Today, October 17th, at 6.41 a.m. Integral (International Gamma Ray
Astrophysics Laboratory), ESA’s astronomy satellite to study cosmic gamma
ray emissions, built by Alenia Spazio (a Finmeccanica company) as prime
contractor, was successfully launched on a Proton rocket from the Baikonur
base in Kazakhstan.

After separation from the launcher, the Proton upper stage took Integral to
its 72-hour elliptical orbit, between 10,000 and 153,000 km from Earth, and
then it too separated. Both solar wings were successfully deployed about two
hours after launch and the satellite is now safe and in a stable
configuration, ready to start the two-month test and verification period.

A fundamental element of ESA’s long-term scientific programme, Horizon 2000,
the satellite is a dedicated observatory for the exploration of natural
high-energy phenomena, typically studied by gamma-ray astronomy, to provide
valuable information on the evolution of our Universe.

In the course of its 2-5 year mission, Integral will utilise high-resolution
spectroscopy, together with the production of high-definition images, to
identify celestial gamma ray sources accurately and study their nature:
White Dwarf Stars, Neutron Stars, potential Black Holes, Novae, Supernovae,
Galactic Clouds, the centre of our Galaxy, etc.

The satellite basically consists of a service module and a payload module
for a total launch mass of around 4,000 kg.

The service module interfaces directly with the launcher and houses a series
of services for the satellite: scientific data acquisition and on-board
handling system (OBDH), the radio frequency system for command reception and
transmission to ground, the silicon photovoltaic panels and the
Nickel-Cadmium batteries used to generate, distribute and store electrical
power to keep the satellite functioning.

The two-tonne payload module is mounted on the upper part of the service
module and consists of four basic instruments. The two main ones, operating
in the gamma band, are the IBIS, that will provides images of the sources
with the best angular resolution, and the SPI spectrometer, that will study
the spectral characteristics.

The other two instruments, the X-ray Monitor (JEM-X) and the Optical
Monitoring Camera 2 (OMC) will permit the position of the gamma sources to
be correlated with maps of other known celestial objects.

SPI, IBIS and JEM-X are coded-mask telescopes – an innovative sensing
technique that is able to give a detailed reconstruction of the image of the
gamma source and therefore identify its position accurately.

Alenia Spazio has developed and constructed Integral, with responsibility
also for the design, integration and testing of the satellite.