[meteorite-list] So Far, All Clear: New Horizons Team Completes First Search for Pluto System Hazards

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 28 May 2015 17:10:48 -0700 (PDT)
Message-ID: <201505290010.t4T0AmCX023598_at_zagami.jpl.nasa.gov>

http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20150528

So Far, All Clear: New Horizons Team Completes First Search for Pluto System Hazards
May 28, 2015

NASA's New Horizons team has analyzed the first set of hazard-search
images of the Pluto system taken by the approaching spacecraft itself -
and so far, all looks clear for the spacecraft's safe passage.

[Image]
This image shows the results of the New Horizons team's first search for
potentially hazardous material around Pluto, conducted May 11-12, 2015,
from a range of 47 million miles (76 million kilometers). The image
combines 48 10-second exposures, taken with the spacecraft's Long Range
Reconnaissance Imager (LORRI), to offer the most sensitive view yet of
the Pluto system.

The left panel is a combination of the original images before any
processing. The combined glare of Pluto and its large moon Charon in the
center of the field, along with the thousands of background stars,
overwhelm any faint moons or rings that might pose a threat to the New
Horizons spacecraft.

The central panel is the same image after extensive processing to remove
Pluto and Charon's glare and most of the background stars, revealing
Pluto's four small moons - Styx, Nix, Kerberos and Hydra - as points of
light. The right panel overlays the orbits and locations of all five
moons, including Charon. Remaining unlabeled spots and blemishes in the
processed image are imperfectly removed stars, including variable stars
which appear as bright or dark dots. The faint grid pattern is an
artifact of the image processing. Celestial north is up in these images.

The observations were made May 11-12 from a range of 47 million miles
(76 million kilometers) using the telescopic Long Range Reconnaissance
Imager (LORRI) on New Horizons. For these observations, LORRI was
instructed to take 144 10-second exposures, designed to allow a highly
sensitive search for faint satellites, rings or dust sheets in the
system. The mission team is looking carefully for any indications of
dust or debris that might threaten New Horizons before the spacecraft's
flight through the Pluto system on July 14; a particle as small as a
grain of rice could be fatal.

The observations, downlinked to Earth May 12-15 and processed and
analyzed May 12-18, detected Pluto and all five of its known moons, but
no rings, new moons, or hazards of any kind. The New Horizons hazard
detection team, led by John Spencer of the Southwest Research Institute
in Boulder, Colorado, determined that small satellites with about half
the brightness of Pluto's faintest known moon, Styx, could have been
detected at this range. Any undiscovered moons outside the orbit of
Pluto's largest and closest moon, Charon, are thus likely smaller than
3-10 miles (5-15 kilometers) in diameter. If any undiscovered rings are
present around Pluto outside Charon's orbit, they must be very faint or
narrow - less than 1,000 miles wide or reflecting less than one
5-millionth of the incoming sunlight.

The next hazard-search images will be taken May 29-30, and should have
about twice the sensitivity of the first batch. The team expects to
complete a thorough analysis of the data and report on its results by
June 12. The New Horizons team has until July 4 to divert the spacecraft
to one of three alternate routes if any dangers are found.

New Horizons is nearly 2.95 billion miles from home, speeding toward
Pluto and its moons at just under 750,000 miles per day. The spacecraft
is healthy and all systems are operating normally.

The Johns Hopkins University Applied Physics Laboratory in Laurel,
Maryland, designed, built, and operates the New Horizons spacecraft, and
manages the mission for NASA's Science Mission Directorate. Southwest
Research Institute, San Antonio and Boulder, Colorado, leads the science
team, payload operations and encounter science planning. New Horizons is
part of the New Frontiers Program managed by NASA's Marshall Space
Flight Center in Huntsville, Alabama.
Received on Thu 28 May 2015 08:10:48 PM PDT