The Huygen's mission: Landing on Titan

 

Illustration of Huygens probe landed on the surface of Titan. Credit: NASA/ESA

Launch Date: October 15, 1997

Launch Site: Launch Complex 40 at Cape Canaveral Florida, United States

Launch Vehicle: Titan 401B-Centaur (TC-21/Titan 401 no. 4B-33)

Mission Type: Lander

Target: Titan

Dimensions: 2.7 Meters across

Mass: 335 Kilograms

Huygens was a lander probe built by the European Space Agency (ESA) and Italian Space Agency (ASI) as their contribution to NASA's Cassini mission. When Cassini approached Saturn, Huygens detatched and entered the atmosphere of Saturn's largest moon: Titan.

The Huygens Mission

Huygens was the first spacecraft to land on a moon in the outer solar system (in fact it was the first spacecraft to land on any moon in the solar system other than our own). It launched with the Cassini mission on October 15, 1997, on a Titan IV rocket (the rockets name has nothing to do with Saturn's moon).

Launch of Cassini-Huygens. Credit: NASA

Cassini-Huygens trajectory to Saturn. Credit: NASA

Huygens was attached to the side of the Cassini spacecraft for its journey to Titan. Cassini made a gravity assist of Venus on April 26, 1998.  Than a second Venus gravity assist on June 24, 1999. Cassini passed by Earth for another gravity assist on August 18, 1999. The two spacecraft reached Jupiter for their final gravity assist on  December 30, 2000. As Cassini apprached Saturn, it deployed the Huygens probe on Christmas day, 2004. Cassini adjusted its trajectory so it wouldn't collide with Titan, and so it could begin its science operations in the Saturn system.

Huygens landing video. Credit: NASA/ESA/DISR/Erich Karkoschka

Animation still of Huygens decending to Titan's surface. Credit: NASA/JPL

Huygens landng site (192.32 Degrees long, 10.25 Degrees lat). Credit: NASA/JPL/Cassini-ISS/Space Science Institute and ESO/NACO-SDI/VLT

Huygens landed on Titan on January 13-14, 2005, after a 2 hour and 27 minute decent. As it decended through the atmosphere, Huygens transmitted scientific data to Cassini, which relayed the information back to Earth. The lander first started taking atmospheric measurements at 1400 kilometres above the surface, all the way until it touched down. During the decent however, scientists found that Huygens was spinning the "wrong way."

 

To keep Huygens stable, it was set spinning anticlockwise at 7.5 rotations per minute. The probe then started speeding up its rotation when it entered the atmosphere. Then it somehow reversed its rotation 10 minutes into the decent. This rotation was later found to be induced by the antenna and seperation subsystems on the lander.

After landing, Huygens was able to take an image, along with many scientific measurements before its battery ran out 72 minutes later. The boulders in the image may look like rocks, but they are actually solid water ice tinted by methane and ethane.

Huygens image of Titan's surface. Credit: NASA/JPL/ESA/University of Arizona

The Target

Titan's Northern Hemisphere. Credit: NASA/JPL/Space Science Institute

• Date Discovered: 1655
• Radius: 2574.7 Kilometres
• Surface Pressure: 1.58 Atmospheres
• Atmospheric Composition: Nitrogen, Methane, Ethane, Ammonia, and Argon
• Mass: 1.34552523083241x10^23 Kilograms
• Density: 1.882 g/cm^3
• Rotational Period: 15.95 Days
• Orbital Period: 15.95 Days