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Orbital Replacement Unit (HST)
An orbital replacement unit or orbital replaceable unit is a modular component of spacecraft that can be replaced upon failure either by robot or by extravehicular activity. The Hubble Space Telescope (HST) was designed with 70 such parts, including scientific instruments and limited-life items such as batteries. On HST some parts were designed from the start as ORUs and all used captive bolts with a standard 7/16" double-height hex head; Section 2.2. later when it was decided to avoid returning HST to Earth for repair, more systems and modules were designated as ORUs (but used a wider variety of fasteners). HST servicing mission 3A (SM3A) replaced (or added) 15 ORUs, e.g. it replaced the DF-224 computer with the ''Advanced Computer''. The electrical system of the International Space Station also has such subsystems that provide power generation, power distribution and energy storage. See also * Hubble Space Telescope#Servicing missions and new instruments * Orbital replacem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Line-replaceable Unit
A line-replaceable unit (LRU), lower line-replaceable unit (LLRU), line-replaceable component (LRC), or line-replaceable item (LRI) is a modular component of an airplane, ship or spacecraft (or any other manufactured device) that is designed to be replaced quickly at an operating location (1st line). The different lines (distances) are essential for logistics planning and operation. An LRU is usually a sealed unit such as a radio or other auxiliary equipment. LRUs are typically assigned logistics control numbers (LCNs) or work unit codes (WUCs) to manage logistics operations. LRUs can improve maintenance operations, because they can be stocked and replaced quickly from distributed nearby on-site inventories (sometimes mobile storage), restoring the mobile systems to service, while the failed (unserviceable) LRU is undergoing complicated repair and overhaul actions in other support locations (lines). Because of their modularity, LRUs also can contribute reducing system costs and i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extravehicular Activity
Extravehicular activity (EVA) is any activity done by an astronaut in outer space outside a spacecraft. In the absence of a breathable atmosphere of Earth, Earthlike atmosphere, the astronaut is completely reliant on a space suit for environmental support. EVA includes ''spacewalks'' and Moon, lunar or planetary surface exploration (commonly known from 1969 to 1972 as ''moonwalks''). In a stand-up EVA (SEVA), an astronaut stands through an open hatch but does not fully leave the spacecraft. EVA has been conducted by the Soviet Union/Russia, the United States, Canada, the European Space Agency and China. On March 18, 1965, Alexei Leonov became the first human to perform a spacewalk, exiting the Voskhod 2 capsule for 12 minutes and 9 seconds. On July 20, 1969, Neil Armstrong became the first human to perform a moonwalk, outside his lunar lander on Apollo 11 for 2 hours and 31 minutes. On the last three Moon missions, astronauts also performed deep-space EVAs on the return to Eart ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hubble Space Telescope
The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versatile, renowned both as a vital research tool and as a public relations boon for astronomy. The Hubble telescope is named after astronomer Edwin Hubble and is one of NASA's Great Observatories. The Space Telescope Science Institute (STScI) selects Hubble's targets and processes the resulting data, while the Goddard Space Flight Center (GSFC) controls the spacecraft. Hubble features a mirror, and its five main instruments observe in the ultraviolet, visible, and near-infrared regions of the electromagnetic spectrum. Hubble's orbit outside the distortion of Earth's atmosphere allows it to capture extremely high-resolution images with substantially lower background light than ground-based telescopes. It has recorded some of the most ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding the National Advisory Committee for Aeronautics (NACA), to give the U.S. space development effort a distinctly civilian orientation, emphasizing peaceful applications in space science. NASA has since led most American space exploration, including Project Mercury, Project Gemini, the 1968-1972 Apollo Moon landing missions, the Skylab space station, and the Space Shuttle. NASA supports the International Space Station and oversees the development of the Orion spacecraft and the Space Launch System for the crewed lunar Artemis program, Commercial Crew spacecraft, and the planned Lunar Gateway space station. The agency is also responsible for the Launch Services Program, which provides oversight of launch operations and countdown m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DF-224
The DF-224 is a space-qualified computer used in space missions from the 1980s. It was built by Rockwell Autonetics. As with many spacecraft computers, the design is very redundant, since servicing in space is at best difficult and often impossible. The configuration had three CPUs, one active and two spares. The main memory consisted of six memory units, each with 8K 24-bit words of plated wire memory, with up to 48K words total. Four memory modules could be powered up at one time, resulting in a maximum of 32K words of available memory, though some applications such as the Hubble Space Telescope used fewer memory banks to allow for graceful failure modes. There were three I/O processors, one operational and two backups. The power supply consisted of 6 independent power converters, with overlapping coverage of the operating functions. The processor used fixed-point arithmetic with a two's complement format. Compared to computers that came later, the DF-224 was big and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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