ISO Mission Overview

The ISO mission resulted from a proposal made to ESA in 1979. After a number of studies ISO was selected in 1983 as the next new start in the ESA Scientific Programme. Following a Call for Experiment and Mission Scientist Proposals, the scientific instruments were selected in mid 1985. The two spectrometers, a camera and an imaging photo-polarimeter jointly covered wavelengths from 2.5 to around 240 microns with spatial resolutions ranging from 1.5 arcseconds (at the shortest wavelengths) to 90 arcseconds (at the longer wavelengths). The satellite design and main development phases started in 1986 and 1988, respectively, with Alcatel (Cannes, F, formerly Aerospatiale) as prime contractor. ISO was launched perfectly in November 1995 by an Ariane 44P vehicle. All went very smoothly in orbit and, at a wavelength of 12 microns, ISO was one thousand times more sensitive and had one hundred times better angular resolution than IRAS. Routine scientific operations commenced in February 1996 and continued until April 1998, with limited operations continuing through May. All data were re-processed with the end-of-mission calibration to populate the first homogeneous ISO Data Archive, which opened to the community in December 1998. By August 1999, all data had entered the public domain.

Through the ensuing four years of the Post-operations Phase, ESA's ISO Data Centre developed and refined the ISO Data Archive to offer the ISO data to the worldwide astronomical community, and together with the several National Data Centres in various member states and in the US (listed below) worked to fill the archive with the best systematically processed and calibrated data products which could be achieved for the huge ISO database. These products allow users to select from the archive data sets of interest for deeper study with interactive analysis tools. ISO's Legacy Archive, containing this reference product set, was released at the end of February 2002.

During ISO's Active Archive Phase, which runs from January 2002 to December 2006, the ISO Data Centre continues to work with active National Data Centres in The Netherlands, Germany and the U.K. to support the community in its use of the ISO data and to leave behind a homogeneous archive as a legacy to future generations of astronomers.

The main thrusts of the Active Archive Phase are to support the community in their use of ISO data and to capture back into the archive as much as possible of the user knowledge so as to maximize the long-term value and usability of the archive.

The responsibilities of the ESA ISO Data Centre in the Active Archive Phase include;

- Archive maintenance and improvements:
During this phase, the archive continues to be improved with new data and information being ingested. Major tasks are: stimulating systematic data reduction and capturing the resulting data products into the archive; tracking of refereed ISO publications and incorporating this information; ingestion of new ISO catalogues and atlases; continuing the process of increasing the inter-operability of archives by linking to other data sets; and maintaining the archive, especially the user interface to maximise its usefulness and ease of use.

- Support in data usage:
The ISO Data Centre continues to be the first line support to the general community on all matters regarding ISO data. This includes provision of advice; support for data reduction either remotely or via visits to the centre; and supply of, and assistance with, software for detailed data analysis.

- Supply of general information:
The existing Helpdesk and WWW services continue and updates made as needed to the ISO Handbook.

- Promotion of awareness of ISO data:
General conferences and specific small "hands-on" data reduction workshops continue to be organised with the proceedings being made widely available.

A mid-term review was held in June 2004, in front of an independent Board, to review progress and make recommendations on any re-directions of effort. The Board, composed of external data providers and users, was impressed with the achievements made in the first half of the Active Archive Phase. Their recommendations focused on making ISO data and results as widely available as possible, by (i) concentrating the activities on maximising the content and visibility of the Highly Processed Data Products (HPDP), the result of dedicated projects focused on cleaning the pipeline products from residual instrument artifacts, (ii) continuing with the integration of the ISO Data Archive into the Virtual Observatory, (iii) ensuring prompt publication of the planned special issue of Space Science Review, a 450 pages compendium summarising the ISO science legacy.

At the end of the Active Archive Phase, in December 2006, maintenance of the historical archive is expected to be carried out in conjunction with the Herschel Science Centre, under the general auspices of the Research and Scientific Support Department.

ISO Data Centres

The Data Centres responsible for ISO User Support were or are as follows (Centres continuing to operate into the Active Archive Phase are marked with a (#) :

ISO Data Centre at ESA, ESAC in Spain (#)

Five Specialist National Data Centres (NDCs) :

French ISO Centres, SAp/Saclay and IAS/Orsay, France;
ISOPHOT Data Centre at MPIA, Heidelberg, in Germany (#);
Dutch ISO Data Analysis Centre - DIDAC) (now part of the HIFI Operations Centre) at SRON, Groningen, in the Netherlands (#);
ISO Spectrometer Data Centre at MPE in Garching, Germany (#);
UK ISO Data Centre at RAL, Didcot, in the United Kingdom (#)

Plus, in the USA, :

The ISO Support Center at NASA's Infrared Processing and Analysis Centre (IPAC).

Alberto Salama,
ISO Project Scientist.