[meteorite-list] New Horizons Successfully Practices The 2015 Pluto Encounter
From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 1 Jun 2012 12:33:10 -0700 (PDT)
It's a Sim: Out in Deep Space, New Horizons Successfully Practices the
2015 Pluto Encounter
June 1, 2012
The science instruments aboard NASA's New Horizons spacecraft were
running at full tilt, with cameras snapping images, sensors scanning the
space environment and the communications system trading radio signals
with ground stations on Earth.
No matter that the target of this activity - the Pluto system - was
still about three years and 850 million miles away. On May 29-30, New
Horizons "thought" it was July 14, 2015, and carried out the most
intense segment of its Pluto flyby as part of the mission's first
onboard encounter simulation. The simulation was conducted at a distance
of 23 astronomical units from the Sun - 23 times the distance between
Earth and the Sun. When the real encounter happens in 2015, Pluto will
be 33 AU from the Sun.
The New Horizons team has been "scripting" the Pluto flyby for the past
several years, building on the experience and success of the
spacecraft's 2007 flight through the Jupiter system. This week marked
the first real test of that code on the spacecraft, in an environment
New Horizons operators can't fully duplicate on their computers. Last
week, mission operators at the Johns Hopkins Applied Physics Laboratory
in Maryland transmitted the 9,675 commands into New Horizons' computers
that guide all activities for the very day the spacecraft is closest to
Pluto and its moons - about 22 hours of activity in all.
"We're really testing the things we can't simulate on the ground very
well, such as the actual slewing - the movement of the spacecraft to
point the science instruments - directed by the guidance and control
system," says Alice Bowman, New Horizons mission operations manager at
APL. "We'll also look hard at those slews to make sure there was enough
time between the end of one observation and the start of another."
The simulation started with a system-health check-in through NASA's Deep
Space Network; New Horizons then turned from Earth and toward the spot
where it was programmed to find Pluto. A few hours later the spacecraft
turned back to Earth, sent a quick burst of housekeeping data to let
operators know it was OK, then returned to the encounter. All told, the
script called for 77 separate observations, with as many as four science
instruments observing at the same time. The simulation ended just before
2 p.m. EDT on May 30.
With the instruments aiming at empty space where Pluto and its various
moons will be on July 14, 2015, the data New Horizons sends back over
the next few weeks might have little science value - but from it the
team will know whether the sequences went off as planned and the
spacecraft pointed in the right directions. "From what we've already
seen, we have a good idea that the spacecraft did what it was supposed
to do," Bowman says.
"This first mission sim both retired a lot of risks by showing the
actual spacecraft can handle the pace of activity we plan at Pluto, and
it prepared the way for a more extensive, nine-day Pluto encounter sim
next year," says New Horizons Principal Investigator Alan Stern, of the
Southwest Research Institute.
New Horizons is about midway through its annual systems and instrument
payload checkout, having been roused from hibernation on April 30. It's
currently humming through space at more than 34,000 miles (nearly 55,000
kilometers) per hour, between the orbits of Uranus and Neptune, about 2
billion miles (3.3 billion kilometers) from Earth. The team will ease
New Horizons back into electronic slumber in early July.
Received on Fri 01 Jun 2012 03:33:10 PM PDT