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Telescopes and space missions

Telescopes and space missions

Revealing the Universe: The Making of the Chandra X-ray Observatory

02 May 2002

Revealing the Universe: The Making of the Chandra X-ray Observatory
Wallace Tucker and Karen Tucker
2001 Harvard University Press 306pp £19.50/$27.95hb

Mission possible

I first approached Revealing the Universe, which tells the story behind NASA’s Chandra X-ray astronomy mission, with a certain amount of scepticism. What I expected was another book telling us how far ahead the US and its science programme are compared with the rest of the world. It quickly became apparent, however, that I had in my hands an in-depth account of the trials and tribulations that lie behind the success of any space-science project.

From my own experience in the space industry, I can say that the long march towards Chandra’s launch in mid-1999 – with all of its technical obstacles, political intrigue and budgetary difficulties – rings very true of other missions. Wallace and Karen Tucker manage to capture this struggle well, in a style suited to the popular-science market.

The book also gives an insight into the early scientific results obtained by Chandra, providing a mouth-watering glimpse into what may be in store when the mission’s full scientific results are interpreted. Although this discussion is confined to the last few pages of the book, I have no doubt that these results will be popularized in due course by other authors. But the book’s strength is in its story of the struggle that led to Chandra’s launch.

The first part of the book reminds us that X-ray astronomy is a young science that only became possible once sounding rockets had been developed in the late 1950s to take scientific instruments beyond the atmosphere. Indeed, many of the great names associated with the birth of this branch of astronomy are still in positions of power and influence in the scientific community. The fact that the science has grown so quickly and has contributed so much to our current understanding of the universe is a tribute to these pioneers. The Chandra mission itself was named in honour of the pioneering Nobel-prize winning astrophysicist Subrahmanyan Chandraseskhar, who died in 1995.

One of the most fascinating aspects of the book is the intrigue, in-fighting and politics involved in the civilian space programme. This aspect is particularly important in the US, where funding for large projects requires approval by Congress and is subject to the whims and aspirations of the various members of the congressional committees. The rocky path to the final approval in 1988 of the Advanced X-ray Astrophysics Facility (AXAF) – as Chandra was originally known – was due as much to the marketing ability of the mission’s supporters both inside and outside NASA as it was to the mission’s scientific merits. Indeed, a final appeal to president Reagan was needed to establish AXAF as a NASA programme.

After describing the story of how the mission was approved, the authors lead us through the technical challenges in the manufacture, grinding and polishing of Chandra’s X-ray mirrors. They consist of delicate glass cylinders, mounted coaxially to form a “Woltjer-type grazing incidence assembly” – the only type of mirror that can focus particles of such high energy. The achievement of reaching the required accuracies was nothing short of a miracle with the technologies available in the late 1980s.

One aspect that the authors bring to life is the absolute dedication of the teams involved. Although their goals were almost out of reach, people were prepared to work seven days a week to ensure success. This aspect of the mission is well covered, which brings the book alive to the reader. The many pitfalls encountered – and the ingenious manner in which these were overcome – make a fascinating story in their own right.

Above all, the authors illustrate the human weaknesses involved when so many “prima donnas” are needed to realize a mission such as AXAF. They included lab technicians designing the ultimate in X-ray detectors, programme managers who had to draw together all the intricate parts into a working spacecraft, as well as the scientists who had the original vision.

The scientific instruments on AXAF are described in terms that can be understood by all. The authors manage to explain the physics of the instruments in sufficient detail while at the same time using enough analogies to everyday objects to help the reader. Their approach provides an understanding of the purpose and operation of the payload that caters for readers with a range of scientific knowledge.

The authors eventually reach the great moment where all depends on the Space Shuttle launch vehicle and its crew to put Chandra into its chosen environment high above the atmosphere. The authors capture the tensions during count down, as well as the two launch postponements. It was eventually third time lucky, as a flawless launch and orbit injection set the stage for the scientists to take over from the engineers and realize the full potential of the mission.

Even in orbit, problems were encountered, including some that had never been predicted on the ground – such is the nature of the harsh environment of space. Eventually the problems were solved and the serious business of analysing the wealth of data coming from the observatory is now under way. The early results and the illustrations from the first data are fascinating, but this is only the tip of the iceberg. The real discoveries of Chandra will be the subject of many scientific papers in years to come.

This is a riveting book in its accurate picture of the trials and tribulations in the life cycle of a large space mission. I found it particularly interesting because of my personal knowledge of many of the characters depicted, but this is certainly not a prerequisite for enjoying what is a good account of the human side of space science.

The two authors have a unique expertise – Wallace and Karen Tucker being the science spokesman and the science writer, respectively, for the Chandra X-ray Center at the Smithsonian Astrophysical Observatory. The combination results in a style that is interesting for both the layreader and the professional, making the book a “damn good read” for all those with an interest in space, science and politics.

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