After the launching of the first artificial satellites preceding
interplanetary vehicles, celestial mechanics is no longer a science of
interest confined to a small group of astronomers and mathematicians; it
becomes a special engineering technique. I have tried to set this book
in this new perspective, by severely limiting the choice of examples
from classical celestial mechanics and by retaining only those useful in
calculating the trajectory of a body in space. The main chapter in this
book is the fifth, where a detailed solution is given of the problem of
motion of an artificial satellite in the Earth's gravitational field,
using the methods of Von Zeipel and of Brouwer. It is shown how
Lagrange's equations can be applied to this problem. The first four
chapters contain proofs of the main results useful for these two
methods: the elliptical solution of the two-body problem and the basic
algebra of celestial mechanics; some theorems of analytical mechanics;
the Delaunay variables and the Lagrangian equations of variation of
elements; the expansion of the disturbing function and the Bessel
functions necessary for this expansion. The last two chapters are more
descriptive in character. In them I have summarized briefly some of the
classical theories of celestial mechanics, and have tried to show their
distinctive characteristics without going into details.