In this edition, I have tried to take into account the full implications of the radical
changes to the NASA programme, which were just beginning when the second edition
was published. The new human exploration programme is now well established and
new rocket vehicles are being designed for it. There are only a few more flights of the
Space Shuttle before its retirement, and the plan to send humans back to the Moon is
well under way. Of course this is not the only major new development: the entry of
China into manned spaceflight has added to the new focus on the need to carry
cosmonauts, astronauts and taikonauts to their destinations, and bring them back
safely. For this reason I have added a new chapter on human spaceflight and planetary
exploration. To accompany this I have expanded other chapters to include combustion
instability and throttling, hybrid rocket motors, and air-breathing engines. The
rest of the book has been revised and updated, and errors corrected.
The change of emphasis in NASA from satellites and Earth orbit operations to
lunar and planetary exploration is likely to have a major effect on new developments
in space; history tells us that other agencies are likely to follow suit.While commercial
uses of space will continue to expand, with a strong emphasis on global monitoring
and security as well as communications, the cutting edge of research in space is more
likely to be in planetary science and human exploration than in the traditional
disciplines of space astronomy and space science. I hope the changes in this edition
will reflect this, and that the third edition will prove a useful handbook on the basics of
space propulsion for students and professionals.