Traces of life in a meteorite from Mars

ALH-77005 has already been through a lot. The lump of stone, which weighs around one pound, was ripped from the surface of Mars 178 million years ago by the impact of a bigger meteorite. The force of the impact flung it into space. Through no fault of its own, ALH-77005 was then put on a course to Earth, where it arrived three million years later.

It was bigger at the time, but its entry into the Earth’s thick atmosphere would have broken it apart. A lump of brown-gray stone, weighing 483 grams and measuring 9.5 cm x 7.5 cm x 5.25 cm, survived the descent and buried itself into Antarctic ice. There it remained for 175 million years until American and Japanese researchers discovered it in 1977.

Scientists quickly determined that ALH-77005 had come from Mars. To get at its real secrets, however, they had to cut it open. This provides an urgent lesson to any aliens out there whose outer appearance might be mistaken for that of a rock: don’t fall to Earth! A thin slice of the stone made its way to Hungary, where researchers put it under a microscope – and discovered some very exciting details that can now be read in a report.

The researchers found four signs that pointed to the earlier presence of bacteria within the stone – Martian bacteria, of course, which would be iron-oxidizing bacteria. This conclusion was indicated by:

  • Structural changes due to coccoidal, filamentous bacteria
  • Presence of organic material (aliphatic and polycyclic aromatic hydrocarbons)
  • Enrichment of elements essential for biology (iron, manganese, phosphorus, zinc)
  • Lower proportions of carbon isotope 13 than normal

Such signs were also found earlier in meteorites from Mars, the researchers acknowledged in their article. But in this case, they can very reliably rule out terrestrial contamination. The meteorite, however, does not reflect the current conditions on Mars today. But 175 million years is not a lot of time geologically. That makes it all the more important to search for life in Mars rocks – by flying there and bringing more rocks back.

Cross section of the meteorite ALH-77005. Researchers found traces of life in a melt pocket, the area enclosed by the yellow rectangle (image: 2019 I. Gyollai et al., published by De Gruyter, CC-BY 4.0)

3 Comments

  • Brandon, 2 questions, 1, how have you managed to write and publish (at the time of postimgI use kindle)) 6 books within the span of (again at the time of posting) six months, and 2, when is The rift coming out? I read the excerpt and it is amazing so far!

    • Hi David, the Enceladus series was in preparation for over a year before publication and it was then published in a quick sequence to get better traction. The Rift will come in May, depending on how quick the editors are. They are already working on it.

      • OK thanks for answering my questions!

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BrandonQMorris
  • BrandonQMorris
  • Brandon Q. Morris is a physicist and space specialist. He has long been concerned with space issues, both professionally and privately and while he wanted to become an astronaut, he had to stay on Earth for a variety of reasons. He is particularly fascinated by the “what if” and through his books he aims to share compelling hard science fiction stories that could actually happen, and someday may happen. Morris is the author of several best-selling science fiction novels, including The Enceladus Series.

    Brandon is a proud member of the Science Fiction and Fantasy Writers of America and of the Mars Society.