First Results from VLBA Astrometry of Juno
Abstract
We have used the Very Long Baseline Array (VLBA) to determine precise positions of the Juno spacecraft during its approach to Jupiter and during its third perijove pass after orbit insertion. VLBA observations will continue during several perijove passes until the end of Juno’s mission. The orbit of Juno about Jupiter is most accurately determined by Doppler tracking near perijove, allowing our Juno position measurements to be transferred to the Jupiter system barycenter. We use angularly nearby extragalactic radio sources with known positions in the International Celestial Reference Frame as phase reference sources during VLBA observations to obtain accurate positions for Jupiter in an inertial reference frame. The planned series of Jupiter position measurements will be used to improve the accuracy of Jupiter’s orbit in the JPL planetary ephemeris. The improvement is most dramatic in orbit inclination and ascending node; spacecraft ranging provides the best constraints on semi-major axis and eccentricity. Similar VLBA observations of the Cassini spacecraft orbiting Saturn during the past decade have improved our knowledge of Saturn’s orbit by nearly an order of magnitude, and we expect a similar improvement for Jupiter. This research is partially funded by a grant from NASA’s Planetary Astronomy program to the Space Science Institute, Boulder, CO. Part of this work is being carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. The Long Baseline Observatory and the National Radio Astronomy Observatory are facilities of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
- Publication:
-
American Astronomical Society Meeting Abstracts #230
- Pub Date:
- June 2017
- Bibcode:
- 2017AAS...23010308J