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End of Life of the Nayif-1

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At DopTrack, we listen to the radio transmission of many cube-sats. One in particular, The Nayif-1 (NORADID: 42017) had captured our attention. The onboard radio was claimed to be very stable and its transmission frequency could be used for tracking purposes. So, we decided to track that satellite and recorded its transmission every time it flew over Delft, since 2019. The transmission seems to be very consistent and strong and it gave use a great dataset to assess the quality of DopTrack. Recorded transmission frequency of the Nayif-1 satellite using the DopTrack station. The onboard frequency of the satellite showed a small linear drift over the years. In the 3.5 years we tracked it, the transmission frequency increased 40 Hz. Furthermore it showed some seasonal change and morning and evening passes showed slightly different transmission frequencies, but the stability was much better compared to other cube-sats we tracked.   After the summer holiday, we noticed that the signal was no
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My education experiment: deconstructing Satellite Laser Ranging (part 1)

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Imagine a spacecraft the size of your car travelling at an altitude of 600 km with a velocity of 7.6 km/s. Now try to determine where the spacecraft is and how fast it is flying, also called its dynamic state. There is no speedometer (no wheels turning) or a pitot tube like in an aircraft (no air to measure). So, we, as astrodynamicists (yes, I think that is a word), have different techniques to accurately determine the state of the spacecraft. Highly accurate measurements of distances (also called range) between the satellite and ground stations are used, as well as the changes in these distances (called range-rate). If you follow this blog a little bit, you know that we work on building a ground station at the TU Delft that measures these range-rates with respect to cubesats. With some complicated, but very elegant mathematics, these measurements are transformed into very precise orbit determinations of satellites. Some of my colleagues can tell you within one cm accurate where thei
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Determine the shape of the Earth 200 years ago with gravity

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A colleague of mine pointed me to a PhD dissertation of Petrus van Galen. He wrote this dissertation in 1830 and two copies can be found in the Tresor of the TU Delft Library. The title of this dissertation is “ Disputatio Mathematica Inauguralis d e Pendulo Ejusque Applicatione ad Telluris Figuram Determinandam ”. Loosely translated: A Mathematical Essay about the Pendulum and its Application to Determine the Figure of the Earth. Of course, as soon I heard about this, I made an appointment with the librarian responsible for the collection in the Tresor for a viewing session. I also found a  link  in Google books, showing almost the complete dissertation, but I wanted to smell the old pages. Furthermore, the appendices of the dissertation were not scanned properly, so the data, that Petrus van Galen used, were not yet available to me. A week later, I cycled to the Library (appointed as one of the 10 most beautiful libraries of the world and known very well to me due to th
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Geology and Whisky on Islay

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Few weeks ago, I visited the Queen of the Hebrides, or better known as the isle of Islay. My dad and I organised the trip for some friends of ours with the main objective to show them the many beauties of the island. Two years ago my dad and I made a ‘reconnaissance’ trip to explore those beauties.  Machir Bay viewed from the old abandon RAF radio station. Photo credit: Maurits Kok. Being true to my blog, which is a more scientific-orientated blog, I will not make this post a travellers log, but lets just say we visited several distilleries (even one that is now under construction), enjoyed the cuisine (which was quite high standards in the hotel we stayed), and made many long walks through the fantastic and overwhelming landscapes of the Scottish island. This island keeps surprising me with its fascinating history, incredible geology, and beautiful whiskies. Whisky Wharehouse tasting at Bruichladdich. Photo credit: Maurits Kok Before the trip I bought a book about the
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Paving the way for our presence on the Moon

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Reading the books and watching the TV series “the Expanse” awoken my old boyish-dreams of our presence on the Moon. Growing up with a dad that introduced me to the fantastic worlds of Larry Niven, Brian Aldiss, Isaac Asimov, Jack Vance, and Arthur C. Clark, gave me hope for the future and it motivated me to start my studies in Space Engineering. The science fiction became real-life science and engineering and I began to understand why the future was not yet achieved. We have made space engineering very complicated and expensive, which allowed only nations to perform this type of activities. But, I am living in the future of my old heroes of words and spaceflight has a permanent role in our daily life.  And more and more young engineers want to participate, because space is not that complicated anymore. We evolve as humans, such that complicated problems in the past are simple issues in the future. James S. A. Corey (A.K.A. Daniel Abraham and Ty Franck) hints to this as well in the
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Delfi-C3 is feeling the power of Spring

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All the trees have blossom, baby ducklings are rooming the ponds, and we get more Sun: we survived the winter! Spring is here to give us our much needed vitamine D.  Spring on the campus of TU Delft Not only on the surface of the Earth this is felt, but also in outer space. The Delfi-C3, now more than 9 years orbiting our Earth, notices that spring has arrived on the Northern Hemisphere. During winter, our ground station (DopTrack) only receives data during the morning and mid day (between 8:00 and 13:00 CET). Starting from April, we start receiving signal around 20:00 CET. Fraction of a 24 hour day (UTC) at Time of Closest Approach (TCA) of the Delfi-C3 with DopTrack. We saw this already last year, when in April the telemetry of Delfi-C3 started appearing in the evening. The Sun was already set on the ground, but at 560 km height light was still shinning on the solar cells of the satellite. The satellite is designed such that when sunlight hits the solar cells and enough
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