All the Weyrs of Pern

infobox Book |
name = All the Weyrs of Pern
title_orig =
translator =


image_caption = Cover of first edition (hardcover)
author = Anne McCaffrey
cover_artist =
country = United States
language = English
series = Dragonriders of Pern
genre = Science fiction
publisher = Bantam Books
release_date = 19 September 1991
media_type = Print (Hardback & Paperback)
pages = 494 pp (first edition, hardback)
isbn = ISBN 0-593-02224-6 (first edition, hardback)
preceded_by = Renegades of Pern
followed_by =

"All the Weyrs of Pern" is a science fiction novel in the Dragonriders of Pern series by Anne McCaffrey. It was first published in 1991, and was nominated for the Hugo Award for Best Novel in1992.

Plot summary

The story follows immediately from the final scene in the Renegades of Pern which concludes with the discovery of a the Admin Building and an advanced computer called "AIVAS" (Artificial Intelligence Voice Address System) at the Landing site which is being excavated. AIVAS has remained undisturbed since the events of Dragonsdawn some 2500 years earlier and, in addition to holding a huge volume of stored information long since lost to the Pernese society, claims to be able to eliminate the threat of Thread forever.

The Weyrs, led by Lessa and F'lar, enthusiastically embrace this possibility, and with the support of the Holds (led in particular by Jaxom) and the Crafthalls (championed by Masterharper Robinton) proceed to implement the ambitious plan under the careful guidance of AIVAS. Aivas itself had been programmed to speak with a masculine-analogue, inquisitive, somewhat humorous personality, which gave the impression of a light-hearted counsellor to the Pernese, who have no real concept of what artificial intelligence entails.

Over the course of the next four years, Pernese society systematically regains much technology that was lost to the colonists in early attempts to survive Threadfall, including marvels such as electricity, plastics manufacture, heating & cooling, printing presses and surgery. Although most technological development focuses on the tools and knowledge needed to eliminate the threat of Thread, there are huge developments in the areas of Medicine and Science, and along the way new Crafthalls are created including the Print Hall, Paper Hall, Computer Hall and Dolphin Hall (this last occurs in a parallel story later in the series The Dolphins of Pern).

The phenomenal advancements in technology lead to a kind of culture shock, manifesting in certain traditionalist elements among the Pernese who label AIVAS an "Abomination" that is corrupting their society. This dissenting opinion results in attempts to sabotage AIVAS itself and the projects it initiates, culminating in the kidnapping of the beloved Masterharper Robinton in an attempt to ransom his life for the destruction of AIVAS. When the conspirators responsible for the kidnapping are brought to justice, a Lord Holder and a Craftmaster are among those sentenced to exile for the crime.

The Weyrs, Holds, and Halls are successful in carrying out AIVAS's plan to transfer the anti-matter engines from the ships used to colonize Pern to the Red Star, and detonate them. The explosion alters the Red Star's orbit, eliminating the configuration which allowed Thread to land on Pern.

AIVAS earlier reveals to Jaxom that in order for the project to succeed, he must mislead the other Dragonriders into using the lesser-known Draconic capability to transfer Between time to deposit two of the three engines 1800 and 600 years in the past. Only the cumulative effect of three interspaced explosions will provide sufficient force to alter the planet's orbit. Jaxom's Ruth, who has an unusually precise ability to always know exactly his location in time, is the only Dragon capable of performing this feat.

In parallel to the primary task to deviate the Red Star's orbit, a team of medical researchers led by Masterhealers Oldive and Sharra develop an improved parasitic vector which is capable of infecting the space-born Ovoids that are the precursors to Thread. During the course of the three engine-transfer missions, Green Dragons are deployed to seed the surface of the Red Star with these infected Ovoids so that they can be dragged back to infect the Oort Cloud, which is the origin of Thread in the Pernese system. The combination of Jaxom's time travel and this infestation is responsible for the two Long Intervals in the history of Pern wherein Thread failed to appear.

The book concludes with the peaceful death of Masterharper Robinton and his fire-lizard Zair, whose health has declined since the kidnapping. Thereafter AIVAS deactivates itself, presumably to prevent Pernese society from idolising the facility as an all-knowing Oracle and thereby stifling the society.