Orbital replacement unit (HST)

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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, [1] including scientific instruments and limited-life items such as batteries. [1]

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 that is designed to be replaced quickly at an operating location. 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.

Extravehicular activity Activity done by an astronaut or cosmonaut outside a spacecraft

Extravehicular activity (EVA) is any activity done by an astronaut or cosmonaut outside a spacecraft beyond the Earth's appreciable atmosphere. The term most commonly applies to a spacewalk made outside a craft orbiting Earth, but also has applied to lunar surface exploration performed by six pairs of American astronauts in the Apollo program from 1969 to 1972. On each of the last three of these missions, astronauts also performed deep-space EVAs on the return to Earth, to retrieve film canisters from the outside of the spacecraft. Astronauts also used EVA in 1973 to repair launch damage to Skylab, the United States' first space station.

Hubble Space Telescope Space telescope

The Hubble Space Telescope 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 and is well known as both a vital research tool and a public relations boon for astronomy. The Hubble telescope is named after astronomer Edwin Hubble and is one of NASA's Great Observatories, along with the Compton Gamma Ray Observatory, the Chandra X-ray Observatory, and the Spitzer Space Telescope.

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; [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). [2] HST servicing mission 3A (SM3A) replaced (or added) 15 ORUs, [2] :fig 2-1 e.g. it replaced the DF-224 computer with the Advanced Computer.

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.

The electrical system of the International Space Station also has such subsystems that provide power generation, power distribution and energy storage. [3]

Electrical system of the International Space Station solar powered electrical system

The electrical system of the International Space Station is a critical resource for the International Space Station (ISS) because it allows the crew to live comfortably, to safely operate the station, and to perform scientific experiments. The ISS electrical system uses solar cells to directly convert sunlight to electricity. Large numbers of cells are assembled in arrays to produce high power levels. This method of harnessing solar power is called photovoltaics.

See also

Orbital replacement unit

Orbital replacement units (ORUs) are key elements of the International Space Station that can be readily replaced when the unit either passes its design life or fails. ORUs are parts of the main systems and subsystems of the external elements of the ISS, none are intended to be installed inside the pressurised modules. Examples of ORUs are: pumps, storage tanks, controller boxes, antennas, and battery units. Such units are replaced either by astronauts during EVA or by the Dextre (SPDM) robotic arm. All are stored on the three external stowage platforms (ESPs) or the four ExPRESS Logistics Carriers (ELCs) mounted on the Integrated Truss Structure (ITS).

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Space Telescope Science Institute Science operations center operated by NASA

The Space Telescope Science Institute (STScI) is the science operations center for the Hubble Space Telescope (HST) and for the James Webb Space Telescope (JWST). STScI is located on the Johns Hopkins University Homewood Campus in Baltimore, Maryland and was established in 1981 as a community-based science center that is operated for NASA by the Association of Universities for Research in Astronomy (AURA). In addition to performing continuing science operations of HST and preparing for scientific exploration with JWST, STScI manages and operates the Mikulski Archive for Space Telescopes (MAST), the Data Management Center for the Kepler mission and a number of other activities benefiting from its expertise in and infrastructure for supporting the operations of space-based astronomical observatories. Most of the funding for STScI activities comes from contracts with NASA's Goddard Space Flight Center but there are smaller activities funded by NASA's Ames Research Center, NASA's Jet Propulsion Laboratory, and the European Space Agency (ESA). The staff at STScI consists of scientists, software engineers, data management and telescope operations personnel, education and public outreach experts, and administrative and business support personnel. There are approximately 100 Ph.D. scientists working at STScI, 15 of which are ESA staff who are on assignment to the HST project. The total STScI staff consists of about 450 people.

STS-31 1990 NASA spaceflight

STS-31 was the 35th mission of the American Space Shuttle program, which launched the Hubble Space Telescope astronomical observatory into Earth orbit. The mission used the Space Shuttle Discovery, which lifted off from Launch Complex 39B on 24 April 1990 from Kennedy Space Center, Florida.

James Webb Space Telescope Space observatory

The James Webb Space Telescope is a space telescope that is planned to be the successor to the Hubble Space Telescope. The JWST will provide greatly improved resolution and sensitivity over the Hubble, and will enable a broad range of investigations across the fields of astronomy and cosmology, including observing some of the most distant events and objects in the universe, such as the formation of the first galaxies. Other goals include understanding the formation of stars and planets, and direct imaging of exoplanets and novas.

Steven Hawley American astronaut

Steven Alan Hawley is a former NASA astronaut who flew on five U.S. Space Shuttle flights. He is professor of physics and astronomy and director of engineering physics at the University of Kansas.

STS-82 human spaceflight

STS-82 was the 22nd flight of the Space Shuttle Discovery and the 82nd mission of the Space Shuttle program. It was NASA's second mission to service the Hubble Space Telescope, during which Discovery's crew repaired and upgraded the telescope's scientific instruments, increasing its research capabilities and achieved the highest altitude ever attained by a STS Orbiter. Discovery launched from Kennedy Space Center, Florida, on 11 February 1997, returning to Earth on 21 February 1997 at Kennedy Space Center.

STS-95 human spaceflight

STS-95 was a Space Shuttle mission launched from Kennedy Space Center, Florida on 29 October 1998, using the orbiter Discovery. It was the 25th flight of Discovery and the 92nd mission flown since the start of the Space Shuttle program in April 1981. It was a highly publicized mission due to former Project Mercury astronaut and United States Senator John H. Glenn Jr.'s return to space for his second space flight. At age 77, Glenn became the oldest person, to date, to go into space. This mission is also noted for inaugurating ATSC HDTV broadcasting in the U.S., with live coast-to-coast coverage of the launch. In another first, Pedro Duque became the first Spaniard in space.

STS-109 human spaceflight

STS-109 (SM3B) was a Space Shuttle mission that launched from the Kennedy Space Center on 1 March 2002. It was the 108th mission of the Space Shuttle program, the 27th flight of the orbiter Columbia and the fourth servicing of the Hubble Space Telescope. It was also the last successful mission of the orbiter Columbia before the ill-fated STS-107 mission, which culminated in the Columbia disaster.

John M. Grunsfeld American astronaut and astronomer

John Mace Grunsfeld is an American physicist and a former NASA astronaut. He is a veteran of five Space Shuttle flights and has served as NASA Chief Scientist. His academic background includes research in high energy astrophysics, cosmic ray physics and the emerging field of exoplanet studies with specific interest in future astronomical instrumentation. After retiring from NASA in 2009, he served as the Deputy Director of the Space Telescope Science Institute in Baltimore, Maryland. In January 2012, he returned to NASA and served as associate administrator of NASA's Science Mission Directorate (SMD). Grunsfeld announced his retirement from NASA in April 2016.

Gregory J. Harbaugh American astronaut

Gregory Jordan Harbaugh is a former NASA astronaut.

Paul W. Richards American engineer and a former NASA Astronaut

Paul William Richards is an American engineer and a former NASA Astronaut. He flew aboard one Space Shuttle mission in 2001.

Great Observatories program series of space telescopes

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. Three remain operational as of 2019.

Near Infrared Camera and Multi-Object Spectrometer

The Near Infrared Camera and Multi-Object Spectrometer (NICMOS) is a scientific instrument for infrared astronomy, installed on the Hubble Space Telescope (HST), operating from 1997 to 1999, and from 2002 to 2008. Images produced by NICMOS contain data from the near-infrared part of the light spectrum.

Wide Field and Planetary Camera

The Wide Field/Planetary Camera (WFPC) was a camera installed on the Hubble Space Telescope until December 1993. It was one of the instruments on Hubble at launch, but its functionality was severely impaired by the defects of the main mirror optics which afflicted the telescope. However, it produced uniquely valuable high resolution images of relatively bright astronomical objects, allowing for a number of discoveries to be made by HST even in its aberrated condition.

The Hubble Origins Probe (HOP) was a proposal for an orbital telescope made in 2005 in response to the first cancellation of the fourth Hubble Space Telescope (HST) servicing mission. It would have used an Atlas V rocket or similar launch vehicle to launch a much lighter, unaberrated mirror and optical telescope assembly, using the instruments that had already been built for SM4, along with a new wide-field imager. It would have cost between $700 million and $1 billion.

Corrective Optics Space Telescope Axial Replacement optical instrument

The Corrective Optics Space Telescope Axial Replacement (COSTAR) is the instrument designed to correct Hubble Space Telescope's spherical aberration for light focused at the FOC, FOS and GHRS instruments. Built by Ball Aerospace Corp., it replaced the High Speed Photometer (HSP) during the first Hubble Servicing Mission in 1993.

STS-125 human spaceflight

STS-125, or HST-SM4, was the fifth and final Space Shuttle mission to the Hubble Space Telescope (HST) and the last solo flight of the Space Shuttle Atlantis. The launch of the Space Shuttle Atlantis occurred on 11 May 2009 at 2:01 pm EDT. Landing occurred on 24 May at 11:39 am EDT, with the mission lasting a total of just under 13 days.

Wide Field Camera 3 astronomical camera on the Hubble space telescope

The Wide Field Camera 3 (WFC3) is the Hubble Space Telescope's last and most technologically advanced instrument to take images in the visible spectrum. It was installed as a replacement for the Wide Field and Planetary Camera 2 during the first spacewalk of Space Shuttle mission STS-125 on May 14, 2009.

Advanced Technology Large-Aperture Space Telescope proposed UV-optical-NIR space telescope

The Advanced Technology Large-Aperture Space Telescope (ATLAST, now evolved and called LUVOIR-B) is an 8–meter UV-optical-NIR space telescope concept proposed by the Space Telescope Science Institute (STScI), the science operations center for the Hubble Space Telescope (HST). If launched, LUVOIR would be a replacement and successor for the HST, with the ability to obtain spectroscopic and imaging observations of astronomical objects in the ultraviolet, optical, and infrared wavelengths, but with substantially better resolution than either HST or the yet-to-be-launched James Webb Space Telescope (JWST). Like JWST, ATLAST would be deployed at the Sun-Earth L2 Lagrange point.

Fine Guidance Sensor (HST)

Fine Guidance Sensor (FGS) for the Hubble Space Telescope is a system of three instruments used for pointing the telescope in space, and also for astrometry and its related sciences. Each FGS uses a combination of optics and electronics to provide for pointing the telescope at a certain location in the sky. There are three Hubble FGS, and they have been upgraded over the lifetime of the telescope by manned Space Shuttle missions. The instruments can support pointing of 2 milli-arc seconds. The three FGS are part of the Hubble Space Telescope's Pointing Control System, aka PCS. The FGS function in combination with the Hubble main computer and gyroscopes, with the FGS providing data to the computer as sensors which enables the HST to track astronomical targets.

References

  1. 1 2 Kinard, William H. "Returned Hardware: Orbital Replacement Units". Hubble Space Telescope Archive System. NASA /Langley Research Center. Archived from the original on 19 February 2013. Retrieved 27 March 2013.
  2. 1 2 3 "Hubble Space Telescope Servicing Mission 3A Media Reference Guide" (PDF). NASA. Lockheed Martin Missiles and Space. Retrieved 21 September 2010. Section 2.2.
  3. ↑ "Glenn Leads Sustaining Engineering of Power System Hardware". NASA /Glenn Research Center. 14 February 2008. Archived from the original on 22 February 2012. Retrieved 27 March 2013.


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