The Explorers program is a NASA exploration program that provides flight opportunities for physics, geophysics, heliophysics, and astrophysics investigations from space. Launched in 1958, Explorer 1 was the first spacecraft of the United States to achieve orbit. Over 90 space missions have been launched since. Starting with Explorer 6, it has been operated by NASA, with regular collaboration with a variety of other institutions, including many international partners.
Ulysses was a robotic space probe whose primary mission was to orbit the Sun and study it at all latitudes. It was launched in 1990 and made three "fast latitude scans" of the Sun in 1994/1995, 2000/2001, and 2007/2008. In addition, the probe studied several comets. Ulysses was a joint venture of the European Space Agency (ESA) and the United States' National Aeronautics and Space Administration (NASA), under leadership of ESA with participation from Canada's National Research Council. The last day for mission operations on Ulysses was 30 June 2009.
High Energy Transient Explorer 1 (HETE-1) was a NASA astronomical satellite with international participation.
Galaxy Evolution Explorer was a NASA orbiting space telescope designed to observe the universe in ultraviolet wavelengths to measure the history of star formation in the universe. In addition to paving the way for future ultraviolet missions, the space telescope allowed astronomers to uncover mysteries about the early universe and how it evolved, as well as better characterize phenomena like black holes and dark matter. The mission was extended three times over a period of 10 years before it was decommissioned in June 2013. GALEX was launched on 28 April 2003 and decommissioned in June 2013.
The Rossi X-ray Timing Explorer (RXTE) was a NASA satellite that observed the time variation of astronomical X-ray sources, named after physicist Bruno Rossi. The RXTE had three instruments — an All Sky Monitor, the High-Energy X-ray Timing Experiment (HEXTE) and the Proportional Counter Array. The RXTE observed X-rays from black holes, neutron stars, X-ray pulsars and X-ray bursts. It was funded as part of the Explorer program, and was also called Explorer 69.
NASA's series of Great Observatories satellites are four large, powerful space-based astronomical telescopes launched between 1990 and 2003. They were built with different technology to examine specific wavelength/energy regions of the electromagnetic spectrum: gamma rays, X-rays, visible and ultraviolet light, and infrared light.
Neil Gehrels Swift Observatory, previously called the Swift Gamma-Ray Burst Explorer, is a NASA three-telescope space observatory for studying gamma-ray bursts (GRBs) and monitoring the afterglow in X-ray, and UV/Visible light at the location of a burst. It was launched on 20 November 2004, aboard a Delta II launch vehicle. Headed by principal investigator Neil Gehrels until his death in February 2017, the mission was developed in a joint partnership between Goddard Space Flight Center (GSFC) and an international consortium from the United States, United Kingdom, and Italy. The mission is operated by Pennsylvania State University as part of NASA's Medium Explorer program (MIDEX).
NuSTAR is a NASA space-based X-ray telescope that uses a conical approximation to a Wolter telescope to focus high energy X-rays from astrophysical sources, especially for nuclear spectroscopy, and operates in the range of 3 to 79 keV.
The Beyond Einstein program is a NASA project designed to explore the limits of General theory of Relativity of Albert Einstein. The project includes two space observatories, and several observational cosmology probes. The program culminates with the Einstein Vision probes, after completion of the Great Observatories program.
Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission began in February 2007 as a constellation of five NASA satellites to study energy releases from Earth's magnetosphere known as substorms, magnetic phenomena that intensify auroras near Earth's poles. The name of the mission is an acronym alluding to the Titan Themis.
Submillimeter Wave Astronomy Satellite is a NASA submillimetre astronomy satellite, and is the fourth spacecraft in the Small Explorer program (SMEX). It was launched on 6 December 1998, at 00:57:54 UTC, from Vandenberg Air Force Base aboard a Pegasus XL launch vehicle. The telescope was designed by the Smithsonian Astrophysical Observatory (SAO) and integrated by Ball Aerospace, while the spacecraft was built by NASA's Goddard Space Flight Center (GSFC). The mission's principal investigator is Gary J. Melnick.
High Energy Transient Explorer 2 was a NASA astronomical satellite with international participation. The satellite bus for the first HETE-1 was designed and built by AeroAstro, Inc. of Herndon, Virginia and was lost during launch on 4 November 1996; the replacement satellite, HETE-2 was built by Massachusetts Institute of Technology (MIT) based on the original HETE design.
Magsat was a NASA/USGS spacecraft, launched on 30 October 1979. The mission was to map the Earth's magnetic field, the satellite had two magnetometers. The scalar and vector magnetometers gave Magsat a capability beyond that of any previous spacecraft. Extended by a telescoping boom, the magnetometers were distanced from the magnetic field created by the satellite and its electronics. The satellite carried two magnetometers, a three-axis fluxgate magnetometer for determining the strength and direction of magnetic fields, and an ion-vapor/vector magnetometer for determining the magnetic field caused by the vector magnetometer itself. Magsat is considered to be one of the more important Science/Earth orbiting satellites launched; the data it accumulated is still being used, particularly in linking new satellite data to past observations.
Space research is scientific study carried out in outer space, and by studying outer space. From the use of space technology to the observable universe, space research is a wide research field. Earth science, materials science, biology, medicine, and physics all apply to the space research environment. The term includes scientific payloads at any altitude from deep space to low Earth orbit, extended to include sounding rocket research in the upper atmosphere, and high-altitude balloons.
The Nancy Grace Roman Space Telescope is a NASA infrared space telescope in development and scheduled to launch by May 2027.
The International X-ray Observatory (IXO) is a cancelled X-ray telescope that was to be launched in 2021 as a joint effort by NASA, the European Space Agency (ESA), and the Japan Aerospace Exploration Agency (JAXA). In May 2008, ESA and NASA established a coordination group involving all three agencies, with the intent of exploring a joint mission merging the ongoing XEUS and Constellation-X Observatory (Con-X) projects. This proposed the start of a joint study for IXO. NASA was forced to cancel the observatory due to budget constraints in fiscal year 2012. ESA however decided to reboot the mission on its own developing Advanced Telescope for High Energy Astrophysics as a part of Cosmic Vision program.
The Neutron Star Interior Composition ExploreR (NICER) is a NASA telescope on the International Space Station, designed and dedicated to the study of the extraordinary gravitational, electromagnetic, and nuclear physics environments embodied by neutron stars, exploring the exotic states of matter where density and pressure are higher than in atomic nuclei. As part of NASA's Explorer program, NICER enabled rotation-resolved spectroscopy of the thermal and non-thermal emissions of neutron stars in the soft X-ray band with unprecedented sensitivity, probing interior structure, the origins of dynamic phenomena, and the mechanisms that underlie the most powerful cosmic particle accelerators known. NICER achieved these goals by deploying, following the launch, and activation of X-ray timing and spectroscopy instruments. NICER was selected by NASA to proceed to formulation phase in April 2013.
Student Nitric Oxide Explorer, was a NASA small scientific satellite which studied the concentration of nitric oxide in the thermosphere. It was launched in 1998 as part of NASA's Explorer program. The satellite was the first of three missions developed within the Student Explorer Demonstration Initiative (STEDI) program funded by the NASA and managed by the Universities Space Research Association (USRA). STEDI was a pilot program to demonstrate that high-quality space science can be carried out with small, low-cost free-flying satellites on a time scale of two years from go-ahead to launch. The satellite was developed by the University of Colorado Boulder's Laboratory for Atmospheric and Space Physics (LASP) and had met its goals by the time its mission ended with reentry in December 2003.
Imaging X-ray Polarimetry Explorer, commonly known as IXPE or SMEX-14, is a space observatory with three identical telescopes designed to measure the polarization of cosmic X-rays of black holes, neutron stars, and pulsars. The observatory, which was launched on 9 December 2021, is an international collaboration between NASA and the Italian Space Agency (ASI). It is part of NASA's Explorers program, which designs low-cost spacecraft to study heliophysics and astrophysics.
The X-ray Polarimeter Satellite (XPoSat) is an Indian Space Research Organisation (ISRO) planned space observatory to study polarisation of cosmic X-rays. It is planned to be launched in 2023 or later on a Polar Satellite Launch Vehicle (PSLV), with mission life of at least five years.
