DeepEarthScience

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 eno...

This year was the second time I gave my tutorial with an SDR dongle. The idea behind this tutorial is to simulate ground-station-to-satellite interaction in the radiowave spectrum. The ground station is replaced by the SDR dongle and the student's computer. For the satellite, I use a radio beacon designed and built by a colleague of mine. The device transmits an FSK modulated signal at a certain frequency. During the tutorial, the students learn to develope software that interacts with the SDR, such that they can process the digital stream observed by the SDR. I made a small video of the signal with GQRX software, such that you can see the signal in the frequency spectrum and listen to the FSK modulation. Last year, I was using an open-source software package "gnuradio" for the signal processing part, but I found out that this introduced a lot of trouble-shouting in the first few hours, because of students having: different operating systems and versions (every s...

Monday 20 October 2014, we started the construction of DopTrack, a satellite tracking station on top of the tallest faculty of Delft University of Technology for students to use in satellite orbit determination. I will try to report on our findings of building it in this blogpost. We are in the process of setting up a dedicated website, but for now you have to do my blog ;) Project DopTrack As a master student, I followed several courses on orbit determination and satellite data analyses in the Astrodynamics & Space Missions group. During this time, I also observed the design and launch of two cube-sats of the space system engineering group. I was inspired by what students and university staff could accomplish. Come on, they launched two satellites in space. SPACE!!! However, after launch and succes of the missions the satellites were left alone. It would be cool to combine the use of these satellites and the knowledge from satellite data analyses courses. So I decided, when...

Last week I finally solved my satellite signal processing problem (with the help of my dear colleague). As I posted a few weeks ago, we are setting up a tracking station for satellites with some students here at the TUDelft. We record the signal coming from satellites and try to extract the frequency and frequency shift of that signal. Using the Doppler effect we can make an educated guess of where the satellites are and how fast they orbit the Earth (which is super-awesome!). However, back to the problem. We record the signal in .wav format. This file consists of two channels, which both represent a signal as a time-serie with deviations from zero (when plotted it looks like a wavy pattern). However, there are two channels and at first I only used one of the two channels (I know now this is wrong, but hé, it was my first time dealing with this). In my first blog-post I showed a figure of the signal, however this figure was made by professional (wel, I think) open-source software. As...

Satellite? But that is just a flying (we say orbiting) robot in outer space. Why am I so enthusiastic about a bit of metal rubble that is flying 7 km/s at an altitude of a few hundreds of kilometers above the roofs of our houses? Just because I can... A few days ago  Holland  was in a high energy state. We broke a record. *sigh* It was the hottest day in March since...well since we measured temperature. The Dutch media had nothing else to report, but this glorious moment in history. Luckily for you guys, there is the DeepEarthScience blog! So what did I do that day? I was standing on the roof of the tallest building in Delft looking at the city centre and thinking by myself: "This could be a good topic for the blog." The view was awesome: In the back, a beautiful view of city center Delft in all its glory. And even further away the city of our government Den Haag. In the front-right of the picture you can see our two antennas...

The sound of satellites can not be heard by our ears. However using complicated (or less complicated) electronics, we are capable of converting the signals into sound and pictures. How does the sound of a satellite looks like? I think it is beautiful. A perfect frequency shift, due to the motion of the satellite with respect to the receiving station. This figure is in the time-frequency domain, after I did a Fourier transformation on the .wav signal. Time runs from bottom to top and the frequency scale is inverted, just to make life easy. We did not know if the satellite would still be alive when we set up the equipment. But when it crossed the horizon, we heard the signal emerge from the noise. There it was, a piece of space junk that was launched a few years ago, still transmitting its daily data. A coded beeping sound, sending data about the status of its tiny solar cells and other components. We tried to tune another radio such that we could actually listen to the sign...