NASA's "Mars Reconnaissance Orbiter Mission"

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This is the latest image from the Mars Orbiter.  The mission team chose this particular crater because one of the Mars Rovers, "Opportunity" which has been roaming around on the surface of Mars for 2 years now, is currently parked at the rim of this crater and the mission managers are contemplating sending it into the crater.  The extremely high resolution of the Orbiter camera can be seen in this zoomed in image of the area around Cape Verde.

The Orbiter has now successfully extended the long-armed antenna of its radar, preparing the instrument to begin probing for underground layers of Mars.  The Shallow Subsurface Radar, provided by the Italian Space Agency, will search to depths of about one kilometer (six-tenths of a mile) to find and map layers of ice, rock and, if present, liquid water.  The radar's antenna had remained safely folded and tucked away throughout the flight to Mars from Aug. 12, 2005, to March 10, 2006, and while the orbiter used the friction of dipping into the top of Mars' atmosphere 426 times in the past six months to shrink the size of its orbit.  Latches on the restraints were popped open on Sept. 16, and the spring-loaded twin arms of the antenna unfolded themselves. Subsequent information from the spacecraft indicates that each arm properly extended to its 5 meter (16.4 feet) length.

The radar received its first radio echo from the Martian surface during a test on Sept.18, providing a preliminary indication that the entire instrument is working properly.  Researchers will use the instrument for more test observations at the end of this month.  Communication with all spacecraft at Mars will be intermittent during most of October while that planet is behind the sun from Earth's perspective.  The two-year-long main science phase of the Mars Reconnaissance Orbiter mission will begin in November.  The Shallow Radar will be used to map buried channels, study the internal structure of ice caps and see boundaries between layers of different materials.  This will provide useful information from just under the Martian surface, where ices might reside that would be accessible for future explorers.

The radar instrument on the Mars Reconnaissance Orbiter will complement a similar instrument that went into use last year on the European Space Agency's Mars Express orbiter, the Mars Advanced Radar for Subsurface and Ionospheric Sounding.  The two instruments use different radar frequencies.  The one on Mars Reconnaissance Orbiter can discriminate between thinner layers, but cannot penetrate as deep underground, compared with the one on Mars Express. Both result from Italian and American partnership in using radar for planetary probes.

The spacecraft has now (September 2006) completed the challenging half-year task of shaping its orbit to the nearly circular, low-altitude pattern from which it will scrutinize the planet.  It fired its six intermediate-size thrusters for 12.5 minutes Monday afternoon, Sept. 11, shifting the low point of its orbit to stay near the Martian south pole and the high point to stay near the north pole.  The altitude of the orbit ranges from 250 kilometers (155 miles) to 316 kilometers (196 miles) above the surface.  This is effectively the "science orbit" from which all the work will be done.  Challenging activities remain ahead this month, such as deploying an antenna 10 meters (33 feet) long and removing a lens cap from a crucial instrument.  The main science investigations will begin in November.


The flight team for the Mars Reconnaissance Orbiter sent the bus-sized spacecraft through the upper fringe of Mars' atmosphere 426 times between early April and Aug. 30.  This "aero-braking" technique used friction with the Martian atmosphere to gradually decrease the highest-altitude point of the elliptical orbit from 45,000 kilometers (28,000 miles) to 486 kilometers (302 miles).  The lowest-altitude point during aero-braking ranged from 98 to 105 kilometers (61 to 65 miles).  It was carefully managed with input from researchers at JPL; Lockheed Martin Space Systems, Denver ; NASA Langley Research Center , Hampton , Va. , and elsewhere, based on spacecraft data and atmospheric fluctuations.

During the first three weeks after it arrived at Mars on March 10, the spacecraft took more than 35 hours to fly each very elongated orbit.  During the final weeks of aero-braking, it was flying more than 10 orbits each day.


The latest manoeuvre was the mission's biggest burn since the 27-minute firing to slow the spacecraft enough for Mars' gravity to snare it into orbit on March 10th.  The benefit of aero-braking is to avoid hauling unnecessary fuel to Mars for thrusters.  Compared with relying solely on thruster firings to shrink and shape the orbit, this cut the mission's fuel needs by about 600 kilograms (about 1,300 pounds).


One key remaining preparation for the mission is deployment of the antenna for the Shallow Subsurface Radar, an instrument provided by the Italian Space Agency.  The antenna, developed by Northrop Grumman Space Technology Astro Aerospace, Carpinteria , Calif. , remained safely stowed during aero-braking.  Later this month it will be released to unfold itself and extend 5 meters (16.4 feet) on either side of the spacecraft.  After this ground-penetrating radar has been checked and calibrated, it has the potential to detect buried channels, buried craters and ice layers.


A series of trial observations by all the instruments will complete the spacecraft checkouts at the end of the month, including tests of all observing modes.  In addition to data acquisition by the radar and spectrometer, images will be taken by the High Resolution Imaging Science Experiment and the Context Imager.  The Mars Colour Imager and Mars Climate Sounder will also begin monitoring Mars' atmosphere.  During the next four years, these instruments will examine Mars to learn about processes that have affected it and to inspect potential landing sites for future missions.  The spacecraft will also serve as a communications relay for Mars surface missions.

Additional information about Mars Reconnaissance Orbiter is available online at:

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