MONITOR- MONTE CARLO INVESTIGATION OF TRAJECTORY OPERATIONS AND REQUIRE-
MENTS

( NASA Goddard Space Flight Center )

     The Monte Carlo Investigation of Trajectory Operations and Require-
ments (MONITOR) program was developed to perform spacecraft mission maneu-
ver simulations for geosynchronous, single maneuver, and comet encounter
type trajectories. MONITOR is a multifaceted program which enables the
modeling of various orbital sequences and missions, the generation of Monte
Carlo simulation statistics, and the parametric scanning of user requested
variables over specified intervals. The MONITOR program has been used pri-
marily to study geosynchronous missions and has the capability to model
Space Shuttle deployed satellite trajectories. The ability to perform a
Monte Carlo error analysis of user specified orbital parameters using pre-
dicted maneuver execution errors can make MONITOR a significant part of any
mission planning and analysis system.

     The MONITOR program can be executed in four operational modes. In the
first mode, analytic state covariance matrix propagation is performed us-
ing state transition matrices for the coasting and powered burn phases of
the trajectory. A two-body central force field is assumed throughout the
analysis. Histograms of the final orbital elements and other state depen-
dent variables may be evaluated by a Monte Carlo analysis. In the second
mode, geosynchronous missions can be simulated from parking orbit injec-
tion through station acquisition. A two-body central force field is as-
sumed throughout the simulation. Nominal mission studies can be conducted;
however, the main use of this mode lies in evaluating the behavior of perti-
nent orbital trajectory parameters by making use of a Monte Carlo analysis.
In the third mode, MONITOR performs parametric scans of user-requested
variables for a nominal mission. Various orbital sequences may be speci-
fied; however, primary use is devoted to geosynchronous missions. A maxi-
mum of five variables may be scanned at a time. The fourth mode simulates a
mission from orbit injection through comet encounter with optional Monte
Carlo analysis. Midcourse maneuvers may be made to correct for burn errors
and comet movements.

     The MONITOR program is written in FORTRAN IV for batch execution and
has been implemented on an IBM 360 series computer with a central memory re-
quirement of approximately 255K of 8 bit bytes. The MONITOR program was de-
veloped in 1980.

     COSMIC, and the COSMIC logo are registered trademarks of the National
Aeronautics and Space Administration. All other brands and product names
are the trademarks of their respective holders.



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LANGUAGE: FORTRAN IV

MACHINE REQUIREMENTS: IBM 360 SERIES

PROGRAM SIZE: APPROXIMATELY 8,369 SOURCE STATEMENTS

DISTRIBUTION MEDIA: 9 Track 1600 BPI EBCDIC Card Image Format Magnetic Tape

PROGRAM NUMBER: GSC-12705

DOMESTIC - DOCUMENTATION PRICE: $56.00    PROGRAM PRICE: $500.00

INTERNATIONAL - DOCUMENTATION PRICE: $112.00   PROGRAM PRICE: $1000.00



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