News and commentary about the Great Frontiers

ISS007-E-10807 (21 July 2003) --- This view of Earth's horizon as the sunsets over the Pacific Ocean was taken by an Expedition 7 crewmember onboard the International Space Station (ISS). Anvil tops of thunderclouds are also visible. Credit: Earth Science and Remote Sensing Unit, NASA Johnson Space Center

Image Credit: ISS007-E-10807 (21 July 2003) – Earth Science and Remote Sensing Unit, NASA Johnson Space Center

Titan’s Surface in Color



Dr. Lyn Doose, Co-Investigator of the Descent Imager-Spectral Radiometer (DISR) instrument on the Huygens probe, presented to a packed crowd tonight at the University of Arizona’s Kuiper Space Sciences Building the first scientific results from Friday’s successful landing on Titan. Highlights of his speech included the display of the first images from the surface of Titan, revealing an orange-color world with a thick atmosphere, rock-like pebbles likely composed of ice, and evidence for rivers and seas of liquid methane or ethane.

The DISR instrument was designed to photograph images as the probe descended by parachute through Titan’s atmosphere before impacting the ground. Dr. Doose stated that he had not been confident that the probe would survive the impact and was surprised that Huygens continued to take images for at least a half hour after it came to rest on the surface. According to Dr. Doose, other surprises include the buffeting Huygen’s took during descent by Titan’s winds, apparent images of methane fog, and the terrain that makes Titan look more like the Earth than other moons in our solar system.

The first color image was created by combining reflective spectra data compiled by Dr. Doose and a colleague with a black and white image previously released by the European Space Agency (ESA). The image depicts the color a human would see from the surface of Titan. Titan has a thick atmosphere of nitrogen and methane, which contribute to the color. The image also shows pebble-sized chunks of rock, likely made out of water ice. The roundness of the pebbles suggests deposition by fluvial processes, perhaps by flows of liquid methane.

During the question-and-answer session that followed Dr. Doose’s talk, a young boy asked what the planet would smell like. Dr. Doose answered that methane is odorless, though other hydrocarbons present in the atmosphere of Titan might contribute to a distinctive smell. He said that because methane is odorless, companies here on the Earth that supply natural gas (of which methane is a primary component) must add a signature odor as a safety measure so that people can smell a leak.

Entitled “Descending to a New World”, the free public event was sponsored by the Planetary Image Research Laboratory (PIRL) and the Department of Planetary Science Lunar and Planetary Laboratory (LPL) at the University of Arizona through LPL’s public outreach program. Guests included members of the team from Lockheed Martin, the company that built DISR. Because of the unexpectedly high public turnout, organizers scrambled to set up a second projector in the atrium outside the auditorium within which Dr. Doose spoke. Waiting for the first images from Titan to be displayed on the screen, people stood shoulder-to-shoulder on several floors of the atrium. A follow-up presentation entitled “New Discoveries on Titan” is planned for next Saturday in the same location.

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