Mars training
NASA experts beleive humans will walk on Mars in twenty years.Mars Society/Facebook

A Nasa official has claimed that he believes life forms exist on other planets.

Charles Frank Bolden Jr., the Administrator of Nasa, confirmed he and many others believe there is life beyond Earth and evidence of this will be discovered in years to come.

Taking questions from members of the public for the First News Hotseat show, he was asked by 10-year-old Carmen Dearing if he believed in aliens.

He responded saying: "I do believe that we will someday find other forms of life or a form of life, if not in our solar system then in some of the other solar systems - the billions of solar systems in the universe.

"Today we know that there are literally thousands, if not millions of other planets, many of which may be very similar to our own earth. So some of us, many of us believe that we're going to find ... evidence that there is life elsewhere in the universe."

He also gave his take on the controversy surrounding the moon landings saying: "I have no doubts we went to the moon and I have no doubts that we're going to Mars in your lifetime. The goal is to have us there in the 2030's" he said adding that would not happen until they worked out how to develop, "a toilet that's not going to break on the way."

His comments come just days after former astronaut, John Grunsfeld, said that aliens may be able to hone in on humans, as a result of the changes we've made to Earth's environment.

"We put atmospheric signatures that guarantee someone with a large telescope 20 light years away could detect us," said Grunsfeld at the Astrobiology Science Conference in Chicago. "If there is life out there, intelligent life, they'll know we're here."

Grunsfeld who is now associate administrator for Nasa's Science Mission Directorate, added: "Are we alone?' is the biggest driving question."

In April, Nasa's chief scientist Ellen Stofan claimed evidence of extraterrestrial life could be found in as little as 20 to 30 years.

"We are not talking about little green men," Stofan said. "We are talking about little microbes. We know where to look, we know how to look, and in most cases we have the technology."

Jeffery Newmark, interim director of heliophysics at the agency, added: "It's definitely not an if, it's a when."

Nasa's next Mars rover mission, which is scheduled to launch in 2020, will search for signs of past life and bring samples for a possible return to Earth for analysis. Nasa also hopes to land astronauts on Mars in the 2030s, to search for life on the planet.

The space agency is also planning a mission to Europa, which may launch as early as 2022. It hopes to find out whether the moon is habitable.