While both microsatellites Diwata-1 and Diwata-2 are classified as Earth-observing (as opposed to astronomical) satellites, they have a feature that allows them to go “stargazing” too: the Star Tracker Telescope (STT).
The STT is one of the technologies on board Diwata-1 and Diwata-2 that help the satellites find their place in space. It acts as a telescope that helps identify star patterns in the sky, helping the satellites identify their location in relation to the patterns around them.
Diwata-2’s Star Trackers
How does the STT look to the stars for assistance? It basically uses a star catalog and matches what it sees with this database, upon which it performs the necessary calculations to identify its orientation. Like the sky conditions that gazers and astronomy buffs favor, STTs also get more information from the stars set against dark skies.
Static attitude determination. A single point on the sphere is specified in which a single star image is fed to the STT, which then estimates the attitude. Visualization courtesy of STAMINA4Space’s PHL-50 Project.
Dynamic attitude determination. Moving star images are fed to the STT, from which the attitude is estimated continuously. Visualization courtesy of STAMINA4Space’s PHL-50 Project.
Diwata-2 in particular is equipped with two STTs to broaden its “viewing” coverage of the star patterns they continuously attempt to identify. In order for the satellite to take a photo of an intended target on Earth (on the ground), an important step is determining first where the satellite is currently “looking” at. The STTs serve as the “eyes” of the satellite that enable it to do just that.
Like how stars guided our ancestors before the advent of modern navigation tools, STTs also turn to the stars to help our microsatellites find their way, bringing our eyes-in-the-skies closer to the mission we sent them on.
Learn more about Diwata-2, or browse, download, or request for images.
