Talk to Zavala

Speak to Zavala in the Hall of Guardians at the Tower.
"Phobos has been a Skyburners fleet asset since the Cabal entered the system. In the years after the Collapse, the City had no way to contest any entrenchment from the armed and supplied legion. Never would have thought the base would fall the way it did." —Hidden report
Added In
The Taken King (2015.09.09)