These definitions are not complete nor are they official. Use them at your own risk. They are intended only to facilitate understanding of some of the reports that appear on this Web site. We will try to keep them updated. Additional astronomical acronyms can be found by using the searchable index on the StarPages.

ASCA Advanced Satellite for Cosmology and Astrophysics. A Japanese X-ray satellite, also known as Astro-D. US provided part of the scientific payload. Launched 20 February 1993.

ADP Astrophysics Data Program. A grants program administered by Code SR for analysis of data obtained by spacecraft.

ATP Astrophysics Theory Program. A grants program administered by Code SR for theoretical astrophysics.

AO Announcement of Opportunity, i.e., an opportunity to submit a proposal to NASA. AOs usually involve a flight mission and production of some "deliverable item" to NASA. These tend to be larger programs than NRAs (see below), but are not as specific as RFPs (also below).

ASO Astronomical Search for Origins (see Origins, below). One of the NASA Space Science themes.

AWG Astrophysics Working Group.

AXAF Advanced X-Ray Astronomy Facility, renamed the Chandra X-Ray Observatory (see below) in 1998 December.

BeppoSAX Satellite per Astronomia X. An Italian X-ray (0.1 - 200 keV) satellite, launched 30 April 1996. "Beppo" is the nickname of Giuseppe Occhialini, a pioneering high-energy physicist.

Chandra X-Ray Observatory The Chandra X-Ray Observatory, formerly known as the Advanced X-Ray Astronomy Facility (AXAF), is the next-generation high spectral and spatial resolution X-ray facility that operates over the 0.1 - 10 keV band. Launched 1999 July 23 on STS-93. Named after the late Indian-American astrophysicist Subrahmanyan Chandrasekhar of the University of Chicago.

CGRO Compton Gamma-Ray Observatory. A satellite for observations at gamma-ray wavelengths (30 keV to 30 GeV). Launched on 5 April 1991.

CHIPS Cosmic Hot Interstellar Plasma, a UNEX selected in 1998 for flight in 2001.

ELV Expendable Launch Vehicle. A vehicle (rocket) that is used only once (in constrast to reusable vehicles, such as the Space Shuttle).

ESA European Space Agency.

EUVE Extreme Ultraviolet Explorer. A satellite for observations at extreme UV wavelengths. Launched in 7 June 1992.

Explorer The Explorer program is NASA's continuing level-of-effort program for orbital astronomy and space physics packages (the Discovery program is the equivalent program for deep-space explorations, i.e., planetary probes). Explorers come in three sizes (each defined by separate entries in this glossary), defined by budget cap: Medium Explorer (MIDEX), Small Explorer (SMEX), and University-class Explorer (UNEX).

FAME Full-Sky Astrometric Mapping Explorer, a MIDEX (see below) selected for flight in 2004.

FIRST Far Infrared and Submillimetre Telescope (renamed to Herschel Space Observatory). An ESA cornerstone mission, currently in the planning stages. Spectroscopy in the 85-900 µm range. Launch anticipated in 2007, on the same carrier as Planck.

FUSE Far-Ultraviolet Spectroscopic Explorer. A satellite for high-resolution observations at far-UV wavelengths. The first MIDEX (see below) mission, launched on 1999 June 24.

GALEX Galaxy Evolution Explorer A UV imaging and spectroscopy SMEX (see below) selected in 1997.

GO Guest Observer. Guest observers are astronomers who use instruments on spacecraft to make scientific observations, but who are not part of the original team that planned and built the spacecraft.

GOCO Government-Owned Contractor-Operated (facility).

GP-B Gravity Probe B. A relativity mission scheduled for launch in 2002.

GSFC Goddard Space Flight Center. A NASA center in Greenbelt, Maryland.

HST Hubble Space Telescope. Launched 24 April 1990.

ITAR "International Trade in Arms Regulations". US government regulations that are intended to regulate export of satellite components and technology.

IUE International Ultraviolet Explorer. A satellite for observations at UV wavelengths. Launched 26 January 1978, mission completed 30 September 1996.

JPL Jet Propulsion Laboratory. A semi-autonomous NASA center, run by the California Institute of Technology under contract from NASA.

LTSA Long-Term Space Astrophysics. A grants program administered by Code SR for research in space astronomy.

MAP Microwave Anisotropy Probe. A MIDEX (see below) satellite scheduled for launch in the autumn of 2000.

MIDEX Medium-class Explorer or MIDEX is a medium-sized (defined by definition and development costs not exceeding $140M) spacecraft that carries one or more science instruments. Compare to SMEX and UNEX; see also Explorer.

MO&DA Mission Operations and Data Analysis. The part of the NASA R&A (see below) budget line that funds mission operations (e.g., ground stations) and data analysis (e.g., grants to investigators) for analysis of data from spacecraft.

MOWG Management Operations Working Group. Small groups of scientists appointed by NASA Office of Space Science to provide an interface between NASA Headquarters and working scientists at universities and NASA centers. Under the old NASA structure, there were individual MOWGs for different wavelength regimes, i.e., HEMOWG (High Energy), IRMOWG (Infrared), and UVMOWG (Ultraviolet/Visible).

MSFC Marshall Space Flight Center. A NASA center in Huntsville, Alabama.

NASA National Aeronautics and Space Administration.

NGST Next Generation Space Telescope. A major mission, in the early stages of study, that is intended to provide a replacement for Hubble Space Telescope at the middle of the next decade.

NRA NASA Research Announcement, an announcement that science proposals to NASA are solicited. NRAs generally involve basic scientific research with end-products that are expected to be published in the scientific literature. These are smaller programs than AOs (see above) or RFPs (see below).

NRC National Research Council is the principal operating agency of the National Academy of Sciences.

NSF National Science Foundation.

OS Origins Subcommittee. A strategic-level group (chaired by David Black of the Lunar and Planetary Institute) that advises OSS on issues pertaining to the Origins theme.

Origins Not an acronym (compare to SEU), it means the Astronomical Search for Origins and Planetary Systems, one of the four science themes in OSS (see below). Often refers to the Origins Subcommittee (OS, see above). Harley Thronson is the Acting Science Program Director for this theme.

OSS Office of Space Science (also known as Code S) at NASA Headquarters, under the direction of Edward Weiler, Associate Adminstrator for Space Science.

OSTP Office of Science and Technology Policy (username/password required). Part of the Executive Branch of the US Government, that advises the President on Science and Technology issues.

Phase (A-E) NASA uses this shorthand to describe where a mission is in the pipeline. "Phase A" is called "concept study". This generally means that a mission has been selected for further study in a competition (often in response to an AO [see above]); this generally results in a "Phase A study", which is essentially a more detailed proposal. Once a mission is selected for flight, it enters "Phase B" which is "definition and preliminary design", which ends with a preliminary design review (PDR). "Phase C" or "detailed design" terminates with a critical design review (CDR), and "Phase D" is "development through launch and checkout", which usually terminates approximately 30 days after launch. "Phase E" is "operations and data analysis".

PLANCK Planck is a primarily European (with some US participation) cosmic-background radiation experiment that will observe in the range 35-900 GHz. It is scheduled for launch in 2007, on the same vehicle as FIRST (above).

R&A Research and Analysis. The NASA budget line that pays for competitively selected data analysis programs. NRAs (above) are paid for out of the NASA R&A budget. SR&T (below) and MO&DA (above) costs are part of this budget.

RFP Request for Proposals, i.e., a solicitation of proposals by NASA for some specific purpose (operation of the SOFIA program provides a recent example). RFPs outline very specific goals for the program, in contrast to the AOs or NRAs (see above). RFPs are reviewed formally by government "Source Selection Board".

ROSAT Röntgen Satellite. An X-ray satellite operated jointly by Germany, the United States, and the United Kingdom. Launched 1 June 1990, mission completed on 12 February 1999.

ROSS NRA A NASA Research Announcement (NRA) for Research Opportunities in Space Science. This is an "omnibus" NRA through which opportunities to propose to several different NASA programs are announced at once. This was first used in 1998 to streamline the complicated grants announcement proceedures that must be followed.

RXTE Rossi X-Ray Timing Explorer. An X-ray satellite. Launched 30 December 1995.

SEC Sun-Earth Connection. One of the four OSS themes. From an astronomer's point of view, SEC can be translated as "space physics".

SEU Structure and Evolution of the Universe. One of the four OSS themes. Alan Bunner is the Science Program Director for this theme.

SEUS Structure and Evolution of the Universe Subcommittee. A strategic-level group (chaired by Bruce Margon of the University of Washington) that advises OSS on issues affecting the Structure and Evolution of the Universe theme.

SIRTF Space Infrared Telescope Facility. A 0.85-m space-based telescope for infrared (3-180 micron) observations. Scheduled for launch in December 2001.

SM As in "Code SM", the Advanced Technology and Mission Studies division of NASA Headquarters.

SMEX Small Explorer, or SMEX is a small-sized (defined by definition and development costs not exceeding $71M) spacecraft that carries one or more science instruments. Compare to MIDEX and UNEX; see also Explorer.

SOFIA Stratospheric Observatory for Infrared Astronomy. A Boeing 747 that carries a 2.5-m telescope for far-infrared observations. Flight operations are expected to begin in 2002.

SOMO Space Operations Management Office, located at Johnson Space Flight Center in Houston, is charged with meeting mission operations needs while finding ways of reducing costs.

SR&T Supporting Research and Technology. Part of the NASA R&A (see above) budget line that pays for competitively selected programs for non-MO&DA items, such development of space hardware (e.g., detectors), laboratory astrophysics, and the astrophysics theory program.

STScI Space Telescope Science Institute. Responsible for Hubble Space Telescope science operations. Operated by Association of Universities for Research in Astronomy, Inc. (AURA) under contract from NASA.

SWIFT The Swift Gamma-Ray Burst Explorer is a MIDEX selected for flight in 2003.

UNEX University-class Explorer or UNEX is a very small-sized (defined by definition and development costs not exceeding $7.5M) spacecraft that carries one or more science instruments. Compare to MIDEX and SMEX. See also Explorer.

WIRE Wide-Field Infrared Explorer. A Small Explorer (see SMEX above) that will carry an infrared imaging telescope (12 and 24 µm). Launched on 4 March 1999 and failed shortly thereafter due to loss of coolant for science instrument.

XMM-Newton X-ray Multi-Mirror-Newton mission. An ESA X-ray (0.2 - 12 keV) satellite launched on 10 December 1999.

XTE See RXTE above.