Huygens probe reaches Saturn moon Titan, January 14, 2005
The probe was part of a European Space Agency (ESA) mission that launched from Earth on October 15, 1997. The probe separated from the Cassini orbiter on December 25, 2004. NASA's Jet Propulsion Laboratory assisted with navigation to the moon and landing.
Huygens’ landing was made near Titan’s Xanadu region and was the first landing ever accomplished in the outer solar system.
The probe was designed to gather data for a few hours in the atmosphere, and possibly a short time at the surface, depending on its state after landing. It continued to send data for about 90 minutes after touchdown, including photos.
The images taken after the probe's landing show a flat plain covered in pebbles. (See NASA image to right) The pebbles, which may be made of water ice, are somewhat rounded, indicating the action of fluids on them. Based on Titan’s estimated sunlight and rate of evaporation, it is believed that long droughts have been interrupted by sudden and torrential rains on the moon, causing flash flooding and quick surface changes.
At 1.3 meters across, the probe was too small to transmit directly back to Earth. The data it collected was sent to its orbiter, which then transmitted the data back to Earth.
Huygens was designed to enter and brake in Titan's atmosphere and parachute a fully instrumented robotic laboratory down to the surface.
The lab included a suite of sensors to measure the physical and electrical properties of Titan's atmosphere as well as gas chemical analyzers designed to identify and measure chemicals in Titan's atmosphere. Additional tools, including those to measure the wind speed in the atmosphere, were also on board.
The measurements were to be sent back to the Cassini orbiter over two channels, A and B. Unfortunately, the ESA announced an operational error that never commanded receiver A to be turned on. Therefore, half of the probe’s data transmitted to the orbiter was not received. A few persistent engineers had warned about a lack of testing prelaunch and discovered the flawed design of the communication equipment after launch.
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Editor's note: This article was originally posted on January 14, 2013 and edited on January 14, 2017.