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Hubble Kuiper Belt survey to focus on binary systems

Hubble Space Telescope during the last servicing mission to the spacecraft STS 125 carried out on Shuttle Atlantis photo Credit NASA - Copy

The Hubble Space Telescope as seen by the crew of Atlantis on STS-125 in April of 2009. Photo Credit: NASA

The Southwest Research Institute (SwRI) is set to use the Hubble Space Telescope to conduct the largest ever survey of the Kuiper Belt, focusing specifically on binary systems in which two objects of similar masses orbit one another as they circle the Sun.

Kuiper Belt binary systems are believed to be among the oldest objects in the solar system, having formed from collapsing groups of pebbles four billion years ago. According to one hypothesis, the objects in these systems initially formed alone via an accretion process and subsequently merged with companions to form binaries. Under this scenario, objects in binaries should have colors and size distributions notably different from individual Kuiper Belt Objects (KBOs).

A competing hypothesis proposes the objects in binaries, along with individual KBOs, formed directly through a rapid collapse process. This would result in both the individual objects and binaries having similar colors and size distributions.

Scientists hope this survey will yield a definitive answer regarding binary KBOs’ formation processes.

“We will use Hubble to test the theory that many planetesimals formed as binary systems from the get-go, and that today’s Kuiper Belt binaries did not come from mergers of initially solitary objects,” said study leader Alex Parker of SwRI.

The survey, funded by a grant from NASA’s Space Telescope Science Institute (STScI), will be the largest ever solar system study conducted by Hubble. A total of 206 Hubble orbits have been assigned to the project, which will measure the colors and binary characteristics of more than 200 KBOs.

Hubble orbits the Earth every 97 minutes at an altitude of 350 miles (560 kilometers). Most of its studies look well beyond the solar system at phenomena in interstellar space. It is the only telescope capable of measuring distant, tiny KBOs.

Because the Kuiper Belt is filled with ancient objects dating back to the dawn of the solar system, the survey is titled the Solar System Origins Legacy Survey (SSOLS). It builds upon previous outer solar system studies, including the Outer Solar System Origins Survey (OSSOS) and the Canada-France Ecliptic Plane Survey (CFEPS).

Data from these earlier surveys, the largest ever done of the Kuiper Belt to date, will be used to select specific KBOs to study.

“The Kuiper Belt is a unique remnant of the solar system’s primordial planetesimal disk,” Parker said. “This cold, calm region has preserved an extraordinarily large population of binary objects, particularly those where the two objects have similar mass. These binary systems are powerful tracers of the processes that built the planets.”

Members of the study team include scientists from the U.S., Canada, and Northern Ireland. STScI, which is administering the SSOLS project, focuses on studying the universe using the most advanced space telescopes and is run by the Association of Universities for Research in Astronomy (AURA), based in Baltimore, Maryland.

The survey will not search for a third flyby target for NASA’s New Horizons mission, according to mission Principal Investigator Alan Stern, also of SwRI. Images and updates on the survey will be posted regularly by the study team on the SSOLS website.




Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.

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