* Astronomy

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RE: Mars Reconnaissance orbiter

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Italian and US space centres on Tuesday picked up the first signals from an Italian radar orbiting Mars to detect water or ice on the Red Planet .

The radar, SHARAD, showed it was working perfectly, Italian officials at NASA's Jet Propulsion Lab in Pasadena said .
The head of the Italian Space Agency, Sergio Vetrella, hailed the strong signal from SHARAD, saying it confirmed "Italy's leadership in the sector".
SHARAD is mounted on the second probe to visit Mars in two years, NASA's Mars Reconnaissance Observer .

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SHARAD

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RE: Mars Reconnaissance orbiter

Blobrana · L

NASA's Mars Reconnaissance Orbiter fired its six intermediate-size thrusters for 210 seconds Tuesday in a manoeuvre to make the shape of its orbit closer to the planned geometry for the mission's main science phase, beginning in November.

The manoeuvre raised the portion of the elliptical orbit at which the spacecraft comes nearest to Mars -- the periapsis -- from 216 kilometres above the surface to 320 kilometres. A thruster firing on Aug. 30 had lifted the periapsis high enough to end a five-month process of dipping into the atmosphere every orbit to gradually shrink the orbit. The spacecraft now completes each loop around Mars in just under two hours.

The Sept. 5 manoeuvre also fine-tuned the orbit's angle relative to Mars' equator, tweaking it less than one degree to 92.5 degrees.

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NASA's Mars Reconnaissance Orbiter has begun the final and fastest-paced portion of its "aerobraking" process of using friction with the top of Mars' atmosphere to shrink the spacecraft's orbit.

After nearly 400 drag passes into the atmosphere during the closest-to-Mars portion of each orbit, the spacecraft has reduced the farthest point in its orbit to an altitude of 1,100 kilometres. The spacecraft takes 2 hours, 7 minutes to complete one orbit, as of Aug. 25. In contrast, during the weeks between Mars Reconnaissance Orbiter's arrival at Mars on March 10 and its start of aerobraking in early April, the most distant point of each orbit was about 43,000 kilometres away from the planet and each orbit lasted about 35 hours. By using the aero braking technique, the project has saved carrying 600 kilograms of additional propellant to the red planet.

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NASA's newest spacecraft at Mars has already cut the size and duration of each orbit by more than half, just 11 weeks into a 23-week process of shrinking its orbit. By other indicators, the lion's share of the job lies ahead.

"The orbits are getting shorter and shorter. We've finished about 80 of them so far, but we have about 400 more to go, and the pace really quickens toward the end" - Dan Johnston, Mars Reconnaissance Orbiter deputy mission manager at NASA's Jet Propulsion Laboratory, Pasadena, California, US.

Supplementing the daily attentions of navigators, engineers and scientists, the orbiter has begun using unprecedented onboard smarts to schedule some of its own attitude manoeuvres during each orbit.
The current phase of the Mars Reconnaissance Orbiter mission, called "aerobraking," began in late March with the spacecraft in a pattern of very elongated, 35-hour orbits. It will end in early September, according to current plans, once hundreds of careful dips into Mars' atmosphere have adjusted the orbit to nearly circular, two-hour loops. Then, after some touch-up engine burns, deployment of a radar antenna and other transitional tasks, the spacecraft will be in the right orbit and configuration to start its main science phase in November.
During the two-year science phase, Mars Reconnaissance Orbiter will examine Mars from subsurface layers to the top of the atmosphere. It will use its 3-meter diameter dish antenna to pump data Earthward at up to 10 times the pace of any previous Mars mission. Besides providing information about the history and extent of Mars' water, the orbiter will assess prospective landing sites for NASA robots launching in 2007 and 2009.
When the spacecraft first entered orbit around Mars, its farthest point from the planet was about 45,000 kilometres. After 11 weeks of aerobraking operations, this distance has been reduced to about 20,000 kilometres. On each orbit since early April, the nearest-to-Mars portion of the orbit has passed through the upper atmosphere, usually at about 105 kilometres above the surface of the planet. The drag created by interaction of the atmosphere with spacecraft surfaces slows the craft.

"Our biggest challenge is the variability of the atmosphere. It's not uncommon to get a 35 percent change in how much drag the spacecraft experiences from one pass to the next. We need to monitor each pass carefully and be prepared to change the altitude to a safe one for the next pass, if necessary" - Dan Johnston.

While the orbiter is above the atmosphere, it can orient its antenna toward Earth and its solar panels toward the sun. Before it enters the atmosphere for each pass, it pivots so that the back surfaces of the solar panels and antenna face the direction of travel. An innovative capability of Mars Reconnaissance Orbiter's onboard software enables it to calculate the time when it needs to reorient itself for the next pass. This feature, called "periapsis timing estimator," was activated in May.

"In the past, the times for turning to aerobraking attitude had to be calculated on the ground and sent to the spacecraft for each pass. Now, the spacecraft can do that itself. This will be especially helpful when the spacecraft gets to the point when it is doing several drag passes per day" - Jim Graf, JPL's project manager for Mars Reconnaissance Orbiter.

Mars Reconnaissance Orbiter is the third NASA Mars mission -- after Mars Global Surveyor in 1997 and Mars Odyssey in 2001 -- to use aerobraking to get into a desired, near-circular orbit. The strategy allows launching the spacecraft with much less fuel than would be required if using just rocket engines to decelerate into the desired orbit. Each drag pass this month is slowing Mars Reconnaissance Orbiter by an average of about 2 meters per second, which would otherwise require consuming about a kilogram of fuel.
Transition activities during the two months between the end of aerobraking and the beginning of the main science phase will include unfolding two 5-meter lengths of antenna for a ground-penetrating radar instrument, removing the lens cap from a mineral-identifying spectrometer instrument and characterizing all instruments' performance in different modes of use. From early October to early November, Mars will be nearly behind the sun as viewed from Earth. Communication with all spacecraft at Mars will be unreliable during portions of that period, so commanding will be minimised.

Source NASA

Blobrana · L

Researchers have released the first Mars images from two of the three science cameras on NASA's Mars Reconnaissance Orbiter.

Images taken by the orbiter's Context Camera and Mars Colour Imager during the first tests of those instruments at Mars confirm the performance capability of the cameras even though the test images were taken from nearly 10 times as far from the planet as the spacecraft will be once it finishes reshaping its orbit. Test images from the third camera of the science payload were released previously.

"The test images show that both cameras will meet or exceed their performance requirements once they're in the low-altitude science orbit. We're looking forward to that time with great anticipation" - Dr. Michael Malin of Malin Space Science Systems, San Diego. Malin is team leader for the Context Camera and principal investigator for the Mars Colour Imager.

The cameras took the test images two weeks after the orbiter's March 10 arrival at Mars and before the start of "aerobraking," a process of reshaping the orbit by using controlled contact with Mars' atmosphere. This week, the spacecraft is dipping into Mars' upper atmosphere as it approaches the altitude range that it will use for shrinking its orbit gradually over the next six months.

The orbiter is currently flying in very elongated loops around Mars. Each circuit lasts about 35 hours and takes the spacecraft about 43,000 kilometres away from the planet before swinging back in close.

On Wednesday, a short burn of intermediate sized thrusters while the orbiter was at the most distant point nudged the spacecraft to pass from approximately 112 kilometres to within 107 kilometres of Mars' surface.

"This brings us well into Mars' upper atmosphere for the drag pass and will enable the mission to start reducing the orbit to its final science altitude" - Dan Johnston of NASA's Jet Propulsion Laboratory (JPL), Pasadena, California, deputy mission manager.

After hundreds of passes through the upper atmosphere, the drag will gradually reduce the far point of the orbit until the spacecraft is in a nearly circular orbit every two hours.
After the spacecraft gets into the proper orbit for its primary science phase, the six science instruments on board will begin their systematic examination of Mars. The Mars Colour Imager will view the planet's entire atmosphere and surface every day to monitor changes in clouds, wind-blown dust, polar caps and other changeable features.

Images from the Context Camera will have a resolution of 6 meters per pixel, allowing surface features as small as a basketball court to be discerned. The images will cover swaths 30 kilometres wide.

View of Argyre Basin from Test of Mars Colour Image

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The Mars Colour Imager (MARCI) camera on NASA's Mars Reconnaissance Orbiter acquired a seven-band colour, wide-angle view of Mars on March 24, 2006, as part of a checkout of the orbiter's payload. This image shows a colour composite made from the MARCI red, green, and blue bands. The view looks northward and includes the large Argyre Basin in Mars' Southern Hemisphere.
Image Credit: NASA/JPL/MSSS

The Context Camera will show how smaller areas examined by the High Resolution Imaging Science Experiment camera -- which will have the best resolution ever achieved from Mars orbit -- and by the mineral-identifying Compact Reconnaissance Imaging Spectrometer fit into the broader landscape. It will also allow scientists to watch for small-scale changes, such as newly cut gullies, in the broader coverage area.

First Context Camera Image of Mars

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This is the first image of Mars taken by the Context Camera on NASA's Mars Reconnaissance Orbiter. The spacecraft began orbiting the red planet on March 10, 2006. During its 10th close approach to Mars, on March 24, it turned its cameras to view the planet's surface. Although the images acquired were about 10 times lower in resolution than will ultimately be obtained when the spacecraft has finished reshaping its orbit for the mission's primary science phase, these test images provide important confirmation of the performance of the cameras and the spacecraft.

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NASA has released the first processed images from the high-resolution telescopic camera aboard its Mars Reconnaissance Orbiter, which arrived at the Red Planet less than a month ago.

The probe went into Martian orbit on March 10, and took a series of eight test pictures, then went into a months-long aerobraking phase to adjust its orbit for full-scale science operations.

The images taken by the High Resolution Imaging Science Experiment, or HiRISE, is follow up on a release of a single black-and-white image on March 24.
Each of the pictures is actually a mosaic of as many as 10 images made by 10 CCD detectors.

This is the first colour image of Mars from the High Resolution Imaging Science Experiment on NASA's Mars Reconnaissance Orbiter. The blankets of material ejected from the many small fresh craters are generally brighter and redder than the surrounding surface, but a few are darker and less red.
The image is centred at 33.65 degrees south latitude, 305.07 degrees east longitude. It is oriented such that north is 7 degrees to the left of up. The range to the target was 2,493 kilometres.

This image shows part of a low mountain belt that rings the Argyre impact basin in Mars' southern hemisphere. The mountains or hills seen here are located in the north-western part of the Charitum Montes. The image is centred at 52.20 degrees south latitude, 300.75 degrees east longitude. It is oriented such that north is 7 degrees to the left of up. The range to the target was 1,470 kilometres.

Charitum Montes

View of terrain northeast of Martz Crater.

This is a topological map of part of the area covered by the first image from Mars.

Bosporos Planum region

Blobrana · L

Nasa is studying the first pictures taken of the surface of the Red Planet by the high-resolution cameras aboard the Mars Reconnaissance Orbiter (MRO).

The spacecraft arrived at the planet two weeks ago with a mission to map the world in unprecedented detail.
The test images released by the US space agency (Nasa) on Friday show a swathe of land in the planet's mid-latitude southern highlands.
The probe is currently correcting its orbit and commissioning instruments.

Image: Nasa/JPL/University of Arizona

Three cameras were used to take the crisp black and white images.
They captured the pictures while the spacecraft was flying about 2,490km above Mars' surface, about nine times the range planned for the orbiter's primary science mission.