TIG Post

Tag: Hubble Space Telescope

  • 37 boulders detected by Hubble in the area of the DART-hit asteroid

    37 boulders detected by Hubble in the area of the DART-hit asteroid

    A cluster of rocks has been seen by the Hubble Space Telescope surrounding the asteroid Dimorphos, which NASA’s DART probe purposefully collided with last autumn.

    On September 26, 2022, the Double Asteroid Redirection Test spacecraft, which weighs roughly 1,200 pounds (544 kilogrammes), collided with Dimorphos head-on at a speed of 13,000 miles per hour (20,921 km per hour) to alter the space rock’s velocity.

    The results demonstrated how this kinetic impact technique could be used to divert asteroids that may be on a collision course with Earth. It was the first time humans attempted to alter the motion of a celestial object. There is no danger to Earth from either Dimorphos or Didymos, the larger asteroid it circles.

    The DART impact was successful, changing Dimorphos’ orbital period around Didymos by 33 minutes. This first test of planetary defense, which took place 7 million miles (11.3 million kilometers) from Earth, also released over 1,000 tons of material into space.

    Some of that material includes 37 boulders, ranging in size from 3 feet to 22 feet (0.9 meters to 6.7 meters) in diameter, according to new data captured by Hubble. The rocks, likely shaken loose from Dimorphos’ surface after impact, are drifting away from the asteroid at about a 0.5 mile per hour (0.8 kilometer per hour), or the walking speed of a giant tortoise, according to a Hubble news release.

    Scientists estimate the boulders represent about 0.1% of Dimorphos’ mass.

    “This is a spectacular observation — much better than I expected. We see a cloud of boulders carrying mass and energy away from the impact target. The numbers, sizes, and shapes of the boulders are consistent with them having been knocked off the surface of Dimorphos by the impact,” said planetary scientist David Jewitt, a distinguished professor at the University of California, Los Angeles, in a statement.

    “This tells us for the first time what happens when you hit an asteroid and see material coming out up to the largest sizes. The boulders are some of the faintest things ever imaged inside our solar system.”

    Jewitt and his colleagues have used Hubble to track changes in Dimorphos both during and after the DART impact, but another mission will take an even closer look.

    The European Space Agency’s Hera mission is set to launch in 2024. The spacecraft, along with two CubeSats, is expected to arrive at the asteroid system in late 2026.

    Hera will study both asteroids, measure physical properties of Dimorphos, and examine the DART impact crater and the moon’s orbit, with the aim of establishing an effective planetary defense strategy.

    “The boulder cloud will still be dispersing when Hera arrives,” Jewitt said.
    “It’s like a very slowly expanding swarm of bees that eventually will spread along the binary pair’s orbit around the Sun.”

    Surface boulders and other possible theories

    Researchers believe the boulders were already sitting on the surface of Dimorphos, based on the final close-up photos taken by the DART spacecraft before impact. It’s much less likely that the rocks are shattered pieces of the asteroid, according to the Hubble observation team monitoring Dimorphos.

    Jewitt estimated that 2% of the boulders on the surface were released into space after the crash. The rocks were likely ejected at the same time as the debris trail, also captured by Hubble. It’s also possible that a seismic wave from the impact lifted the rocks.

    “The boulders could have been excavated from a circle of about 160 feet across (the width of a football field) on the surface of Dimorphos,” he said.

    Future observations from Hera could help scientists pin down the actual size of the impact crater left by DART.

    Scientists think Dimorphos may have formed from material shed by Didymos as it collided with another object, according to the European Space Agency. The material from Didymos would have formed a ring that eventually came together due to gravity, so Dimorphos may be what’s known as a rubble pile asteroid — rocky debris loosely held together by gravity, rather than a solid space rock.

    Studying the DART experiment’s aftermath can help space agencies determine whether this impactor technology is the right approach to deflecting asteroids that may pose a threat to Earth in the future — or if it may result in creating more rocky hazards heading toward the planet.

  • After an intended impact by a spacecraft, an asteroid creates a debris cloud

    After an intended impact by a spacecraft, an asteroid creates a debris cloud

    Detailed views of the debris streaming out from the collision caused by the Double Asteroid Redirect Test can be seen in new photographs published by scientists using the European Southern Observatory’s Very Large Telescope in Chile on Tuesday.

    In an effort to alter the asteroid Dimorphos’ velocity, the DART spacecraft, which weighs roughly 1,200 pounds (544 kilograms), collided head-on with the space rock at a speed of 13,000 miles per hour (20,921 kilometers per hour).

    The results demonstrated how this kinetic impact technique could be used to divert asteroids that may appear to be on a collision course with Earth. This was the first time humans attempted to alter the motion of a celestial object.
    Both Dimorphos and Didymos, the larger asteroid it circles, are not dangerous to Earth.

    The DART impact was successful, changing Dimorphos’ orbital period around Didymos by 33 minutes. This first test of planetary defense, which took place 7 million miles (11.3 million kilometers) from Earth, also released tons of material into space.

    Two different teams of astronomers used the Very Large Telescope to study the aftermath of the event.

    “Impacts between asteroids happen naturally, but you never know it in advance,” said lead study author Cyrielle Opitom, an astronomer and chancellor’s fellow at the University of Edinburgh, in a statement. “DART is a really great opportunity to study a controlled impact, almost as in a laboratory.”

    Opitom and her fellow researchers tracked the debris cloud that resulted from the collision for a month using the telescope’s Multi Unit Spectroscopic Explorer instrument, also called MUSE.

    The cloud of rocks and debris initially blasted off of Dimorphos’ surface first appeared to be made of fine particles. Days later, the team spied other structures in the debris cloud, like clumps and spirals of larger particles, as well as a long cometlike tail streaming behind the asteroid.

    The MUSE instrument allowed the researchers to look at the cloud through a rainbow of light to look for telltale signatures of chemicals and gases. But the team couldn’t detect any water or oxygen.

    “Asteroids are not expected to contain significant amounts of ice, so detecting any trace of water would have been a real surprise,” Opitom said.

    The team also kept an eye out for any trace of the DART spacecraft itself, including the propellant it used to journey to the asteroid.

    “We knew it was a long shot, as the amount of gas that would be left in the tanks from the propulsion system would not be huge. Furthermore, some of it would have travelled too far to detect it with MUSE by the time we started observing,” she said.

    Other recent research included a “movie” captured by the Hubble Space Telescope showing the evolution of the asteroid’s new tail and just how many tons of material were sprayed into space at impact.