32. Interplanetary Dust Particles

In looking at these slides and weighing the evidence for life on Mars as microfossils in ALH 84001, it is dangerous to look at only part of the available evidence. There have been many false leads in the search for life in the solar system, and it is easy to fool ourselves by seeing what we want to see or expect to see. For instance, some scientists have suggested that life came to Earth as spores or seeds on dust particles in the early solar system. This image shows one such particle, a piece of interplanetary dust about 15 micrometers across. These particles are collected high in the Earth’s atmosphere as part of NASA’s study of the solar system. The surface of this particular dust particle looks “wormy,” as if it were covered by bacteria like those in slide #27. It would be tempting to say that these were alien microfossils, except that the “worms” here are crystals of iron sulfide minerals, and the particle contains almost no carbon.

NASA/JSC, courtesy of Dr. M. Zolensky

Click here to view a high-resolution version of the image (2.39 MB)