Martian radium projectiles

Martian radium projectiles are explosive ammunition designed for the long-range rifles used on Mars. Their power depends on a chain of material conditions: a projectile’s casing is broken on impact, sunlight reaches the radium-based substance inside, and the exposed material detonates. This mechanism shapes when the ammunition can be made and used, and even when a battle’s explosions may occur.

Construction and Operation

The projectiles are fired from rifles with long barrels and small-caliber ammunition. Their forward end contains a nearly solid glass cylinder with a minute particle of radium powder. An opaque outer coating protects the powder until impact breaks the casing; sunlight, including diffused sunlight, then reaches the exposed material and triggers an explosion.

The account describes the powder as radium, while noting that this is the narrator’s Earth-based approximation: the substance is named in the written language of Helium in Captain Carter’s manuscript. Its physical effect is presented concretely, but its exact composition is not established beyond the narrator’s belief that radium is the base of a mixture.

Manufacture and Battlefield Timing

The ammunition must be manufactured under artificial light because exposure to sunlight can cause an explosion. Dejah Thoris explains that she and Sola have been made to work in pits below the buildings, mixing the powder and making projectiles. The dangerous material is thus not only a battlefield technology: its preparation imposes arduous labor on captives, a fact that alarms John Carter more than the technical explanation itself.

The sunlight-dependent mechanism also produces a distinctive delay in the effects of night fighting. Non-exploding projectiles are generally used at night. When radium projectiles are fired after dark, they do not explode on impact; the following morning, sunrise can set off the powder in the missiles left from the previous night’s battle. Their violence can therefore outlast the exchange of fire and reappear with daylight.

Military Significance

The rifles that fire these projectiles are described as light weapons with barrels made from a hard alloy of aluminum and steel, and stocks of a light, hard wood unknown on Earth. Together, the rifle’s long barrel, small-caliber explosive ammunition, and wireless finders and sighters give it exceptional range. Its theoretical effective radius is three hundred miles; in actual service, the best range is a little over two hundred miles.

For John Carter, the weapons’ capabilities immediately affect his choices: seeing them in the hands of the warriors convinces him that an escape attempt in broad daylight would be too dangerous. The projectiles are therefore not merely destructive devices. Their range and explosive force help determine who can move safely, while their dependence on sunlight governs the conditions under which their manufacture and use are possible.