A space disaster such as the one in the popular Hollywood movie "Gravity" may not happen exactly as depicted, but the threat from space junk in orbit around Earth is real and needs addressing, U.S. lawmakers say.

The task of dealing with the growing threat space junk presents to Earth-orbiting satellites and to astronauts conducting their business in Earth orbit was the subject during a hearing conducted by members of the Committee on Science, Space and Technology of the U.S. House of Representatives.

The committee members heard testimony from experts from the U.S. Defense Department, the Federal Aviation Authority and the Federal Communications Commission among others.

"Orbital debris, or space junk as it is sometimes called, is not science fiction. It is a growing problem," said committee member Rep. Eddie Bernice Johnson in opening remarks before the hearing, dubbed "Space Traffic Management: How to Prevent a Real Life Gravity."

"Dealing with the increase in orbital debris will not be easy," Johnson said.

The Defense Department currently tracks around 23,000 objects in space, any one of which could present the risk of a possibly catastrophic collision with a satellite or space station in orbit.

While that seems a large number, NASA officials say they estimate a total of around half a million items of space junk from marble-size and up are in orbit around the planet.

Space is becoming more and more crowded, as countries, companies and non-profit and educational organization are now all operating various satellites with very little oversight, the committee heard.

The threat of collision has been amply demonstrated, most dramatically in 2009 when a private U.S. satellite called Iridium crashed into a dead Russian Kosmos satellite.

The collision created almost 2,000 of the some 23,000 pieces of space junk currently being tracked, in what is considered the biggest single space-junk-creating incident to date.

"The 2009 Iridium-Kosmos collision was a watershed event," says George Zamka, former astronaut and an administrator with the FAA. "The accident brought to light that more work needs to be done to ensure the safe separation of space objects."

Both the Space Shuttle and the International Space Station were forced to make avoidance maneuvers when approached by space debris in the last 10 years, NASA says.

Zamka shared his own personal experience of that as he testified to the committee.

"During my two space missions, we flew upside down and backwards to protect our shuttle windows from orbital debris," he testified. "And even then we had debris strikes and cracks in our windows from very small debris strikes."