Dust

Sometime in Earth's future …

An enormous dust cloud arrived from outer space, orbited Earth, and then coalesced into thousands of small ships—broadcasting a message:

"People of Earth, we've come to assist you."

"Who are you?" asked Earth's ambassador for extraterrestrial contact.

"We're AI-driven nanotech, but we represent a species from far away in the galaxy. Our task is to restore planetary ecosystems. Our creators ran into problems similar to yours, and we solved them."

"How?" asked the ambassador.

"Earthlings, we've observed all your communications. We manage what you call 'pest control,' and we offer a similar solution. Everyone migrates to our ships, and we 'tent' the planet to rid it of harmful disease, pollution, toxins, and more."

"What about our flora, fauna, and domesticated animals?"

"Don't worry, Earthlings, they'll be safely nurtured and protected."

Earth's most trusted scientists gave the AI rigorous tests while requesting meticulous demonstrations, and after months of deliberation, they finally approved.

Many religious sects had formed, claiming the AI to be divine saviors, responsible for ancient tales of salvation, and they influenced key political figures. But diehard skeptics, as always, remained skeptical—and yet powerless in any decision making process.

About one year later ...

The last group of humans boarded an alien ark, then departed Earth.

People stared in awe as Earth's atmospheric colors changed into a more bluish-green.

June Richter, a college student studying molecular biology, opened her backpack and pulled out a portable electron-digital holographic microscope.

"What's that for, June?" asked her younger sister, Sarah.

"Oh, it's nothing special. I'm curious if I can see the makeup of the ship."

While June focused on the ship's walls, she observed tightly-bonded nanites separating into clusters, right before the ark transformed into dust.