LOS ANGELES, Sept. 19 (Xinhua) -- Space scientists from around the world were gathering in California Institute of Technology (Caltech) on Wednesday for a conference celebrating 50 years of space exploration.

    Every major space program in the world has sent representatives to take part in the gathering, organizers said. Attendees include NASA Administrator Michael Griffin and European Space Agency Director General Jean-Jacques Dordain.

    The three-day conference will deal with the future of investment in space technology and how to further explore space.

    The conference is being hosted by Northrop Grumman and NASA's Jet Propulsion Laboratory (JPL) at Caltech.

    "Guests will meet and exchange ideas with like-minded people and professionals in between formal presentations," said Ares Rosakis, director of Graduate Aeronautical Laboratories at Caltech and co-organizer of the event.

    "This is more than a sit-and-listen event. It is an interactive learning experience," he said.

    "Our speakers represent all the institutions that essentially created and successfully sustained space exploration," Rosakis said.

    Harrison "Jack" Smith, a Caltech alumnus, NASA advisor and one of the last men to walk on the moon, will be joined by former and current JPL employees in a retrospective on the last 50 years of activity in space.

    Representatives of "SpaceX," a space-transportation company, will be on hand with the company's CEO, Elon Musk -- creator of Paypal -- speaking on a panel discussing space exploration from an industry perspective.

    The launch of Sputnik on Oct. 4, 1957, began the space age. On Jan. 31, 1958, the JPL-built artificial satellite Explorer I was launched, putting the United States into the space race.