Infrared Space Observatory

Launch Time
Fri Nov 17, 1995 01:20 UTC

Flight V80.


Ariane 44P
Image Credit: Arianespace
Status: Retired
Liftoff Thrust: 4,334 kN
Payload to GTO: 3,460 kg
Stages: 3
Strap-ons: 4
Rocket Height: 58.72 m

Mission Details

Infrared Space Observatory

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 (part of JAXA as of 2003) and NASA. The ISO was designed to study infrared light at wavelengths of 2.5 to 240 micrometres.

The €480.1-million satellite was launched on 17 November 1995 from the ELA-2 launch pad at the Guiana Space Centre near Kourou in French Guiana. The launch vehicle, an Ariane 44P rocket, placed ISO successfully into a highly elliptical geocentric orbit, completing one revolution around the Earth every 24 hours. The primary mirror of its Ritchey-Chrétien telescope measured 60 cm in diameter and was cooled to 1.7 kelvins by means of superfluid helium. The ISO satellite contained four instruments that allowed for imaging and photometry from 2.5 to 240 micrometres and spectroscopy from 2.5 to 196.8 micrometers.

Payloads: 1
Total Mass: 2,498.0 kg
Highly Elliptical Orbit


ELA-2, Guiana Space Centre, French Guiana, France



68th orbital launch attempt


71st mission
10th mission of 1995
66th successful mission
10th consecutive successful mission

Ariane 4

52nd mission
10th mission of 1995
49th successful mission
10th consecutive successful mission