Ok, ok some of you may think of this as a stupid idea... but here it goes
Why did humans buildt a starship, and gone somewhere?
They have been traveling for ~30 years around the galaxy, and they found only a desert planet.
Why did they go when they could been in the orbit of Earth?
Ok, this is how i would do.
1. Launch a orbiting facility to go around Earth.
2. Wait fo some time that temp. dust and dangerous particles calm (sit back on Earth) and tha do following:
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2.1 Make facilities on Earth, low ground, on areas where the comet didn't do too much damage.
2.2 Afterwards, analyze Earth's atmosphere and chemical stats
IF POSSIBLE TO COLONIZE DO NEXT:
2.3 Colonize the part that are not damaged
2.4 Start growing plants in Agridomes
2.5 Repopulate Earth
IF NOT POSSIBLE, DO NEXT:
2.6 Back to the Orbiting facility
2.7 go to a planet (i would take the Moon)
2.8 start growing plants in agridomes
2.9 repopulate humanity.
:op2: