The primary mirror of a reflective telescope receives light from objects being observed, enabling the viewing of distant objects. Telescopes designed for deep space exploration, like the Thirty Meter Telescope (TMT) now under development in Hawaii, use primary mirrors comprised of many smaller segmented mirrors. These small mirrors need to be replaced for recoating periodically, but each measures 1.44 meters diagonally and weighs over 250 kilograms, making this a time consuming and costly process. So we employed our technological expertise in precision industrial robotics in the development of a solution.
The Thirty Meter Telescope Will Show Us Deep Space More Clearly than Ever Before
Expected to offer nine times the area of the current largest visible-light telescope, and with resolution over 12 times clearer than the renowned Hubble Space Telescope, the TMT will give astronomers the power to investigate some of the most perplexing mysteries posed by our vast universe.
The 492 segmented mirrors that make up the 30-meter primary mirror—the core technology of the TMT—are spaced no more than 2.5 millimeters apart. Replacing these mirrors once every two years to ensure top performance is no mean feat.
To ensure the precise and efficient replacement of the segmented mirrors while maintaining a high operational rate for the TMT, we’re developing the first-ever Segment Handling System, the crown jewel of which is the Segment Handling Robot for TMT.
Three Unique Technologies Working in Harmony
The Segment Handling Robot for TMT will be driven by three of our unique technologies. Vision sensor technology—through which a sensor projects a checked pattern onto the highly reflective surface of the mirror—will help the robot recognize the mirror’s position and attitude relative to its own, enabling it to approach the mirror safely.
Force control technology will allow the robot—using its three independent arms—to either carefully lift the mirror from its installed position, or to gently set a new mirror into place within a margin of just 0.5 millimeters. This technology will reduce mirror replacement times by up to 60 percent.
And to secure the safety of each mirror, original mechanics/drive technology will ensure that the right amount of space between the robot and the mirror is maintained. "We experienced many issues in developing the parallel link mechanism," said Sho Kawaguchi of the Communication Systems Center, "But one day when my piano at home was being moved using a pantograph jack, it hit me that its structure would enable long-stroke motion even in a tight space." You never know where big ideas will come from.
Amazing Design and Extraordinary Technology
The formation and evolution of the universe has long been the object of humankind’s fascination. Much research has been done, but epoch-making innovations like our Segment Handling Robot—winner of a special Good Design Award in 2016, and a device that on first glance doesn’t look like it would have anything to do with outer space—will help to make the maintenance of telescopes for deep space exploration more practical. This will go a long way in helping humanity unravel the mysteries of the cosmos. Said Masaki Haruna of the Advanced Technology R&D Center, "I feel that only a company like Mitsubishi Electric, with technology and experience in both large telescope development and factory automation, could have brought this technology to fruition."