picture of the encyclopedia
previous next
Version 0.81 comes with a new web design! Please allow popups for navigation.


Infrared Space Observatory


Designation 23715 / 95062A
Launch date 17 Nov 1995
Country of origin Europe
Operator ESTEC (European Space TEchnology Center) for ESA
Mission Scientific: IR astronomy
Perigee/Apogee 1036/70578 km
Inclination 5.2°
Period 1436 min
Launch vehicle Ariane V80

The primary objectives of the Infrared Space Observatory are to provide spectroscopic, photometric, imaging, and polarimetric observations of selected celestial sources at infrared wavelengths from 2.3 um to 200 um with the highest possible sensitivity and spatial resolution. The instruments are cooled at -270°C in a cryostat which contained 2400 liters of superfluid helium at liftoff.

The satellite was initially planned for 1993 but the mission was delayed for two years while engineers worked on problems related to the temperature control system. The two-year delay added 20 percent to the project's final cost of $850 million for the satellite and launch. US astronomers will be granted 20 percent of the ISO's observation time in exchange for ground station support.

The first light image was taken on Nov 28.

End of life

Out of service 8 Apr 1998
Cause lack of helium

The helium consumption was smaller than planned; this enabled the satellite to operate during 28 months. The satellite was deorbited and shutoff on 16 May 1998.

External resources


sat-index articles

Technical data


Prime contractor Aerospatiale
Mass at launch 2498 kg
Payload mass 1515 kg
Mass in orbit 2418 kg
Dimension 3.56 x 2.77 x 5.31 m
Solar array  
Stabilization 3-axis
DC power  
Design lifetime 1.5 years

Telemetry: 2266.5 MHz (4, 8, 16 & 32 kbps)
Command: 2087.069 MHz (2000 bps)

Cassegrain telescope

Diameter 0.6 m
Focal length 9.0 m
Temperature control 3K (-270°C)

Other payloads

Imaging photopolarimeter: ISOPHOT
Long Wavelength Spectrometer: LWS
Short Wavelength Spectrometer: SWS

Frequency bands

ISOCAM 3-17 µm
ISOPHOT 3-200 µm
LWS 45-180 µm
SWS 3-45 µm

Pointing stability: 2.7 arcsecs

© TBS Internet, all rights reserved. All reproduction, copy or mirroring prohibited. Legal notice
francais anglais contact