NOAA weather satellites

Image of Europe as observed by the NOAA-18 weather satellite on January 9, 2015, at 4:51 pm. The red cross denotes the location of Munich.

One of the courses I have just finished teaching is a "project" course in which the engineering students have to do some kind of project, working in a team environment - like they will do when they graduate and get out into industry - give presentations on their progress, and write a final report. Since I'm teaching it, they must speak and write in English - at least when they're interacting with me. This is essential because even in Germany, many of the aerospace companies have their important documentation in English. Of course, the engineers communicate with each other in German, but when they interact with international companies, both spoken and written, they use English.

In this particular course, the students had to solve three tasks: 1) learn enough orbital mechanics to write a computer program that would predict when a particular Earth-orbiting satellite (in this case a NOAA weather satellite) was overhead, 2) build an antenna to receive the (open) signal that the satellite was transmitting, and 3) send that signal to their computer and display the image. Above you see one of the images that one of the teams was able to record.

And below you see the antenna of one of the groups. In their case, they decided to build a "quadrifilar helix" antenna, which consists of four wires, each wrapped in a helical shape. The total length of the antenna is about 1 m, which is one-half of the wavelength of the 137 MHz signal that the NOAA satellites transmit. This is the antenna that received the image above.

A quadrifilar helix antenna on the roof of the R building at Hochschule München.

In order to check that their code for predicting the satellite "pass" was correct, they checked it against the website Heavens Above, which has pass predictions for not only NOAA satellites, but also the ISS, Hubble, and in fact any orbiting object that is tracked. If you're interested in seeing the International Space Station, or Hubble, or Tiangong 1 (China's low Earth orbiter), I recommend that you enter your location in Heavens Above, and go outside the next dusk or dawn, and look up!