Finished 3001 this morning, cat in lap.  I think it was the best of the four books, because it dealt more with the human experience of the extraordinary events and contexts created by Clarke, as he depicted human society a thousand years from now.  But then (as mentioned previously) I like the very-human element in fiction, to get inside the characters observations, experience, emotions.

But as to the very end of the book first:  Unlike many fictional works, Clarke included an afterword acknowledging the scientific sources for some of his concepts, a few parallel real-life developments of his imagined technologies, and numerous mentions of how other people — scientists and people in the publishing industry — influenced his works.  Most interesting set of acknowledgments I’ve seen in a long time, not just for their breadth, but for their readability. 

The book traces Poole’s reintroduction into human society of the fourth millenium, and his parallel quest for contact with the alien Europans (not to be confused with Europians; they are sea creatures (or possibly plants) on Jupiter’s moon Europa.  It’s a good depiction, all the way to the end, of a man amazed by his new environment, but determined to just roll with it as best he can.  He does so all the way to the end of the story, pursuing information about the Europans and the monolith because it’s the best reason he can think of to take advantage of his second life.  It rewards him:  he reconnects with two of the most intimate beings from his 2001-era life:  Dave Bowman and HAL, each “emulated” by the monolith, each having something of their essence captured by the technology of the monolith.

Along the way we get to see multiple inventions and extension of current technology.  One of the most amazing is a kilometers-high tower (four of them, actually) , reaching to an orbiting structure, like a belt around the earth. 

From 3001: The Final Odyssey:
He was looking down on the distant Mediterranean from the face of a cylindrical tower, whose gently curving wall indicated a diameter of several kilometers. But that was nothing compared with its length, for it tapered away down, down, down–until it disappeared into the mists somewhere over Africa. He assumed that it continued all the way to the surface.

“How high are we?” he whispered.

“Two thousand kay. But now look upward.” This time, it was not such a shock: he had expected what he would see. The tower dwindled away until it became a glittering thread against the blackness of space, and he did not doubt that it continued all the way to the geostationary orbit, thirty-six thousand kilometers above the equator. Such fantasies had been well known in Poole’s day: he had never dreamed he would see the reality–and be living in it.

He pointed toward the distant thread reaching up from the eastern horizon.

“That must be another one.” +”Yes–the Asian Tower. We must look exactly the same to them.”

“How many are there ?”

 “Just four, equally spaced around the Equator. Africa, Asia, America, Pacifica. The last one’s almost empty–only a few hundred levels completed. Nothing to see except water. . .”

Poole was still absorbing this stupendous concept when a disturbing thought occurred to him.

“There were already thousands of satellites, at all sorts of altitudes, in my time. How do you avoid collisions?”

lndra looked slightly embarrassed.

“You know-1 never thought about that–it’s not my field.” She paused for a moment, clearly searching her memory. Then her face brightened. .

“I believe there was a big cleanup operation, centuries ago. There just aren’t any satellites, below the stationary orbit.”

That made sense, Poole told himself. They wouldn’t be needed–the four gigantic towers could provide all the facilities once provided by thousands of satellites and space stations.

“And there have never been any accidents–any collisions with spaceships leaving Earth, or reentering the atmosphere ?”

Indra looked at him with surprise. “But they don’t, anymore.” She pointed to the ceiling. “All the spaceports are where they should be–up there, on the outer ring. I believe it’s four hundred years since the last rocket lifted off from the surface of the Earth.”

I found the physical structure of the towers and “Star City” fascinating — more details are flushed out throughout the novel.  One of the special aspects of SF stories are the infinte possibilities of context — environment, time, technology, social behavior, biology, whatever you can think of is up for grabs, as long as what the author presents is at least vaguely consistent with, at minimum, itself.  Clarke imagined a good one here, but also notes in the back of the book:

The concept of a “ring around the world” in the Geostarionary Orbit (GEO), linked to the Earth by towers at the Equator, may seem utterly fantastic but in fact has a firm scientific basis.  It is an obvious extension of the “Space Elevator” invented by the St. Petersburg engineer Yri Artsutanov…

He goes on to reference real-life scientific speculations by both American and Soviet research programs, suggested that these ideas may be currently out of reach, but not impossible given the right means and materials.

Recommend this book, recommend the series.