The Ulysses Mission
News story originally written on June 30, 1997

"..Come, my friends, tis not too late to seek a newer world."
-Tennyson in "Ulysses"

The Ulysses Mission is indeed seeking a newer world, a world that is encompassed by our Sun. Ulysses is a space mission designed to explore the unknown region of space above the poles of the Sun. It is the first spacecraft to explore space at high solar latitudes. Ulysses is a joint endeavor of the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA). The ESA provided the spacecraft and the operations team for the spacecraft. NASA launched the spacecraft on the Shuttle Discovery in October 1990. NASA is also responsible for radio communications and data management for the overall mission.

The Ulysses spacecraft flew by Jupiter in February 1992, for the gravity assist needed to place the spacecraft into its solar polar orbit. This high-latitude orbit allowed Ulysses to fly over the south pole of the Sun in 1994 and over the north pole in 1995.

The primary scientific objective of the Ulysses mission is to characterize the fields and particles of the Sun in relation to latitude, with particular emphasis on the regions above the poles. So Ulysses has been and will be investigating the solar magnetic field, solar wind plasma, and galactic cosmic rays coming from the Sun. Its instruments are geared toward studying these particular solar topics.

The phenomena being studied by the Ulysses mission are strongly influenced by the 11 year solar cycle. The primary mission which ended in September 1995, extended over half of the solar cycle. The secondary mission (or second pass around the Sun) makes coverage of the second half of a cycle possible. It is here at solar maximum that Ulysses will encounter solar flares, coronal mass ejections, and high-latitude streamers.

The Ulysses mission has already made many new findings concerning our knowledge of the Sun. For instance, our prior knowledge of the Sun suggested that the Sun had a dipolar magnetic field. In the dipolar model, field lines form closed loops except at the poles, where field lines are open and extend far into interplanetary space. Also in this model we know that field strength at the poles is twice that at the equator. But Ulysses has found that the dipolar model does not hold for the Sun. It seems that the magnetic field strength or flux is similar regardless of latitude. It is thought that immense pressure forces of the Sun take part to equally distirbute the solar magnetic flux.

The Ulysses mission is also participating in the GRB (Gamma Ray Bursts) study. Twice a day the Earth is blasted by pulses of gamma-rays. Since their discovery about 20 years ago, there have been over 100 suggested theories to explain these gamma-rays and their source. Ulysses stands as one component in an interplanetary network set up to trace the gamma-ray bursts. The network includes the Pioneer Venus Orbiter, the Compton Gamma-Ray Observatory spacecraft, Russia's GRANAT mission, the Japanese Yohkoh satellite, and the Indian SROSS-C mission. Ulysses' unique trajectory around the Sun will only aid in tracing the gamma-ray bursts with further accuracy.

With the first phase of its mission successfully completed, Ulysses is now in its second orbit of the Sun. This secondary phase will be finished in December 2001.

Last modified March 6, 2001 by Jennifer Bergman.

You might also be interested in:

Cool It! Game

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Helmet Streamers and the Magnetic Structure of the Corona

The gas in the solar corona is at very high temperatures (typically 1-2 million kelvins in most regions) so it is almost completely in a plasma state (made up of charged particles, mostly protons and electrons)....more

Ulysses Going Strong During Solar Maximum

The Ulysses space probe has begun to investigate the Sun during solar maximum. In September of 2000, Ulysses began to creep around the underside of the Sun. Ulysses has passed this way before, but during...more

Total Solar Eclipse - Coming Soon!

There is a solar eclipse coming to a theater near you! Well, Shakespeare said all the world's a stage, didn't he? There really will be a total solar eclipse on February 26th. The complete eclipse will...more

TRACING the Sun...

On March 30, 1998, the TRACE spacecraft will be launched. TRACE stands for Transition Region and Coronal Explorer. This spacecraft has four telescopes aboard that are sensitive to the extreme-ultraviolet...more

TRACING the Sun...

The TRACE spacecraft was launched April 1st at 9:42 p.m. EST from the central California coast. TRACE stands for Transition Region and Coronal Explorer. TRACE will operate in polar orbit about 400 miles...more

1999--A Year in Review...

It was another exciting and frustrating year for the space science program. It seemed that every step forward led to one backwards. Either way, NASA led the way to a great century of discovery. Unfortunately,...more

STS-95 Launch: "Let the wings of Discovery lift us on to the future."

The Space Shuttle Discovery lifted off from Kennedy Space Center at 2:19 p.m. EST, October 29th. The sky was clear and the weather was great as Discovery took 8 1/2 minutes to reach orbit for the Unitied...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA