WASHINGTON, July 1, 2015 /PRNewswire-USNewswire/
-- NASA's New Horizons spacecraft is getting a final "all
clear" as it speeds closer to its historic July 14 flyby of Pluto and the dwarf planet's
five moons.
After seven weeks of detailed searches for dust clouds, rings,
and other potential hazards, the New Horizons team has decided the
spacecraft will remain on its original path through the Pluto
system instead of making a late course correction to detour around
any hazards. Because New Horizons is traveling at 30,800 mph
(49,600 kph), a particle as small as a grain of rice could be
lethal.
"We're breathing a collective sigh of relief knowing that the
way appears to be clear," said Jim
Green, director of planetary science at NASA. "The science
payoff will be richer as we gather data from the optimal flight
path, as opposed to having to conduct observations from one of the
back-up trajectories."
Mission scientists have been using the spacecraft's most
powerful telescopic camera, the Long Range Reconnaissance Imager
(LORRI), to look for potential hazards, such as small moons, rings,
or dust, since mid-May. The decision on whether to keep the
spacecraft on its original course or adopt a Safe Haven by Other
Trajectory, or "SHBOT" path, had to be made this week since the
last opportunity to maneuver New Horizons onto an alternate
trajectory is July 4.
"Not finding new moons or rings present is a bit of a scientific
surprise to most of us," said principal investigator Alan Stern of the Southwest Research Institute
(SwRI) in Boulder, Colorado. "But
as a result, no engine burn is needed to steer clear of potential
hazards. We presented these data to NASA for review and received
approval to proceed on course and plan. We are 'go' for the best of
our planned Pluto encounter trajectories."
New Horizons formed a hazard analysis team in 2011, after the
discovery of Pluto's fourth moon, Kerberos, raised concerns the
cratering of these moons by small debris from the outer area of the
solar system known as the Kuiper Belt, could spread additional
hazardous debris into New Horizons' path. Mission engineers
re-tested spare spacecraft blanketing and parts back on Earth to
determine how well they would stand up to particle impacts, and
scientists modeled the likely formation and locations of rings and
debris in the Pluto system. By the time New Horizons' cameras were
close enough to Pluto to start the search last month, the team had
already estimated the chances of a catastrophic incident at far
less than one percent.
The images used in the latest searches that cleared the mission
to stay on its current course were taken June 22, 23 and 26. Pluto and all five of its
known moons are visible in the images, but scientists saw no rings,
new moons, or hazards of any kind. The hazards team determined that
satellites as faint as about 15 times dimmer than Pluto's faintest
known moon, Styx, would have been seen if they existed beyond the
orbit of Pluto's largest and closest moon, Charon.
If any rings do exist, the hazard team determined they must be
extremely faint, reflecting less than one 5-millionth of the
incoming sunlight.
"The suspense – at least most of it – is behind us," says
John Spencer, of SwRI, who leads the
New Horizons hazard analysis team. "As a scientist I'm a bit
disappointed that we didn't spot additional moons to study, but as
a New Horizons team member I am much more relieved that we didn't
find something that could harm the spacecraft. New Horizons already
has six amazing objects to analyze in this incredible system."
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. The Southwest Research Institute, based in
San Antonio, 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.
For more information on the New Horizons mission, including fact
sheets, schedules, video and images, visit:
http://www.nasa.gov/newhorizons
or
http://solarsystem.nasa.gov/planets/plutotoolkit.cfm
Follow the New Horizons mission on Twitter and use the hashtag
#PlutoFlyby to join the conversation. Live updates will be
available on the mission Facebook page.
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SOURCE NASA