user: ### NOW ANSWER:
Question: What is the effective exhaust velocity in a Space shuttle vacuum?
Columns: ['Engine type', 'Scenario', 'SFC in lb/(lbf·h)', 'SFC in g/(kN·s)', 'Specific impulse (s)', 'Effective exhaust velocity (m/s)']
Types: ['text', 'text', 'text', 'text', 'real', 'real']
Sample row: ['NK-33 rocket engine', 'Vacuum', '10.9', '309', 331.0, 3240.0]
SQL:

assistant: SELECT COUNT("Effective exhaust velocity (m/s)") FROM "Table" WHERE "Scenario" = 'Space shuttle vacuum';