Space / Astronomy

  1. Home
  2. Education
  3. Space / Astronomy

Ulysses Mission to the Sun - Jupiter - Comets

From Asif A. Siddiqi; NASA/JPL, for About.com

See More About:

Artist's Rendition of Ulysses

Artist's Rendition of Ulysses

NASA
  • Organization/Nation: ESA and U.S. (1)
  • Objective(s): heliocentric orbit
  • Spacecraft: Ulysses
  • Spacecraft Mass: 371 kg
  • Mission Design and Management: ESA and NASA JPL
  • Launch Vehicle: STS-41 Atlantis
  • Launch Date and Time: 6 October 1990 / 11:47:16 UT
  • Launch Site: ETR / launch complex 39B
Scientific Instruments:
  1. BAM solar wind plasma experiment
  2. GLG solar wind ion composition experiment
  3. HED magnetic fields experiment
  4. KEP energetic-particle composition/ neutral gas experiment
  5. LAN low-energy charged-particle composition/anisotropy experiment
  6. SIM cosmic rays and solar particles experiment
  7. STO radio/plasma waves experiment
  8. HUS solar x-rays and cosmic gamma-ray bursts experiment
  9. GRU cosmic dust experiment
Key Dates & Milestones:
  • 10.06.90: Launch (11:47:16 UT)
  • 02.08.91: 1st Jupiter Gravity Assist
  • 06.26.94 - 11.05.94: 1st South Polar Pass
  • 03.13.95: 1st Ecliptic Crossing
  • 06.19.95 - 09.29.95: 1st North Polar Pass
  • 05.01.96: End of Comet Mission
  • 02.04.04: 2nd Jupiter Gravity Assist
  • Status: Returning to the Sun
Results: The Ulysses mission was an outgrowth of the abandoned International Solar Polar Mission (ISPM) that involved two spacecraft flying over opposite solar poles to investigate the Sun in three dimensions.

Eventually, ESA built a single spacecraft for launch on the Space Shuttle. The vehicle was designed to fly a unique trajectory that would use a gravity-assist from Jupiter to take it below the elliptic plane, past the solar south pole, and then above the elliptic to fly over the north pole.

Eventually, thirteen years after ESA's science council had originally approved the mission, Ulysses was sent on its way via a Shuttle/PAM-S motor combination. Escape velocity was 15.4 kilometers per second, higher than had been achieved by either of the Voyagers or Pioneers, and the fastest velocity ever achieved by a humanmade object.
After a midcourse correction on 8 July 1991, Ulysses passed within 378,400 kilometers of Jupiter at 12:02 UT on 8 February 1992. After a seventeen-day period passing through and studying the Jovian system, the spacecraft headed downwards and back to the Sun.
From about mid-1993 on, Ulysses was constantly in the region of space dominated by the Sun's southern pole, as indicated by the constant negative polarity measured by the magnetometer. South polar observations extended from 26 June to 6 November 1994, when the vehicle was above 70° solar latitude. It reached a maximum of 80.2° in September 1994. Its instruments found that the solar wind blows faster at the south pole than at the equatorial regions.
Flying up above the solar equator on 5 March '95, Ulysses passed over the north polar regions between 19 June & 30 Sep. 1995 (maximum latitude of 80.2°). The closest approach to the Sun was on 12 March 1995 at a range of 200 million km. ESA officially extended Ulysses's mission on 1 Oct 1 1995, renaming this portion as the Second Solar Orbit. The spacecraft made a second pass over the south pole between Sep 2000 and Jan 2001, and it made a pass over the northern pole in Oct 2001.
In October 2000, ESA announced that Ulysses had discovered the most distant gamma-ray burst yet recorded, about 11 billion light years from Earth. At that time, the Sun was at the peak of its eleven-year cycle.

ESA's Science Programme Committee, during a meeting on 5-6 June 2000, agreed to extend the Ulysses mission from the end of 2001 to 30 September 2004.

Destination Sun: Ulysses is the first spacecraft to study the unexplored region of space above our Sun's poles.

The spacecraft was launched aboard the Space Shuttle Discovery and sent towards Jupiter with powerful booster rockets. After studying Jupiter for 17 days, Ulysses used the giant planet's gravity to hurl it into an orbit out of the Ecliptic Plane, where planets orbit our Sun. No manmade vehicle has the power to break out of the ecliptic plane, but with the help of Jupiter's powerful gravity Ulysses settled into an orbit that allows it to fly over the Sun's polar regions.

Now well into an extended mission, Ulysses continues to send back valuable information on the inner working of our star, especially its magnetic field and how it influences our solar system.

Destination Jupiter: Ulysses main focus is the polar regions of the Sun. But since no rocket engines are powerful enough to boost the spacecraft above the Ecliptic Plane (where most planets and spacecraft orbit the Sun), Ulysses used Jupiter's gravity to hurl it onto the correct trajectory.

During the Jupiter flybys, scientists use Ulysses' instruments to study the giant planet and its influence on the solar system, which is second only to the Sun.

Comet Encounter: Ulysses unexpectedly encountered the tail of comet Hyakutake in May 1996. At the time, Hyakutake's nucleus was close to the Sun - more than 525,000,000 km (326,000,000 miles) away. The measurement was the longest comet tail ever recorded.

The discovery revealed comet tails - streams of ions, gas and dust extending away from the Sun - were much longer than previously believed.

Explore Space / Astronomy

About.com Special Features

Browse All About.com

Space / Astronomy

  1. Home
  2. Education
  3. Space / Astronomy
  4. Missions to Space
  5. Ulysses Mission
  6. Ulysses Mission to the Sun - Jupiter - Comets

©2009 About.com, a part of The New York Times Company.

All rights reserved.