Fact sheet number: FS-2001-11-185-MSFC
Missions: Expedition Four, ISS Mission STS-110/8A Space Shuttle Flight, Return flight ISS Mission STS-111/UF-2
Experiment Location on ISS: Russian FGB Module
Principal Investigator: Dr. Alexander McPherson, University of California, Irvine
Project Manager: Raymond A. French, NASA's Marshall Space Flight Center in Huntsville, Ala.
The Enhanced Gaseous Nitrogen Dewar is a stainless steel and aluminum container assembly, similar to a thermos bottle, for carrying biological crystallization experiments aboard the Space Shuttle to the International Space Station. Approximately 500 plastic tubes, each containing a specific crystal-growth experiment, can fit inside the dewar assembly. The primary purpose of these experiments is to grow crystals of biological macromolecules in the low-gravity environment of space. These macromolecules include proteins, viruses and nucleic acids.
A low-gravity environment often improves the quality of biological crystals beyond those grown on Earth. Researchers expect these experiments to contribute to their understanding of the three-dimensional and chemical structure of proteins, viruses and nucleic acids. Knowledge of the precise three-dimensional molecular structure is an important component in biotechnology, particularly in the areas of protein engineering and rational drug design. The structural information obtained from crystals grown in space can be used to generate computer models of the biological macromolecules, and further advance the progress of biotechnology.
The Enhanced Gaseous Nitrogen Dewar is a vacuum-jacketed container with an absorbent inner liner saturated with liquid nitrogen. Before launch, the biological samples are frozen to -321 degrees Fahrenheit (-196 degrees Celsius), packed in an aluminum insert, placed in the dewar and stowed aboard the Space Shuttle. Once in orbit, the crew transfers the dewar from the Shuttle to the Space Station. During this time, the liquid nitrogen warms and boils off, changing to gas, and the samples begin to thaw. After about eight days, when the nitrogen has completely boiled off and thawing has completed, the crystallization process begins. The experiment is self-activating and does not require crew interaction while aboard the Space Station. The dewar and biological crystals will launch on STS 110 and will remain aboard the Space Station until the May 2002 ISS mission STS-111, when they will be returned to Earth for study.
The Enhanced Gaseous Nitrogen Dewar hardware is an upgrade from similar hardware and experiments flown on the Russian space station Mir. This earlier dewar version allowed the biological samples to crystallize over periods up to 140 days, but without temperature recording capability. These were flown to Mir on seven Shuttle-Mir missions -- STS-71, STS-74, STS-76, STS-79, STS-81, STS-84 and STS-89.
The enhanced dewar incorporates devices for recording the temperatures inside the dewar and storing the data. This enhanced dewar was delivered to the Space Station on the STS-106/2A2B mission in September 2000, the STS-98/5A mission in February 2001 and the STS-104/7A mission in July 2001.
The dewar is also used as a learning tool for scores of high school students from across the U.S. From 1999 to 2001, students prepared biological samples at workshops in Alabama, California, Florida and Michigan. The Enhanced Gaseous Nitrogen Dewar delivered the student samples to the Station during the three Space Shuttle missions mentioned above.
So far, samples prepared by over 230 students from classes at over 60 schools in six states have traveled to the Space Station and returned to Earth. The results are still preliminary, but some molecules have been crystallized for the first time. Crystals from many of the samples have been obtained with varying size and quality. Some of the higher quality crystals have been examined at synchrotron facilities. The X-ray diffraction patterns obtained from those crystals have been used for the determination of their three-dimensional structures.
Participating in the experiment on the STS-110 mission will be students from schools in California, Illinois, Indiana, Michigan, Ohio and West Virginia.
With science being performed on the International Space Station, scientists have more flexibility regarding the duration of flights on which to conduct structural biology experiments. This research will enable the more accurate mapping of the three-dimensional structure of biological macromolecules. Once the structure of a particular macromolecule is known, it may become much easier to determine its function. Proteins and other macromolecules play an important role in biochemical reactions in plants and animals. In order to better understand the basic processes of living things, scientists must first understand the structure and function of these macromolecules.
Additional information on the Enhanced Gaseous Nitrogen Dewar, biological crystal growth and other Expedition Four experiments is available at: