NASA and the European Space Agency are about to pull the plug on a robotic solar probe that just wouldn’t quit. The Ulysses probe was launched from the space shuttle Discovery in 1990. It was supposed to last five years. But it’s now nearing 19 years, 5.8 billion miles and still going.
Sixteen months ago, the two space agencies announced that Ulysses was freezing up and about to die in a matter of weeks. Somehow it kept operating, sending important science information about an extraordinarily quiet year for the sunspots and solar wind.
That will end on Tuesday when the space agencies turn off Ulysses’ transmitter. Officials say issues with power, location and antennas make it no longer useful.
The solar probe Ulysses was decommissioned on June 30, 2009, when ground controllers at NASA’s Jet Propulsion Laboratory issued final commands to switch off its transmitter and shift to low-gain antennas, ending all communication.
This “going dark” marked the natural conclusion of the mission due to declining RTG power output (from ~285 W at launch to critically low levels), which could no longer sustain heaters to prevent hydrazine fuel from freezing or power all instruments simultaneously. Earlier predictions had forecasted an end in 2008, but the spacecraft’s resilience allowed an extra year of data collection.
