Ulysses scores a hat-trick

February 7, 2007
Ulysses scores a hat-trick
This artist's impression shows the ESA-NASA Ulysses spacecraft. Launched in 1990, the European-built spacecraft visits both polar regions once every 6.2 years as it circles the Sun in an orbit that is almost perpendicular to the ecliptic, the plane in which the Earth and the planets move. Credits: ESA - image by C.Carreau

Today the joint ESA-NASA Ulysses mission has marked another high point in its mission. For the third time in a long and highly successful career, Ulysses has reached its maximum south solar latitude of 80 degrees as it flies over the Sun's southern polar cap.

Launched in 1990, the European-built spacecraft visits both polar regions once every 6.2 years as it circles the Sun in an orbit that is almost perpendicular to the ecliptic, the plane in which the Earth and the planets move.

Although originally designed for a mission lasting 5 years, the Ulysses space probe and its suite of 9 scientific experiments are still going strong after more than 16 years in orbit.

Operating the spacecraft has become more demanding over the years, however, as one consequence of the mission's longevity is a decrease in the electrical power available on board. "Ulysses uses a Radioisotope Thermoelectric Generator, or RTG for short, to generate the electricity needed for the spacecraft subsystems and science instruments", said Nigel Angold, ESA's Mission Operations Manager for Ulysses.

The RTG converts the heat produced by radioactive decay of its fuel into electrical power. "As a result of the decay process, the RTG output decreases with time", said Angold. In recent years, this has necessitated sharing the available power among the science instruments in such a way that key instruments are kept on permanently, while others are operated only part of the time.

Starting in May, as Ulysses comes closer to the Sun, one of the power-hungry heaters on board the spacecraft will be switched off. "This will free up sufficient power to have the full suite of instruments switched on during a key phase of the mission, the rapid transit from the south to the Sun’s north polar cap", said Richard Marsden, ESA's Ulysses Project Scientist and Mission Manager.

Source: ESA

Explore further: What is the asteroid belt?

Related Stories

What is the asteroid belt?

August 24, 2015

In the 18th century, observations made of all the known planets (Mercury, Venus, Earth, Mars, Jupiter and Saturn) led astronomers to discern a pattern in their orbits. Eventually, this led to the Titius–Bode law, which ...

Why don't we send probes "up" in the solar system?

July 10, 2015

Dammit, science people! Why are you always firing probes "outwards"? Then they have to go past all this stuff, like planets and asteroids and crap to escape the solar system. Don't you realize that if we want to see what's ...

Jupiter-bound craft runs into problem after flyby (Update)

October 9, 2013

NASA's Jupiter-bound spacecraft hit a snag Wednesday soon after it used Earth as a gravity slingshot to hurtle toward the outer solar system, but mission managers said it's on course to arrive at the giant planet in 2016.

Ames celebrates the 40th anniversary of Pioneer 10

March 1, 2012

Launched on March 2,1972, Pioneer 10 was the first spacecraft to travel through the Asteroid belt, and the first spacecraft to make direct observations and obtain close-up images of Jupiter. Famed as the most remote object ...

Recommended for you

How to prepare for Mars? NASA consults Navy sub force

October 5, 2015

As NASA contemplates a manned voyage to Mars and the effects missions deeper into space could have on astronauts, it's tapping research from another outfit with experience sending people to the deep: the U.S. Navy submarine ...

Researchers find a new way to weigh a star

October 5, 2015

Researchers from the University of Southampton have developed a new method for measuring the mass of pulsars – highly magnetised rotating neutron stars formed from the remains of massive stars after they explode into supernovae.

NASA selects investigations for future key planetary mission

October 1, 2015

NASA has selected five science investigations for refinement during the next year as a first step in choosing one or two missions for flight opportunities as early as 2020. Three of those chosen have ties to NASA's Jet Propulsion ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.