Centuries ago, your spaceship lifted off from a dying planet to find a new home. One million people inhabit this ship, which recycles the water, uses fusion energy, and has enough food stores to last for the length of the trip. The ship is one vast metal city, with all the amenities of a ultra modern ecosystem where greed, want, poverty, crime, addiction, tribalism, and war is known only in history classes.

As Captain, your chief advisor, who is the ship’s computer has some disturbing news one morning. In one hundred years, you will reach the planet which has been the destination of the ship for the last thousand years, but probes sent have recently shown an asteroid has destroyed all life on the planet, and it will not be suitable for at least another five to six thousand years, at best.

The ship you are traveling in does not have an infinite lifespan. Built to withstand a lengthy voyage, it was also designed to shed its outer shell, which at some point would be weakened by radiation and impact with objects in space. If not shed, the shell will certainly collapse and its natural demise would be catastrophic.

The computer has a plan to dismantle the outer shell, which will revitalize the ship, and extend its life until the secondary planet can be reached.

The only issue is of the one million people onboard, one quarter of the population will have to be reduced, at least. One third would be optimum.

What is your criteria for this?