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Mars Odyssey Mission Status
NASA's Mars Odyssey Changes Views about Red Planet
Mars Odyssey Mission Status
June 04, 2002
Flight controllers for NASA's Mars Odyssey spacecraft completed the last major technical milestone today in support of the science mission by unfurling the boom that holds the gamma ray spectrometer sensor head instrument.
Engineers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., received confirmation from the spacecraft that the 6.2-meter (20-foot) boom was successfully deployed at noon Pacific time.
The gamma sensor head is part of the gamma ray spectrometer suite. It sits at the end of the boom to minimize interference from any gamma rays coming from the spacecraft itself. The two other gamma ray spectrometer instruments, the neutron spectrometer and the high-energy neutron detector, are mounted on the main spacecraft structure.
During the past few months, while the boom was in the stowed position, the instrument suite has provided significant information about the hydrogen abundance on Mars. This allowed scientists to conclude there are large quantities of water ice just below the surface.
"Deploying the boom enhances the sensitivity and accuracy of the gamma ray spectrometer instrument and will improve the accuracy of the hydrogen measurements," said Dr. William Boynton, principal investigator for Odyssey's gamma ray spectrometer suite at the University of Arizona, Tucson. Now the instrument will begin measuring many other important elements such as iron, aluminum, potassium, chlorine, thorium, uranium and others.
"Today's deployment is a continuation of the excellent performance of this flight team. They have done an outstanding job," said Roger Gibbs, Odyssey's project manager at JPL. "I look forward to many exciting discoveries to come as we continue our mission."
The 2001 Mars Odyssey spacecraft will be launched on a Delta II rocket from Launch Pad 17A at Cape Canaveral Air Station, Florida. The launch window opens on April 7, 2001, and the first launch opportunity will be at 11:02 AM EDT. The Delta rocket will fly up the east coast of North America, then over Europe, and spacecraft separation from the rocket will occur over the Middle East. The spacecraft will leave Earth at a relative velocity of 11.5 kilometers/second, or 25,724 mph.
Odyssey will be launched on Boeing's Delta II 7925 that uses nine strap-on solid rocket motors. Each of the nine solid rocket motors is 1 meter (3.28 feet) in diameter and 13 meters (42.6 feet) long; each contains 11,765 kilograms (25,937 pounds) of hydroxyl-terminated polybutadiene (HTPB) propellant and provides an average thrust of 485,458 newtons at liftoff. The casings on the solid rocket motors are made of lightweight graphite epoxy.
The main body of the first stage houses the Rock LR101-NA-11 vernier engines. The vernier engines provide roll control during main engine burn and attitude control after main engine cutoff before the second stage separation. The RS-27 main engine is a single start, liquid bipropellant load that carries 96,000 kilograms (211,000 pounds) of RP-1 (rocket propellant 1, a highly refined form of kerosene) as its fuel and liquid oxygen as an oxidizer.
The second stage is 2.4 meters (8 feet) in diameter and 6 meters (19.7 feet) long, and is powered by a AJ10-118K engine. The propellant is 6000 kilograms (13,228 pounds) of Aerozine 50 fuel, a 50/50 mixture of hydrazine and unsymmetric dimethly hydrazine and nitrogen tetroxide as the oxidizer. The engine is restartable and will perform two separate burns during the launch.
The third and final stage of the Delta II 7925 will provide the final velocity required to place Odyssey on a trajectory to Mars. This upper stage, called a PAM-D, consists of a spin table to support, rotate and stabilize the spacecraft/PAM-D combination before separating from the second stage, a Star-48B solid rocket motor for propulsion, and active nutation control system to provide stability after ignition of the PAM-D motor, a payload attach fitting to mount the spacecraft to the Star 48B motor and a yo-yo despin system designed to decrease the spin rate of the spacecraft/PAM-D combination stack prior to spacecraft separation.
During launch and ascent through Earth's atmosphere, the spacecraft PAM-D upper stage combination is protected from aerodynamic forces by a 2.9 meter (9.5 foot) diameter payload fairing, that is jettisoned from the launch vehicle during second stage powered flight at an average altitude of 131 kilometers (81 miles).