LOS ANGELES, Sept. 5 (Xinhua) -- Forty years after launching, humanity's farthest mission, the U.S. National Aeronautics and Space Administration (NASA)'s Voyager 1, now is drifting through interstellar space at about 38,000 miles an hour (61,000 km an hour), nearly 13 billion miles (21 billion km) from Earth.
Tuesday marks the 40th anniversary of the launch of the only probe to pass beyond the limits of our own Solar System.
"In exploration terms, Voyager was and still is, to me and to so many, the Apollo 11 of space science. It's a mission that changed everything," Thomas Zurbuchen, NASA's deputy administrator, said Tuesday at a news conference on the mission.
On September 5th, 1977, Voyager 1 spacecraft launched from Cape Canaveral, Florida, only a little over eight years after the blast-off to Apollo 11 in 1969. Meanwhile, its sister spacecraft, Voyager 2, which launched two weeks earlier, trails shortly behind, nearly 11 billion miles from its starting point.
"Voyager 1 launched second, but it is travelling the fastest. It's in interstellar space as of the August 25th, 2012," Suzann Dodd, Voyager project manager at NASA' s Jet Propulsion Laboratory (JPL), said in a news conference on the mission. The researchers said they anticipate Voyager 2 reaching that boundary within the next few years.
Today, Voyager 1 and 2 are "as healthy as senior citizens can be," Dodd said. "Each of them has had different ailments over the years."
Since their launches, the twin probes have transmitted astounding views of the solar system back to Earth, giving scientists the first close-up looks of Jupiter and Saturn's planetary systems, plus Uranus and Neptune between 1979 and 1989.
According to NASA, the Voyager 1 spacecraft has become the first human-made object to reach interstellar space, the distance between stars.
"From many points of view, Voyager really represents humanity's most ambitious journey of discovery," Voyager principal investigator Ed Stone said on Tuesday. "It's really I think legacy."
In an earlier interview with Xinhua, the renowned U.S. scientist said that space is the "newest realm of human activity," and a new frontier for humankind.