ISO

Infrared Space Observatory

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General

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.

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End of life

Out of service	8 Apr 1998
Cause	lack of helium
Decay

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.

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External resources

http://isowww.estec.esa.nl/

sat-index articles

Technical data

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Specifications

Prime contractor	Aerospatiale
Platform
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)

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Cassegrain telescope

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

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Other payloads

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

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Frequency bands

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

Pointing stability: 2.7 arcsecs

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