What Is a Ground Detector?

The Ulysses probe was launched by the US space shuttle Discovery on October 6, 1990, flying to Jupiter and the Sun. This mission is a joint program of NASA (NASA) and ESA (European Space Agency), which aims to detect the sun and Jupiter ^[1] .

In the late 1970s, NASA and ESA decided to build a spacecraft for international solar polar ecliptic out-of-plane exploration (ISPM) missions. This mission was originally scheduled for 1983, but has been repeatedly delayed due to the delay in the development of the space shuttle. Until the launch of Ulysses, eight changes were made.

In 1984, the United States cancelled its commitment to provide a spacecraft for this cooperative program, which largely canceled the scientific nature of the entire mission and dampened the European space program personnel who have been working for this project for years. In addition, NASA also said that the launch time of the European Ulysses spacecraft was postponed to 1986.

Soon, in January 1986, the Challenger incident occurred, which caused the launch date to be postponed again and was not launched until the second half of 1990. After the Challenger incident, the choice of the upper stage of the shuttle changed from the upper stage of the low-temperature Centaur to the two-stage inertial upper stage with the PAM third stage.

In 1988, ESA renamed the mission to the Ulysses detection vehicle based on Greek mythology. Legend has it that Ulysses has traveled beyond the sun to explore the uninhabited world of humans ^[1]

On November 18, 2006, the European Space Agency (ESA) released news that the ESA-NASA joint implementation of the Ulysses mission reached another important milestone on November 17: the third pass through the solar South Pole .

Ulysses was made in Europe and launched in 1990 to detect heliospheres, the air bubbles blown out by the solar wind. Due to the unpredictable nature of the Sun, the third visit will undoubtedly reveal new and unexpected properties of our star.

The first polar crossing occurred in 1994 (Antarctica) and 1995 (Arctic) low solar activity years, while the second occurred in 2000 and 2001 high solar activity years. According to ESA's Ulysses project scientist and mission manager Richard Marsden, "A well-sorted heliosphere was found during the first crossing, and the solar wind in the polar regions was significantly different from the solar wind in the equator. And in the high solar activity It is more complicated and it is difficult to distinguish specific areas from others.

By the time Ulysses reached the polar region for the third time, the sun had quietened again and was approaching a low year of activity. Marsden said, "Ulysses orbits the sun every 6.2 years, which is very suitable for studying the 11-year solar cycle. In fact, Ulysses is exploring the heliosphere in four dimensions, and three-dimensional space plus time."

Ulysses is also an important member of the Heliosphere Detector Fleet, which includes the Solar and Heliosphere Observatory (SOHO), NASA's Advanced Composition Detector (ACE), Wind, and Traveler Spacecraft. Recently, the network added two new members, two twin "Sun-Earth Relationship Observatory" (STEREO) launched by NASA at the end of October. During Ulysses's Antarctic-Arctic flyover in 2007, joint observations using STEREO, ACE and SOHO will be exciting.

Illustration of the third polar orbit of Ulysses. The Ulysses probe was launched in 1990 and first passed through the South Pole and the North Pole when solar activity was low in 1994 and 1995; it passed the solar pole when the solar activity was high in 2000 and 2001. ^[3]