[This text is based on stories from the Associated Press and an announcement from the Society for Planetary SETI Research.]
Succeeding in a critical set of maneuvers that apparently destroyed its predecessor Mars Observer in 1993, the Mars Global Surveyor went into a highly eliptical polar orbit around the Red Planet late Thursday afternoon (California time), September 11, 1997
The orbit was designed to bring the spacecraft slightly into the planet's atmosphere on each round, utilizing a technique called aerobraking to gradually adjust the orbit to an almost perfect circle within about four months. This technique, though tricky, eliminates the need for a great deal of extra fuel and is one of several ways the mission was designed to accomplish more on a smaller budget.
Mars Global Surveyor, launched on November 7, 1996, carries scientific instruments salvaged from a backup copy of the much more elaborate and costly Mars Observer. The failed Observer mission cost an estimated 1 billion dollars. Global Surveyor will cost about 20% of that amount, but can ideally accomplish about 75% of Observer's mission goals.
Global Surveyor's successful orbital insertion on September 11 means that NASA remains on a roll that began with the spectacular July 4 touchdown of the Pathfinder spacecraft on the Martian surface.
NASA now plans to dispatch pairs of orbiters and landers to Mars every 26 months.
"We are at Mars to stay," exulted NASA's Wesley T. Huntress Jr. at the Jet Propulsion Laboratory in Pasadena, California, after Global Surveyor went into orbit.
The spacecraft's first orbit of Mars took about 45 hours, but as it shrinks and becomes circular, the duration of each orbit will drop to about two hours. Its polar orientation will allow it to photograph and map every square inch of the Martian surface, using a variety of sensors, during its more than two year active mission.
Data collected by Global Surveyor is expected to create the foundation for an extended program of Mars exploration, as scientists search for signs that life once existed on Mars, or perhaps might exist even today.
A group of scientists who have specialized in analyzing controversial photographs of the Cydonia region of Mars are especially hopeful that the Global Surveyor will perform up to expectations. If so, it could return photos that will settle once and for all whether the famous "face" and "pyramid" landforms at Cydonia are natural surface features, or artificial structures.
In a press announcement released on Friday, September 12, the Society for Planetary SETI Research (SPSR) praised NASA for reaffirming on Thursday that the Global Surveyor would "definitely" take detailed pictures of the controversial Cydonia region.
NASA chief administrator Daniel Goldin has previously given several public assurances that the Cydonia region will be rephotographed. SPSR scientists remain concerned, however, that only certain kinds of photos from the most powerful of the spacecraft's three optical cameras will actually provide the definitive data they seek.
According to SPSR spokesman Professor Stanley V. McDaniel of Sonoma State University, separate statistical studies by Professor Horace W. Crater of the University of Tennessee Space Institute, imaging expert Dr. Mark J. Carlotto, and archaeologist Dr. James F. Strange of the University of South Florida, have shown a "reasonably high probability" in favor of some of the objects turning out to be artifacts designed by intelligent beings.
NASA has continuously downplayed any particular significance to the Cydonia site, located on the northern plains of Mars.
"Our major concern," McDaniel says, "is to ensure that NASA will photograph the entire Cydonia area, not just the 'face,' with the intermediate resolution capability of the camera."
McDaniel stated that an intermediate setting on the Global Surveyor's high-resolution camera would provide images five times better than those from the Viking spacecraft taken in 1976, and could also show a long strip of terrain which would include all of the important Cydonia landforms, not just the face.
In any event, the photo and mapping part of Global Surveyor's mission remains several months away. First, the spacecraft must adjust its orbit. To do so, it will fire its engine five more times -- the first firing will be on September 16 -- each time bringing its orbit closer to the planet's atmosphere and increasing the aerobraking effect.
So far, Global Surveyor has been a nearly perfect exercise in precision navigation. The angle of its entry into Mars orbit was designed so that a "perfect" first orbit would take exactly 45 hours. The actual first orbit took 44 hours, 59 minutes and 34 seconds, according to NASA chief navigator Pasquale Esposito -- a remarkable success.
Original file name: CNI - Mars.Surveyor.final
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