Ulysses (spacecraft) - Results

Results

During cruise phases, Ulysses provided unique data. As the only spacecraft out of the ecliptic with a gamma-ray instrument, Ulysses was an important part of the InterPlanetary Network (IPN). The IPN detects gamma ray bursts (GRBs); since gamma rays cannot be focused with mirrors, it was very difficult to locate GRBs with enough accuracy to study them further. Instead, several spacecraft can locate the burst through triangulation (or, more specifically, multilateration). Each spacecraft has a gamma-ray detector, with readouts noted in tiny fractions of a second. By comparing the arrival times of gamma showers with the separations of the spacecraft, a location can be determined, for follow-up with other telescopes. Because gamma rays travel at the speed of light, wide separations are needed. Typically, a determination came from comparing: one of several spacecraft orbiting the Earth, an inner-Solar-system probe (to Mars, Venus, or an asteroid), and Ulysses. When Ulysses crossed the ecliptic twice per orbit, many GRB determinations lost accuracy.

Additional discoveries:

• Ulysses discovered that the Sun's magnetic field interacts with the Solar System in a more complex fashion than previously assumed.
• Ulysses discovered that dust coming into the Solar System from deep space was 30 times more abundant than previously expected.
• In 2007-2008 Ulysses determined that the magnetic field emanating from the Sun's poles is much weaker than previously observed.
• That the solar wind has "grown progressively weaker during the mission and is currently at its weakest since the start of the Space Age."