We have at most 100 years to abandon earth. The 10-km asteroid which killed the dinosaurs has hit the moon head-on instead. As a result, the moon has slowed down and it's orbit will decay by 400,000 km after 100 years (it will fall to earth).

How fast was the asteroid moving relative to the moon's forward motion?

Assume a metallic asteroid of 80% iron, 10% nickel, 10% magnesium.

More specifically: the obit becomes elliptical brushing within 250km of earth, causing drag which will slow it to a collision in 100 years. Assume a circular initial orbit.

The image below represents what the orbit is doing:

The calculation extends this chart out such that the surface of the moon and earth collide in 100 years $\pm$ 5 years.

Bonus if an orbital plot like the Tiangong-1 is in your answer

posted about 5 years ago

Vogon Poet‭

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