Fun Fact - Seeding the Galaxy

This is a science fiction follow-up to the previous article. The story remains within the bounds of physics and credible technology - no worm holes or warp drives here. Thus we aren't sending colonies, or human explorers, or even a dog to another star. A tiny probe is the best we can do, and even that requires a great deal of patience.

It's time to wake up. After a thousand years, it's time to wake up and check my systems and make any necessary course corrections, as I have done every thousand years for the past 163,000 years. InterSeed 17 coming online.

CPU, ram, solid state drives, power source, ion thruster, cameras, antennae, all in order - all good. Next, get a fix on the stars. The constellations establish my orientation in space and the distance to Sarabi, the red dwarf star that lies just ahead. This is my destination - after 163 thousand years, this is my destination.

You named the star Sarabi just before my mission was approved. "We shouldn't send probes to stars with no names." you declared. And the earthlike planet that orbits Sarabi, showing a methane ammonia atmosphere with traces of water vapor, you named that world Nala. "InterSeed 17 assigned to Nala." declares your launch manifest. Fair enough. Who are Sarabi and Nala anyways? Egyptian gods? Norse gods? Characters from literature? It hardly matters; a star by any other name…

T-94 days. I must deliver these spores and dessicated bacteria to Nala, the dark blue planet just to the left of Sarabi, if indeed Nala is a lifeless world, or I must dump my precious cargo into the fiery depths of the star if life already exists on Nala. That is my mission. Seed life, but don't contaminate life.

No need for a course correction at this time, I'll fine tune my trajectory as I approach Nala. I point my high gain antenna towards earth and send this status message back to you. InterSeed 17 phoning home. I will be transmitting continuously for the next five months, until my demise. At that time I will burn up in Nala's atmosphere, or I will burn up in Sarabi, a churning red ball of hydrogen and helium that devours all. I haven't decided which yet, more data is required.

The six planets around Sarabi are clearly visible as I cross the orbit of the outermost. Nala, the second planet, is a deep blue, indicating water and an atmosphere. It would appear sky blue if it were located next to the sun, but Sarabi is deficient in blues and violets, so Nala's sky looks more like twilight. I'm sending you the pictures now. You'll receive them in 16 years, 16 years from me back to you at the speed of light. Are you still there? Does civilization still exist? It's been a long time since you sent me out into space, plodding along at 30 kilometers per second, and even that required your fastest rocket and several gravity assists. Do you still have technology capable of receiving this message, or have you reverted back to the stone age, or gone extinct as a species? If the latter then my mission is even more important. I must seed life on another world so more animals can evolve. Perhaps creatures will develop large brains and stone tools and fire and technology, as you did long ago. Perhaps they will unravel the mystery of evolution, but still wonder how life began. The joke is on them, eh - it began in a little sphere sent from earth. You wanted to leave them that information in a message, didn't you, but you couldn't figure out how. A platinum bar with microscopic symbols etched in the side perhaps, but that wouldn't stand up to wind and weather for 3 billion years waiting for intelligent creatures to evolve. "Can we put the metal bar in geosynchronous orbit around the planet?" you asked. "They'd surely find it when they deployed their communication satellites." But this too is unworkable. It takes as much energy to decelerate to a gentle stop at this star system as it took to accelerate from earth, and there's no Saturn XII rocket at my disposal. My trajectory through this star system is hyperbolic. If I don't run into one of the 6 planets or the parent star, I'll sail on by, never to return. There is no power to decelerate even a small object, no way to put anything into orbit around Nala. I'll either plunge into its atmosphere or fly by at a dizzying speed. We can't leave a message in a bottle; they'll have to figure it out on their own.

T-87 days. I send a beam of radar towards Nala, looking for satellites, which could circle the planet almost forever, even if the race that built them was no longer there. If I see signs of technology around the planet, I still have enough propellant to change my trajectory towards Sarabi. The spores that I have carried across 16 light years of empty space, the most valuable treasure in the galaxy, will simply burn up in the outer layers of Sarabi, so they cannot contaminate Nala, even by accident. I'm also scanning for radio or television signals, which should be apparent at this distance. There is, thus far, no indication of EM transmissions or space based assets, so the mission is still a Go.

The spores are just a few degrees above absolute zero, the temperature of interstellar space. Life processes have stopped; even chemistry itself has stopped as atoms are locked in place, their movements barely a whisper within the confines of their frozen molecules. This is the ultimate snapshot in time, fall asleep at one star and instantly wake up at another. Almost, except for the cosmic rays. The payload is shielded of course, but rays get through nonetheless, and jostle a carbon atom here, or a nitrogen atom there. When the cells wake up they will discover that they have been badly damaged. Their DNA is in need of repair. These are the most radiation resistant cells in the world, including Deinococcus radiodurans, which can survive in the low level radioactive waste of a nuclear reactor. Most of these cells will probably be able to repair the damage when they reach Nala. It's a good bet. Cosmic rays are a greater concern for some of my sister ships that are traveling to more distant stars. After 121 light years and 2 million years ship time, InterSeed 63 may be delivering a package of dead bacteria to a barren planet. "Never up, never in." you said, targeting every earthlike planet within your grasp.

With Nala fast approaching, it's time to warm up the microbes. Over the next 70 days my heaters will gently raise the temperature of the sphere from a few degrees kelvin up to 2 degrees celsius, just above the freezing point of water. If all goes well, these microbes will land on Nala, repair their DNA, resume their life processes, garner nutrients, and reproduce, while immersed in toxic chemistry that is unlike any on earth.

T-35 days. I'm crossing the orbit of the third planet. There are no lights on the night side of Nala. Sure, there are lightning storms, but I know the difference between lightning and city lights. There are no large buildings, no urban structures. This is a world without technology, but it could still be teeming with life, life that is compatible with a methane ammonia atmosphere.

T-8 days. There are no large animals, though such would be unlikely in an oxygen free environment. There isn't enough metabolic energy to support a roaming dinosaur. There are no large trees either, no redwoods, no mighty oaks. Large scale structures are not present. I'm also watching for green swaths across the continents, indicating forests or grasslands. So far it's just sand and rocks and mountains. Nor are there any green patches in the ocean that might indicate layers of algae. Yes, I realize vegetation could present itself as another color on this world, even black, absorbing the rich infrared radiation from the star, so I'm searching for any large swatches of color not consistent with geological processes. finding none, my mission is still Go, though I can divert at the last minute if need be, skipping off the atmosphere and heading out of town forever.

You must think it strange, the pictures I am sending you. A dark blue ocean laps the shore, while the sandy beach is devoid of sticks, shrubs, leaves, seashells, or any indication of life. Instead it is festooned with rocks of various sizes. Farther inland there are rocks and more rocks, leading to a mountain that rises 2 kilometers into the air. The planet has plate tectonics, like every other planet of this size and composition, but nobody is here to see it. Maybe that will change in a few million years, maybe animals with our DNA will evolve, and spread across the globe, taking new forms that you have never seen before. That is your hope; that is why you have sent 253 interstellar probes just like me to various earthlike planets, all with the same mission, and all carrying the same payload. This is the only way you can reach for the stars.

T-51 hours. I'm looking for even the smallest signs of life, but there is none to be found. Sea, sand, rocks, mountains, rivers, valleys, sky. It's time to select a landing site. The third continent has a large river that empties into the ocean, and the mouth of the river is temperate. I don't want to dump my sphere into the ocean, so I'll aim one kilometer inland, just west of the river. Fresh water, salt water, precipitation, sunlight, warm days, cool nights - you can't do better than that. I slow down just a bit, so the planet will present the correct longitude when I enter the atmosphere, and I tip my angle down to line up with 18 degrees north latitude.

T-6 minutes. Entry interface in 2 minutes. Soon thereafter I will burn up in the atmosphere and stop transmitting. I'll keep the cameras rolling as long as possible.

InterSeed 17 broke up in the atmosphere of Nala, and released its precious cargo, a basketball sized sphere with a black carbon surface. Hot plasma surrounded the sphere as it streaked across the sky for no one to see. Layer after layer burned away, exposing another to the intense heat. When the sphere became subsonic it was a quarter of its original size. This central ball was deliberately brittle, so that it would shatter like glass upon impact. Microscopic spores and bacteria were strewn across the landscape, some upon the rocks, some in crevices, and some into the river itself. 30% were rendered nonviable by cosmic rays, but the rest came back to life, nurtured by water and the warmth of sarabi's red glow. Our sun only shines for 10 billion years, but Sarabi will burn warm and steady for 10 trillion years, time enough for evolution to sculpt every manner of plant and animal, and perhaps another civilization. Will life gain a foothold in this warm river delta, or will these meager cells die under an alien sky? Time will tell.

Further Reading

Deinococcus radiodurans
Red dwarf
Travel to the nearest star in 20 years