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  (pdf file) Click for complete acronyms list.

ACS — Advanced Camera for Surveys
This will consist of three electronic channels and a complement of filters and dispersers that detect light from the ultraviolet at 1200 angstroms to the near infrared at 10,000 angstroms, with 10 times the efficiency of current instruments.

ASLR(K) — Aft Shroud Latch Repair (kits)
This kit will fix door latches in the aft shroud area of the Hubble that have been damaged by extreme temperature changes and high torques.

BAPS — Berthing and Positioning System
This is the unit that holds and maneuvers HST while it is attached to the orbiter. The BAPS can orient the telescope at a variety of angles and can rotate the HST a full 360 degrees to bring any part of HST within the reach of the astronauts and the RMS, or robot arm.

BPS — BAPS Support Post
This post is installed to keep the BAPS immobile during activities which generate high torques on the HST, for example during reboost.

A heavy logistics global transport aircraft designed to provide massive strategic airlift and express delivery of padded or oversized cargo as well as passengers; transported HST flight hardware and personnel to and from GSFC and KSC.

COS — Cosmic Origins Spectrograph
Fourth Generation Spectrometer. COS is an ultraviolet spectrograph optimized for observing faint point sources with moderate spectral resolution. To be installed during SM4 in 2004.

COSTAR — Corrective Optics Space Telescope Axial
Second Generation Corrective Optics. COSTAR is not an actual instrument, it consists of mirrors which refocus the abberated light from the HST optical system for first generation instruments. Only FOC utilizes its services today. It has been deactivated since FOC will be removed during SM3B.

Onboard Digital Fixed Point 2's complement 24-bit word Rockwell computer module. This is the main computer which controls the attitude (orientation) of the Hubble Space Telescope.

ESA — European Space Agency

EVA — Extravehicular activity
outside the spacecraft; activity in space conducted by suited astronauts. This is also known as a spacewalk.

FGS — Fine Guidance Sensor
Science/Guidance instruments. The FGS's are used in a "dual-purpose" mode serving to lock on to "guide stars" which help the telescope obtain the exceedingly accurate pointing necessary for observation of astronomical targets. These instruments can also be used to obtain highly accurate measurements of stellar positions.

FOC — Faint Object Camera
First Generation Imaging camera. FOC is used to image very small field of view, very faint targets. The last of the original instruments on HST.

FOS — Faint Object Spectrograph
First Generation Spectrometer. FOS was used to obtain spectra of very faint or far away sources. FOS also had a polarimeter for the study of the polarized light from these sources.

FSS — Flight Support System (Structure)
This is the name for the structure which holds HST and provides power and computer interfaces while it is berthed to an Orbiter during Servicing.

GHRS — Goddard High Resolution Spectrograph
First Generation Spectrograph. GHRS was used to obtain high resolution spectra of bright targets. It was removed during SM2 in 1997. Parts of GHRS are being reused for COS.

GSFC — Goddard Space Flight Center
Greenbelt, Maryland. The HST Project is located here.

HOST mission — Hubble Space Telescope Orbital Systems Test (1998)
This mission tested several pieces of equipment in preparation for SM3A and SM3B. Designated shuttle mission STS-95.

HST — Hubble Space Telescope

KSC — Kennedy Space Center, Cape Canaveral, FL
KSC is responsible for launches.

MLI — Multi-layer insulation
This is the highly reflective material which is attached to spacecraft to act as a thermal barrier. It consists of many sheets of 25 µm thick polyester or polyamide layers sewn together. It is often silver or gold in color.

MULE— Multi-use Lightweight Equipment
One of the transport modules used in the shuttle's bay. For SM3B, the mule will transport the Nicmos Cooling System (NCS).

NASA — National Aeronautics and Space Administration

NCS — NICMOS Cooling System
This mechanical cooler which was tested during the HOST mission and will be installed during SM3B will allow NICMOS to resume science operations.

NICMOS — Near Infrared Camera and Multi-Object Spectrometer
Second Generation Imager/Spectrograph. NICMOS is HST's only NIR instrument.

NIR — Near Infrared
Near Infrared light is not visible to human eyes, but many celestial objects shine brightly with this light. Typically associated with heat, NIR images show the presence of molecules and complex compounds.

NOBL — New Outer Blanket Layer
The NOBL are stainless steel panels covered with a protective thermal coating. These panels fit over existing, degraded insulation on Hubble's exterior surface, to control Hubble's internal temperature. In 1997, astronauts on Servicing Mission 2 discovered damaged areas of insulation and performed temporary repairs. The NOBL will be permanently attached.

OCE-EK — Optical Control Electronics Enhancement Kit

ORU/ORI — Orbital Replacement Unit / Orbital Replacement Instrument
Since HST was designed to be serviced on-orbit, many of the systems, and all of the instruments were designed and built as replaceable units.

ORUC — Orbital Replacement Unit Carrier
Special boxes which isolate the delicate instruments and other ORUs from the forces and vibrations of launch and ascent to orbit.

PCU— Power Control Unit
Hubble's power switching station. The PCU controls and distributes electricity from the solar arrays and batteries to other parts of the telescope.

RAC— Rigid Array Carrier
One of the transport modules used in the shuttle's bay. For SM3B, the RAC will transport the new solar arrays (SA3) and bring back the old ones (SA2).

RSU — Rate Sensor Unit
Hubble houses three RSU's and each RSU contains two gyroscopes. The gyroscopes are part of Hubble's pointing system. The gyroscopes work by comparing Hubble's motion relative to the axis of the spinning masses inside the gyroscopes. In the absence of external forces, these axes remain stable relative to the fixed stars in the sky. By keeping Hubble fixed relative to these axes, Hubble stays stable relative to the stars.

SA3— Solar Array 3
Hubble's new solar arrays which will be installed on servicing mission 3B. Although 45 percent smaller than its predecessors, they will produce 25 percent more power.

SAC— Second Axial Carrier
One of the transport modules used in the shuttle's bay. For SM3B, the SAC will transport the Advanced Camera for Surveys (ACS).

SM1 — HST Servicing Mission 1, December 1993

SM2 — HST Servicing Mission 2, February 1997

SM3A — HST Servicing Mission 3A, December 1999

SM3B — HST Servicing Mission 3B, planned for 2002

SSAT — S-band Single-Access Transmitter
This replacement transmitter uses radio waves to send data to the ground. The older unit it replaces will be returned to Earth and refurbished for a later flight.

SSDIF — Spacecraft Systems Development and Integration Facility
This building is located at GSFC. The SSDIF is a 7,989 square meters (86,000 square ft) facility designed to provide support for the integration and testing of spacecraft hardware. It is unique in the fact that it contains a 36,816 cubic meters (1.3 million cubic ft) horizontal, unidirectional flow cleanroom. Additional features include: Automated Data Processing Area, Shipping/Receiving Area, Flight Hardware Storage Area, and Precision Cleaning facilities.

SSR — Solid State Recorder
Hubble's original data recorders were mechanical, reel-to-reel tape recorders with many moving parts that wear out over time. The digital SSR has no moving parts or tape to break, so it is much more robust. This next-generation recorder is faster and more reliable, and it can store 10 times as much data as a mechanical recorder.

SSRF — Shell/Shield Repair Fabric
Sheets of flexible, aluminized Teflon® fabric that fit over the original multi-layer insulation on Hubble's forward shell and light shield to add thermal protection. In 1997, astronauts on Servicing Mission 2 discovered damaged areas of insulation and performed temporary repairs. The SSRF will be permanently mounted over these temporary coverings.

STIS — Space Telescope Imaging Spectrograph
Second Generation Imager/Spectrograph. STIS is used to obtain high resolution spectra of resolved objects. The special ability of STIS is to simultaneously obtain spectra from many different points along the target.

STOCC — Space Telescope Operations Control Center
Located at Goddard Space Flight Center, the STOCC is where all commanding to the HST originates.

STS — Space Transportation System
This is the formal name of the Space Shuttle Program.

STScI — Space Telescope Science Institute
This institute, located at the Johns Hopkins University campus in Baltimore, is the home of HST science operations. The STScI is responsible for allocating observing time and for calibration, data storage, retrieval, and distribution of science data. STScI also provides software tools for manipulating the data.

USAF — United States Air Force

USN — United States Navy

USS — United States Ship

VEST — Vehicle Electrical Systems Test
Hubble high fidelity mock-up trains astronauts on installation and removal of flight hardware components.

VIK — Voltage/Temperature Improvement Kit
These protect Hubble's batteries from overcharging and overheating when in safe mode.

WFC3 — Wide Field Camera 3
Fourth Generation Imaging camera. This camera will supplement ACS and guarantee imaging capability for HST after Servicing Mission 4.

WFPC — Wide Field/Planetary Camera
The dual-channel (visible and near-IR) camera currently in use is the second-generation instrument WFPC2, installed during Servicing Mission 1 in December 1993. It replaced WFPC1 and was built with optics to compensate for the spherical aberration of the primary mirror.

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