Gravity measuring spacecraft exceeds expectations

Scientists say experimental spacecraft is five times more accurate than hoped, paving way for larger mission.

    LISA Pathfinder is part of a mission to test technology for future gravitational-wave observatories [ESA]
    LISA Pathfinder is part of a mission to test technology for future gravitational-wave observatories [ESA]

    LISA Pathfinder details

    • LISA Pathfinder is parked in space 1.5 million km from Earth
    • The probe measures movements as small as one part in 10 millionths of a billionth of Earth's gravity
    • By detecting gravitational waves it will allow scientists to "see" more of the Universe
    • Success of LISA Pathfinder paves the way for large-scale experiment involving three satellites

    Two months into an experimental mission to test advanced gravity-sensing technology, the European Space Agency says the results have exceeded their expectations.

    The craft, called LISA Pathfinder, is parked in space 1.5 million kilometres from Earth, midway between our planet and the Sun, where the gravitational pull of both objects is cancelled by the other.

    Onboard are two small identical cubes of solid gold-platinum alloy free-falling through space at the same speed as the craft, while a laser measures their relative motion with unprecedented accuracy; movements as small as one part in 10 millionths of a billionth of Earth's gravity.

    The technology is a first step toward developing a space-based observatory to detect gravitational waves.

    "We now know gravitational waves are detectable - they exist - and now, thanks to Lisa Pathfinder, we know that we have sufficient sensitivity to observe them from space, and therefore a new window to the Universe has been opened," Fabio Favata, from ESA's Directorate of Science, told a briefing on the mission.

    Gravitational wave-test spacecraft launched

    Most of our knowledge about the Universe is based upon our observation of electromagnetic waves including visible light, infrared, X-rays and gamma rays.

    But 100 years ago Albert Einstein, in his theory of general relativity, predicted that another form of wave existed, and these gravitational waves have a profound effect on the Universe.

    "When a gravitational wave is produced, for example when two massive back holes at the centre of galaxies smash into each other, it creates these ripples in space-time," Paul McNamara, LISA Pathfinder's project scientist, told Al Jazeera when the craft launched last year.

    "But because it is stiff, the ripples are not very big so we have to have a very precise instrument which allows us to pick up the minuscule changes in space-time itself."


    The Dark Universe

    Previous research has led scientists to believe that current telescopes are able only to detect just 4 percent of the matter in the Universe.

    It is hoped a gravitational wave detector will help them "see" some of the other 96 percent of matter, including dark matter.

    "When we open the gravitational wave window to the Universe we are seeing completely new objects, things that we have never been able to see before and never will be able to see using electromagnetic spectrum,"  McNamara said.

    "We're really on the cusp of observing the Universe in a whole new way."

    The initial success of LISA Pathfinder paves the way for a large-scale experiment involving three satellites, placed a million kilometres apart, planned for launch in 2034.

    SOURCE: Al Jazeera


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