At a Glance

• Plasma physicist John Brandenburg argues that isotope measurements on Mars may indicate ancient nuclear explosions that destroyed a supposed extraterrestrial civilization.
• Planetary scientist Timothy Swindle challenges the theory, saying Brandenburg’s predicted xenon isotope levels do not match the measurements from Mars.
• A peer-reviewed 2024 study offers a natural explanation for much of Mars’s xenon isotope pattern: impacts during the planet’s early history may have stripped gases from its atmosphere.
• Scientists have found no confirmed evidence of an ancient technological civilization on Mars, and the nuclear-destruction theory remains unsupported by the isotope evidence discussed in the report.

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A controversial theory suggesting that nuclear explosions wiped out an ancient civilization on Mars is facing renewed scientific scrutiny, with researchers challenging the interpretation of the planet’s chemical composition. Plasma physicist John Brandenburg argues that xenon and argon isotope measurements point to a catastrophic event, but planetary scientist Timothy Swindle says the evidence does not match the predicted signatures of nuclear fission.

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Key Statements and Focus Areas

Brandenburg’s Nuclear-Explosion Theory

In a 2014 paper published in the Journal of Cosmology, Brandenburg argued that the chemical composition of Mars and features he interpreted as possible remnants of an ancient civilization could indicate a planetary catastrophe.

His argument focuses partly on elevated levels of xenon-129 and the ratio of argon-40 to argon-36. He suggests that these measurements could be consistent with nuclear explosions in the Martian atmosphere.

Brandenburg has argued that the possibility warrants investigation, including because humanity could theoretically face similar threats. However, the interpretation is disputed, and the chemical measurements alone do not establish that an explosion occurred or that an extraterrestrial civilization existed.

Xenon Isotopes: The Main Scientific Objection

Xenon occurs in several isotopic forms, and their relative abundance can provide clues about a planet’s geological and atmospheric history.

Swindle, a professor emeritus and former director of the University of Arizona’s Lunar and Planetary Laboratory, argues that Brandenburg’s model fails to reproduce the measured distribution of xenon isotopes.

According to Swindle’s analysis, several isotopes used in Brandenburg’s comparison are not produced by nuclear fission in the way the theory requires. For heavier isotopes, the predicted quantities diverge from actual measurements; the model reportedly predicts about 50% more xenon-136 than scientists have measured on Mars.

Swindle also points to a possible natural source of xenon-129: the radioactive decay of iodine-129 during the planet’s early history.

Argon Measurements and Alternative Explanations

Brandenburg also cites the ratio of argon-40 to argon-36 on Mars, which is higher than Earth’s, as evidence of an unusual event.

Swindle counters that the ratio does not necessarily indicate an excess of argon-40. Mars has substantially less argon-36 per gram than Earth, which can raise the ratio even when the absolute amount of argon-40 is lower.

A separate peer-reviewed study published in Science Advances in 2024 found that repeated impacts during the first 200–300 million years of the solar system could have removed gases from Mars’s early atmosphere and altered the proportions of xenon isotopes. The researchers concluded that this natural process could explain much of the xenon depletion and isotope fractionation observed today.

What the Evidence Actually Establishes

The existence of unusual isotope ratios does not, by itself, establish the cause of those ratios. Scientists must test whether a proposed explanation reproduces the full set of measurements and whether alternative processes can account for the same observations.

The evidence described in the report supports ongoing research into Mars’s atmospheric evolution. It does not establish that a nuclear attack occurred, that an extraterrestrial civilization lived on the planet, or that any such civilization was destroyed.

A theory proposing that nuclear explosions destroyed an ancient civilization on Mars has drawn renewed attention, but scientists cited in a recent Popular Mechanics report say the chemical evidence does not convincingly support the claim.

John Brandenburg, a plasma physicist, proposed in a 2014 paper that features he interpreted as possible remnants of a civilization, together with the chemical composition of Mars, could point to a planetary catastrophe. His argument focuses on xenon and argon isotopes measured in the Martian atmosphere and in material associated with the planet.

Brandenburg highlights the relative abundance of xenon-129, arguing that nuclear explosions could have produced the isotope. He also points to the ratio of argon-40 to argon-36, which is higher on Mars than on Earth.

Timothy Swindle disputes that interpretation. He argues that Brandenburg’s model does not reproduce the full distribution of xenon isotopes measured on Mars. In particular, the model predicts substantially more xenon-136 than scientists have observed. Swindle also notes that some of the isotopes Brandenburg uses in his comparison are not produced by nuclear fission in the way the theory assumes.

The argon argument faces a separate challenge. Swindle says Mars’s higher argon-40-to-argon-36 ratio can be explained by the relative scarcity of argon-36, rather than by an unexplained surplus of argon-40.

Natural processes offer another explanation for the isotope patterns. A 2024 study led by Oliver Shorttle and colleagues examined how impacts affected the early Martian atmosphere. Published in Science Advances, the research found that repeated collisions during the solar system’s first 200–300 million years could have removed atmospheric gases and altered the balance of xenon isotopes.

The study does not settle every question about Mars’s atmospheric history, including the full origin of xenon-129. It does, however, provide a physically grounded mechanism that can explain much of the observed xenon depletion and fractionation without requiring a nuclear catastrophe.

The broader question of whether life ever existed on Mars remains an active area of scientific research. Evidence that the planet once had rivers, lakes and potentially habitable environments makes it a significant target for exploration, but habitability is not proof that life emerged there, much less that a technologically advanced civilization existed.

FYI

The debate illustrates the distinction between identifying an unusual scientific measurement and demonstrating what caused it. Mars’s isotope composition contains important clues about the planet’s early atmosphere, but a nuclear-explosion hypothesis must explain the complete pattern of measurements more successfully than established natural mechanisms.

The 2024 research on impact-driven atmospheric loss shows how planetary scientists test such questions by combining laboratory experiments, measurements and models. Natural explanations are not automatically correct simply because they are conventional; they must also fit the evidence. In this case, however, the mismatch between Brandenburg’s predicted isotope abundances and observed values weakens his nuclear-destruction argument.

The possibility of ancient life on Mars remains scientifically important, but claims of an advanced civilization and its destruction require independent, direct evidence. At present, the theory described in the report is not an established finding in planetary science.

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