http://www.nasa.gov/feature/nasa-s-new-horizons-team-selects-potential-kuiper-belt-flyby-target
NASA's New Horizons Team Selects Potential Kuiper Belt Flyby Target
August 28, 2015
NASA has selected the potential next destination for the New Horizons
mission to visit after its historic July 14 flyby of the Pluto system.
The destination is a small Kuiper Belt object (KBO) known as 2014 MU69
that orbits nearly a billion miles beyond Pluto.
New Horizons flyby
This remote KBO was one of two identified as potential destinations and
the one recommended to NASA by the New Horizons team. Although NASA has
selected 2014 MU69 as the target, as part of its normal review process
the agency will conduct a detailed assessment before officially approving
the mission extension to conduct additional science.
"Even as the New Horizon's spacecraft speeds away from Pluto out into
the Kuiper Belt, and the data from the exciting encounter with this new
world is being streamed back to Earth, we are looking outward to the next
destination for this intrepid explorer," said John Grunsfeld, astronaut
and chief of the NASA Science Mission Directorate at the agency headquarters
in Washington. "While discussions whether to approve this extended mission
will take place in the larger context of the planetary science portfolio,
we expect it to be much less expensive than the prime mission while still
providing new and exciting science."
Like all NASA missions that have finished their main objective but seek
to do more exploration, the New Horizons team must write a proposal to
the agency to fund a KBO mission. That proposal - due in 2016 - will
be evaluated by an independent team of experts before NASA can decide
about the go-ahead.
Early target selection was important; the team needs to direct New Horizons
toward the object this year in order to perform any extended mission with
healthy fuel margins. New Horizons will perform a series of four maneuvers
in late October and early November to set its course toward 2014 MU69
- nicknamed "PT1" (for "Potential Target 1") - which it expects
to reach on January 1, 2019. Any delays from those dates would cost precious
fuel and add mission risk.
"2014 MU69 is a great choice because it is just the kind of ancient
KBO, formed where it orbits now, that the Decadal Survey desired us to
fly by," said New Horizons Principal Investigator Alan Stern, of the
Southwest Research Institute (SwRI) in Boulder, Colorado. "Moreover,
this KBO costs less fuel to reach [than other candidate targets], leaving
more fuel for the flyby, for ancillary science, and greater fuel reserves
to protect against the unforeseen."
New Horizons was originally designed to fly beyond the Pluto system and
explore additional Kuiper Belt objects. The spacecraft carries extra hydrazine
fuel for a KBO flyby; its communications system is designed to work from
far beyond Pluto; its power system is designed to operate for many more
years; and its scientific instruments were designed to operate in light
levels much lower than it will experience during the 2014 MU69 flyby.
The 2003 National Academy of Sciences' Planetary Decadal Survey ("New
Frontiers in the Solar System") strongly recommended that the first
mission to the Kuiper Belt include flybys of Pluto and small KBOs, in
order to sample the diversity of objects in that previously unexplored
region of the solar system. The identification of PT1, which is in a completely
different class of KBO than Pluto, potentially allows New Horizons to
satisfy those goals.
But finding a suitable KBO flyby target was no easy task. Starting a search
in 2011 using some of the largest ground-based telescopes on Earth, the
New Horizons team found several dozen KBOs, but none were reachable within
the fuel supply available aboard the spacecraft.
The powerful Hubble Space Telescope came to the rescue in summer 2014,
discovering five objects, since narrowed to two, within New Horizons'
flight path. Scientists estimate that PT1 is just under 30 miles (about
45 kilometers) across; that's more than 10 times larger and 1,000 times
more massive than typical comets, like the one the Rosetta mission is
now orbiting, but only about 0.5 to 1 percent of the size (and about 1/10,000th
the mass) of Pluto. As such, PT1 is thought to be like the building blocks
of Kuiper Belt planets such as Pluto.
New Horizons Path
Unlike asteroids, KBOs have been heated only slightly by the Sun, and
are thought to represent a well preserved, deep-freeze sample of what
the outer solar system was like following its birth 4.6 billion years
ago.
"There's so much that we can learn from close-up spacecraft observations
that we'll never learn from Earth, as the Pluto flyby demonstrated so
spectacularly," said New Horizons science team member John Spencer,
also of SwRI. "The detailed images and other data that New Horizons
could obtain from a KBO flyby will revolutionize our understanding of
the Kuiper Belt and KBOs."
The New Horizons spacecraft - currently 3 billion miles [4.9 billion
kilometers] from Earth - is just starting to transmit the bulk of the
images and other data, stored on its digital recorders, from its historic
July encounter with the Pluto system. The spacecraft is healthy and operating
normally.
New Horizons is part of NASA's New Frontiers Program, managed by the
agency's Marshall Space Flight Center in Huntsville, Ala. The Johns
Hopkins University Applied Physics Laboratory in Laurel, Md., designed,
built, and operates the New Horizons spacecraft and manages the mission
for NASA's Science Mission Directorate. SwRI leads the science mission,
payload operations, and encounter science planning.
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