The museum surveyed 250 visitors to its website in connection with its Search for a Space Ace programme, offering five days of astronaut training to a winning eight- to 16-year-old.
Overall, 76% of those responding said that they were interested in a holiday in space, and 93% said they believed it would be possible in the next 50 years.
But 29% said that rather than following US financier Dennis Tito, who became the world's first space tourist when he flew to the International Space Station aboard a Russian Soyuz spacecraft, they would prefer a holiday on Earth over a holiday in space.
Destination Moon
Over a third of those who replied said that they would most like to go to the Moon.
But there were plenty of takers for staying closer to home, with 9% preferring Scotland over the Moon, Mars or the Maldives.
When it came to the likelihood of people living on Mars, opinions were divided.
Sixteen per cent thought people would be living on the red planet within the next 20 years, but a full quarter thought it would never happen.
Space ace search
The Science Museum's Search for a Space Ace programme runs until 3 June.
It is open to eight- to 16-year-olds, who can undergo a series of tests to determine their suitability for space travel.
The museum will choose a winner to send for five days and nights training at a European centre in Belgium.