ASTRONAUTS CAPTURE HIGH-RESOLUTION GLACIER IMAGERY
November 14, 2002More articles in ISS
David E. Steitz
Catherine E. Watson
Johnson Space Center, Houston
Russian researchers are studying images taken by the crew of the International Space Station to better understand the catastrophic glacier collapse and landslide that occurred on the northern slope of Mount Kazbek in September -- information that may help us better understand our home planet.
On Sept. 20, 2002, the collapse of a hanging glacier on the slope of Mount Dzhimarai-Khokh onto the Kolka glacier on Mount Kazbek triggered an avalanche of ice and debris that buried several small villages in the Russian Republic of North Ossetia. The avalanche killed dozens of people. Glacial debris dammed rivers and formed several lakes. One of these lakes flooded a village, and others are threatening to burst their new banks and form debris flows downstream.
Russian scientists at Moscow State University are using images taken by the crew aboard the Station to measure small changes near the glacier. "We can see a slight increase in the area of a new lake near the Kolka Glacier terminus," said Dr. Olga Tutubalina, a scientist at Moscow State University. "We first sighted this lake during our field trip on Oct. 5, and the lake surface has increased from Oct. 6 to 19. It is potentially dangerous, because it can produce disastrous outburst mudflows," she said.
The Russian investigators also include Moscow State University scientists Dr. Dmitry Petrakov, Dr. Victor Popovnin and Sergei Chernomorets. The Russian Foundation for Basic Research supports their activities. In September 2001, the team visited the Kolka Glacier to assess its state. After the recent collapse, the team conducted an analysis of images taken by the Station crew and then organized another field trip to gather additional information. They plan to continue monitoring the area using both satellite images and astronaut photography.
Dr. Lev Dessinov, of the Russian Academy of Sciences, collaborated with scientists at NASA's Johnson Space Center, Houston, to establish global glacier sites as a research topic for the Crew Earth Observations project. Dessinov was also part of the team of scientists called to the Kolka area immediately after the glacier collapsed. "We collected a lot of information and [NASA astronaut photographs] were one of our main data sources," Dessinov said.
The Expedition 5 crew, Commander Valery Korzun, Flight Engineer Sergei Treschev and NASA Station Science Officer Peggy Whitson, have been photographing this area since the beginning of the mission in June as part of the Russian URAGAN and U.S. Crew Earth Observations projects, which are studying changes in the world's glaciers. On Aug. 13, about one month before the glacier collapsed, the crew photographed the mountain. Although scientists have predicted the possibility of large glacial collapses, at the time of the first image, no one predicted that tragedy would strike the mountain village of Karmadon a little more than a month later. On a visit to the Station, Shuttle crewmembers photographed the aftermath of the collapse on Oct. 17. Station crewmembers then took a spectacular three-dimensional oblique image on Oct. 19.
The crew has been able to provide international scientists with images, such as those taken for the glacier researchers, by using motion compensation techniques developed by previous Station crews. Crewmembers can use high-magnification lenses to survey features around the world from their relatively low orbit, obtaining spatial resolutions as good as six meters. This means scientists can use photographs taken from the Station to study changes that are occurring in very small features on the Earth's surface. These images can augment satellite data, especially when astronauts take advantage of varying Sun angles on the landscape to capture three-dimensional views. This technique, which was used to take a photo of the glacier area on Oct. 19, provides imagery that is both visually spectacular and easy to interpret.
"The (Oct. 19) image gives us a rare opportunity to try and estimate the volume of the initial glacier collapse," said Chernomorets.
The first five Space Station crews have taken more than 41,000 images of the Earth using digital still cameras, 35 mm cameras, 70 mm cameras and a variety of lenses. Crewmembers are able to produce higher-resolution photographs with the high-magnification lenses by learning to compensate for the relative motion of the Earth below them as they point their cameras through a specially built window in the Station's Destiny laboratory.
The photographs of the Kolka glacier are on the Internet at: http://www.jsc.nasa.gov/images/eol/kolka.html
A searchable database containing more than 35 years of astronaut photography is also available at: http://eol.jsc.nasa.gov/sseop