SRI International Makes First Observation of Atomic Oxygen Emission in the Night Airglow of Venus.Business Editors/Science Writers MENLO PARK Menlo Park. 1 Residential city (1990 pop. 28,040), San Mateo co., W Calif.; inc. 1874. Electronic equipment and aerospace products are manufactured in the city. Menlo College and a Stanford Univ. research institute are there. 2 Uninc. , Calif.--(BUSINESS WIRE)--Jan. 18, 2001 Science Magazine Details SRI's Extra-Terrestrial Atmospheric Discoveries in its January 19, 2001 Issue SRI International (company) SRI International - One of the world's largest contract research firms. Founded in 1946 in conjuction with Stanford University as the Stanford Research Institute, they later became fully independent and were incorporated as a non-profit organisation under U.S. , a leading research institute based in Silicon Valley, reported the first observation of visible light emitted by oxygen atoms in the night-side airglow airglow, faint diffuse illumination of the night sky originating in the upper atmosphere. The energy in the form of visible light is derived from the sun's ultraviolet light, which ionizes atoms and dissociates molecules at heights between 40 and 200 mi (64–322 ("nightglow night·glow n. Airglow occurring at night. ") of Venus. Published in the January 19, 2001 issue of the journal Science, this novel study of a non-Earth atmosphere provides new insight into the atmosphere of Venus Venus, the second planet from the Sun, has an atmosphere very different from that of Earth. In comparison to Earth it is much denser, heavier, and extends to a much higher altitude. and the composition and chemical interactions taking place in the absence of sunlight. Although much is known about the earth's nightglow, in the visible spectral region there is very limited information concerning Venus or Mars. With the recent discoveries of planets circling other suns, the time may come when it will be possible to view the emissions from these planets and compare them to what is known about our own solar system solar system, the sun and the surrounding planets, natural satellites, dwarf planets, asteroids, meteoroids, and comets that are bound by its gravity. The sun is by far the most massive part of the solar system, containing almost 99.9% of the system's total mass. . Earth-based Look at Venus is a Hundred-fold Improvement Over 1975's Orbiters The W. M. Keck telescope and the associated HIRES spectrometer on Mauna Kea Mauna Kea (mou`nə kā`ə), dormant volcano, 13,796 ft (4,205 m) high, in the south central part of the island of Hawaii. It is the loftiest peak in the Hawaiian Islands and the highest island mountain in the world, rising c. , Hawai'i were used by SRI researchers in the Molecular Physics Laboratory to obtain unprecedented detail of the terrestrial nightglow. These results prompted Drs. Tom G. Slanger, David L. Huestis, Philip C. Cosby, and collaborator Thomas A. Bida (currently at Lowell Observatory) to pursue the investigation of the visible nightglow on the dark side of Venus. The only previous measurement was done by the Russian Venera 9/10 orbiters in 1975, with a spectral resolution 100 times inferior to that of Keck-HIRES. One of the most prominent features in the terrestrial nightglow is the 5577-angstrom atomic oxygen green line, first detected by A. J. Angstrom angstrom (ăng`strəm), abbr. Å, unit of length equal to 10−10 meter (0.0000000001 meter); it is used to measure the wavelengths of visible light and of other forms of electromagnetic radiation, such as ultraviolet in 1868, then quantified by Lord Rayleigh in 1930. The Venera probes found this emission to be absent in the Venus nightglow. The apparent difference between the terrestrial and Venusian visible nightglows has been attributed to the different atmospheric compositions: oxygen and nitrogen for the earth, carbon dioxide carbon dioxide, chemical compound, CO2, a colorless, odorless, tasteless gas that is about one and one-half times as dense as air under ordinary conditions of temperature and pressure. and nitrogen for Venus. Initial Discoveries May Inspire Future Extra-Terrestrial Atmospheric Studies Measurements to record the nightglow of Venus were carried out with the Keck telescope just before sunrise on November 20, 1999. Analysis of the resultant spectrum at the position of the oxygen green line showed strong emission from the terrestrial atmosphere and a comparable signal from Venus, with an intensity some 25 times greater than the upper limits set by the Venera results. Further measurements will be needed to determine if the Venus atmosphere really exhibits such large variations in green line intensity. Until the present result, the claim could be made that the nightglow green line is only associated with planets with molecular oxygen in their atmospheres. Now there is evidence that this is not the case. Therefore the green line is not an effective diagnostic for atmospheric molecular oxygen, but only indicates the presence of oxygen atoms. Mars is a potential target for similar observations, which will help to develop a more coherent picture than presently exists of the nightglows of all three planets. The research was funded by the Planetary Astronomy section of NASA NASA: see National Aeronautics and Space Administration. NASA in full National Aeronautics and Space Administration Independent U.S. . About SRI International Menlo Park-based SRI International (www.sri.com) is one of the world's foremost independent research and technology development organizations. Founded in 1946 as Stanford Research Institute Stanford Research Institute - Former name of SRI International. , SRI has been meeting the strategic needs of global markets for more than 50 years. As part of its strategy to bring its high-value innovations to the marketplace, SRI licenses its technologies, forms strategic partnerships, and creates spin-off companies. SRI's Molecular Physics Laboratory is known worldwide for its fundamental and applied research in collisional and radiative processes involving ions, atoms, and molecules. The group helps clients resolve key problems in areas ranging from lasers to planetary atmospheres and plasmas. |
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