N° 33–1995: ESA to launch six scientific satellites

The Infrared Space Observatory, ISO, will lead the trio into space. It will be launched on an Ariane 4 rocket in early November from the European launch site at Kourou, French Guiana. It will be followed in mid-December by SOHO, the Solar and Heliospheric Observatory, which will be launched by an Atlas IIAS rocket from Cape Canaveral, USA. Finally, in mid-January the four Cluster probes will be carried into space on the inaugural flight of Ariane 5.

ISO is the world's only orbiting infrared observatory and is the most sophisticated ever. Its sensitive detectors will be cooled to below -270 degrees C, allowing it to observe cool objects in space, invisible through ordinary telescopes. ISO's many scientific goals include studying newly formed stars and planets, investigating the aging process of galaxies and search for the universe's elusive 'dark matter' that is believed to outweigh visible stars and galaxies.

The SOHO observatory will provide scientists with a comprehensive study of the sun, the nuclear powerhouse in the centre of our solar system. Its twelve experiments, developed by scientists from Europe and the United States, will investigate the sun from its core outwards -from the very inner workings of the star, to the solar wind which blows through the solar system.

The four identical Cluster spacecraft will focus on studying the interaction of the sun with plasmas of the Earth and the magnetic field in a region known as the magnetosphere. The four probes, flying in formation, will allow scientists to build up a three-dimensional picture of the battle between the sun's streams of wind and the Earth's protective magnetic field. These missions represent years of work by scientists across Europe and around the world. The data they gather will provide us with a greater understanding of our own solar neighbourhood and deep space.

 

SPACECRAFT STATUS AS AT 1 SEPTEMBER 95

ISO
The ISO satellite, together with all the associated equipment, was transported in June by ship to Europe's spaceport in Kourou, French Guiana. Since then, all the satellite subsystems and scientific instruments have been thoroughly tested and found to be in order. ISO is now waiting its turn to be mated with the Ariane 44P launcher. The launch campaign will resume in early October for a launch on 3 November.

Preparations for flight operations by ESA's space operation centre, ESOC in Darmstadt, Germany and the flight control centre at Villafranca, near Madrid, Spain are also in the final stages. Most of the work in the last two months before a launch involves training and performing simulations to prove flight readiness. The scientific community is eagerly awaiting the preliminary results of ISO's first look into space in November.

SOHO
SOHO arrived at Kennedy Space Centre on 1 August. It was given a welcome by hurricane ERIN, which forced an immediate transfer to its reserved NASA facility just after its transport plane had safely landed.

Spacecraft preparation for launch has started with a thorough check of all the systems and instruments onboard SOHO and will proceed with an end-to-end test with the NASA control station at Goddard Spaceflight Centre.

Parallel activities are proceeding in Europe on the final testing and inspection of the four reaction wheels which the spacecraft control system uses to keep all its instruments pointed very precisely at the sun.

At the end of its preparation, the spacecraft will be mated to its Atlas IIAS launcher, which is due to lift off in the first week of December.

CLUSTER
All four Cluster spacecraft, together with all ancillary equipment, have now arrived at Europe's spaceport in Kourou, French Guiana. The spacecraft have been set up for final electrical testing in the Final Assembly Building , a new Ariane 5 facility.

Major milestones in the campaign are the start of spacecraft fuelling operations at the beginning of November and the start of integration of the spacecraft with the launch vehicle in mid- December.

The Cluster launch campaign is proceeding on schedule for the planned launch date of 17 January 1996. At the same time, final acceptance tests are being carried out on the new Ariane 5 launch vehicle components.

Note to TV editors:
Video indexes describing in detail the ISO, SOHO and Cluster missions will be available on request from ESA PR as from 15 September 1995.