When (each of) Opportunity and Spirit Rovers finally cease functioning, the US government should order flags over government buildings be flown at half-staff.
Seriously. These little space probes have done more for our knowledge of Martian conditions than any others, and have operated well beyond their '90 Sols' (Day) primary missions/expected lifespan.
Discussion (4)
At NASA headquarters, sure.
Also, their LJs are a riot.
D'A
No, all US flags.
The Mars Exploration Rover mission is one of, if not the, greatest robotic space mission ever undertaken (okay, besides Voyager 1 and 2).
It's true, but I don't think that makes the end of their missions a national tragedy, which is I think the only reason for lowering all US flags.