Galactic Panspermia: Interstellar Dust Could Transport Life from Star to Star

The theory of Panspermia states that life exists through the cosmos, and is distributed between planets, stars and even galaxies by asteroids, comets, meteors and planetoids. In this respect, life began on Earth about 4 billion years ago after microorganisms hitching a ride on space rocks landed on the surface. Over the years, considerable research has been devoted towards demonstrating that the various aspects of this theory work.

The latest comes from the University of Edinburgh, where Professor Arjun Berera offers another possible method for the transport of life-bearing molecules. According to his recent study, space dust that periodically comes into contact with Earth’s atmosphere could be what brought life to our world billions of years ago. If true, this same mechanism could be responsible for the distribution of life throughout the Universe.

For the sake of his study, which was recently published in Astrobiology under the title “Space Dust Collisions as a Planetary Escape Mechanism“, Prof. Berera examined the possibility that space dust could facilitate the escape of particles from Earth’s atmosphere. These include molecules that indicate the presence of life on Earth (aka. biosignatures), but also microbial life and molecules that are essential to life.

The theory of Panspermia states that life is distributed throughout the Universe by microbes traveling on objects between star system. Credit: NASA/Jenny Mottor

Fast-moving flows of interplanetary dust impact our atmosphere on a regular basis, at a rate of about 100,000 kg (110 tons) a day. This dust ranges in mass from 10-18 to 1 gram, and can reach speeds of 10 to 70 km/s (6.21 to 43.49 mps). As a result, this dust is capable of impacting Earth with enough energy to knock molecules out of the atmosphere and into space.

These molecules would consist largely of those that are present in the thermosphere. At this level, those particles would consist largely of chemically disassociated elements, such as molecular nitrogen and oxygen. But even at this high altitude, larger particles – such as those that are capable of harboring bacteria or organic molecules – have also been known to exist. As Dr. Berera states in his study:

“For particles that form the thermosphere or above or reach there from the ground, if they collide with this space dust, they can be displaced, altered in form or carried off by incoming space dust. This may have consequences for weather and wind, but most intriguing and the focus of this paper, is the possibility that such collisions can give particles in the atmosphere the necessary escape velocity and upward trajectory to escape Earth’s gravity.”

Of course, the process of molecules escaping our atmosphere presents certain difficulties. For starters, it requires that there be enough upward force that can accelerate these particles to escape velocity speeds. Second, if these particle are accelerated from too low an altitude (i.e. in the stratosphere or below), the atmospheric density will be high enough to create drag forces that will slow the upward-moving particles.

Photo of an aurora taken by astronaut Doug Wheelock from the International Space Station on July 25th, 2010. Credit: Image Science & Analysis Laboratory, NASA Johnson Space Center

In addition, as a result of their fast upward travel, these particle would undergo immense heating to the point of evaporation. So while wind, lighting, volcanoes, etc. would be capable of imparting huge forces at lower altitudes, they would not be able to accelerate intact particles to the point where they could achieve escape velocity. On the other hand, in the upper part of the mesosphere and thermosphere, particles would not suffer much drag or heating.

As such, Berera concludes that only atoms and molecules that are already found in the higher atmosphere could be propelled into space by space dust collisions. The mechanism for propelling them there would likely consist of a double state approach, whereby they are first hurled into the lower thermosphere or higher by some mechanism and then propelled even harder by fast space dust collision.

After calculating the speed at which space dust impacts our atmosphere, Berera determined that molecules that exist at an altitude of 150 km (93 mi) or higher above Earth’s surface would be knocked beyond the limit of Earth’s gravity. These molecules would then be in near-Earth space, where they could be picked up by passing objects such as comets, asteroid or other Near-Earth Objects (NEO) and carried to other planets.

Naturally, this raises another all-important question, which is whether or not these organisms could survive in space. But as Berera notes, previous studies have borne out the ability of microbes to survive in space:

“Should some microbial particles manage the perilous journey upward and out of the Earth’s gravity, the question remains how well they will survive in the harsh environment of space. Bacterial spores have been left on the exterior of the International Space Station at altitude ~400km, in a near vacuum environment of space, where there is nearly no water, considerable radiation, and with temperatures ranging from 332K on the sun side to 252K on the shadow side, and have survived 1.5 years.”

The tiny Tardigrade: Nature's toughest creature? (Image Credit: Katexic Publications, unaltered, CC2.0)
The tiny Tardigrade (aka. “water bear”), which could be the toughest creature on Earth. Credit: Katexic Publications, unaltered, CC2.0)

Another thing Berera considers is the strange case of tardigrades, the eight-legged micro-animals that are also known as “water bears”. Previous experiments have shown that this species is capable of surviving in space, being both strongly resistant to radiation and desiccation. So it is possible that such organisms, if they were knocked out of Earth’s upper atmosphere, could survive long enough to hitch a ride to another planet

In the end, these finding suggests that large asteroid impacts may not be the only mechanism responsible for life being transferred between planets, which is what proponents of Panspermia previously thought. As Berera stated in a University of Edinburgh press statement:

“The proposition that space dust collisions could propel organisms over enormous distances between planets raises some exciting prospects of how life and the atmospheres of planets originated. The streaming of fast space dust is found throughout planetary systems and could be a common factor in proliferating life.”

In addition to offering a fresh take on Panspermia, Berera’s study is also significant when it comes to the study of how life evolved on Earth. If biological molecules and bacteria have been escaping Earth’s atmosphere continuously over the course of its existence, then this would suggest that it could still be floating out in the Solar System, possibly within comets and asteroids.

These biological samples, if they could be accessed and studied, would serve as a timeline for the evolution of microbial life on Earth. It’s also possible that Earth-borne bacteria survive today on other planets, possibly on Mars or other bodies where they locked away in permafrost or ice. These colonies would basically be time capsules, containing preserved life that could date back billions of years.

Further Reading: University of Edinburgh, Astrobiology

Bio-Mimicry and Space Exploration

A close-up of the spiral pattern in a sunflower. (Image Credit: Vishwas Krishna, unaltered, CC2.0)

“Those who are inspired by a model other than Nature, a mistress above all masters, are laboring in vain.

-Leonardo DaVinci

What DaVinci was talking about, though it wasn’t called it at the time, was biomimicry. Biomimicry is the practice of using designs from the natural world to solve technological and engineering problems. Were he alive today, there’s no doubt that Mr. DaVinci would be a big proponent of biomimicry.

Nature is more fascinating the deeper you look into it. When we look deeply into nature, we’re peering into a laboratory that is over 3 billion years old, where solutions to problems have been implemented, tested, and revised over the course of evolution. That’s why biomimicry is so elegant: on Earth, nature has had more than 3 billion years to solve problems, the same kinds of problems we need to solve to advance in space exploration.

The more powerful our technology gets, the deeper we can see into nature. As greater detail is revealed, more tantalizing solutions to engineering problems present themselves. Scientists who look to nature for solutions to engineering and design problems are reaping the rewards, and are making headway in several areas related to space exploration.

Continue reading “Bio-Mimicry and Space Exploration”

What Animals Have Been to Space?

When we think of astronauts, we think of humans. But there have been plenty of animals who have traveled in space as well.

When we think of spaceflight, we think astronauts. You’re a human, you perceive the Universe with your human-centric attitudes. You… specist.

The reality is that the vast number of living things sent to space were our animal buddies. This is a tough topic to hit, as it’s kinda sad. More sensitive animal loving viewers might want might to skip this one, or at least grab some tissue. Just don’t shoot the messenger.

We’ve thrown so many different kinds of animals into space, a better question might be: what animals haven’t been in space? It’s a Noah’s Ark salad of living things.

Mice, monkeys, fish, reptiles, frogs, insects, dogs, and of course, those hardy hardy tardigrades, who laugh at the rigors of spaceflight, and eat vacuum for breakfast. We’ve brought them all home safe and sound. Well, some of them. A good number of them. All the tardigrades are fine. I think.

At the beginning of the space age, scientists sent a series of animals in high altitude balloons to test the physical demands of spaceflight. Scientists had no idea whether creatures could even survive high altitude or radiation, so they sent insects, mammals and even primates nearly halfway to space.

This is how we roll. Mostly we make all kinds of weird assumptions about what might happen, and really it’s better to send a handful of bugs than a person. When we first worked out flight, there were concerns all the air would get sucked out of our lungs and we’d just pass out. Sometimes we get a little freaked out.

This high altitude business all seemed to go well enough. So they packed the poor creatures, I mean our brave animal adventurer friends onto left-over German V-2 rockets and fired them on ballistic trajectories, including a few monkeys.

The Russians… oooh, Russians… were the first to send dogs into space, with Tsygan and Dezik. They didn’t actually reach orbit, and were both brought home safely. Good dogs!

Sputnik 2
Laika inside Sputnik 2

Here’s the one you’re waiting for… Laika was launched aboard the second spacecraft to ever orbit the Earth, Sputnik 2 on November 3, 1957. At that point, scientists weren’t sure if humans could even survive spaceflight, or if we’d just dissolve after soiling our space pantaloons.

Oh, you hu-mans. Soviets chose the toughest dog they could find, a stray mutt they found living on the streets of Moscow. You can’t make this stuff up. Well, I could.

If I did, I’d make it more like, they went to the toughest dog bar in all of Moscow and met the bouncer, Laika at a high stakes winner take all poker-slash-Russian roulette game for all the bones, in a dark smokey dog house in the back.

Originally, it was reported Laika lasted 6 days in orbit, but in 2002, it was uncovered that she actually died shortly after launch. Either way, Laika was doomed, as technology to recover a capsule from space was still a few years off. Apparently there was some kind of race on.

Five months after launch, Sputnik 2 burned up in the Earth’s atmosphere, and Laika’s name still lives on to this day in legend.

In the 50s and 60s, there was a whole series of monkeys sent to space. A third survived their flights and then went on to live long monkey lives, reminiscing about their days of monkey glory hanging out in the primate version of that bar in “The Right Stuff”.

In 1961, Ham the Chimp was sent into space on board a Mercury-Redstone rocket. Ham was trained to believe he was flying the spacecraft. The brave little tyke demonstrated that human astronauts could do the same, as long as they were rewarded with fruit.

Three months later, Alan Shepard followed in Ham’s footsteps, becoming the first American in space. Whether the fruit rewards program was retained is classified.

Chimps in Space
Ham, the Chimpanzee

From that point on, it was a river of living things traveling into space: crickets, ants, spiders, newts, frogs, fish, jellyfish, sea urchins, snails and shrimp.

Even cockroaches. Seriously, somebody thought that would be a good idea. I suspect it was part of some kind of secret Atomic SuperRoach program.

One of the most poignant stories of animals traveling to space has got to be the nematode worms that flew to orbit with the Space Shuttle Columbia in 2003.

When the shuttle tore up on re-entry, killing all 7 astronauts, the nematode worms survived the re-entry and crash landing. There were 60 other science experiments on board Columbia, many of which included animals: fish, insects, spiders, bees and even silk worms. Only the nematodes survived.

It wasn’t the originals that they found. Nematodes have a lifecycle of 7-10 days, so the ones they discovered were probably 5th generation removed from the initial spaceketeers.

As you can see, we aren’t the only creatures to go to space. In fact, we’re the minority. Space belongs to the tardigrades, mice and nematode worms.

I for one welcome our horrible waterbear overlords.

Okay, I’m going to brace myself for this one. Do you think it’s ethical to use animals in spaceflight? Tell us your opinion in the comments below.