On July 20, 1969, four days after launching into space, the Apollo 11 command and service module Columbia landed on the Earth's moon. People watched televisions and tuned radio stations to follow the dramatic landing. It was the culmination of years of hard work and training. Designing a vehicle capable of transporting humans to the moon and back to Earth safely was a challenge.
The Columbia returned safely to Earth on July 21, 1969. The entire mission lasted 195 hours, 18 minutes and 35 seconds -- that's a little longer than eight days. The distance from Earth to the moon back in July 1969 was approximately 222,663 miles (358,342 kilometers). That might make your daily commute seem insignificant, but it's still just a hop, skip and a jump away compared to a visit to a neighboring planet.
A trip to Venus, Earth's closest neighboring planet, would require you to cross 0.6989 astronomical units of space on average. That's just less than 65 million miles or around 104.5 million kilometers. And conditions on Venus aren't ideal for a getaway -- the surface temperature on the planet is 460 degrees Celsius (860 degrees Fahrenheit). A better vacation bet is a trip to Mars or one of its moons, but they're even further away.
With these vast distances in mind, it's important to come up with efficient systems that use as few resources as possible. Otherwise, getting off the ground could become a problem. By its very nature, interplanetary travel needs to be green to work. We've got five technologies, not listed in any particular order, that could help humans reach the astounding goal of setting foot on another planet.