The Panspermia Paradox

If Life Came from Another World, How Did it Get to There?

Panspermia is the theory that life spreads through space between worlds, with spores or microorganisms drifting from one planet to another. The theory is very old, but in its modern form, it was first proposed in 1903 by Swedish chemist Svante Arrhenius, who suggested that spores or bacteria might be propelled through space by the pressure of sunlight or starlight. He was a bit hazy about how the spores could escape from a planet’s gravity to begin with. More recently, the late British astronomer Fred Hoyle and his colleague Chandra Wickramasinghe, a Sri Lankan-born astronomer, mathematician, and astrobiologist supported the theory.

Dr. Wickramasinghe believes that the universe is “biologically constructed” and that life has always been present. He believes that many epidemics, including diseases like SARS, may come from comets or cometary fragments. In 1971, Francis Crick, the co-discoverer of the DNA double helix, and his associate, British chemist Leslie Orgel, suggested intelligent aliens traveling about the galaxy and seeding planets might direct that panspermia. Of course, this leaves an unanswered question: who seeded their world and started the process? Recent discoveries have provided more evidence for panspermia and also shed new light on how the process might work.

In 1984, researchers from America’s National Science Foundation discovered meteorite ALH84001 on the Antarctic ice cap, where meteors are clearly visible. Since we have landed men on Earth’s Moon and unmanned craft on Mars, we have learned that each planet has a slightly different ratio of isotopes of common elements. The 1984, meteorite’s isotope ratio shows that it originated on Mars; other meteorites are believed to have originated on our Moon. The theory is that asteroid impacts on a planet can sometimes blow fragments of the planet’s crust into space, exceeding escape velocity. Then they drift about, sometimes for millions or billions of years, finally landing on someplace like Earth.

The rock composing the 1984 meteorite is mostly carbonate, apparently formed some 4.5 billion years ago, and it contains very tiny microscopic objects, perhaps 3.6 billion years old, that resemble nano-bacteria fossils. If they are fossils, that raises another question. Could living bacteria sometimes survive the shock and heat of an asteroid impact, the journey through the vacuum of space, the heat of hypersonic flight through Earth’s atmosphere, and the heat and shock of landing on Earth? Some small meteors have struck buildings, cars, and even people, and have been only moderately hot on the surface and much cooler inside. Since asteroids might also blast Earth rocks into space, a kind of interplanetary “sex” seems possible, with Earth and Mars seeding one another. Then the basic cells and DNA would be the same on both worlds.

Most NASA and JPL researchers believe that Mars was once warmer than today, with a denser atmosphere and even an ocean (there is still plenty of water on Mars, but most of it is frozen in the polar ice caps or in permafrost). Note that the reddish color of the planet is due to iron oxide, but, for substantial quantities of iron to oxidize, there had to have been free oxygen in the atmosphere at some time in the past, and the only known process that can produce large amounts of oxygen is photosynthesis performed by plants. So there is a good chance that Mars once hosted life. Perhaps it still does.

Mars orbiters have photographed structures that at least look like huge trees and a line of objects resembling a migrating herd of animals. At the very least, bacteria may still exist underground. The Mars rover Opportunity photographed objects resembling fossils at Eagle, Fram, and Endurance craters, including the famous “blueberries,” many of them supported by “stalks.” But at Endurance Crater the rover also photographed objects that exactly resemble fossil animals known as crinoids, or sea lilies, found on Earth. There were cylindrical structures resembling crinoid stalks and feathery structures like the ones on terrestrial crinoids. The implications of this are mind-boggling. Could almost identical complex organisms “evolve” on both worlds, or is this an example of intelligent design (I discussed intelligent design in Atlantis Rising #112)?

On September 23, 2001, there was a rain of “blood” in and around Kerala, India. Locals claimed that there was a bright flash just prior to the fall, but that may have been just lightning. There were also reports of trees in the area shedding discolored, grayish leaves, as if something had poisoned them. Under a microscope the “blood” appeared to consist of tiny particles, round or oval, with depressed centers—in other words, they resembled organic cells. Analysis showed that they were mostly composed of carbon and oxygen, with some silicon and traces of iron and other heavy metals. An Indian government report claimed that they were spores from a local green algae—but, if so, how could such a huge quantity be suddenly released and climb high enough in the air to mix with the rain? In 2006, Godfrey Louis and Santosh Kumor of Mahatma Gandhi University proposed that the particles were cells of extraterrestrial origin. And on January 20, 2001 the Indian Space Research Organization sent a balloon 25 miles up, where the air is almost as thin as a vacuum, and found bacteria there, including three new species. Did they somehow blow up from the Earth, or fall from space? And rains of “blood” have been reported many times and in many places, but there have also been falls of (often living) fish, frogs, etc. These animals, even if they originated in space, could not survive there, so they must have a different origin. But perhaps the “blood” may have come from a comet—more on that later.

In 2014, Russian cosmonauts on the International Space Station (ISS) reported finding plankton on the outside of the ISS. Plankton consists of tiny animals, eggs, larvae, and microscopic algae and diatoms living in the ocean. But the rockets carrying crews and supplies to the ISS are launched from inland, far from the sea. This raises the possibility that the plankton (few details are available on what type of organisms comprise it) came from space.

Comets have been described as “dirty snowballs,” or, more recently, as “snowy dirtballs,” made of a mixture of rock fragments and dust, mostly silicates, plus various “ices,” including water ice, carbon dioxide, carbon monoxide, and methane, and interestingly, a variety of organic compounds. The nucleus of a typical comet is about ten miles in diameter (some are far larger), and, when a comet is heated by the Sun as it enters the inner Solar System, a coma made of gas forms around the nucleus, feeding a long tail pushed outward by the solar wind and the pressure of sunlight. Short-period comets, with orbits of 200 years or less, mostly originate in the Kuiper Belt, beyond the orbit of Neptune. Centaurs are very large comets orbiting between the orbits of the outer planets. There are also comets in the asteroid belt (between Jupiter and Mars), and, perhaps, a trillion comets are in the vast Oort Cloud, extending from the outer Kuiper Belt perhaps halfway to the nearest star, Proxima Centauri, which, presumably, has its own Oort Cloud.

The organic compounds in comets typically include methanol, cyanide, formaldehyde, ethanol, ethane, some longer-chained hydrocarbons, and even amino acids. When a comet enters the inner Solar System, it may shed 112,000 pounds of dust and gas per minute. And there is one more thing: astronomers found that comet 67P/C-G contains oxygen. As mentioned above, oxygen in large quantities generally means plants are present. Could algae or diatoms (as in plankton) survive in a frozen state for decades or longer, and then revive briefly when a comet gets closer to the Sun? As the comet sheds dust and gas, these would find their way to the surface of planets (and the outside of the ISS). If they somehow originated even on just one comet, it could seed others. Some comets follow a hyperbolic orbit, approaching the Sun and then flying out of the Solar System entirely, eventually approaching other stars. The seeds of life might be carried everywhere.

Complex organic compounds are not only found in comets; they are present throughout space. Meteorites may come from the fragments of comets or asteroids, and there is no sharp line separating the two. There are nickel-iron meteorites, chondrites (stony meteorites), and carbonaceous chondrites, which contain organic compounds like amino acids, carboxylic acid, alcohols, and amines, as well as water. It is estimated that perhaps 40,000 tons of dust and meteorites strike the Earth each year, carrying these compounds, and, possibly, living organisms. Even in interstellar space, astronomers have found Buckminster Fullerenes (cage-shaped carbon molecules), water, formaldehyde, formic acid, cyanamide, acetic acid, and urea. No wonder that Dr. Wickramasinghe has suggested that the universe is “biologically constructed.”

It is beginning to appear that truly Earth-type planets, with surface conditions amenable to life, may be very rare in the universe. However, many planets, moons, and Kuiper belt objects may have liquid water and even life underground, either in oceans under deep ice caps or in pores in the rocks. Large planets generate internal heat (the source of this heat is not really understood, as conventional explanations like residual heat from planetary formation and radioisotope decay don’t quite add up). Even much smaller worlds orbiting gas giant planets like Jupiter may be heated by tidal flexing and have habitable conditions either just below the surface or deeper, depending on how much heat is being produced. Astronomers believe that Jupiter’s moon Europa has a vast, deep ocean of liquid water beneath a thick ice cap. Saturn’s moons Titan and Enceladus appear to have liquid water underground, and Ganymede and Callisto, other moons of Jupiter, and Neptune’s moon Triton. Chemosynthetic bacteria and possibly more complex life forms might thrive in all these places and within similar worlds in the Kuiper Belt, and perhaps even in worlds between the stars. Comets could spread the same basic type of DNA and life throughout the universe, and there may be more living biomass in these places than on the surface and in the seas of Earth-type worlds.

But worlds like our own, though rare, almost certainly exist. Just how similar would their life forms be to our own? The incredible resemblance of the Martian fossils to terrestrial crinoids suggests that someone (dare I suggest the Supreme Being?) may be controlling “evolution” everywhere and producing similar plants and animals on multiple worlds. Perhaps someday we will go there, or they will come here (or already have), and we will know. But for now we are confronted with a fascinating but unsolved mystery.

By William B. Stoecker