LOS ANGELES — The unstoppable Voyager 1 spacecraft has sailed into a new realm of the solar system that scientists did not know existed.
Voyager 1 and its twin, Voyager 2, have been speeding away from the sun toward interstellar space, or the space between stars.
Over the summer, Voyager 1, which is farther along in its journey, crossed into this new region where the effects from the outside can be felt.
‘‘We do believe this may be the very last layer between us and interstellar space,’’ said chief scientist Ed Stone of the NASA Jet Propulsion Laboratory, which manages the spacecraft.
Stone presented Voyager 1’s latest location at a meeting of the American Geophysical Union in San Francisco.
Voyager 1 is on track to become the first human-made object to exit the solar system. Exactly when that day will come is unknown, partly because there’s no precedent.
Stone estimated Voyager 1 still has two to three years to travel before reaching the boundary that separates the solar system from the rest of space.
Scientists were surprised to discover the unexpected region at the fringes of the solar system — a testament to the mysteries of space.
For the past year, the team has seen tantalizing clues that heralded a new space environment. The amount of high-energy cosmic rays streaming in from outside the solar system spiked. Meanwhile, the level of lower-energy particles originating from inside the solar system briefly dropped.
Because there was no change in the direction of the magnetic field lines, scientists were confident that Voyager 1 had not yet broken through. They have dubbed this new zone a kind of ‘‘magnetic highway.’’
The Voyagers launched 35 years ago on a mission to tour the outer planets. Though Voyager 2 — currently 9 billion miles from the sun — launched first, Voyager 1 is closer to leaving the solar system behind. It is more than 11 billion miles from the sun.
That’s because after the duo beamed home stunning pictures of Jupiter’s big red spot, Saturn’s shimmering rings, and their moons, Voyager 2 ventured onward to Uranus and Neptune.
Instead of following its twin, Voyager 1 used Saturn’s gravity to propel itself toward the solar system’s edge.
Though the cameras aboard the nuclear-powered Voyagers have long been turned off, the probes have enough power to operate the other instruments until around 2020.
In a separate development Monday, scientists described the latest findings of NASA’s Curiosity rover on Mars. The results were presented at a meeting of the American Geophysical Union in San Francisco.
The rover has indeed found something in the Martian dirt but, so far, there’s no definitive sign of the chemical ingredients necessary to support life. A scoop of sandy soil analyzed by Curiosity’s chemistry laboratory contained water and a mix of chemicals, but not complex carbon-based molecules considered essential for life.
That the soil was not more hospitable did not surprise mission scientist Paul Mahaffy since radiation from space can destroy any carbon evidence.
‘‘It’s not unexpected necessarily,’’ said Mahaffy of NASA’s Goddard Space Flight Center, who is in charge of the chemistry experiments. ‘‘It’s been exposed to the harsh Martian environment.’’
The mission managed by the NASA Jet Propulsion Laboratory is trying to determine whether conditions on Mars could have been favorable for microbes when the red planet was warmer and wetter.
Scientists think the best chance of finding complex carbon is at Mount Sharp, a mountain rising 3 miles from the center of Gale Crater near the Martian equator. Curiosity won’t trek there until early next year. Images from space reveal intriguing layers at the base and many think it’s the ideal place to search for carbon.
‘‘The real new science may have to wait until the rover gets to the ancient layered terrain at the base,’’ said University of Arizona senior research scientist Peter Smith, who is not involved in the latest mission.
Hopes for a ‘‘Mars-shaking’’ discovery peaked two weeks ago after mission chief scientist John Grotzinger told National Public Radio: ‘‘This data is gonna be one for the history books. It’s looking really good.’’
The Internet lit up with excitement. NASA later clarified that Grotzinger was referring generally to the mission and not a specific result. Days before the science gathering, the space agency sought to contain expectations and issued a statement insisting there'd be no big news.
So what did Curiosity find after baking the soil and analyzing the resulting gases?
Water, sulfur, and perchlorate, a highly oxidizing salt that was also detected by one of NASA’s previous spacecraft, the Phoenix lander, in the northern Martian latitudes.