| | Published 17 June 2010 System Tests, Science Observations And A Course Correction
New Horizons fourth annual checkout is nearing its mid-point, and continues with a workout for the
spacecraft systems, cameras and other instruments that will deliver the first data from Pluto and its
moons. Preparations for a small but necessary course-correction maneuver are also on track.
Since ACO-4 began on May 25, mission operators have uploaded new software for New
Horizons on-board autonomy system, and checked out most of the spacecrafts backup systems,
including guidance and control, communications, command and data handling, thermal control, power and
propulsion. All of these backup systems have performed well.
During an annual spacecraft checkout, the
Mission Operations Center
at the Johns Hopkins Applied
in Maryland, is a hub of activity
Photo by: JHU/APL
On June 21 the project starts an eight-day encounter-mode test, in which key spacecraft and
ground components will be configured to run as they will during the Pluto flyby, five years from next
month. This gives mission controllers a chance to make sure New Horizons will, among other
operations, steady itself, point the science instruments in the right directions and correctly send data
back to Earth. It also ensures that the systems on the ground, needed to send commands to and
acquire data sent from the spacecraft, are correctly configured for encounter dress rehearsals in 2012
So many systems have to work perfectly, together, for any spacecraft to take that amazing picture
or collect any other data, says Alice Bowman, New Horizons mission operations manager at the Johns
Hopkins University Applied Physics Laboratory (APL) in Laurel, Md. This summer were
validating the behind-the-scenes support and the spacecraft systems – from tracking to communications –
that well use at Pluto in 2015.
Surrounding and even during the encounter-mode test, New Horizons science instruments will
undertake a comprehensive list of data-collection and calibration activities that includes long-distance
imaging of Jupiter, Uranus and Neptune, as well as observations of the charged subatomic particles –
space plasma – near the orbit of Uranus.
Did you know? Taking Aim
New Horizons is nearly 16 astronomical units from Earth – close to 1.5 billion miles
(2.4 billion kilometers), or 16 times the distance between Earth and the Sun. A radio signal
from Earth, traveling at light speed, reaches the spacecraft in 2 hours, 13 minutes.
On June 15, New Horizons passed the halfway point – in miles – from Earth’s
location at launch to Pluto’s location during the 2015 flyby.
NASAs Deep Space Network antennas are collecting tracking data that the Navigation team from
KinetX, Inc. is using to pinpoint New Horizons location and predict where its headed.
Based on this prediction, the navigators are collaborating with the Mission Design and Guidance and
Control teams from APL to design a trajectory correction maneuver, or TCM, for June 30
that will slightly adjust the spacecrafts velocity and put New Horizons on course to Pluto.
So far they estimate that this TCM – only the fourth course correction since New Horizons launched on
January 19, 2006, and the first since September 25, 2007 – will last only about 35 seconds and change
the spacecrafts speed by about one mile per hour. But with five years of travel time to go,
those miles would add up, so the maneuver is needed to keep the spacecraft on the precise track to reach
the aim point for the Pluto encounter on July 14, 2015.
This summers ACO is probably our busiest in the span from 2008 to 2011, and its off to
a great start, says New Horizons Principal Investigator Alan Stern, from the Southwest Research
Institute in Boulder, Colo. As our spacecraft pushes ever farther outward at almost a
million miles per day, we never cease to realize how lucky we are to be on our way to explore such a
distant and important planet for NASA, for the American public, and really, for all humankind.
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