Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space or on the surface of the Earth without relying solely on estimated positional calculations, commonly known as dead reckoning. Celestial navigation is performed without using satellite navigation or other similar modern electronic or digital positioning means.
The Chandra X-ray Observatory (CXO), previously known as the Advanced X-ray Astrophysics Facility (AXAF), is a Flagship-class space telescope launched aboard the Space ShuttleColumbia during STS-93 by NASA on July 23, 1999. Chandra was sensitive to X-ray sources 100 times fainter than any previous X-ray telescope, enabled by the high angular resolution of its mirrors. Since the Earth's atmosphere absorbs the vast majority of X-rays, they are not detectable from Earth-based telescopes; therefore space-based telescopes are required to make these observations. Chandra is an Earth satellite in a 64-hour orbit, and its mission is ongoing as of 2024.
The Fermi Gamma-ray Space Telescope, formerly called the Gamma-ray Large Area Space Telescope (GLAST), is a space observatory being used to perform gamma-ray astronomy observations from low Earth orbit. Its main instrument is the Large Area Telescope (LAT), with which astronomers mostly intend to perform an all-sky survey studying astrophysical and cosmological phenomena such as active galactic nuclei, pulsars, other high-energy sources and dark matter. Another instrument aboard Fermi, the Gamma-ray Burst Monitor, is being used to study gamma-ray bursts and solar flares.
A pulsar is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. This radiation can be observed only when a beam of emission is pointing toward Earth, and is responsible for the pulsed appearance of emission. Neutron stars are very dense and have short, regular rotational periods. This produces a very precise interval between pulses that ranges from milliseconds to seconds for an individual pulsar. Pulsars are one of the candidates for the source of ultra-high-energy cosmic rays.
The Extreme Universe Space Observatory onboard Japanese Experiment Module (JEM-EUSO) is the first space mission concept devoted to the investigation of cosmic rays and neutrinos of extreme energy (E > 5×1019 eV). Using the Earth's atmosphere as a giant detector, the detection is performed by looking at the streak of fluorescence produced when such a particle interacts with the Earth's atmosphere.
X-ray pulsar-based navigation and timing (XNAV) or simply pulsar navigation is a navigation technique whereby the periodic X-ray signals emitted from pulsars are used to determine the location of a vehicle, such as a spacecraft in deep space. A vehicle using XNAV would compare received X-ray signals with a database of known pulsar frequencies and locations. Similar to GPS, this comparison would allow the vehicle to calculate its position accurately (±5 km). The advantage of using X-ray signals over radio waves is that X-ray telescopes can be made smaller and lighter. Experimental demonstrations have been reported in 2018.
The National Aeronautics and Space Administration is an independent agency of the U.S. federal government responsible for the civil space program, aeronautics research, and space research. Established in 1958, it succeeded the National Advisory Committee for Aeronautics (NACA) to give the U.S. space development effort a distinct civilian orientation, emphasizing peaceful applications in space science. It has since led most of America's space exploration programs, including Project Mercury, Project Gemini, the 1968–1972 Apollo Moon landing missions, the Skylab space station, and the Space Shuttle. Currently, NASA supports the International Space Station (ISS) along with the Commercial Crew Program, and oversees the development of the Orion spacecraft and the Space Launch System for the lunar Artemis program.
Commercial Resupply Services (CRS) are a series of flights awarded by NASA for the delivery of cargo and supplies to the International Space Station (ISS) on commercially operated spacecraft. The first CRS contracts were signed in 2008 and awarded $1.6 billion to SpaceX for twelve cargo Dragon and $1.9 billion to Orbital Sciences for eight Cygnus flights, covering deliveries to 2016. The Falcon 9 and Antares rockets were also developed under the CRS program to deliver cargo spacecraft to the ISS.
Gamma-ray astronomy is a subfield of astronomy where scientists observe and study celestial objects and phenomena in outer space which emit cosmic electromagnetic radiation in the form of gamma rays, i.e. photons with the highest energies at the very shortest wavelengths. Radiation below 100 keV is classified as X-rays and is the subject of X-ray astronomy.
Gravity and Extreme Magnetism Small Explorer mission was a NASA space observatory mission. The main scientific goal of GEMS was to be the first mission to systematically measure the polarization of X-ray sources. GEMS would have provided data to help scientists study the shape of spacetime that has been distorted by a spinning black hole's gravity and the structure and effects of the magnetic fields around neutron stars. It was cancelled by NASA in June 2012 for potential cost overruns due to delays in developing the technology and never moved into the development phase.
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.
SpaceX CRS-10, also known as SpX-10, was a Dragon Commercial Resupply Service mission to the International Space Station (ISS) which launched on 19 February 2017. The mission was contracted by NASA as part of its Commercial Resupply Services program and was launched by SpaceX aboard the 30th flight of the Falcon 9 rocket. The mission ended on 19 March 2017 when the Dragon spacecraft left the ISS and safely returned to Earth.
SpaceX CRS-11, also known as SpX-11, was a Commercial Resupply Service mission to the International Space Station, launched successfully on 3 June 2017. The mission was contracted by NASA and was flown by SpaceX. The mission utilized a Falcon 9 launch vehicle and was the first reuse of C106, a CRS Dragon cargo vessel that was previously flown on the CRS-4 mission.
SpaceX CRS-12, also known as SpX-12, was a Commercial Resupply Services mission to the International Space Station launched on 14 August 2017. The mission was contracted by NASA and was flown by SpaceX using a new Dragon capsule. The Falcon 9 rocket's reusable first stage performed a controlled landing on Landing Zone 1 (LZ1) at Cape Canaveral Air Force Station. After delivering more than 2,900 kilograms (6,400 lb) of cargo, the Dragon spacecraft returned to Earth on 17 September 2017.
SpaceX CRS-16, also known as SpX-16, was a Commercial Resupply Service mission to the International Space Station launched on 5 December 2018 aboard a Falcon 9 launch vehicle. The mission was contracted by NASA and is flown by SpaceX.
Dragon, also known as Dragon 1 or Cargo Dragon, was a class of fourteen partially reusable cargo spacecraft developed by SpaceX, an American private space transportation company. The spacecraft flew 23 missions between 2010 and 2020. Dragon was launched into orbit by the company's Falcon 9 launch vehicle to resupply the International Space Station (ISS).
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) manufactured space observatory to study polarisation of cosmic X-rays. It was launched on 1 January 2024 on a PSLV rocket, and it has an expected operational lifespan of at least five years.
SpaceX CRS-26, also known as SpX-26, was a Commercial Resupply Service mission to the International Space Station (ISS) launched on 26 November 2022. The mission was contracted by NASA and flown by SpaceX using a Cargo Dragon. This was the sixth flight for SpaceX under NASA's CRS Phase 2 contract awarded in January 2016.
SpaceX CRS-27, also known as SpX-27, was a Commercial Resupply Service mission to the International Space Station (ISS) launched on 15 March 2023. The mission was contracted by NASA and was flown by SpaceX using Cargo Dragon C209. This was the seventh flight for SpaceX under NASA's CRS Phase 2.
