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Mission: Phobos
| Article
# : |
14291 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
7 / 1988 |
3,506 Words |
| Author
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Joann Temple Dennett
Joann Temple Dennett is a research associate of the office of
the associate vice president for research at the University
of Colorado. |
Glowing red as it shifts against the backdrop of the stars in the nighttime sky, Mars has fascinated people since they first began to observe the movements of celestial bodies. This fascination has continued into the era of spaceflight: In the first 25 years of planetary exploration, spacecraft laden with scientific instruments have left Earth for Mars 15 times. Images of giant mountains, planet-wide dust storms, and permanent ice caps whetted the public interest, much as scientific data on the Martian surface, atmosphere, plasma, and magnetic environments sharpened scientific curiosity.
Both public interest and scientific curiosity will be further satisfied as two Soviet spacecraft, each bearing more than 800 pounds of instrumentation, get ready to explore Mars and its nearer moon Phobos. The Soviet Phobos mission marks a number of firsts--the first space laser experiment to sample a celestial body, the first to land on a Martian moon, and the first planetary exploration mission to take advantage of the 1987 Space Cooperative Agreement between the Soviet Union and the United States.
The Soviet Phobos mission is truly an international effort. Scientists from Austria, Bulgaria, Czechoslovakia, East and West Germany, France, Hungary, Poland, Sweden, and the European Space Agency have instruments and coexperiments aboard the spacecraft. Although no U.S. hardware is aboard, a number of U.S. scientists are cooperating on both the interdisciplinary planning level and as coinvestigators on specific experiments.
Captive Asteroid
Primarily on a Mars mission, both Phobos spacecraft will nonetheless be busy during their flights to Mars. Instruments will study cosmic rays, the solar wind, and the Sun during the 200-day-long flight. However, the major mission objective is Phobos, the cratered, rock-like moon (egg-shaped, 17 by 13 by 12 miles) that whips around Mars more than three times each Earth day. In orbit around Mars, Phobos and its brother moon Deimos (nearly 10,000 miles farther out) both turn only one side toward Mars. Their orbits are practically circular and are close to the Martian equatorial plane. Phobos is about 5,800 miles from Mars and is apparently moving closer to the planet. In contrast, Deimos is very slowly moving away from it. Some scientists estimate that Phobos will fall into Mars in the next 30 to 70 million years.
If this is true, it is possible that Mars once had many small satellites of which only
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