There's no welcome home party. No cheers. No applause. No one.
The planet looks dark and dead, and is completely radio silent.
Meanwhile a half-broken Dyson Sphere floats in the sky, covering what's left of the sun.
It doesn't matter much any more.
You have to land now - despite of a functional fusion engine, the tritium energy core is depleting fast and wouldn't make it back to the green planet you discovered.
After landing, the ship scanned all possible communication channels across the globe but only detected one weak signal. With the ship fuel depleted, there's no other choice - you decide to help the ground survivors trace the weak signal, in hopes of finding an answer, and a way to escape Earth.