The reality of space tourism is still years away, but wealthy individuals continue to lineup for the day they can enjoy a gravity-free vacation.

XCOR, one of the companies vying to carve out a space in the fledgling industry, has already sold some 150 advance tickets to high-net-worth individuals angling for a space on one of their space voyages. Tickets sell for $150,000 a pop for a 40-minute ride into outer space on the Lynx space craft.

“There have been several setbacks that companies have had to overcome, but I think that in the next two to five years we will see a lot of exciting progress in the space tourism sector,” said Eric Stallmer, president of the Commercial Spaceflight Federation, whose member companies include commercial spaceflight developers, operators, spaceports, suppliers and service providers.

No scheduled dates for first flights are set, but there’s steady interest, according to Jay Gibson, CEO of XCOR, a developer and producer of highly reusable rocket engines and spacecraft.

“The obstacles are technical,” Gibson told Private Wealth. “We are closer to being finished than we have ever been in developing, building and flying our first prototype.”

XCOR is the only space tourism company that has chosen to take off and land horizontally to complete round trip travel from Earth to space and back. Other space tourism companies that are offering trips into outer space sometime in the future include Virgin Galactic and Blue Origin.

“Blue Origin is employing a vertical take off and landing,” said Gibson. “Virgin Galactic space flights are air dropped and come in for horizontal landing.”

While both Blue Origin and Virgin Galactic will carry multiple space tourists on each flight, XCOR only accommodates one passenger, who is required to wear a pressure suit.

“We operate with reusable engines, low-toxicity fuel and our spacecraft has stop-and-start capabilities like a commercial aircraft so you can fly multiple times a day from an authorized spaceport,” Gibson said.

Gibson estimates the space rides for all the people who currently have paid up to $75,000 in advance as a deposit could be completed in one year once the first commercial flight is launched.

“One of the remaining challenges is getting licenses from the FAA Office of Space Transportation,” Stallmer told Private Wealth. “The process is long and extremely detailed, so companies need to establish communications with the office early on to ensure that their commercial operations can start.”

Ryan Hodson, who is eyeing space travel as an option in the future, feel it's too early to plan for such a trip.

“It’s easier to get to outer space than Antartica from America, but it’s not as safe,” said Hodson, who manages his family’s Wall Street fortune within a family office.

Hodson’s position is based on the crash of a Virgin Galactic commercial test flight over the Mojave Desert in California last year. But that hasn’t stopped Virgin Galactic from preparing travel agents.

Stewart Lieberman is an accredited space agent, which means he is certified by Virgin Galactic to sell space tourism travel packages, but only to travelers between the ages of 18 and 80 years old who qualify.

“You have to be medically fit and cleared by a doctor,” said Lieberman, who completed five days of Virgin Galactic training with other travel agents at the Kennedy Space Center in New Mexico. “You can’t just board the spaceship [just because] you have the money to pay for it.”

That’s because the two-hour round-trip flight involves traveling 63 miles away from  Earth and circling it for three hours before gliding back to planet.

“After going up, you will accelerate at a fast pace and some people might black out because of the intense pressure that happens for a couple of minutes,” said Lieberman, who works as a travel agent with Protravel International.