Three enemy spacecraft have been causing trouble in the asteroid belt. they always travel in a line, evenly spaced apart, attempting to chase down local spacecraft to steal their goods. the local asteroid colonists have decided to set a trap to capture these three spacecraft. they'll get them to chase one of their fastest ships into an asteroid with a large hole in it and, once the three enemy ships are inside, close two giant trapdoors on each side of the asteroid to catch them. these spacecraft all travel close to the speed of light so the locals will have to take relativity into account. intelligence about the enemy spacecraft reveals that, in their reference frame, they always travel 90 m behind their teammate, each spacecraft is 10 m in length, and their maximum velocity is 90% the speed of light (relative to the asteroids). the asteroid tunnel is only 215 m in length. in this problem we will analyze whether the locals will be able to capture the enemy spacecraft after taking into account relativity.
now the locals can see that, taking into account relativity, the enemy spacecraft will be in a line that is only 91.5 m long when they're traveling at 90% the speed of light relative to the asteroid. for how long a time period will all three spacecraft be inside of the asteroid? express your answer in microseconds to two significant figures.