Two astronauts are at rest in outer space, one $20.0 \mathrm{~m}$ from the Space Shuttle and the other $40.0 \mathrm{~m}$ from the shuttle. Using a $100.0-\mathrm{W}$ laser, the astronaut located $40.0 \mathrm{~m}$ away from the shuttle decides to propel the other astronaut toward the Space Shuttle. He focuses the laser on a piece of totally reflecting fabric on her space suit. If her total mass with equipment is $100.0 \mathrm{~kg},$ how long will it take her to reach the Space Shuttle?