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NASA 's ''Mars Reconnaissance Orbiter'' ('''MRO''') is a multipurpose Spacecraft , launched August 12 , 2005 to advance knowledge of Mars through detailed observation, to examine potential landing sites for future surface missions, and to provide a high-data-rate communications relay for those missions. It is intended to orbit for four or more years. It entered orbit around Mars on March 10 , 2006 , and it became Mars's fourth active artificial satellite (joining '' Mars Express '', '' Mars Odyssey '', and '' Mars Global Surveyor ''), and its sixth active probe (the satellites plus the two '' Mars Exploration Rovers ''), in an historic scientific focus on Mars. OVERVIEW carrying the ''Mars Reconnaissance Orbiter'', 11:43:00 UTC August 12 , 2005 ]] ''MRO'' will conduct its science mission for an expected two-year period after Aerobraking and technical checks are completed in November 2006. After that, extended science and communications relay missions are expected. The ''Mars Reconnaissance Orbiter'' will lay the groundwork for NASA's planned surface missions: a lander called '' Phoenix '' selected in a competition for a 2007 launch opportunity, and the '' Mars Science Laboratory '', a highly capable rover being developed for a 2009 launch opportunity. The ''MRO'' LAUNCH AND CRUISE ''Mars Reconnaissance Orbiter'' launched on August 12 , 2005 . Between August 10 and August 30 , two-hour Launch Window s were available almost every day. It was launched from Space Launch Complex 41 at Cape Canaveral Air Force Station , aboard an Atlas V -401 rocket equipped with a Centaur Upper Stage . Fifty-six minutes after launch the Centaur completed its burns placing ''MRO'' in interplanetary transfer orbit towards Mars. ''MRO'' cruised through interplanetary space for 7½ months before reaching Mars. During the cruise testing and calibrations of most of the scientific instruments and experiments were conducted. Four trajectory correction maneuvers were planned for any need to correct the trajectory for proper orbital insertion upon reaching Mars. Only three trajectory correction maneuvers were undertaken, a fourth correction was deemed unnecessary; also a fifth emergency trajectory correction option was skipped. Launch and cruise timeline
ORBITAL INSERTION AND AEROBRAKING The start of the orbital insertion occurred as ''MRO'' approached Mars for the first time on March 10 2006 , passing above the Martian southern hemisphere at an altitude of about 370–400 km (190 mi). All six of the orbiter’s main engines burned for 27 minutes reducing the speed of the probe (relative to Mars at closest approach) from ~2900 m/s to ~1900 m/s (6500 mph to 4250 mph). The helium pressurization tank was colder than expected which caused about 21 KPa (3 Psi ) less pressure in the fuel tank, which caused the engine thrust to be reduced by 2%. ''MRO'' automatically compensated for the reduced thrust by extending the burn time by 33 seconds. The final speed of MRO relative to Mars was only 0.17 m/s (0.4 mph) faster than expected.2,3,4 Orbital insertion has placed the orbiter in a highly Elliptical polar orbit. The Periapsis , the closest point in the orbit to Mars, is 3806 km from the center of Mars (~426 km from the surface). The Apoapsis , or farthest point in the orbit from Mars, is 47,972 km from the center of Mars(about 43,000 km from the surface). The orbital period is approximately 35.5 hours. Aerobraking is currently being conducted to bring the orbiter to a lower, quicker orbit. Aerobraking cuts the fuel needed to reach the desired orbit roughly in half, and consists of three steps: # ''MRO'' will drop the periapsis of its orbit to aerobraking altitude using its thrusters. Aerobraking altitude will be determined at that time depending on the thickness of the Martian atmosphere (Martian atmospheric density changes over the seasons on Mars). This step will take about five orbits or one Earth week. # ''MRO'' will remain in aerobraking altitude for 5½ Earth months, about 550 orbits. Correct aerobraking altitude will have to be maintained with occasional corrections in periapsis altitude using its thrusters. Through aerobraking the apoapsis of the orbit will be reduced to 450 km (280 mi). # To end aerobraking, the ''MRO'' will use its thrusters to move its periapsis out of the edge of the Martian atmosphere. After aerobraking another week or two will be spent to make additional adjustments in the orbit with thrusters. These corrections will likely occur before Solar Conjunction when Mars will appear to pass behind the Sun from Earth perspective, between October 7 and November 8 , 2006 . After this, science operations will begin. Final or science operations orbit will be at approximately 255 km to 320 km (160 Statute Mile s to 200 mi) above the Martian surface. After reaching science operational orbit the SHARAD will be deployed. Orbital insertion timeline
SCIENCE OPERATIONS AND EXTENDED MISSION From November 2006, science operations will be conducted for a nominal period of two Earth years. After this extended mission operations will include communication and navigation for lander and rover probes. INSTRUMENTATION The broad goals of the ''Mars Reconnaissance Orbiter'' are to search for evidence of water, and characterize the atmosphere and geology of Mars. Six science instruments are included on the mission along with two "science-facility instruments", which use data from engineering subsystems to collect science data. Three technology experiments are also included to demonstrate new technologies for future missions.7
Science instrumentation HiRISE The High Resolution Imaging Science Experiment camera consists of a 0.5 - Green or B-G), 550-850 nm ( Red ) and 800-1,000 nm ( Near Infrared or NIR).8 Red color images are at 20,264 Pixel s wide (6 km in a 300 km orbit), and Green-Blue and NIR are at 4,048 pixels wide (1.2 km). HiRISE's onboard computer reads out these lines in time with the orbiter's Ground Speed , meaning the images are potentially unlimited in height. Practically this is limited by the onboard computer's 28 Gb memory capacity. The nominal maximum resolution of red images is 20,000 × 40,000 pixels, or 800 Megapixel s and 4,000 × 40,000 pixels (160 megapixels) for the narrower images of the B-G and NIR bands. A single uncompressed image will use 16.4 Gb. However, these images will be transmitted compressed, at a total size of 5 Gigabits. These images will be released to the general public on the HiRISE website via a new format called JPEG 2000 . 9 ( PDF ),10 ( PDF ), Luner and Planetary Sciences, University of Arizona (2005). "''HiRISE Facts Sheet''" The general public will be allowed to request sites to take pictures of Mars with the HiRISE camera. For this reason, and due to the unprecidented access of pictures to the general public, shortly after they have been received and processed, the camera has taken the philosophy "The People's Camera". 11 To facilitate the mapping of potential landing sites, HiRISE can produce stereo pairs of images from which the topography can be measured to an accuracy of 0.25 meter. |
Image:MRO HiRISE ComparisonjpgComparison Of Resolution Of MRO HiRISE Camera With Predecessor, The
| "http://wwwinformationdelightinfo/encyclopedia/entry/Mars_Orbital_Camera" class="copylinks">MOC aboard MGS |
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