Standing height - 5 meters
Weight - more than4 tones
The satellite has two main parts where service module situated the lower part of the satellite which contains all spacecraft subsystems essential to support the mission. The service module carries scientific instruments where the payload module is mounted on it
XMM-Newton (ESA's X-ray observatory) rebuilt to develop service module, which limited the mission cost. The closed structure is made of a combination of aluminum and carbon fiber. It also houses the whole satellite systems that includes,
- Power conditioning and control
- Solar power generation
- Telecommunications and thermal
- Data handling
- Attitude and orbit control.
The four scientific instruments situated in INTEGRAL payload module are weigh 2 tones. The detectors' large area gave this weight that needed to penetrating gamma rays and capture spare .The need to shield the detectors from background radiation also added up lot of weight so that the detectors will be more sensitive.
Following two instruments are main components in INTEGRAL and help todetect gamma rays.
- An imager -gives the sharpest gamma-ray images so far
- A spectrometer - gauge gamma-ray energies very precisely
Two other instruments, which is also included
- X-ray monitor
- Optical camera,
Gamma-ray sources are identifying by above instruments.
An orbit scenario such as the INTEGRAL orbit must conform to the constraints handed out by the ground segment configuration, launcher capabilities as well as the scientific objectives along with the requirements of the orbit.
Optimization of the time spent beyond the Earths radiation belts (proton and electron belts) will allow undisturbed scientific measurements as well as guaranteeing the highest scientific throughput. In the equatorial plane the proton (electron) belts are usually assumed to widen out to a geocentric radius of about 4 RE (10 RE), with the highest flux of protons with Ep > 10 MeV (Ee > 1 MeV) occurring at 2 RE (4 RE). Although according to the measurements obtained by SIGMA analyzed by M. Vargas at ICDC who points out that the influence of the radiation belts of the gamma ray instruments extends up to 60,000km with an inclination of a degree greater than 50° which was selected as orbital constraints. As a starting point for a satisfactory INTEGRAL orbit evolution analysis a minimum perigee height of 7000 km, maximum time above 60000 km and an inclination greater than 50° were selected as orbital constraints.
Full ground station coverage if the operational orbit above 40000km along with the maximum use of coverage available below is a must because of the real-time nature of the INTEGRAL mission. Further more scientific observations will be possible towards the end of the extended mission whilst therefore the orbit shall be steady for 5.2 years after the Launch, restricting mainly the perigee height evolution.
A high inclination and an apogee position in the Northern Hemisphere is imposed because of the requirement for maximum visibility from ESA's European ground stations.
The number of required ground stations will be kept to a minimum due to technical, operational (less station hand-over) and also for cost reasons whilst for crucial operations (such as orbital maneuvers) simultaneous coverage from two stations is needed. In order to keep the best possible coverage pattern for all revolutions and to let repetitive working shifts on ground the orbital time period will be a multiple of 24 hours.
The needs of the Satellite on the orbital scenarios are handed out by power, thermal and operational considerations. The Solar Aspect Angle has to be limited to within 40° from the S/C axis during the nominal mission as to guarantee enough power all the way through the mission. The maximum period of (umbra plus penumbra) eclipses shall not go beyond 1.8 hours for thermal and energy reasons. More over, there will be no eclipse from the division of INTEGRAL from the launcher up to the first apogee, and the perigee shall be raised by a total delta-v of not more than 223 m/s through three individual maneuvers.
As to launcher requirements, INTEGRAL is to be meeting the requirements with PROTON (baseline) and ARIANE 5 (backup) launchers. Thus two different orbit scenarios will be the result.
Once every three days, INTEGRAL circles the Earth in a highly elliptical orbit. Above 60 000 kilometers is the normal altitude of INTEGRAL - outside Earth's radiation belts - because of this orbit background radiation effects can be avoided which would interfere with the measurement of gamma rays.
Russia's largest operational launch vehicle Proton rocket launched Integral; it was launched on 17 October 2002 from the Baikonur Cosmodrome in Kazakhstan. A powerful launcher was use to orbit the heavy spacecraft to the unusually high earth orbit.
The Proton used three booster stages to place the spacecraft into a low 'parking' orbit
- Proton upper stage
- Then the satellites being put in to a highly eccentric 'transfer' orbit
- Finally spacecraft then is taken to its operational 72-hour orbit by Integral's own propulsion system
9000 kilometers which is the lowest point that grows to 13000 km after 5 years and the highest point 153 000 kilometers where During the 5 years the inclination (the angle compared with earth's equator) also changes considerably in addition to the orbit shape.
Long periods of uninterrupted observation are guaranteed with nearly a constant background from the high and eccentric orbit and that also far away from trapped radiation in Earth's electron and proton belts. This way above an altitude of 60 000 kilometers, scientists use more than 80% of their time in the orbit for precise observations.
An optimal coverage pattern is guarantied by the orbital period of 72 hours that is a multiple of 24 hours, from the ground stations. For all revolutions this coverage is continuous for Integral's orbit and allows repetitive operational shifts on the ground.