A geostationary transfer orbit (GTO) or geosynchronous transfer orbit is a type of geocentric orbit. Satellites that are destined for geosynchronous (GSO) or geostationary orbit (GEO) are (almost) always put into a GTO as an intermediate step for reaching their final orbit.
A geocentric orbit, Earth-centered orbit, or Earth orbit involves any object orbiting Earth, such as the Moon or artificial satellites. In 1997, NASA estimated there were approximately 2,465 artificial satellite payloads orbiting Earth and 6,216 pieces of space debris as tracked by the Goddard Space Flight Center. More than 16,291 objects previously launched have undergone orbital decay and entered Earth's atmosphere.
Explorer 3 was an American artificial satellite launched into medium Earth orbit in 1958. It was the second successful launch in the Explorer program, and was nearly identical to the first U.S. satellite Explorer 1 in its design and mission.
The Pegasus Project was a NASA initiative to study the frequency of micrometeoroid impacts on spacecraft by means of a constellation of three satellites launched in 1965. All three Pegasus satellites were launched by Saturn I rockets, and remained connected with their upper stages.
The Space Test Program (STP) is the primary provider of spaceflight for the United States Department of Defense (DoD) space science and technology community. STP is managed by a group within the Advanced Systems and Development Directorate, a directorate of the Space and Missile Systems Center of the United States Space Force. STP provides spaceflight via the International Space Station (ISS), piggybacks, secondary payloads and dedicated launch services.
The Multi-Application Survivable Tether (MAST) experiment was an in-space investigation designed to use CubeSat spacecraft connected by tethers to better understand the survivability of tethers in space. It was launched as a secondary payload on a Dnepr rocket on 17 April 2007 into a 98°, 647 x 782 km orbit. The MAST payload incorporated three picosatellites, named "Ralph," "Ted," and "Gadget," which were intended to separate and deploy a 1 km (0.62 mi) tether. The experiment hardware was designed under a NASA Small Business Technology Transfer (STTR) collaboration between Tethers Unlimited, Inc. (TUI) and Stanford University, with TUI developing the tether, tether deployer, tether inspection subsystem, satellite avionics, and software, and Stanford students developing the satellite structures and assisting with the avionics design.
USA-200, also known as NRO Launch 28 or NROL-28, is an American signals intelligence satellite, operated by the National Reconnaissance Office. Launched in 2008, it has been identified as the second satellite in a series known as Improved Trumpet, Advanced Trumpet, or Trumpet follow-on; a replacement for the earlier Trumpet series of satellites.
The Polymer Battery Experiment (PBEX) demonstrates the charging and discharging characteristics of polymer batteries in the space environment. PBEX validates use of lightweight, flexible battery technology to decrease cost and weight for future military and commercial space systems. PBEX was developed by Johns Hopkins University and is one of four On Orbit Mission Control (OOMC) packages on PicoSat 9:
Omid was Iran's first domestically made satellite. Omid was a data-processing satellite for research and telecommunications; Iran's state television reported that it was successfully launched on 2 February 2009. After being launched by an Iranian-made carrier rocket, Safir 1, the satellite was placed into a low Earth orbit. President Mahmoud Ahmadinejad supervised the launch, which coincided with the 30th anniversary of the Iranian Revolution; NASA verified the launch's success the following day. Its Satellite Catalog Number or USSPACECOM object number is 33506.
Kosmos 1, also known as DS-2 No.1 and occasionally in the West as Sputnik 11 was a technology demonstration and ionospheric research satellite launched by the Soviet Union in 1962. It was the first satellite to be designated under the Kosmos system, and the first spacecraft launched as part of the Dnepropetrovsk Sputnik programme to successfully reach orbit.
Discoverer 20, also known as KH-5 9014A, was a USAF photographic reconnaissance satellite under the supervision of the National Reconnaissance Office (NRO) which was launched in 1961. Discoverer 20 was the first KH-5 ARGON satellite to be launched.
Pegasus 2 or Pegasus II, known before launch as Pegasus B was an American satellite which was launched in 1965 to study micrometeoroid impacts in Low Earth orbit. It was the second of three Pegasus satellites to be launched, following the launch of Pegasus 1 three months earlier. The Pegasus spacecraft were manufactured by Fairchild Hiller, and operated by NASA.
Pegasus 3 or III, also known as Pegasus C before launch, was an American satellite which was launched in 1965 to study micrometeoroid impacts in Low Earth orbit. It was the last of three Pegasus satellites to be launched, the previous two having been launched earlier the same year. It was manufactured by Fairchild Hiller, and operated by NASA.
BeeSat-1 or Berlin Experimental and Educational Satellite 1, is a German satellite operated by the Technical University of Berlin. The spacecraft is a single unit CubeSat, which was designed to test systems intended for use on future spacecraft, including a new design of reaction wheel. It has also been used for amateur radio, and is equipped with a small camera.
A number of space tethers have been deployed in space missions. Tether satellites can be used for various purposes including research into tether propulsion, tidal stabilisation and orbital plasma dynamics.
Space Tethered Autonomous Robotic Satellite II or STARS-II, was a nanosatellite built by Japan's Kagawa University to test an electrodynamic tether in low Earth orbit, a follow-on to the STARS mission.
Explorer 19,, was a NASA satellite launched on 19 December 1963, as part of the Explorer program. It was the third of six identical Explorer satellites launched to study air density and composition, and the second to reach orbit. It was identical to Explorer 9.
Explorer 39, also known as AD-C, was a NASA scientific satellite belonging to series Air Density. It was launched on 8 August 1968, join with Explorer 40, from Launch Complex 5 of the Vandenberg Air Force Base, through a Scout launch vehicle.
Elektron ('electron'), in American sources sometimes called Electron, was the first Soviet multiple satellite program, comprising two identical pairs of particle physics satellites launched by the Soviet Union in 1964. The four spacecraft simultaneously monitored the lower and upper Van Allen radiation belts and returned a considerable volume of data regarding radiation in space and atmospheric conditions to an altitude of more than 58,000 kilometres (36,000 mi) above the Earth. Two of the four launched satellites are still in orbit As of 2023, the other two having reentered.
Orbiting Picosat Automatic Launcher is an American technology testing and amateur radio satellite that was developed by students at the Space Systems Development Laboratory at Stanford University in Palo Alto, California. The aim was to test the feasibility of launching several picosatellites from one parent satellite. The satellite's secondary payloads are an accelerometer testbed and a magnetometer testbed, which will perform component characterization. The main satellite ejected 6 nanosatellites in orbit. The development started in 1995 and was completed in May 1999.
