Win A four day holiday for four to Orlando inc flights and car hire National Geographic Traveller

National Geographic Traveller - Family has teamed up with leading attraction ticket provider Attraction Tickets Direct to offer a family holiday to Kennedy Space Center Visitor Complex in Florida.
Family fun
Attraction Tickets Direct is one of the UK’s leading attraction ticket providers and is offering an out-of-this-world holiday to Florida. The winning family of four will be entitled to VIP tickets to Kennedy Space Center Visitor Complex and the chance to meet veteran NASA astronauts such as Brian Duffy, who has flown on four space shuttle missions and visited the International Space Station.
attraction-tickets-direct.co.uk
Sky’s the limit
Kennedy Space Center is more interactive than a museum, more inspirational than a science centre and more educational than a theme park. It offers an insight into space travel where you can walk among giant rockets, tour rocket launch areas, train in spaceflight simulators, touch a piece of the moon, and feel the full-on g-forces of a space shuttle launch. Kennedy Space Center Visitor Complex is located around 45 minutes from Orlando, the fun capital of the world with an abundance of activities for the whole family.
kennedyspacecenter.com
Win an out-of-this-world holiday to Florida
A holiday for a family of four to Orlando, Florida, with two-day Space Passes to Kennedy Space Center Visitor Complex including Lunch With An Astronaut. Also included is four night’s accommodation on a room-only basis in an Orlando hotel, return flights from the UK and 4 days economy car hire up to the value of £200.
Answer the following question
How many space shuttle missions has astronaut Brian Duffy flown on?