Planet Earth working on 3 Mars landers to follow InSight
https://phys.org/news/2018-12-planet-earth-mars-landers-insight.html
That's about the distance from San Francisco to Pasadena, California, home to Mission Control for Mars.
InSight—the eighth successful Martian lander—should be wrapping up two years of digging and quake monitoring by the time rovers arrive from the U.S., Europe and China.