The Integral project started a bit more than 10 years ago, in July 1993, with the aim to provide a full size high-energy observatory at a medium size budget. ESA used even less than the medium size budget but it certainly needed full size high energy to get there. The project had to struggle with a series of challenges: the spacecraft bus was common to XMM but to be procured and integrated by a different prime contractor, Alenia. This worked remarkably well. The launcher Proton was to be provided by Russia in return for observation time but due to the political, social and economical turmoil in the change from the Soviet Union to Federal Russia it took many long and agonizing years to turn the intention to commitment and then to reality. But finally we got a wonderful launch and Russia is getting wonderful science data.
The biggest challenge however, was the payload. Just after the start of the project NASA, which was supposed to provide the spectrometer, pulled out due to lack of priority and the UK, which was supposed to provide the imager and optical monitor, pulled out due to lack of funds. Never was Integral closer to cancellation, so soon after its inception.
However, in a truly European spirit brave volunteers stood up to take over. A French-German team took on the spectrometer, an Italian-French team the imager and a Spanish team the optical monitor. How brave they really were soon became evident. The development of these observatory type instruments with little technology heritage proved to be a formidable challenge. The project team had to get more deeply involved and had to provide much more support than foreseen. The launch date had to be postponed three times due to payload problems! Again, we finally got there.
In view of these challenges and looking back to all the busy, exciting and exhaustive years of our life dedicated to Integral we are even more satisfied and happy to have achieved a perfect launch and a smooth commissioning and then to witness a year of flawless spacecraft operation and promising scientific observations.