As this book is (I hope) more of a novel than an engineering treatise, those who wish to go into technical details are referred to the now rapidly expanding literature on the subject. Recent examples include Jerome Pearson's “Using the Orbital Tower to Launch Earth-Escape Payloads Daily” (Proceedings of the 27th International Astronautical Federation Congress, October 1976) and a remarkable paper by Hans Moravec, “A Non-Synchronous Orbital Skyhook” (American Astronautical Society Annual Meeting, San Francisco, 18-20 October 1977).

I am much indebted to my friends the late A. V. Cleaver of Rolls-Royce, Dr. Ing. Harry 0. Ruppe, Professor of Astronautics at the Technical University of Munich's Lehrstuhl fьr Raumfahrttechnic, and Dr. Alan Bond of the Culham Laboratories for their valuable comments on the Orbital Tower. They are not responsible for my modifications.

Walter L. Morgan (no relation to Vannevar Morgan, as far as I know) and Gary Gordon of the COMSAT Laboratories, as well as L. Perek of the United Nations' Outer Space Affairs Division, have provided most useful information on the stable regions of the synchronous orbit; they point out that natural forces (particularly sun-moon effects) would cause major oscillations, especially in the north-south directions. Thus “Taprobane” might not be as advantageous as I have suggested; but it would still be better than anywhere else.

The importance of a high-altitude site is also debatable, and I am indebted to Sam Brand of the Naval Environmental Prediction Research Facility, Monterey, for information on equatorial winds. If it turns out that the Tower could be safely taken down to sea level, then the Maldivian island of Gan (recently evacuated by the Royal Air Force) may be the twenty-second century's most valuable piece of real estate.

Finally, it Seems a very strange – and even scary – coincidence that, years before I ever thought of the subject of this novel, I myself should have unconsciously gravitated (sic) towards its locale. For the house I acquired a decade ago on my favourite Sri Lankan beach (see The Treasure of the Great Reef and The View From Serendip) is at precisely the closest spot on any large body of land to the point of maximum geosynchronous stability.

So in my retirement I hope to watch the other superannuated relics of the Early Space Age, milling around in the orbital Sargasso Sea immediately above my head.

Colombo

1969-1978

And now, one of those extraordinary coincidences I have learned to take for granted.

While correcting the proofs of this novel, I received from Dr. Jerome Pearson a copy of NASA Technical Memorandum TM-75174, “A Space 'Necklace' About the Earth” by G. Polyakov. This is a translation of “Kosmicheskoye 'Ozherel'ye' Zemli”, published in Teknika Molodezhi, No 4, 1977, pp. 41-43.

In this brief but stimulating paper, Dr. Polyakov, of the Astrakhan Teaching Institute, describes in precise engineering details Morgan's final vision of a continuous ring around the world. He sees this as a natural extension of the space elevator, whose construction and operation he also discusses in a manner virtually identical with my own treatment.

I salute tovarich Polyakov, and am beginning to wonder if – yet again, I have been too conservative. Perhaps the Orbital Tower may be an achievement of the twenty-first century, not the twenty-second.

Our own grandchildren may demonstrate that – sometimes – Gigantic is Beautiful.

Colombo

18 September 1978

END