by Staff Writers
Laurel MD (SPX) May 26, 2017
On New Year's Day 2019, more than 4 billion miles from home, NASA's New Horizons spacecraft will race past a small Kuiper Belt object known as 2014 MU69 - making this rocky remnant of planetary formation the farthest object ever encountered by any spacecraft.
But over the next six weeks, the New Horizons mission team gets an "MU69" preview of sorts - and a chance to gather some critical encounter-planning information - with a rare look at their target object from Earth.
On June 3, and then again on July 10 and July 17, MU69 will occult - or block the light from - three different stars, one on each date. To observe the June 3 "stellar occultation," more than 50 team members and collaborators are deploying along projected viewing paths in Argentina and South Africa. They'll fix camera-equipped portable telescopes on the occultation star and watch for changes in its light that can tell them much about MU69 itself.
"Our primary objective is to determine if there are hazards near MU69 - rings, dust or even satellites - that could affect our flight planning," said New Horizons Principal Investigator Alan Stern, of Southwest Research Institute (SwRI) in Boulder, Colorado. "But we also expect to learn more about its orbit and possibly determine its size and shape. All of that will help feed our flyby planning effort."
What Are They Looking at?
"If you're in the path of an eclipse, it means you're in the path of the shadow on Earth that's created by the moon passing between us and the sun. If you're standing in the right place at the right time, the solar eclipse can last up to a few minutes."
The team will have no such luxury with the MU69 occultations. Marc Buie, the New Horizons co-investigator from SwRI who is leading the occultation observations, said that because MU69 is so small - thought to be about 25 miles (40 kilometers) across - the occultations should only last about two seconds. But scientists can learn a lot from even that, and observations from several telescopes that see different parts of the shadow can reveal information about an object's shape as well as its brightness.
A Space Challenge
Without a precise fix on the object's position - or on the exact path its narrow shadow might take across Earth - the team is spacing the telescope teams along "picket fence lines," one every 6 to 18 miles (10 or 25 kilometers), to increase the odds that at least one or more of the portable telescopes will catch the center of the event and help determine the size of MU69.
The other telescopes will provide multiple probes for debris that could be a danger to the fast-moving New Horizons spacecraft when it flies by MU69 at about 35,000 miles per hour (56,000 kilometers per hour), on Jan. 1, 2019.
"Deploying on two different continents also maximizes our chances of having good weather," said New Horizons Deputy Project Scientist Cathy Olkin, from SwRI. "The shadow is predicted to go across both locations and we want observers at both, because we wouldn't want a huge storm system to come through and cloud us out - the event is too important and too fleeting to miss."
The team gets help from above for the July 10 occultation, adding the powerful 100-inch (2.5-meter) telescope on NASA's airborne Stratospheric Observatory for Infrared Astronomy (SOFIA). Enlisting SOFIA, with its vantage point above the clouds, takes the bad weather factor out of the picture. The plane also should be able to improve its measurements by maneuvering into the very center of the occultation shadow.
Insight for Encounter Planning
"We were only able to start planning the MU69 encounter after we flew by Pluto in 2015," she said. "That gives us two years, instead of almost seven years we had to plan the Pluto encounter. So it's a very different and, in many ways, more challenging flyby to plan."
If weather cooperates and predicted targeting proves on track, the upcoming occultation observations could provide the first precise size and reflectivity measurements of MU69. These figures will be key to planning the flyby itself - knowing the size of the object and the reflectivity of its surface, for example, helps the team set exposure times on the spacecraft's cameras and spectrometers.
"Spacecraft flybys are unforgiving," Stern said. "There are no second chances. The upcoming occultations are valuable opportunity to learn something about MU69 before our encounter, and help us plan for a very unique flyby of a scientifically important relic of the solar system's era of formation."
Greenbelt MD (SPX) May 19, 2017
The combined power of three space observatories, including NASA's Hubble Space Telescope, has helped astronomers uncover a moon orbiting the third largest dwarf planet, catalogued as 2007 OR10. The pair resides in the frigid outskirts of our solar system called the Kuiper Belt, a realm of icy debris left over from our solar system's formation 4.6 billion years ago. With this discovery, mos ... read more
The million outer planets of a star called Sol
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