Metal Monster with Jointed Limbs
A large robotic device with legs.

The Doom From Planet 4 (1931)

Meteor Miner
Someone who roams the solar system, hunting for metal in meteors.

Salvage in Space (1933)

Moon-Terror
A syndrome common to people who live in less than half Earth-normal gravity.

Star of Dreams (1941)

Motor Torpedo
A terrestrial torpedo, driven by ion beams.

The Prince of Space (1931)

Negative Safety-Field
A paragravity-based shield for space craft.

Collision Orbit (1942)

Neutronic Dust
What's left over when you've annihilated matter.

Twelve Hours To Live (1931)

New Moon Casino Satellite
An enormous artificial moon, it was far easier to get to than the Old Moon.

One Against The Legion (1939)

Orbiting Casino Advertising Sign
The mightiest billboard in the Solar System!

One Against The Legion (1939)

Osprey Space Armor
Space suit you can live in.

Salvage in Space (1933)

Outbound Interplanetary Traffic
The rules of the spacelanes.

One Against The Legion (1939)

Paragravity
Artificial gravity.

Collision Orbit (1942)

Photoelectric Telescope (Photoelectric Eyes) - astronomical pictures produced automatically
An astronomical telescope that uses the photoelectric effect to gather light, and then to present the finished image on a screen.

The Cometeers (1936)

Photograph of Earth from Space
An aerial photograph from outside the atmosphere.

The Prince of Space (1931)

Pilot-Robot
The piloting gear of a space tug.

Collision Orbit (1942)

Planetary Engineering
Remaking or modifying an entire planet.

The Cometeers (1936)

Plastifoam
Used to seal large leaks in space craft.

Collision Orbit (1942)

Pleasure Planet
A vast world devoted to enjoyment.

After World's End (1939)

Positive Ray Propulsion (Ion Drive)
An ion drive.

The Prince of Space (1931)

Prime Directive
The first and most important rule; usually protective.

With Folded Hands (1947)

Protonite - for space exploration
Radioactive fuel for spacecraft.

Twelve Hours To Live (1931)