View News Archive »


For Release: December 11, 2007

New Horizons Team to Talk Jupiter Science at AGU Fall Meeting

The New Horizons spacecraft’s spectacular flight past Jupiter earlier this year – which gave it a gravitational boost on the way to a 2015 encounter with Pluto – also provided an opportunity to test the instruments on the NASA probe while gathering new scientific data. Members of the New Horizons team will present findings from that encounter during the American Geophysical Union (AGU) Fall Meeting this week in San Francisco.

A combination of technology, trajectory and good timing allowed New Horizons to explore details that no spacecraft had seen before, such as lightning near Jupiter’s poles, the life cycle of fresh ammonia clouds in Jupiter’s atmosphere, the structure inside volcanic eruptions on Jupiter’s planet-sized moon Io, and the path of charged particles traversing the previously unexplored length of Jupiter’s long magnetic tail.

One AGU session will cover that flight down Jupiter's magnetotail, which gave the piano-sized New Horizons spacecraft an unprecedented look at the vast region dominated by the planet's strong magnetic field. In “Magnetotails of Jupiter and Saturn” on Dec. 13, Dr. David McComas of the Southwest Research Institute and Dr. Ralph McNutt of the Johns Hopkins University Applied Physics Laboratory will present recent analyses of these particle measurements. McNutt, McComas and Dr. Fran Bagenal of the University of Colorado will also discuss the measurements in a media briefing that same day at 10 a.m. PST.

“These are very exciting data because New Horizons is the first spacecraft to fly almost directly down Jupiter’s magnetotail,” says McComas, who serves as principal investigator of the New Horizons Solar Wind at Pluto (SWAP) instrument. “We are observing absolutely uncharted territory here.”

Looking specifically at the fluxes of charged particles that flow hundreds of millions of miles beyond the giant planet, the New Horizons particle detectors saw evidence that tons of material from Io’s volcanoes move down the tail in large, dense, slow-moving blobs. By analyzing the observed variations in particle fluxes over a wide range of energies and scales, New Horizons scientists are exploring how the volcanic gases from Io are ionized, trapped and energized by Jupiter's magnetic field, then ultimately ejected from the system.

New Horizons’ observations indicate that the dynamics of Jupiter’s magnetosphere are driven by the prodigious source of material from Io and by coupling to Jupiter's rapid spin. Jupiter's magnetosphere is roughly 100 times larger than Earth’s and encompasses the orbits of the planet’s four largest moons.

“This is a very different story from what we see at Earth, where the solar wind controls magnetospheric dynamics,” says McNutt, principal investigator of the New Horizons Pluto Energetic Particle Spectrometer Science Investigation instrument, or PEPSSI.

The “New Horizons and the Upheaval at Jupiter” session on Dec. 14 will include data from the spacecraft’s cameras. New Horizons’ visible light, infrared and ultraviolet remote-sensing instruments probed Jupiter’s atmosphere for data on cloud structure and composition. These sensors saw clouds form from ammonia welling up from the lower atmosphere and heat-induced lightning strikes in the polar regions – the first polar lightning ever observed beyond Earth, demonstrating that heat moves through water clouds at virtually all latitudes across Jupiter. They made the most detailed size and speed measurements yet of “waves” that run the width of the planet and indicate violent storm activity below.

New Horizons also snapped the first close-up images of the Little Red Spot, a storm about half the size of Jupiter’s larger Great Red Spot and about 70 percent of Earth’s diameter, gathering new information on storm dynamics.

The mission’s investigations of Jupiter’s four largest moons focused on Io; New Horizons spotted 11 different volcanic plumes of varying size, three of which were seen for the first time and one – a spectacular 200-mile-high eruption rising above the volcano Tvashtar – that offered a first-time opportunity to trace the structure and motion of the plume as it condensed at high altitude and fell back to the moon’s surface. In addition, New Horizons spotted the infrared glow from at least 36 Io volcanoes, and measured lava temperatures up to 1,900 degrees Fahrenheit, similar to many volcanoes on Earth.

Designed, built and operated by the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., New Horizons lifted off from Cape Canaveral Air Force Station, Fla., in January 2006. The fastest spacecraft ever launched, it needed just 13 months to reach Jupiter. New Horizons is now more than halfway between the orbits of Jupiter and Saturn, nearly 849 million miles (1.36 billion kilometers) from Earth. It will fly past Pluto and its three moons in July 2015 before heading deeper into the Kuiper belt of icy rocky objects on the planetary frontier.

New Horizons is the first mission in NASA’s New Frontiers Program of medium-class spacecraft exploration projects. Dr. Alan Stern of NASA Headquarters leads the mission and science team as principal investigator; APL manages the mission for NASA’s Science Mission Directorate. The mission team also includes Southwest Research Institute, Ball Aerospace Corporation, the Boeing Company, NASA Goddard Space Flight Center, NASA Jet Propulsion Laboratory, Stanford University, KinetX Inc. (navigation team), Lockheed Martin Corporation, University of Colorado, the U.S. Department of Energy, and a number of other firms, NASA centers, and university partners.

Preliminary results from the New Horizons flyby of Jupiter were published in the Oct. 12 issue of the journal Science. Links to those articles and related images are available on the New Horizons Web site at

Highlights from the New Horizons AGU presentations and briefings are below. For more information, visit

Press Conference: Jupiter’s Enormous Magnetosphere
Thursday, Dec. 13, 10 a.m. PST (1 p.m. EST), 2010 Moscone West
Presenters: Fran Bagenal, University of Colorado; Ralph McNutt, Johns Hopkins University Applied Physics Laboratory; David McComas, Southwest Research Institute.

Magnetotails of Jupiter and Saturn (Session SM44A)
Thursday, Dec. 13, 4 p.m. PST (7 p.m. EST), Moscone South-306
Invited papers: SM44A-01, New Horizons Plasma Observations of Jupiter's Magnetotail to >2,500 RJ, David McComas, Southwest Research Institute; SM44A-02, Energetic Particles in the Jovian Magnetotail, Ralph McNutt, Johns Hopkins University Applied Physics Laboratory.

New Horizons and the Upheaval at Jupiter (Session P53C)
Friday, Dec. 14, 1:40 p.m. PST (4:40 p.m. EST) Moscone South-102    
Invited papers: P53C-01, New Horizons At Jupiter: Overview Of Results, Jeff Moore, NASA Ames Research Center; P53C-02, New Horizons at Jupiter: From Polar Lightning to Equatorial Waves, Amy Simon-Miller, NASA Goddard Space Flight Center; P53C-03, Observations of Jupiter Supporting the New Horizons Encounter and During a Period of "Global Upheaval,” Glenn Orton, NASA Jet Propulsion Laboratory.

Media Contacts:

M. Buckley
Johns Hopkins University Applied Physics Laboratory

Dwayne Brown
NASA Headquarters, Washington                                                                                   

View The News Archives