If there was ever a satellite that deserves an award for longevity, it’s Terra. Designed for a mission of 6 years (or 30,000 orbits), the bus-sized spacecraft continues to cruise 705 kilometers (438 miles) above Earth’s surface nearly 19 years after launch. The spacecraft officially surpassed 100,000 orbits on October 6, 2018. To celebrate, here are ten things to know about the intrepid Earth-observing satellite. Click on each image to find out more.
1. Terra had to be designed from scratch. Unlike many of the smaller satellites that preceded it, engineers couldn’t riff off of an existing design.
2. The bus-sized spacecraft carries five scientific sensors — MODIS, MOPITT, MISR, ASTER, and CERES. All of them continue to send back useful data.
3. The MODIS sensor captures stunning images of hurricanes, wildfires, volcanoes, dust storms, oil spills, and other hazards.
4. Using MOPITT, atmospheric scientists have tracked global trends in carbon monoxide for nearly two decades. The good news: concentrations of the toxic air pollutant are declining.
5. Likewise, they have used the CERES sensor to measure whether Earth’s reflectivity—or albedo—has changed. Despite some fluctuations, there does not appear to be a trend.
6. The MISR sensor can detect the height of volcanic plumes, smoke plumes, dust plumes, and other aerosols. This is key to understanding where plumes will go and whether they will pose a threat to people on the ground.
7. Terra orbits 705 kilometers (438 miles) above the surface, about the distance between Boston, MA, and Washington, D.C.
8. A widely used global digital elevation map is based on data collected by ASTER.
9. Experts use Terra MODIS observations of NDVI — a measure of the greenness of plants — to help anticipate food shortages.
10. While in space, Terra has traveled the equivalent of 2.5 billion miles — nearly the distance to Neptune.