RIP: Ulysses Spacecraft

After almost 17 years in orbit, the Ulysses spacecraft (launched from the space shuttle Discovery on October 6, 1990) suffered a fatal altitude-control system defect and was forced to end its mission on June 30th. The satellite was originally designed to study the solar wind and interstellar dust from an orthogonal orbit around the sun's poles over a 5-year period. It has been called "one of the most productive science missions ever flown."

Here are a few of the scientific gems we got from Ulysses:

• Extended knowledge of the sun's influence on its surroundings through its outflowing solar wind from two dimensions into three
• The sun's magnetic field can capture charged particles ejected from the sun's poles and redirect them toward Earth and the other planets
• Created a massive change in the way we think about the global structure of the solar wind and the sun's magnetic field
• Found a surprising amount of neutral helium atoms arriving from deep space in interstellar dust--a find from which scientists have deduced that the universe contains too little matter to halt its expansion. And the spacecraft found that the dust itself was 30 times more abundant than expected.