the.com/star tracker
A camera that gazes at constellations so spacecraft never forget which way is up.
means A star tracker is an optical device that photographs the sky, identifies stars by matching them against a stored catalog, and uses their known positions to calculate a spacecraft's precise orientation in space.
from A compound of plain English parts. "Star" descends from Old English "steorra," a relative of Latin "stella" and Greek "aster," all reaching back toward a Proto-Indo-European root for the heavenly lights. "Tracker" comes from "track," a word that arrived in English from Old French "trac," meaning a trail or footprint, and which carried the sense of following something's path. Joined together in the aerospace age, the term names a machine that literally follows the stars to keep its bearings.
- star map
- Compares the sky to an onboard catalog of stars
- precision
- Pinpoints orientation to arcseconds, finer than a hair's width
- sun shy
- Must shield itself from sunlight to see faint stars
- old roots
- Sailors used star sightings to navigate centuries earlier
- voyager
- Tracked Canopus on probes now beyond the solar system
hubble space telescope — uses fine guidance sensors to track stars with 0.05 arcsecond precision since 1990
gaia space observatory — mapped positions and brightness of 1.7 billion stars since 2013 launch
james webb space telescope — employs star trackers to maintain alignment within 10 micrometers since 2021