Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_15944_5 (effective_exhaust_velocity__m_s_ VARCHAR, scenario VARCHAR)
### Question:
What is the effective exhaust velocity in a Space Shuttle Vacuum?
### Answer:
SELECT COUNT(effective_exhaust_velocity__m_s_) FROM table_15944_5 WHERE scenario = "Space shuttle vacuum"