PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov
Contact: Diane Ainsworth
FOR IMMEDIATE RELEASE
January 24, 1996
NEW 3-D SOFTWARE TRANSFORMS VIEW OF SPACECRAFT TRAJECTORIES
It used to take scores of spacecraft coordinates,
long-hand arithmetic and a good old-fashioned slide ruler to
calculate a spacecraft's location in space. Now computer-savvy
flight operators are using a new, three-dimensional software tool
to pinpoint spacecraft positions instantly.
Software engineers at NASA's Jet Propulsion
Laboratory have developed the new software tool -- called
"TrajTool" for trajectory tool -- especially for the Galileo
navigation team as their spacecraft begins a two-year tour of
Jupiter and its moons. The trajectory visualization program,
though, has broad applicability for use on other spaceflight
missions.
With the ease of a simple point-and-click menu,
TrajTool will present a three-dimensional picture of a
spacecraft's trajectory and provide vital orbital information. In
Galileo's case, TrajTool gives navigators instant measurements on
the spacecraft's distance from Jupiter, any of its moons or
Earth.
"The program reads in two ephemeris files, which are
tables of the computed positions of celestial bodies," said Alan
Quan, technical group leader and developer of the software
application along with Dr. Patti Koenig, for JPL's Flight
Projects Office Information Systems Testbed. "One of these files
is for the spacecraft and one is for the planets. The software
then calculates the Cartesian coordinates of the objects and
their trajectories."
The information is next plotted and displayed on
a graphical user interface. Using the mouse the user can
manipulate a slider on the graphical interface to move the
spacecraft and planets forward or backward in time to their
relative positions at any point within the time span of the
ephemeris file.
TrajTool can also overlay on the display certain
parameters that are of interest to navigators, including the
distances between the spacecraft and planets and the angles
between the Sun, Earth and spacecraft, added Dr. Ursula
Schwuttke, manager of the Flight Projects Office Information
Systems Testbed.
"The tool gives us a three-dimensional view of
space," she said, "in which the user can translate and rotate the
viewing position along any axis."
Perhaps the most beneficial feature of the new
software tool is its ability to let users see trajectory
information, rather than having to gather data that were
previously only available in text form from a trajectory
characteristics document, Schwuttke said.
"The navigator can observe when critical events
occur, when occultations or eclipses begin, or when the Sun-
Earth-probe angle will reach its maximum or minimum," she said.
"It gives us a global, intuitive understanding of the trajectory
and trajectory events at a glance."
Navigators also can go immediately to a point of
interest in a trajectory, whereas in the past it took about 15
minutes of manual searching through paper text, tables and charts
to accomplish the task.
First developed for the Galileo magnetometer team, who
wanted to display their data in three dimensions, TrajTool is
being refined for other spaceflight missions, Quan said. The
software is currently being developed for NASA's New Millennium
missions, which will feature miniaturized spacecraft and a host
of revolutionary new technologies designed to study phenomena in
Earth's atmosphere, the solar system and celestial events
unfolding in galaxies beyond the Milky Way.
"We've demonstrated the software to the New
Millennium project and are working on incorporating modifications
that will allow us to tailor the software to their specific
needs," Quan said. "TrajTool will also be used after launch,
during normal operations, to verify trajectory data that will be
sent from spacecraft to the Deep Space Network."
Development of TrajTool was carried out with
funding from the Jet Propulsion Laboratory Multimission Ground
Systems Office for NASA's Office of Space Science, Washington,
D.C.
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1/19/96 DEA
#9604