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DPTRAJ/ODP - DOUBLE PRECISION TRAJECTORY ANALYSIS AND ORBIT DETERMINATION PROGRAM
Author and Affiliation:
Breckheimer, P. J.
Abstract: The Double Precision Trajectory Analysis Program, DPTRAJ, and the Orbit Determination Program, ODP, have been developed and improved over the years to provide the NASA Jet Propulsion Laboratory with a highly reliable and accurate navigation capability for their deep space missions such as VOYAGER. DPTRAJ and ODP are each collections of programs which work together to provide the desired computational results. DPTRAJ, ODP, and their supporting utility programs are capable of handling the massive amounts of data and performing the various numerical calculations required for solving the navigation problems associated with planetary fly-by and lander missions. They were used extensively in support of NASA's VOYAGER project. DPTRAJ produces a spacecraft ephemeris by numerical integration of the equations of motion, which can be formulated using a full set of acceleration models. For each particular trajectory case the extent of the modeling employed and the precision of the integration process are controlled by user input specifications. The equation of motion used includes four types of terms. An acceleration term accounts for the basic conic motion of the spacecraft with respect to the central body. Terms that measure the attraction of the perturbing bodies on the spacecraft and terms that indirectly affect the motion as perturbations on the central body may be included. Terms are also provided to account for other gravitational and non-gravitational effects on the motion. ODP's function is the processing of the observational data in order to compute precise estimates of the spacecraft, or lander, position coordinate histories. This function is executed by processing the observation data and auxiliary calibration information. ODP also computes a spacecraft state vector, or a lander position vector, along with parameters which define the acceleration. The heart of the ODP process is a data fitting subprocess in which validated, edited, and corrected observational data is transformed into a state vector estimate. The derived state vector estimate may then be used to generate an estimated trajectory. This trajectory contains the final product of the orbit determination process, which is the time evolution of the estimated spacecraft, or lander, position coordinates. DPTRAJ-ODP is written in FORTRAN V, SFTRAN, PL/I and ASSEMBLER for use on DEC VAX series computers running VMS, and has a central memory requirement of 3.4Mb. This program is available on a 1600 BPI 9-track magnetic tape in VAX BACKUP format. DPTRAJ and ODP were originally developed on a UNIVAC 1100 series computer. The VAX/VMS version was developed in 1987.
Publication Date: Jan 01, 1994
Document ID:
19940003159
(Acquired Dec 28, 1995)
Accession Number: 94M10702
Subject Category: ASTRODYNAMICS
Report/Patent Number: NPO-17201
Document Type: Computer Program
Publisher Information: United States
Financial Sponsor: Cal Tech/Jet Propulsion Lab.
Description: In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: No Copyright
NASA Terms: DPTRAJ-ODP; ORBITAL MECHANICS; ORBITAL POSITION ESTIMATION; SPACE NAVIGATION; TRAJECTORY ANALYSIS
Other Descriptors: FORTRAN 77(58%), SFTRAN3(41%), RAN 77(58%), T; DEC VAX SERIES
Miscellaneous Notes: Approximately 379,270 source statements
Availability Source: Other Sources
Availability Notes: Program $7,000.00
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