As of March 6, 2019, information was available about ## nations that deployed and operated ### spacecraft during 2018. The number of nations operating spacecraft grew ##% from…
Satellites include a wide variety of systems performing an even wider range of missions from their different orbits. In 2015, launch operators attempted to place ### spacecraft into orbit (including both satellites and other types of payloads), a decrease of ##% from ### spacecraft in 2014. The following exhibit shows all satellites successfully launched into orbit during a year’s span, including small satellites. To see the number of small satellites launched during that span into orbit, select the wrench icon and choose the appropriate size. Then hit “sub
According to the Union of Concerned Scientists, a total of ## satellites were still operational at the end of 2015. These satellites are mostly located in low Earth orbit (LEO) between 200 and 2,000 kilometers (124–1,242 miles) of altitude. LEO is home to ## active satellites, or ##% of the total. This family of orbits remains the main orbital location of satellites due to the wide range of missions it allows and to the low energy required to reach it, which typically results in lower launch costs.
Satellites include a wide variety of systems performing an even wider range of missions from their different orbits. In 2014, launch operators attempted to place ## spacecraft into orbit (including both satellites and other types of payloads), an increase of ##% from ## spacecraft in 2013. The majority of spacecraft are launched to LEO—in 2014, this was the destination for ##% of all spacecraft, or ##% when excluding nanosatellites, which have masses of less than 10 kilograms (22 pounds).
The closer proximity to the Earth also greatly reduces signal delay from a LEO satellite to ground stations and allows for smaller receivers on the ground. While minimizing signal delay is not vital for DTH services or corporate networks, it makes the orbit ideal for voice traffic being sent directly to handheld devices. These lower orbits are challenging since the satellites constantly move in and out of view of individual ground receivers. If it is necessary to maintain a continuous link despite the movement of the satellites, a fleet of spacecraft is required to form a constellation.
Telecommunications technology has made the world a much more intimate place. This is in no small part due to satellites circling the globe providing communications, scientific research, broadcasting, navigation, imagery, and support for national defense efforts. The first satellite, Sputnik, was launched by the Soviet Union in 1957 and served to demonstrate that man-made objects can reach and maintain a simple orbit. This small craft with limited instrumentation did little more than measure the density of the upper atmosphere and provide information on how radio waves propagate through the ionosphere.
In March 2011, the U.S. Air Force launched the ## test flight of the top secret X-37B space plane. Originally scheduled to land after ## days, the mission was extended and the spacecraft was still in orbit at the end of 2011. The 2010 maiden flight of the X-37B lasted for ## days. The military has not divulged specifics about the space plane’s cargo or mission, but it is speculated that it carries advanced Air Force experiments, sensors, and other research payloads. Some space technology experts believe the X-37B is a reconnaissance tool, given its ability to land, change payloads, and alter its orbit more rapidly than a LEO satellite.
The national defense needs of many countries help to drive demand for satellite capacity. Armed forces and international peacekeeping organizations from across the globe lease capacity from various commercial satellite operators or acquire Earth imagery services from commercial companies. Military forces are also building more of their own dedicated satellites due to increased capacity demands and the need for secure connectivity for deployed troops.
Earth observation satellites produce the largest amounts of data to be transmitted to Earth on a regular basis and thus require dedicated data processing ground stations. While all satellites require ground stations to keep track of them and relay commands, Earth observation satellites are specifically intended to gather large amounts of data through a variety of sensors and then transmit that data back down for interpretation and storage.