Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_20437 ( "Engine type" text, "Scenario" text, "SFC in lb/(lbf\u00b7h)" text, "SFC in g/(kN\u00b7s)" text, "Specific impulse (s)" real, "Effective exhaust velocity (m/s)" real )

### Question ###
What engine type is used in a Space Shuttle Vacuum scenario?

### Accurate SQL ###

SELECT "Engine type" FROM table_20437 WHERE "Scenario" = 'Space shuttle vacuum'