Solar Sails &
                                                 Other Spaceflight


Spacecraft for experimental purposes belong to the most interesting objects to capture. Because these are mostly new objects, we can not always predict how they will look in telescopic images or how they will behave dynamically. Experiments with space debris elimination purposes involved are popular among orbital experiments nowadays because of their importance with regard to the current affairs. In 2010, I took images of a Fregat upper stage with inflatable panels. In 2011, I did several attempts to capture a solar sail experiment in Earth orbit. In 2013, I managed to photograph a biological laboratory (actually a space zoo) in orbit. Beside new launched experiments, we sometimes can find remains of older experiments in Earth orbit. The telescopic imaging technique needed to capture space experiments in low Earth orbit differs not from the general technique that is used to photograph images of other smaller satellites and spacecraft. 


Experimental Solarsail Nanosail D-2

The experimental solarsail Nanosail D, developed by NASA (Marshall Space Flight Center and Ames Research Center) was a fascinating object in our night sky. Although it is described as a solarsail which is originally meant to propel on radiation pressure of the sun, its main function is to experiment how such sails could be used with future satellites and space debris to increase the drag, resulting in a faster deorbit, one of the current techniques in development for future space safety technologies. Nanosail-D was orbited in November 2010. However, its separation from FASTSAT (Fast, Affordable, Science and Technology Satellite) occurred later than expected because of an ejection failure. On 19 January 2011 the separation happened unexpectedly and the experiment could continue. With the help of radio amateurs around the world, confirmation was quickly collected that the sail indeed deployed. Now it was time for a first visual confirmation of a deployed sail, so an optical image.

                            Well succeeded images of Nanosail-D-2, taken April 24, 2011 (left) and exactly a month later on May 24, 2011 (right) with a 10 inch telescope

With the resources in-house, I participated in this effort and my first attempts to observe the sail started around February 2011 but failed. The sail turned out to be not an easy object; it failed to adhere to the predictions. It sometimes emerged shortly during a session but was very faint and it disappeared again after a few seconds. It strongly looked like Nanosail-D was tumbling. Suddenly, late April during one of the many new attempts, it finally appeared as a favorable object in the southeast. Apparently I now had the luck of a favorable angle of the sail with the sun towards the observer. I managed to grab some first images and those had a nice obvious blue or cyan color, which is probably reflected Earth light, as the sail’s reflectivity is very high. In April, the brightness of the sail only varied slowly during the pass, I suspect it was slowly tumbling but the frequency of this rotation would quickly increase as it showed a great and irregular flashing appearance in May.

                    Sequence of images of Nanosail-D-2, taken on May 24, 2011. We can see the sail approaching and 'growing' bigger while getting brighter at the same time

Below are some processed results from the great Nanosail-D imaging session on May 24, 2011 were the sail reached an altitude of 62 degrees and it was wildly flashing for the naked eye. Because the seeing was good, many frames were sharp so it was worthy to show a part of the image sequence during closest approach (only the very best frames) in a movie. You clearly see the sail approaching when it is visible from an angle and looks elongated, then near closest approach we look straight onto the surface of the sail. Note also the attitude of the sail which looks similar in all frames.

The images shown in the set below are from the May 24, 2011 imaging session and show surprising detail in the sail. We even see a sign of the 4 triangular segments. Those appear to reflect the sunlight each in a slightly different direction, with the result of showing differences in brightness over the surface of the sail. The level of imaging becomes clear when we consider the ratio: A square with dimensions of 3 by 3 meters seen from a distance of in this case 667 kilometers. The images are taken in secondary focus of a 10 inch aperture reflecting telescope using manually tracking.

The tumbling motion of Nanosail D-2 with flares registered in color on May 22, 2011 using a manually tracked 10 inch telescope

  The first image I obtained from Nanosail-D2 on April 24, 2011 with a JVC camcorder attached to an eyepiece on a 10 inch telescope. Note the striking blue Earth light reflection

                             Below: Set of images of Nanosail-D2 from the April 24, 2011 session taken with a 10 inch telescope. The image in the mid shows a flare.

Rocket Stage with Inflatable Panels  
Fregat / IRIS

I have photographed many rocket upper stages, as they remain in orbit for a long time. Many satellites have solar panels, but upper stages with some kind of panels mounted on it are very rare. On September 17, 2009, the Russian technology experiment Fregat / IRIS was launched as a secondary payload on a Soyuz 2-1b rocket from Baikonur Cosmodrome in Kazakhstan. IRIS stands for Inflatable and Rigidizable Structure. Two experimental inflatable panels are mounted on a Fregat upper stage. The panels were deployed after the main and smaller payloads were inserted. Contractors of the project are NPO Lavochkin and EADS Astrium. The propulsion-less and battery powered satellite was inserted into an elliptical orbit with a 490 km perigee and a 504 km apogee, with an inclination of 98.8 degrees. The orbit has already decreased to 482 x 497 km. The ground-tracking shows that the upper stage is currently in a polar orbit.

                                                                                         Proposed model of the Fregat / IRIS upper stage with panels

One of the other payloads from this launch – the Meteor-M 1 – is a new Russian meteorological satellite. The other payloads were the satellites Sterkh 2, Universitetsky 2, UGATUSAT, Sumbandila and BLITS. There is almost no information available about the goals of Fregat / IRIS. Despite that, it is strongly plausible that the experiment involves testing of a satellite/debris deorbit technology, since increasing the surface, and thus the drag, of orbiting objects causes a faster decay. Solar sails are another example of a similar technique, which can in turn increase safety of operation in low Earth orbit by clearing it up.

On September 5,  2010,  I took a first telescopic image of this Fregat upper stage at a range of 531 kilometers. The session provided several useful frames. Two of them are shown in the picture below. The image show two elongated segments shifted in a certain angle of each other, one brighter, longer part and a dimmer short part. The dim short segment tends to show more structure, and considering the proportion between the dimensions of the IRIS panels and the Fregat, based on models, this is probably the Fregat. The panels, which reflect more sunlight, are probably the brightest parts. We can clearly see only one panel: this may mean that just one panel has been deployed, but we cannot be certain. Based on experiences with imagery of  the Space Shuttle’s wings and satellite’s solar panels, it often happens that just one wing or panel is favorably illuminated, while the other one is invisible due to shade, unfavorable angle or poor illumination.

Ground-based images I obtained  in September 2010 of the Fregat / IRIS upper stage. Obviously, there are two separated elements visible 

 Biological Laboratory Bion M-1

Space Zoo

On April 19, 2013, the Bion-M1 satellite lifted up on a Soyuz 2-1a rocket from Baikonur. Five days later, there was one favorable pass of the spacecraft over my observing location in the south of the Netherlands. The ‘Space Zoo’ passed almost directly overhead, ironically enough through the stars of the Big Dipper. The resulting images of this Bion satellite showed a surprising resolution. At a range of 581 kilometers and an altitude of 575 kilometers, the small spacecraft with a comparable design to that used for the early Vostok flights, is a really small object. But the images show a comparable detail level to that of  my Progress/Soyuz images at the altitude of the ISS, at a 175 kilometer lower altitude. We see the service module and the recovery module (the capsule) clearly resolved and also some parts of the solar panels are visible in the image, which was obtained with a 25 cm aperture reflecting telescope and manual tracking.

Telescopic image of Bion M-1 on April 24, 2013. Some details including solar panels are visible


                     The Bion M-1 spacecraft captured on April 24, 2013. Note especially the visible shape of the capsule and albedo variations between the different segments

First Images Secretive ShiJian 16 Spacecraft

Two ShiJian 16 spacecraft have been launched - 16-01 in October 2013 and 16-02 in June 2016. In both cases, the exact mission purposes were unclear and there were only assumptions for the possible type of spacecraft used for these missions. It's generally believed that these satellites are used for conducting experiments in the field of space environmental research and there are technological experiments on board. Little details about the ShiJian spacecraft are known and there are no (published) factory images of the ShiJian 16 satellites available.

Below are images of ShiJian 16-01 taken in good conditions on May 20, 2020 over a distance of 629 kilometers during an 85 degrees WNW pass. 


 Processings of some of the best frames of the imaging session on May 20, 2020. The 2 images on the right are turned 90 degrees to the left to get a different image impression