Simplify the Expression $5 ^ { - \frac { 1 } { 3 } } 5 ^ { - \frac { 5 } { 3 } }$

Simplify the expression. Write the answer without negative exponents. $5 ^ { - \frac { 1 } { 3 } } 5 ^ { - \frac { 5 } { 3 } }$