Editing Infrared Space Observatory

{{Short description|Orbital satellite telescope}}
{{more footnotes needed|date=May 2019}}
{{Infobox spaceflight
| name               = Infrared Space Observatory
| names_list         = ISO

<!--image of the spacecraft/mission-->| image              = Schema-telescope-ISO.png
| image_caption      = Scheme of the telescope
| image_alt          = <!--image alt text-->
| image_size         = <!--include px/em; defaults to 220px-->

<!--Basic details-->| mission_type       = 
| operator           = [[European Space Agency|ESA]] with significant contributions from [[Institute of Space and Astronautical Science|ISAS]] and [[NASA]]
| Harvard_designation = <!--spacecraft launched 1962 and earlier only (eg. 1957 Alpha 2)-->
| COSPAR_ID          = 1995-062A
| SATCAT             = 23715
| website            = [http://sci.esa.int/science-e/www/area/index.cfm?fareaid=18 ISO at ESA science]
| mission_duration   = 28 months 22 days
| distance_travelled = <!--How far the spacecraft travelled (if known)-->
| orbits_completed   = <!--number of times the spacecraft orbited the Earth - see below for spacecraft beyond Earth orbit-->
| suborbital_range   = <!--downrange distance reached if spacecraft did not enter orbit-->
| suborbital_apogee  = <!--altitude reached if spacecraft did not enter orbit-->

<!--Spacecraft properties-->| spacecraft         = <!--Spacecraft name/serial number (eg. Space Shuttle ''Discovery'', Apollo CM-118), etc-->
| spacecraft_type    = 
| spacecraft_bus     = <!--eg. A2100M, Star-2, etc-->
| manufacturer       = [[Aérospatiale]]
| launch_mass        = <!--fuelled mass at launch, not including rocket or upper stage-->
| BOL_mass           = 2498 kg
| landing_mass       = <!--Mass after landing (recovered spacecraft only)-->
| dry_mass           = <!--spacecraft mass in orbit without fuel-->
| payload_mass       = <!--Mass of cargo carried by spacecraft (eg. for Space Shuttle), or total mass of instrumentation/equipment/experiments for mission-->
| dimensions         = <!--body dimensions and solar array span-->
| power              = <!--end-of-life power, in watts-->

<!--Expedition details-->| space_station      = <!--space station the expedition occurred aboard-->
| start_date         = <!--date the crew took command of the station-->
| end_date           = <!--date the crew ceased command of the station-->
| arrival_craft      = <!--spacecraft the crew arrived aboard-->
| departure_craft    = <!--spacecraft the crew departed aboard-->

<!--Crew details-->| crew_size          = <!--number of astronauts/cosmonauts aboard the spacecraft-->
| crew_members       = <!--crew who launched AND landed aboard the spacecraft-->
| crew_launching     = <!--crew who only launched aboard the spacecraft-->
| crew_landing       = <!--crew who only landed aboard the spacecraft-->
| crew_callsign      = <!--spacecraft's callsign-->
| crew_expedition    = <!--space station expedition(s) the mission was in support of, do NOT use if the mission is an expedition itself-->
| crew_EVAs          = <!--number of EVAs conducted during the mission-->
| crew_EVA_duration  = <!--time spent on EVA-->
| crew_photo         = <!--omit the "file" prefix-->
| crew_photo_alt     = <!--alt text for image-->
| crew_photo_caption = <!--image caption-->
| crew_photo_size    = <!--defaults to 220px-->

<!--Launch details-->| launch_date        = {{start date|1995|11|17|01|20|7=Z|df=y}}
| launch_rocket      = [[Ariane 4]] 4P
| launch_site        = [[Centre Spatial Guyanais#ELA-2|ELA-2]]
| launch_contractor  = <!--organisation(s) that conducted the launch (eg. United Launch Alliance, Arianespace, etc)-->
| deployment_from    = <!--place where deployed from-->
| deployment_date    = <!--date deployed-->
| entered_service    = <!--date on which the spacecraft entered service, if it did not do so immediately after launch-->
<!-- * - e.g. Proton-M/Briz-M not Proton-M, but Titan IV(401)A not Titan IV(401)A-Centaur-->

<!--end of mission-->| disposal_type      = |
| deactivated        = 16 May 1998 12:00 UTC
| destroyed          = <!--when craft was destroyed (if other than by re-entry)-->
| last_contact       = <!--when last signal received if not decommissioned-->
| recovery_by        = <!--recovered by-->
| recovery_date      = <!--recovery date-->
| decay_date         = <!--when craft re-entered the atmosphere, not needed if it landed-->
| landing_date       = <!--when the spacecraft made a controlled landing, not needed if it did not return intact-->
| landing_site       = <!--where the craft landed; site/runway or coordinates-->
<!--
    The following template should be used for ONE of the three above fields "end_of_mission", "decay" or "landing" if the spacecraft is no longer operational.
    If it landed intact, use it for the landing time, otherwise for the date it ceased operations, or the decay date if it was still operational when it re-entered.
    {{end date|YYYY|MM|DD|hh|mm|ss|TZ=Z}} (for Zulu/UTC) or {{end date|YYYY|MM|DD}} (if time unknown) 
-->

<!--orbit parameters-->
<!--as science-related articles, SI units should be the principal units of measurement, however we usually use {{convert}} to display imperial units in parentheses after the initial values-->| orbit_reference    = [[geocentric orbit|Geocentric]]
| orbit_regime       = [[Elliptic orbit|Highly elliptical]]
| orbit_longitude    = <!--geosynchronous satellites only-->
| orbit_slot         = <!--Designation of orbital position or slot, if not longitude (e.g plane and position of a GPS satellite)-->
| orbit_semimajor    = <!--semimajor axis-->
| orbit_eccentricity = <!--orbital eccentricity-->
| orbit_periapsis    = 1000 km
| orbit_apoapsis     = 70600 km
| orbit_inclination  = <!--orbital inclination-->
| orbit_period       = 24 hr
| orbit_RAAN         = <!--right ascension of the ascending node-->
| orbit_arg_periapsis = <!--argument of perigee/periapsis-->
| orbit_mean_anomaly = <!--mean anomaly at epoch, only use in conjunction with an epoch value-->
| orbit_mean_motion  = <!--mean motion of the satellite, usually measured in orbits per day-->
| orbit_repeat       = <!--repeat interval/revisit time-->
| orbit_velocity     = <!--speed at which the spacecraft was travelling at epoch - only use for spacecraft with low orbital eccentricity-->
| orbit_epoch        = <!--the date at which the orbit parameters were correct-->
| orbit_rev_number   = <!--revolution number-->
| apsis              = gee
| interplanetary     = <!--Infobox spaceflight/IP can be called multiple times for missions with multiple targets or combined orbiter/lander missions, etc-->
 {{Infobox spaceflight/IP
   |type                = orbiter
   |object              = <!--body visited - e.g. Jupiter, Venus, etc-->
   |orbits              = <!--number of orbits completed at target body (if applicable and known)-->
   |component           = <!--part of the spacecraft involved, if spacecraft split into multiple components-->
   |arrival_date        = <!--Flybys: date/time of closest approach; Orbiters; orbital insertion date; Impactors/Landers/Rovers: impact/landing date/time; Atmospheric probes: atmospheric entry time-->
   |departure_date      = <!--Date of leaving orbit for orbiters, date of launch for landers which took off again-->
   |location            = <!--landing/impact site, including EOM impacts for atmospheric probes and lunar/asteroid orbiters-->
   |distance            = <!--closest approach distance for flybys, distance travelled on surface for rovers, omit for others-->
   |sample_mass         = <!--mass of samples returned (sample return missions only)-->
   |surface_EVAs        = <!--number of EVAs on the surface-->
   |surface_EVA_time    = <!--time spent on surface EVAs-->
   
   <!--Orbit parameters, ONLY USE IF THE ABOVE ORBIT PARAMETERS SECTION DOESN'T APPLY TO THE TARGET-->
   |periapsis           = <!--periapsis altitude-->
   |apoapsis            = <!--apoapsis altitude--> 
   |inclination         = <!--inclination to the object's equator-->
   |apsis               = <!--planet specific apsis term, as above-->
 }}

<!--Telescope parameters-->| instrument_type    = <!--converts telescope fields to suit a camera or other similar instrument-->
| telescope_name     = <!--name, if different to the satellite-->
| telescope_type     = [[Ritchey-Chrétien telescope|Ritchey-Chrétien]]
| telescope_diameter = 60 cm
| telescope_focal_length = 900 cm, ''f''/15
| telescope_area     = <!--collecting area-->
| telescope_wavelength = 2.4 to 240 [[micrometre]] ([[infrared]])
| telescope_resolution = <!--resolution of telescope-->

<!--transponder parameters-->| trans_band         = <!--Transponder frequency bands-->
| trans_frequency    = <!--specific frequencies-->
| trans_bandwidth    = <!--bandwidth-->
| trans_capacity     = <!--capacity of the transponders-->
| trans_coverage     = <!--area covered-->
| trans_TWTA         = <!--TWTA output power-->
| trans_EIRP         = <!--equivalent isotropic power-->
| trans_HPBW         = <!--half-power beam width-->
| instruments_list   = {{Infobox spaceflight/Instruments
 | acronym1  = ISOCAM  | name1 = ISO Infrared Camera
 | acronym2  = ISOPHOT | name2 = ISO photo-polarimeter
 | acronym3  = LWS     | name3 = Long Wave Spectrometer
 | acronym4  = SWS     | name4 = Short Wave Spectrometer
}}
| insignia           = File:ISO insignia.png
| insignia_caption   = Legacy ESA insignia for the ''ISO'' mission
| insignia_alt       = ISO legacy mission insignia
| insignia_size      = 180x180px
| programme          = 
| previous_mission   = 
| next_mission       = 
}}

The '''Infrared Space Observatory''' ('''ISO''') was a [[space telescope]] for [[infrared]] light designed and operated by the [[European Space Agency]] (ESA), in cooperation with ISAS (now part of [[Japan Aerospace Exploration Agency|JAXA]]) and [[National Aeronautics and Space Administration|NASA]]. The ISO was designed to study infrared light at [[wavelengths]] of 2.5 to 240 [[micrometres]] and operated from 1995 to 1998.<ref name="ESA-ISO" />

The [[Euro|€]]480.1-[[million]] satellite<ref>{{Cite web |last=Kessler |first=Martin |date=November 2003 |title=ISO - Mission & Satellite Overview Volume I |url=https://general-tools.cosmos.esa.int/iso/manuals/HANDBOOK/gen_hb/gen_hb.pdf}}</ref><ref>{{Cite web |title=ISO Handbook Volume I (GEN) |url=https://general-tools.cosmos.esa.int/iso/manuals/HANDBOOK/gen_hb/node12.php |access-date=2024-05-17 |website=ESA COSMOS}}</ref> was launched on 17 November 1995 from the [[Centre Spatial Guyanais#ELA-2|ELA-2]] [[launch pad]] at the [[Guiana Space Centre]] near [[Kourou]] in French Guiana. The [[launch vehicle]], an [[Ariane 4]]4P rocket, placed ISO successfully into a [[Elliptic orbit|highly elliptical]] [[geocentric orbit]], completing one revolution around the [[Earth (planet)|Earth]] every 24 hours. The [[primary mirror]] of its [[Ritchey-Chrétien telescope]] measured 60&nbsp;cm in diameter and was cooled to 1.7 [[kelvin]]s by means of [[superfluid]] [[helium]]. The ISO satellite contained four instruments that allowed for imaging and [[Photometry (astronomy)|photometry]] from 2.5 to 240 [[micrometre]]s and [[spectroscopy]] from 2.5 to 196.8 micrometers.

ESA and the [[Infrared Processing and Analysis Center]] made efforts to improve the data pipelines and specialized software analysis tools to yield the best quality calibration and data reduction methods from the mission. IPAC supports ISO observers and data archive users through in-house visits and workshops.

== History and development ==

In 1983, the US-Dutch-British IRAS inaugurated space-based [[infrared astronomy]] by performing the first-ever 'all-sky survey' at infrared [[wavelength]]s. The resulting map of the infrared sky pinpointed some 350,000 infrared sources waiting to be explored by IRAS' successors. In 1979, IRAS was in an advanced stage of planning and the expected results from IRAS led to the first proposal for ISO made to ESA in the same year. With the rapid improvements in infrared detector-technology, ISO was to provide detailed [[Observational astronomy|observations]] for some 30,000 infrared sources with much improved [[Sensitivity (electronics)|sensitivity]] and [[Angular resolution|resolution]]. ISO was to perform 1000 times better in sensitivity and 100 times better in angular resolution at 12 micrometres compared to IRAS.

A number of follow-up studies resulted in the selection of ISO as the next installment for the ESA Scientific Programme in 1983. Next came a '''Call for Experiment and Mission Scientist Proposals''' to the scientific community, resulting in the selection of the [[scientific instrument]]s in 1985. The four instruments chosen were developed by teams of researchers from France, Germany, the Netherlands and United Kingdom.

[[Engineering|Design]] and development of the [[satellite]] started in 1986 with [[Aérospatiale]]'s space division (currently absorbed into [[Thales Alenia Space]]) leading an international [[consortium]] of 32 companies responsible for [[Manufacturing|manufacture]], [[System integration|integration]] and testing of the new satellite. Final assembly took place at the [[Cannes Mandelieu Space Center]].

== The satellite ==
[[File:Animation of Infrared Space Observatory's orbit.gif|thumb|Animation of Infrared Space Observatory's orbit<br>{{legend2| Magenta | Infrared Space Observatory}}{{·}}{{legend2| RoyalBlue | Earth }}]]
The basic design of ISO was strongly influenced by that of its immediate predecessor. Like IRAS, ISO was composed of two major components:
* '''Payload module''', composed of a large [[cryostat]] holding the telescope and the four scientific instruments.
* '''Service module''', supports the activities of the payload module by providing [[Electricity|electrical power]], thermal control, [[Attitude dynamics and control|attitude and orbit control]] and [[telecommunication]]s.

The payload module also held a [[cone (geometry)|conical]] sun shade, to prevent [[stray light]] from reaching the telescope, and two large [[Attitude dynamics and control|star trackers]]. The latter were part of the Attitude and Orbit Control Subsystem (AOCS) which provided three-axis [[Directional stability|stabilisation]] of ISO with a pointing [[Accuracy and precision|accuracy]] of one [[Minute of arc#Astronomy|arc second]]. It consisted of Sun and Earth sensors, the before-mentioned star trackers, a quadrant star sensor on the telescope axis, [[gyroscope]]s and [[reaction wheel]]s. A complementary [[reaction control system]] (RCS), using [[hydrazine]] [[propellant]], was responsible for orbital direction and finetuning shortly after [[Rocket launch|launch]]. The complete satellite weighed just under 2500&nbsp;kg, was 5.3 m high, 3.6 m wide and measured 2.3 m in depth.

The service module held all the warm [[electronics]], the hydrazine propellant tank and provided up to 600 [[watt]]s of electrical power by means of [[solar cell]]s mounted on the sunpointing side of the service module-mounted sunshield. The underside of the service module sported a load-bearing, ring shaped, physical interface for the launch vehicle.

The [[cryostat]] of the payload module surrounded the telescope and science instrument with a large [[Vacuum flask|dewar]] containing a [[Toroid (geometry)|toroidal]] tank loaded with 2268 [[litre]]s of superfluid helium. [[Conduction (heat)|Cooling]] by slow [[evaporation]] of the helium kept the [[temperature]] of the telescope below 3.4 K and the science instruments below 1.9 K. These very low temperatures were required for the scientific instruments to be sensitive enough to detect the small amount of infrared radiation from cosmic sources. Without this extreme cooling, the telescope and instruments would see only their own intense infrared [[Emission (electromagnetic radiation)|emissions]] rather than the faint ones from afar.

== Optical telescope ==

The ISO telescope was mounted on the [[Centre (geometry)|center line]] of the dewar, near the bottom-side of the toroidal helium tank. It was of the [[Ritchey-Chretien telescope|Ritchey-Chrétien]] type with an effective [[entrance pupil]] of 60&nbsp;cm, a [[Focal length|focal length ratio]] of 15 and a resulting focal length of 900&nbsp;cm. Very strict control over straylight, particularly that from bright infrared sources outside the telescope's [[field of view]], was necessary to ensure the guaranteed sensitivity of the scientific instruments. A combination of light-tight shields, baffles inside the telescope and the sunshade on top of the cryostat accomplished full protection against straylight. Furthermore, ISO was constrained from observing too close to the Sun, Earth and Moon; all major sources of infrared radiation. ISO always pointed between 60 and 120 degrees away from the Sun and it never pointed closer than 77 degrees to Earth, 24 degrees to the [[Moon]] or closer than 7 degrees to [[Jupiter]]. These restrictions meant that at any given time only about 15 [[Percentage|percent]] of the sky was available to ISO.

A [[Pyramid (geometry)|pyramid-shaped]] mirror behind the [[primary mirror]] of the telescope distributed the infrared light to the four instruments, providing each of them with a 3 arc-minute section of the 20 arc-minute field of view of the telescope. Thus, pointing of a different instrument to the same cosmic object meant repointing the entire ISO satellite.

[[File:Iso lsw flight spare.jpg|thumb|[[Flight spare]] for the LWS instrument in ISO]]

== Instruments ==

ISO carried an array of four scientific instruments for observations in the infrared:
* '''Infrared Camera (ISOCAM)''' – A [[Image resolution|high-resolution]] camera covering 2.5 to 17 micrometre wavelength with two different [[Sensor|detectors]]. Like a visible-light camera it takes pictures of astronomical objects, but the image shows what the object looks like in infrared light.
* '''Photo-polarimeter (ISOPHOT)''' – An instrument designed to measure the [[Polarimetry|polarisation]] of infrared radiation emitted from an astronomical object. The very broad wavelength range from 2.4 to 240 micrometre allowed this instrument to see the infrared emissions of even the coldest astronomical objects such as [[Interstellar cloud|interstellar]] [[Cosmic dust|dust clouds]]
* '''Short Wave Spectrometer (SWS)''' – A [[spectrometer]] covering the 2.4 to 45 micrometre wavelength. Observations with this instrument provided valuable information about the [[Chemistry|chemical composition]], density and temperature of the universe.
* '''Long Wave Spectrometer (LWS)''' – A spectrometer covering the 45 to 196.8 micrometre wavelength. 

All four instruments were mounted directly behind the primary mirror of the telescope, in a circular arrangement,  with each instrument taking up an 80 [[Degree (angle)|degree]] segment of the cylindrical space. The field of view for each instrument was offset to the central axis of the telescope's field of view. This means that every instrument 'saw' a different portion of the sky at a given moment. In standard operational mode one instrument was in primary operation.

== Launch and operations ==

After a very successful development and integration phase ISO was finally launched into orbit on 17 November 1995, on board an Ariane-44P launch vehicle. Performance of the launch vehicle was very good with the apogee only 43&nbsp;km lower than expected. [[European Space Operations Centre|ESA's Space Operations Centre]] in [[Darmstadt]] in Germany had full control over ISO in the first four days of flight. After early commissioning primary control over ISO was handed over to the Spacecraft Control Centre (SCC) at [[Villanueva de la Cañada]] in Spain ([[European Space Astronomy Centre|VILSPA]]) for the remainder of the mission.
In the first three weeks after launch the [[orbit]] was [[Fine-tuning (physics)|fine-tuned]] and all satellite systems were activated and tested. Cool-down of the cryostat proved to be more efficient than previously calculated, so the anticipated mission length was extended to 24 months. Between 21 and 26 November all four science instruments were switched on and thoroughly checked out. Between 9 December 1995 and 3 February 1996 the 'Performance Verification Phase' took place, dedicated to commissioning all instruments and fixing problems. Routine observations started from 4 February 1996, and lasted until the last helium coolant depleted on 8 April 1998.

The perigee of ISO's orbit lay well inside the [[Van Allen radiation belt]], forcing the science instruments to be shut down for seven hours during each pass through the radiation belt. Thus, 17 hours in each orbit remained for scientific observation. A typical 24-hour orbit of ISO can be broken down into six phases:
* [[Orbital pass|Acquisition-of-Signal]] (AOS) by the primary [[Mission Control Center]] VILSPA in Spain and activation of the satellite.
* Science operations during the VILSPA window, starting four hours after perigee, and lasting for up to nine hours.
* Handover of operations to the secondary [[Mission Control Center|mission control center]] at [[Goldstone Deep Space Communications Complex|Goldstone]] at apogee. During this 15 minute periode the science instruments could not be operated.
* Science operations during the Goldstone window, lasting up to eight hours.
* De-activation of the instruments upon approach of the Van Allen radiation belt and Loss-of-Signal (LOS) at Goldstone.
* Perigee passage.

Contrary to IRAS, no science data was recorded on-board ISO for later transmission to the ground. All data, both science data and housekeeping data were transmitted to the ground in real-time. The perigee point of ISO's orbit was below the [[radio horizon]] of the mission control centers at both VILSPA and Goldstone, thus forcing the science instruments to be switched off at perigee.

== End of mission ==

At 07:00 UTC on 8 April 1998 [[flight controller]]s at VILSPA noticed a rise in temperature of the telescope. This was a clear sign that the load of superfluid helium coolant had depleted. At 23:07 UTC the same day, the temperature of the science instruments had risen above 4.2 K and science observations were ceased. A few detectors in the SWS instrument were capable of making observations at higher temperatures and remained in use for another 150 hours to make detailed measurements of an additional 300 [[star]]s. In the month following depletion of coolant the 'Technology Test Phase' (TTP) was initiated to test several elements of the satellite in off-nominal conditions. After completion of TTP, the perigee of ISO's orbit was lowered sufficiently enough to ensure ISO will burn up in Earth's atmosphere in 20 to 30 years after shutdown. ISO was then permanently switched off on 16 May 1998 at 12:00 UTC.

== Results ==

On average, ISO performed 45 observations in each 24-hour orbit.  Throughout its [[Service life|lifetime]] of over 900 orbits ISO performed more than 26,000 successful scientific observations. The huge amounts of scientific data generated by ISO was subject to extensive [[Archive|archiving]] activities up to 2006. The full data-set has been available to the scientific community since 1998 and many discoveries have been made, with probably many more still to come:
* ISO detected the presence of water vapour in [[Stellar evolution|starforming]] regions, in the vicinity of stars at the end of their lives, in sources very close to the [[Galactic Center|Galactic Centre]], in the atmospheres of [[planet]]s in the [[Solar System]] and in the [[Orion Nebula]].
* [[Nebular hypothesis|Planet formation]] was detected around old, dying stars. This discovery contradicted theories that planet formation was only possible around young stars.
* [[Hydrogen fluoride]] gas was for the first time detected in [[Interstellar medium|interstellar gas clouds]].
* The first detection of the earliest stages of stellar formation. The [[pre-stellar core]] L1689B was found and studied in great detail with ISO's LWS instrument.
* ISO discovered large amounts of cosmic dust in the previously thought empty space between [[Galaxy|galaxies]].
* Observations of the [[Luminosity|most-luminous]] object in the universe, [[Arp 220]], revealed that the source for its enormous emission of infrared radiation is an outburst of star formation.
* Observations with the LWS instrument confirmed the previous discovery by IRAS of large cloud-like structures of very cold [[hydrocarbon]]s radiating primarily in the infrared. These [[infrared cirrus]] clouds affect the [[First law of thermodynamics|energy balance]] of the entire universe, acting as a kind of [[Galaxy|galactic]] refrigerator.
* ISO searched for, and found several [[protoplanetary disk]]s: rings or disks of material around stars which are considered to be the first stage of [[Nebular hypothesis|planet formation]].
* ISO pointed its sensitive instruments on several of the planets in the Solar System to determine the chemical composition of their atmospheres.

== See also ==
{{Portal|Spaceflight}}
* [[Infrared Array Camera]] (Spitzer near to mid infrared camera)
* [[List of largest infrared telescopes]]
* [[Near Infrared Camera and Multi-Object Spectrometer]] (NICMOS, Hubble near-infrared instrument installed in 1997)

== References ==
{{Reflist
|refs=

<ref name="ESA-ISO">{{cite web
  |title      = ESA's Infrared Space Observatory (ISO)
  |publisher  = ESA – European Space Agency
  |url        = http://sci.esa.int/iso/
  |access-date = 1 February 2017}}</ref>

}} <!-- end of reflist -->

== External links ==
* [https://web.archive.org/web/20060504142148/http://www.iso.esac.esa.int/manuals/HANDBOOK/gen_hb/ The ISO handbook], volume 1, ISO - Mission and satellite overview
* [http://sci.esa.int/iso/47361-fact-sheet/ ISO – all the facts]
* [http://sci.esa.int/iso/33310-summary/ ISO – mission summary]
* [http://sci.esa.int/iso/31400-spacecraft/ ISO spacecraft details] at ESA science website
* [http://sci.esa.int/iso/31401-instruments/ ISO telescope details] at ESA science website
* [http://sci.esa.int/iso/31401-instruments/?fbodylongid=847 ISOCAM details] at ESA science website
* [http://sci.esa.int/iso/31401-instruments/?fbodylongid=848 ISOPHOT details] at ESA science website
* [http://sci.esa.int/iso/31401-instruments/?fbodylongid=866 ISO SWS details] at ESA science website
* [http://sci.esa.int/iso/31401-instruments/?fbodylongid=867 ISO LWS details] at ESA science website
* [http://sci.esa.int/iso/31432-launch-and-orbit/ ISO launch and orbit details] at ESA science website
* [https://web.archive.org/web/19990117013807/http://www.iso.vilspa.esa.es/ The ISO Data Centre], with an overview about the project and a gallery of pictures

{{Space observatories}}
{{European Space Agency}}
{{Orbital launches in 1995}}
{{Authority control}}

[[Category:Spacecraft launched in 1995]]
[[Category:Satellites orbiting Earth]]
[[Category:European Space Agency satellites]]
[[Category:Infrared telescopes]]
[[Category:Space telescopes]]
[[Category:Spacecraft launched by Ariane rockets]]