This is the written version of a dinner speech I gave February 12 2019 at the occasion of the 12th INTEGRAL conference.


INTEGRAL is a space telescope operating in the hard X-ray and gamma ray domains of the electromagnetic spectrum, those photons that are used also in medical imagery. The mission was launched in 2002 and is still in operation 17 years later. It yields an impressive array of results and led to the discovery of a number of new types of cosmic sources.  


INTEGRAL, ESA’s astronomy gamma ray telescope, was conceived in the early 1990s like all scientific missions of the European Space Agency, ESA, as a collaboration between the agency, who was to provide the spacecraft, the operations and the ground segment, and national entities expected to provide the detectors. The US were to take care of one of the major instrument, that with which nuclear astronomy was to progress. And a group in the UK was to develop and deliver the hard X-ray/gamma ray imager. All relevant authorities had expressed officially their support, a key element at the time of the mission selection. All these official and formal agreements notwithstanding, both the US and the UK pulled out of the mission few months after selection. This brought the project close to collapse. A large effort was, however, launched in Europe to reorganise the payload responsibilities. The development of the instrument dedicated to nuclear astrophysics was taken over by groups in Toulouse and Garching bei Muenchen, the imager was put in the hands of groups in Rome, Paris and Bologna and the X-ray monitor, which should have been built by an Italian group, was developed by a Danish institute, which was busy developing a somewhat similar instrument for a Soviet project. ESA took a larger share of the whole mission than anticipated, and the launch was negotiated with the Soviet Union. With ESA taking a large part of the mission, there was no room anymore in its budget for the scientific data handling. This was a golden opportunity for the Swiss community to valorise the experience gained previously through the EXOSAT mission and use it to develop what would become the INTEGRAL Science Data Centre, ISDC. It was all but easy, however, to bring into the Swiss funding scheme a completely new element, namely software development and science operations. The Swiss space science activity was geared to work through the PRODEX programme, a programme designed to allow university groups, in particular in Switzerland, to build space hardware, the cost of which goes way beyond normal research grants. The Swiss confederation in various guises did meet the challenge together with a wide international consortium and provided the funds needed to support INTEGRAL’s science operations, a team that grew to some 50 colleagues at the height of the activities.

All these difficulties had to be dealt with in the light of being a second choice science, beneath “classical” X-ray astronomy, where observations are made in the soft X-rays, at a few keV, a spectral domain where imaging is possible and where the flux of photons is very high. A fraction of those thinking that they were the real X-ray astronomers despised their colleagues working at higher energies, and in particular the INTEGRAL community, and claimed that there would never be enough photons in hard X-rays and gamma rays to do anything sensible. XMM was the project to be part of in Europe at the time. INTEGRAL was seen as a clear second choice.

Politics had been hard at the beginning of the project, engineering was a major difficulty for a decade thereafter. Lots of difficulties appeared in the instrument development, interestingly many of them had to do with glue. Glue that had to be used to connect detector crystals and electronics and caused innumerable problems in both major instruments. Interestingly when fighting systematic uncertainties it is also the opacity of the poorly known quantity of glue used in the optical system that needed very detailed measurement and modelling. It is somewhat sobering when entering a major space project and expecting to be confronted with complex electronic, thermal or mechanical challenges, to be battling gluing issues!

All these difficulties were overcome. This required tremendous human efforts. People responsible for the mission, the instruments development and the ground system invested an impressive amount of nervous strength, guts, soul and heart over many years. Meetings were sometimes of an intensity unexpected in the development of a set of instruments by a highly rational group of people. There was nonetheless sometimes blood on the walls and tears in eyes. Whereas “blood on the walls” is an image, tears in the eyes has been a reality. INTEGRAL had become a major element of the life of a number of key actors. This aspect of the development of the mission is not easily visible. The results of intense meetings were most of the time a few terse sentences in the style : “This type of data from the satellite will be distributed to the ISDC so many seconds after having been received at the ground antenna”. These statements appeared in documents which title were abstruse acronyms, and lost in a sea of project documents. The human side of the INTEGRAL development will never be the object of vibrant widely read novels, although there is plenty of material for lively stories.

In the end the INTEGRAL development was a success. The launch on October 17 2002 put a well functioning satellite and detectors in the designed orbit with a high precision. A very rich scientific harvest followed. INTEGRAL did discover a surprisingly rich set of physics taking part cloaked behind the veils of absorption, where INTEGRAL only could unveil it. Thus INTEGRAL turned into a real discovery machine, one which considerably enriched modern astronomy. In addition INTEGRAL finds itself now as a key link between the astronomy that uses electromagnetic waves to probe the Universe and the tools that begin to open new windows on our environment, using the detection of cosmic neutrinos or gravitational waves. INTEGRAL results outnumber by a large factor the expectations we, and even more so “classical X-ray astronomers”, could have at the time of launch. INTEGRAL is now, in 2019, still perfectly functioning 17 years after its launch and, so we hear, could function for another 10 years. In the present state of astrophysics this is a most welcome perspective. The results presented at this conference are a testimony to this success.

This is science at its best: At the onset there was a question; the tools needed to study the question and to seek answers were developed; these tools were successfully applied to the original question; and they did open fully new avenues of research. The data are public, the software is public too, so are the results. This story should be told often and loudly at an epoch when society doubts about science. It is also worth underlying that this success comes at a modest price. The cost of the mission, all in all a bit short of a billion Euros, should be compared to the GDP of Europe including Russia over a decade or so (the GDP of more than 500 million people for 10 years). In this frame it appears clearly that a very modest effort from the European people yielded a very significant increase in human knowledge. One might also note in these days of political uncertainty that a mission like INTEGRAL costs considerably less than many inconsiderate moves of our policy makers.

When looking into the future one does find that X-ray and gamma ray astronomy missions are few and far apart. The community is therefore active during a very long time simulating the expected observations in order to optimise missions and detectors. Since simulation of observations allows only known physics to be used and since the missions do take a long time from concept to launch, there is a danger that these activities, deprived of fresh data, stiffen creativity. This danger comes on top of a worrisome trend that pushes researchers to produce a steady stream of papers that should be cited as often as possible. Which again encourages research along lines known to lead to certain results, rather than to original thoughts that may take time to be accepted by the community. I would therefore like to urge members of our community, and prime among us those who do not need to compete for positions any more, to think along original paths, also along those far from beaten tracks.

Society did change significantly since 1990. It is even true that those born in 1990 will soon be thirty years old. We are told that people from that generation consider their lives rather differently than we did. They do not let their professional activities impinge on their lives as much as we did. As we saw that INTEGRAL development was rendered possible by the investment of considerable human efforts, I’m wondering how a new mission, bound to have its set of problems and difficulties, will emerge from the people in charge of its development. I certainly trust that people in their thirties now can pull major successes in all domains of science and society, but somehow, I’m curious to know how this will happen.

In any case the INTEGRAL key actors did survive the human adventure of the INTEGRAL mission, several grew stronger from this experience. A number of them are present tonight and at this conference. I encourage all of you to question them about this period of their lives and, possibly, to express your gratitude for the investment they consented to allow all of us to reap a very rich harvest of results.