[meteorite-list] Mars Express Acquires Sharpest Images of MartianMoon Phobos

[Jeff Kuyken]

Absolutely stunning!!! Thanks for the post Ron.

Cheers,

Jeff


----- Original Message ----- 
From: "Ron Baalke" <baalke at zagami.jpl.nasa.gov>
To: "Meteorite Mailing List" <meteorite-list at meteoritecentral.com>
Sent: Friday, August 01, 2008 9:06 AM
Subject: [meteorite-list] Mars Express Acquires Sharpest Images of 
MartianMoon Phobos



>

> http://www.esa.int/esaCP/SEM5H48N9JF_index_0.html

>

> Mars Express acquires sharpest images of martian moon Phobos

> European Space Agency

> 30 July 2008

>

> Mars Express closed in on the intriguing martian moon Phobos at 6:49 CEST

> [0449 UTC] on 23 July, flying past at 3 km/s, only 93 km from the moon. 

> The

> ESA spacecraft's fly-bys of the moon have returned its most detailed

> full-disc images ever, also in 3-D, using the High Resolution Stereo 

> Camera

> on board.

>

> Phobos is what scientists call a 'small irregular body'. Measuring 27 km x

> 22 km x 19 km, it is one of the least reflective objects in the Solar

> System, thought to be a capture-asteroid or a remnant of the material that

> formed the planets.

>

> The best images of Phobos ever

>

> The HRSC images, which are still under processing, form a bounty for

> scientists studying Phobos. They are a result of observations carried out

> over several close fly-bys of the martian moon, performed over the past

> three weeks. At their best, the pictures have a resolution of 3.7 m/pixel

> and are taken in five channels (in the stereo channel) for images in 3-D 

> and

> (in the photometric channels) to perform analyses of the physical 

> properties

> of the surface.

>

> The images obtained by several other spacecraft so far have either been of 

> a

> lower resolution, or not available in 3D and have not covered the entire

> disc of Phobos. This is also the first time that portions of the far-side 

> of

> the moon have been imaged in such high resolution (Phobos always faces 

> Mars

> on the same side).

>

> Scientific bounty

>

> In observing Phobos, Mars Express benefits from its highly elliptical 

> orbit

> which takes it from a closest distance of 270 km from the planet to a

> maximum of 10 000 km (from the centre of Mars), crossing the 9000 km orbit

> of the martian moon. Mars Express imaged the far-side of Phobos (with

> respect to Mars) for the first time after NASA's Viking mission, by flying

> outside the spacecraft's orbit around Mars.

>

> Phobos-Grunt (Phobos soil), a Russian sample-return mission, is due to for

> launch in 2009. It is expected to land on the far-side of Phobos at a 

> region

> between 5 deg south to 5 deg north, and 230 deg west to 235 deg west. This

> region was last imaged in the 1970s by the Viking orbiters.

>

> The HRSC observations have been awaited eagerly to better assess and

> characterise the choice of the landing site.

>

> The moon's remarkably grooved surface can be seen in the pictures quite

> clearly. The origin of these grooves is still debated. It is not known

> whether they are produced by ejecta thrown up from impacts on Mars, or if

> they result from the surface regolith, or soil, slipping into internal

> fissures.

>

> In this image, at least two families of grooves with distinct orientations

> can be seen along with an elongated crater.

>

> The stereo observations (resolution 3.7 m/pixel) are important for

> structural analysis and they will be used to derive a digital terrain 

> model

> (a 3-D map of the surface that includes elevation data). The extra

> photometric channels (at 7.4 m/pixel) make it possible to study the

> properties of the Phobos regolith at micron to millimetre scales.

>

> An operational challenge

>

> Managing the close fly-bys was an operational challenge, made possible by

> spacecraft operations engineers and scientists who worked together to

> specially optimise Mars Express's trajectory and obtain the best possible

> views.

>

> The observation made use of a spacecraft slew, a special manoeuvre whereby

> the body of the spacecraft is rotated against the direction of motion, to

> effectively lower the speed at which the target passes in the field of 

> view

> of the camera. This makes it possible to avoid blurring of the pictures

> despite the high fly-by velocities, whilst maintaining acceptable exposure

> time.

>

> The HRSC Super Resolution Channel (SRC) also observed during this close

> fly-by, with a nominal resolution of 90 cm/pixel. As expected, despite the

> slew, some residual motion blur has crept into the image, but much detail 

> is

> expected to be recovered after further processing.

>

> In the days running up to the observation, the primary star-tracker - a

> navigation device that helps the spacecraft point its instruments at the

> target accurately - experienced some temporary difficulty in recognising 

> the

> star constellations in its field of view, leaving the spacecraft operating

> on its secondary system. Concerned that this might affect this critical

> observation, the team at ESA's European Space Operations Centre (ESOC) in

> Darmstadt, Germany, worked intensely to recover the primary system and 

> were

> able to switch back successfully two days before the fly-by.

>

> Notes for editors:

>

> The Principal Investigator (PI) for the HRSC experiment on ESA's Mars

> Express is Prof. Dr Gerhard Neukum, who also designed the camera

> technically. The HRSC science team consists of 45 Co-Investigators from 32

> institutions located in 10 nations. The camera was developed at the German

> Aerospace Center (DLR) under the PI in cooperation with industrial 

> partners

> (EADS Astrium, Lewicki Microelectronic GmbH and Jena-Optronik GmbH). It is

> operated through ESA/ESOC by the DLR Institute of Planetary Research, 

> where

> systematic processing of the image data is carried out. The scenes shown

> here were processed by the PI group at the Institute for Geosciences of 

> the

> Freie Universitaet Berlin in cooperation with the DLR Institute of 

> Planetary

> Research, Berlin.

>

> [NOTE: Images and weblinks supporting this release are available at

> http://www.esa.int/esaCP/SEM5H48N9JF_index_1.html ]

>

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