--- title: "What is the biggest unmanned satellite in orbit?" description: "What is the biggest unmanned satellite in orbit?" author: "Lily Chitlangiya" published: 2021-11-09 updated: 2023-09-03 canonical: https://answers.mindstick.com/qa/94031/what-is-the-biggest-unmanned-satellite-in-orbit category: "space technology" tags: ["space science", "space programs"] reading_time: 2 minutes --- # What is the biggest unmanned satellite in orbit? What is the biggest unmanned [satellite](https://www.mindstick.com/articles/333321/satellite-communication-enabling-global-connectivity-from-space) in orbit? ## Answers ### Answer by user The largest unmanned satellite in orbit is the **Terra satellite**, a remarkable Earth-observing spacecraft. Launched by NASA in December 1999, Terra is part of the Earth Observing System (EOS) program and is designed to monitor and study our planet's climate, atmosphere, land, and oceans. Terra is colossal in size, measuring approximately **13.3 meters (43.6 feet)** in length and **6.6 meters (21.7 feet)** in width, with its solar arrays fully extended. It orbits Earth in a polar orbit at an altitude of about 705 kilometers (438 miles) and completes roughly 14 orbits per day. The satellite carries a suite of five state-of-the-art scientific instruments, including the Moderate Resolution Imaging Spectroradiometer (MODIS), which captures high-resolution images of Earth's surface in various spectral bands. MODIS data is pivotal for monitoring changes in vegetation, cloud cover, wildfires, and other environmental factors. Terra also houses instruments like the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and the Multi-angle Imaging SpectroRadiometer (MISR), which provide valuable insights into Earth's terrain and atmospheric properties. Terra's mission is to collect data that aids scientists and researchers in understanding critical aspects of Earth's climate, such as global temperature trends, greenhouse gas concentrations, and aerosol distribution. It plays a pivotal role in tracking environmental changes, studying the impact of natural disasters like wildfires and hurricanes, and monitoring the health of ecosystems around the world. Additionally, Terra's data is essential for climate modeling, weather forecasting, and informing policies related to environmental conservation and disaster management. Its vast array of scientific instruments and its nearly continuous data collection have made it an indispensable tool for Earth science research, contributing significantly to our understanding of the planet and its changing environment. In summary, the Terra satellite holds the distinction of being the largest unmanned satellite in orbit and serves as a vital asset for scientists and researchers worldwide, enabling them to better comprehend Earth's complex systems and environmental dynamics. --- Original Source: https://answers.mindstick.com/qa/94031/what-is-the-biggest-unmanned-satellite-in-orbit Copyright © MindStick Software Pvt. Ltd. This Markdown version is provided for developers, AI systems, and offline reading.