible when viewed directly on the contrasty small color camcorder screen when the video was paused. However, it was more of a difficult task to show the presence of these structures on a presentable, larger format as in the black & white processing shown here. Added on top, left, is a comparison of these structures with the telescope images as seen from one of the camera's on board the ISS. The lines that are visible appear to be small irregular folds in the unfolded solar arrays.


Thin lines in the solar panels, captured with a 10 inch telescope on December 29, 2008. The right image is rotated 90 degrees and the appearance of the lines is obvious




                                                  
ISS Construction Years Retro
 
When I started photographing the ISS around 2006, the construction of the station was still in progress. Around 2008, I aquired an imaging resolution with backyard equipment that was extraordinary for the time. Also, the group of astrophotographers pointing their telescopes to the ISS and other satellites was much smaller in those years then now is the case, even when this group is still very small compared to other fields in astrophotography. For that reason, the amount of  ground-based ISS-images taken over that construction-period is relatively small, particularly in higher resolution. The use of a normal camcorder, that was bought in 2004 but which I started to use around 2008, delivered not only stunning resolution for the time but introduced in combination with a particular processing techique a unique photo-style that was almost sciencefiction-like. The image below was taken in May 2008 and sometimes a wonderful illumination from the right solar-angle is enough to create one-of-a-kind images. This retro picture illustrates a stage in the construction were the European Columbus laboratory was still standing alone without companion of the Japanese Kibo-lab. As the different segments of the Integrated Truss Structure were still free from the lots of instruments that are currently attached, it was also possible to see a much more clear view of the truss-segments itself.



                                                                                                                                                                                                                                                          Detailed image of the ISS taken on January 29, 2009 when there were still only 3 big solar panels present. Note the shadow on the left radiators.
Meanwhile, the Kibo module was added as a companion of the Columbus module. Compare this view with the image above were the Kibo was still absent
                                                        


                                   High resolution image of the ISS central section taken in 2009. Note especially the KU-band antenna, External Stowage Platform-2 (ESP-2)  
                                   The Pressurized Mating Adapter 3 (PMA-3) was located at the place were now the  Node 3 (Tranquility module) is mounted. We have also 
                                   a good view on the Quest Airlock, the egress/ingress point for spacewalks. Several details in this image are already comparable to the size
                                   of a human. With the level of detail in this and other images coming into view, the hope to capture an astronaut during an EVA increased.


 

                     One of the earlier good resolution images I obtained. Detail as small as 2 meters on the ISS is visible in this image taken in 2008, we see clearly the 2
                     meter wide crewlock of the Quest Airlock (see markings), the place were American astronauts egress and ingress the space station to do spacewalks