NSSDC has now produced the third volume of the trajectories of heliospheric spacecraft. The first volume, published in 1986, provided trajectory-related plots in the ecliptic plane of the then-operational eight spacecraft for the years from launch through 1989. The second volume, published five years later, extended the trajectory-related plots or lists to the year 2000, in ecliptic as well as heliographic coordinates for the 12 spacecraft expected to be operational until 2000. It also carried plots for quick-look identification of time intervals when pairs (or more) of spacecraft are radially aligned with the Sun.
The newly published third volume addresses trajectories of those spacecraft that may remain operational from 2000 to 2015: primarily Voyager 1 and 2 and Ulysses with some information for Galileo, Near Earth Asteroid Rendezvous (NEAR), and Cassini. The information includes radial distance, heliographic latitude, ecliptic longitude, and Earth-Sun-probe angle. As a special case Ulysses is also radially projected onto the Sun's visible disk (as seen by Earth observers) and its invisible counterpart. These radial projections will be useful for quick-look selection of Ulysses data (solar wind, B-Field, and energetic particles) with respect to observed features on the Sun. More decisive identification could then be readily made by invoking the measured solar wind speed and its delay time.
Examples of trajectories available in the new trajectories book.
Visible in the plots and listings are the eight solar polar passes of Ulysses in the pre-2015 period and the attainment of heliocentric distances of 133 AU and 110 AU by Voyager 1 and Voyager 2, respectively, by the end of 2015. (1 AU is the mean distance between the Earth and the Sun, about 150,000,000 km.)
All three of the volumes are now accessible through the URL http://nssdc.gsfc.nasa.gov/space/helios/heli.html, which also provides long-standing capabilities for user-specified heliospheric trajectory determination for many spacecraft and natural bodies.
Erin D. Gardner, firstname.lastname@example.org, (301) 286-0163
Hughes STX, Code 633, NASA Goddard Space Flight Center
Greenbelt, MD 20771, U.S.A.