ESA Science News 15 Oct 1999

Signature of the Launcher Adaptation Contract for Integral

The contract for the Proton Launcher Adaptation for Integral was signed today at the ESA Permanent Mission in Moscow. This followed the successful completed of a lengthy approval process for the Arrangement between ESA and Russia on Cooperation on the Integral Project.

ESA's Integral gamma-ray space observatory will be launched on Russia's Proton rocket in October 2001 from the Baikonur cosmodrome, Kazakhstan.

Energia Space Corporation and the Khrunichev Space Centre had already been contracted by the Russian Aviation and Space Agency (Rosaviakosmos) for the procurement of the launcher. However, to be able to accommodate Integral, the launcher requires certain adaptations. These concern the technical interface with the DM Upper Stage of Proton, designed and manufactured by RSC Energia, and the launcher system configuration for which the Khrunichev Space Centre is responsible.

It is these modifications that were the subject of today's contract signature between ESA, Rosaviakosmos, RSC Energia and the Khrunichev Space Centre. ESA was represented by Mr Kai Clausen, Integral Project Manager, for ESA; for Rosaviakosmos Mr. Alexander Medvedchikov, Deputy General Director; Mr. Alexander Strekalov, Vice-President, for RSC Energia; Mr. Vyacheslav Ivanov, Deputy General Designer of Salyut Design Bureau, for Khrunichev.

Also present at this meeting were representatives of the Russian Academy of Science, Sergei Grebenev and Natan Eismont, both directly involved in setting up the Russian Scientific Data Centre in the Space Research Institute (IKI), where Russian scientists will be able to receive and process Integral data. Mr. Leonardo Pavoni, was the chief representative of Finmeccanica/Alenia companies in Moscow. Alenia Spazio is the prime contractor for the Integral mission.

Under the terms of the agreement, Rosaviakosmos provides a Proton launch for Integral, in return for 24% of the guaranteed observation time and 27% of the open observation time.

As for all ESA scientific missions, each Integral scientific instrument is provided by a collaborative team of scientists headed by a Principal Investigator, with funding from national organisations. The Integral Science Data Centre (ISDC) based in Switzerland will process raw data for distribution to observers. The ISDC is complemented by the Russian Space Data Centre which receives pre-processed data to assist and support Russian observers.


The 3.6 t and 6 m long Integral spacecraft, will be launched into a highly eccentric geosynchronous orbit with a period of 72 h and an initial apogee height of 153 000 km. Such an orbit maximises the time for observations above 60 000 km altitude thus minimising the influence of the earth's radiation belts. The spacecraft is designed for a nominal operational life of two years, with consumables enabling an extension of up to five years.

Gamma ray telescopes -- like Integral -- detect radioactive materials in the Universe, but they also pick out events and scenes of tremendous releases of energy. ESA's Integral will perform detailed imaging and spectrometry of gamma-ray sources and will be a major step forward in the field of gamma-ray astrophysics in the 21st century.


More about Integral
Russian Space Agency

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ESA Science News

24 Sep 1999

Russian launcher for Integral

Russian Prime-Minister Vladimir Putin has signed a governmental letter approving an arrangement between the European Space Agency (ESA) and the Russian Space Agency (RSA). According to the arrangement a Proton launcher will put ESA1s Integral, the International Gamma-Ray Astrophysics Laboratory, into orbit. The spacecraft will be launched in 2001 from Baikonur, Kazakhstan.

The Proton rocket will put the 4 tonne satellite into a high eccentric orbit around the Earth thereby minimizing the influence of the Earth's radiation belts and allowing uninterrupted observations of powerful Gamma-Radiation coming from distant objects in the Universe. The arrangement now ratified by the government of the Russian Federation regulates the details of the cooperation between ESA and RSA. The Integral Project Team was pleased to hear about the Russian Prime-Minister's signature. "It is a crucial step and two years before the launch of the spacecraft it came just in time", says Integral Project Manager Kai Clausen. Project Scientist Christoph Winkler says: "The Proton is capable to put Integral into an orbit which is crucial for the scientific success of the mission."

In exchange for RSA providing the launch by a Proton rocket, ESA will provide to the Russian Academy of Sciences access to and use of scientific data of the Integral mission. According to the agreement, now included in the Russian Federal Space Program are the works related to the manufacturing of the Proton launcher, the upper stage and the launch services, as well as the task of establishing a Russian scientific data center for the Integral Project. This work will be financed from the Russian Federal Budget.


Integral mission summary
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Paris, 9 September 1998

ESA presents INTEGRAL, its space observatory for Gamma-ray astronomy

Deciphering the processes of the Universe's alchemy which fabricate the elements of stars and galaxies, as well as the endpoints of stellar life, will be the tasks of ESA's INTEGRAL satellite, the INTErnational Gamma-Ray Astrophysics Laboratory. Gamma-rays are a million times more energetic than visible light and bring us information from stupendous physical events that made the universe habitable.

Gamma-ray astronomy - why?

Gamma-rays cannot be detected from the ground since the earth's atmosphere shields us from high energetic radiation. Only space technology has made gamma-astronomy possible. To avoid background radiation effects INTEGRAL will spend most of its time in the orbit outside earth's radiation belts above an altitude of 40.000 km.

Gamma-rays are the highest energy form of electromagnetic radiation. Therefore gamma-ray astronomy explores the most energetic phenomena occurring in nature and addresses some of the most fundamental problems in physics. We know for instance that most of the chemical elements in our bodies come from long-dead stars. But how were these elements formed? INTEGRAL will register gamma-ray evidence of element-making.

Gamma-rays also appear when matter squirms in the intense gravity of collapsed stars or black holes. One of the most important scientific objectives of INTEGRAL is to study such compact objects as neutron stars or black holes. Besides stellar black holes there may exist much bigger specimens of these extremely dense objects. Most astronomers believe that in the heart of our Milky Way as in the centre of other galaxies there may lurk giant black holes. INTEGRAL will have to find evidence of these exotic objects.

Even more strange than the energetic radiation coming from the centre of distant galaxies are flashes of extremely powerful radiation that suddenly appear somewhere on the gamma-sky and disappear again after a short time. These gamma-bursts seem to be the biggest observed explosions in the Universe. But nobody knows their source. Integral will help to solve this long-standing mystery.

ESA, the pioneer in gamma-ray astronomy

The satellite as it can now be seen at ESA's test centre is five meters high and weighs more than four tonnes.

Two main instruments observe the gamma-rays. An imager will give the sharpest gamma-ray images. It is provided by a consortium led by an Italian scientist. Gamma-rays ignore lenses and mirror, so INTEGRAL makes its images with so-called coded-masks. A coded-mask telescope is basically a pinhole camera, but with a larger aperture, i.e. many pinholes.

A spectrometer will gauge gamma-ray energies extremely precisely. It is developed by a team of scientists under joint French-German leadership and will be a 100 times more sensitive than the previous high spectral resolution space instrument. It is made of a high-purity Germanium detector that has to be cooled down to minus 188 degree Celsius.

These two gamma-ray-instruments are supported by two monitor instruments that play a crucial role in the detection and identification of the gamma-ray sources. An X-ray monitor developed in Denmark will observe X-rays, still powerful but less energetic than gamma-rays. An optical telescope provided by Spain will observe the visible light emitted by the energetic objects. Switzerland will host the Integral Science Data Centre which will preprocess and distribute the scientific data.

The mission is conceived as an observatory led by ESA with Russia contributing the launcher and NASA providing tracking support with its Deep Space Network. Alenia Aerospazio in Turin, Italy is ESA's prime contractor for building INTEGRAL. Launch by a Russian Proton rocket from Baikonur is actually scheduled for 2001.

ESA pioneered gamma-ray astronomy in space with its COS-B satellite (1975). Russia's Granat (1989) and NASA's Compton GRO (1991) followed. But INTEGRAL will be better still. With this mission ESA will further strengthen its lead in gamma-astronomy.

ESA Science News 27 Aug 1999

Integral Engineering Model test campaign successfully completed

On 23 August 1999 ESA's new gamma-ray observatory, Integral, has passed a most important milestone in its development. The Engineering Model tests, which lasted more than a year and which were to verify that all satellite subsystems and instruments interface well and function as a system, were successfully completed.

Electrical hardware and software from contractors all over Europe was assembled and tested at Integral's prime contractor Alenia in Turin, Italy, to make up the spacecraft Engineering Model. Engineering Models of all four of Integral's scientific instruments that will gather radiation from exotic objects far away in space were sent to Alenia from Italy, France, Spain and Denmark. Would all the different parts together operate as planned? This was the question the engineers were eager to answer. They tested the complete satellite model consisting of the service module and the payload module that carries the scientific instruments. All electrical and software interfaces and all functions were thoroughly tested. The instruments operated together as expected and without cross-interferences. A couple of sensitivities were identified, but minor modifications will correct these. This is precisely the purpose of the Engineering Model -- to demonstrate a sound design and to allow for small adjustments before testing of the Flight Model itself.

Instead of having a summer break, engineers at Alenia have been busy completing the last phase of the campaign which is testing for electromagnetic interference. Electromagnetic interference is a common problem in our everyday life. Every airline passenger is familiar with the instruction during take-off and landing to turn off all computers, headsets, radios and mobile phones as the electromagnetic waves radiated by these objects can interfere with the aircraft's electronics. Your vacuum cleaner may cause snow on your TV or your car radio may buzz when you drive under a power line. In satellites such interference can be fatal.

To verify the electromagnetic compatibility the engineers place the satellite into a special anechoic test chamber lined with black cones, which absorb electromagnetic radiation rather than to reflect them, thus simulating deep space. The electromagnetic emissions of the satellite were measured over a wide range of frequencies. Then the satellite was irradiated with electromagnetic radiation from various antennas and its proper function carefully monitored to ensure that the satellite will function safely in an environment which is even worse than what it will be exposed to in orbit.

The testing of the Engineering Model showed that all systems operate together well and demonstrated that the Integral satellite is strong enough to withstand electromagnetic interference. The few minor disturbances discovered during testing have been identified and will serve to ensure that the Flight Model is as perfect as possible. The campaign was completed on time and construction of the satellite is well on schedule for Integral's launch in 2001. But there is no respite for the busy engineers -- preparations are already underway for the integration of the Flight Model itself.


More about Integral
Alenia AeroSpazio
SPI instrument
IBIS instrument


[Image 1]
The Egineering Model of the Integral spacecraft in the large clean room at Alenia Aerospazio in Torino, Italy.

[Image 2]
Different models of the Integral spacecraft in Alenia Aerospazio's clean room. Left: Payload Module structure -- Flight Model; middle front: Service module with Reaction Control System intgrated -- Flight Model; middle rear: Structural Thermal Model; right: Engineering Model

[Image 3]
The Service Module (Flight Model) and -- in the background -- the Engineering Model. The cylindrical object is the Spectrometer (SPI).

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