ISS Tracker Always Points Towards the Satellite
To find the space station's position, Redditor Contradius built this ISS Tracker Pedestal.
The International Space Station (ISS) is one of humanity's greatest achievements. That isn't true only because of the impressive engineering achievements, but also because of the global cooperation required for the project to be a success. Those of us that remember the launch in 1998 and the preceding years recall the sense of accomplishment and pride that surrounded the program. While the ISS won't remain in service for much longer before NASA starts its de-orbit, we still have a few years to look up at the space station. To find its position, Redditor Contradius built this ISS Tracker Pedestal.
ISS trackers are not uncommon, but they're always cool. Not only does NASA (among other space agencies) track the exact position of the ISS in its orbit, they also publish that information for the public to access. That means that anyone can find the ISS's location in the sky at any given moment. If you know that information and your own coordinates on the Earth's surface, you can calculate the direction of the ISS relative to you. This ISS tracker relies on that information to physically point towards the ISS — even if it is on the opposite side of the planet.
This is a mechanical tracker, so it moves a physical pointer to indicate the direction of the ISS. That requires two movement axes: rotation is the XY (horizontal) plane and rotation perpendicular to the Z axis. The enclosure, gears, and pointer are all 3D-printable. A stepper motor spins a gear, which turns the entire upper structure in the XY plane. A micro servo motor mounted on that structure turns the pointer.
An Adafruit Feather M0 Express development board controls those two motors. It also displays the relevant data (azimuth and elevation) on an OLED screen FeatherWing. The M0 Express doesn't have any WiFi connectivity, so this tracker includes an ESP32 Featherwing as a co-processor. That is able to connect to the internet and pull the ISS's location from celestrak.org. The user can either manually orient the tracker to face North, or they can add a compass module so the tracker knows which way North is for orientation.
If you're a NASA fan and think the ISS is as cool as we do, then this is a great project to show your enthusiasm. Contradius published the 3D files and code, so you can download those to build your own ISS Tracker Pedestal.