This is actually by John W Campbell rather than Jack Vance, and would be of interest to those researching Campbell's work. It's one of the Ace Double releases from 1966, which featured two novels back to back in one volume (with two front covers).
The Ultimate Weapon (from 1936) is a bit of a vintage piece. Back in the day, heroes of space were built like brick outhouses, had an IQ of 209 and were, for the most part, filthy rich having made a mint from a science-based private business.
Buck Kendall is no exception and, having accepted a bet from his friend and Technical Engineer, Rad Cole, has taken up extraterrestrial mining and is – at the start of this tale – zipping around the outer Solar System hunting for rare minerals. They are therefore the first to witness an advance scouting party from the system of Mira, a vast red variable sun whose output of radiation is getting a bit too much for the residents of its habitable worlds. They have set their sights on our Solar System as a new home and don’t intend to let the humans stand in their way.
Serialised in ‘Amazing’ this is essentially a tale of rapid scientific development on the part of the humans in order to repel the highly advanced invaders.
The Solar System has to suffer a lot of death and space battles before Kendall comes up trumps with the Ultimate Weapon, developed around the concept of Heisenberg’s Uncertainty Principle.
It reads a little like EE ‘Doc’ Smith, although Smith at least understood literary concepts such as pace, drama and suspense and whose aliens, however dated they may seem today, came across as fully-rounded alien individuals.
The Planeteers
Consists of:-
The Brain Stealers of Mars (Thrilling Wonder Stories, December 1936)
The Double Minds (Thrilling Wonder Stories, August 1937)
The Immortality Seekers (Thrilling Wonder Stories, October 1937)
The Tenth World (Thrilling Wonder Stories, December 1937)
The Brain Pirates (Thrilling Wonder Stories, October 1938)
Penton and Blake are pioneers of atomic power, and having caused devastation on Earth with their experiments, have taken to space in a nuclear rocket and through these five stories visit various planets and moons of the Solar System, all of which have life and civilisations of various kinds.
Despite the fact that 'The Brain Stealers of Mars' has to be one of my favourite SF titles, the tales are somewhat dated, but have a nostalgic charm which many may appreciate.