PREFACE

The objective of this report is to present in tabular and graphical form information on the trajectories of the international fleet of spacecraft that will be probing the far reaches of the heliosphere during the 1990s. In particular, the following spacecraft are addressed.
                           Pioneer 10 and 11
                           Pioneer Venus Orbiter (PVO)
                           Voyager 1 and 2
                           Galileo
                           Ulysses
                           Suisel, Sakigake
                           Giotto
                           International Cometary Explorer (ICE)
                           Interplanetary Monitoring Platform 8 (IMP 8)

Yearly resolution listings of position information in inertial space are given for the Pioneer and Voyager spacecraft from the times of their launches in the 1970s. Monthly resolution listings of parameters relative to a fixed Earth-Sun line are given for the inner-heliosphere spacecraft. Algorithms are given for the inertial space positions of Earth (IMP 8) and Venus (PVO) and for the Earth-Sun-Venus angle.

One series of plots shows the radial distances, latitudes, and longitudes of the Pioneers and Voyagers. The longitude plot of this series also shows the excursion of the Earth in ecliptic longitude each year. A Ulysses-dedicated plot is next given, showing at monthly resolution the latitude and radial distance excursion over the 1990s. Then a series of four plots, each covering successive three-year intervals, shows the Earth-Sun-spacecraft angles for all the spacecraft addressed in the report. Finally, two plots show the ICE and Sakigake trajectories in fixed Sun-Earth line systems, from their launches to their 2014 (ICE) and 1992 Earth vicinity returns, and one cartoon shows the Ulysses spacecraft from 1990 launch through 1992 Jupiter encounter to the 1994 and 1995 south and north solar pole passes.

The solar ecliptic inertial coordinate system is used in this report. In this system, the Z axis is normal to the ecliptic plane and the X axis is towards the first point of Aries (from Earth to Sun on the vernal equinox). In addition, hellographlc latitudes are also used, which are latitudes defined relative to the solar equatorial plane and solar spin vector.

This report is a follow-up to a 1986 National Space Science Data Center (NSSDC) report that listed and plotted heliospheric spacecraft trajectory information for the 1970s and 1980s. That report was Trajectories of Pioneers 6-1 1. Helios A and B, and Voyagers 1 and 2 (NSSDC report 86-03, 1986) and is available, as are additional copies of this report, by request to the NSSDC Coordinated Request and User Support Office (301-286-6695; NCF::REQUEST).

On-Line Files

In addition to the plots and listings of the report mentioned above, NSSDC also makes available on- line files with dally resolution of 1989- l999 trajectory information (Cartesian) for those users for whom the lower resolution information of this report, or the coordinates used herein, are unsuitable. One of the files Is an executable code; the Interface offered to users enables the specification of the spacecraft. the time resolution of the output listing, and the parameters to be listed (available parameters are radial distance. solar ecliptic latitude and longitude, and heliographic latitude and longitude).

The on-line files were created by the several NSSDC codes from the ephemeris tapes generated at the Flight Dynamics Branch, Goddard Space Flight Center (GSFC), by running the GTDS code against sets of orbital elements for the various spacecraft involved. The files are presently held in an ANONYMOUS account on an NSSDC VAX. They may be copied to Individual VAX accounts using the command

COPY NSSDCA: :ANON_DIR: [ACTIVE.HELIO]FILE.NAME FILE.NAME

An annotated 11st of precomputed files and a brief description of the executable code (executable from DECnet nodes only) are available in a file named JHK.RP, This file should be copied first and read via

COPY NSSDCA: :ANON_DIR: [ACTIVE.HELIO]JHK.RP FILE.LIST.

Those in nodes other than DECnet may access files via FTP as follows: At the prompt, type FTP NSSDCA. GSFC. NASA. GOV At the next prompt, type ANONYMOUS At the message PASSWORD ( NS SDCA . GSFC . NASA. GOV: ANONYMOUS ):, press return. At the next prompt, type GET ANON _ DIR: [000000 .ACTIVE. HELIO] JHK. RP FILE. LIST ([here are six zeros in this response.) At the following prompt, type QUIT

NSSDC offers many data and services via its no-password NODIS account, which is accessible over DECnet via SET HOST NSSDCA, USERNAME=NSSDC. It is probable that after some time the deep space trajectory files described herein and now held in the ANONYMOUS account will be moved to the NODIS account.

Acknowledgment

The authors appreciate the untiring efforts of Frank Ferrier for providing the final versions of the GIDS ephemeris tapes (IBM binary). John Vanderpool enabled VAX ASCII versions of them. The Jet Propulsion Laboratory has been the main source for the orbital element set collection used.

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