Workers prepare the cover called the manhole on the bottom of external tank number 119 that will be refoamed.

In the transfer aisle of the Vehicle Assembly Building, workers prepare the cover, called the "manhole," on the bottom of external tank number 119 that will be refoamed. The manhole was removed to access the area where the tank's four liquid hydrogen engine cutoff sensors were replaced. The tank is being prepared to launch Space Shuttle Discovery on mission STS-121 in July. Photo credit: NASA/Jim Grossmann