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Re: New Mars Global Surveyor Images

ANY NEWS ABOUT LAST MONTH FALL IN SOUTHERN ARIZONA...NEAR CASA GRANDE? 
THANKS ..ANDRE

----------
> From: Ron Baalke 
> To: meteorite-list@meteoritecentral.com
> Subject: New Mars Global Surveyor Images
> Date: Friday, June 26, 1998 1:11 PM
> 
> NEW MARS GLOBAL SURVEYOR IMAGES
> 
> The following images taken by the Mars Global Surveyor spacecraft
> are now available on the web:
> 
>
http://mars.jpl.nasa.gov/mgs/msss/camera/images/6_26_98_herschel_release/ind
ex.html
>
http://mars.jpl.nasa.gov/mgs/msss/camera/images/6_19_98_na_release/index.htm
l
>         
> Image captions are appended below.
> 
> Ron Baalke
>
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>                 
>                             Mars Global Surveyor
>                              Mars Orbiter Camera
> 
>               Mars Orbiter Camera (MOC) High Resolution Images
>                              SPO-2 Observations:
>             Windblown Dunes on the Floor of Herschel Impact Basin
> 
> 
> 
> Mars Global Surveyor Mars Orbiter Camera Release:          MOC2-55a, -55b
> Mars Global Surveyor Mars Orbiter Camera Image ID:        
582313884.36507
>                                                            P365-07
> 
>                                 (A) [Image]
> 
>                              88 KByte GIF image
> 
> (A) Herschel Impact Basin. White box shows the approximate location of
the
> MOC image 36507 subframe shown in (B). Herschel is about 300 kilometers
(186
> miles) across, and its center is located around 14°S, 230.#176;W. North
is
> up. Picture is part of U.S. Geological Survey Viking orbiter photomosaic
> 1:64-scale map.
> 
>                                 (B) [Image]
> 
>                             117 KByte GIF image
> 
> (B) MOC image 36507 subframe. Resolution is about 10.7 meters (35 feet)
per
> pixel. Illumination is from the right.
> 
>   You may need to adjust the images for the gamma of your monitor to
insure
>                                proper viewing.
> 
>   Note: This MOC image is made available in order to share with the
public
>   the excitement of new discoveries being made via the Mars Global
Surveyor
>   spacecraft. The image may be reproduced only if the image is credited
to
>      "Malin Space Science Systems/NASA". Release of this image does not
>   constitute a release of scientific data. The image and its caption
should
>   not be referenced in the scientific literature. Full data releases to
the
>    scientific community are scheduled by the Mars Global Surveyor Project
>   and NASA Planetary Data System. Typically, data will be released after
a
>                  6 month calibration and validation period.
> 
>   Click Here for more information on MGS data release and archiving
plans.
> 
>                                    CAPTION
> 
> Herschel Basin, one of many meteor impact craters on Mars, has some dark
> material on its floor that appeared from earlier spacecraft missions to
have
> been blown and/or deposited by wind. Herschel Basin was imaged at low
> resolution by the Mariner 9 and Viking orbiters ((A) above) in the 1970s,
> and again by the Phobos 2 orbiter in 1989.
> 
> On June 14, 1998, Mars Global Surveyor's Mars Orbiter Camera revealed
that
> part of the dark surface on the floor of Herschel Basin consists of a
field
> of sand dunes ((B) above). These dunes have a distinct crescent-like
shape
> characteristic of dunes on Earth called barchan dunes. They result from
> winds that blow from a single dominant direction.
> 
> In the case of Herschel Basin, the dunes indicate that the strongest
winds
> blow approximately north-to-south. The crescent horns on the ends of some
of
> the dunes in this image are elongated. This condition indicates that the
> dominant winds do not always blow in exactly the same
direction--sometimes
> the winds blow from the northeast, sometimes from the northwest, and
> sometimes from the north. The local topography probably influences the
wind
> direction--and hence dune shape--because this dune field is located on a
> narrow, low plain between a high crater rim to the east, and a narrow
> mountain range-- the inner ring of the Herschel impact basin--to the west
> (see image (A)).
> 
> MOC image 36507 was obtained on Mars Global Surveyor's 365th orbit around
> 10:51 a.m. PDT on June 14, 1998. The subframe (B) is centered around
> 14.27°S, 231.68°W.
> 
>
----------------------------------------------------------------------------

> 
>                             Mars Global Surveyor
>                              Mars Orbiter Camera
> 
>               Mars Orbiter Camera (MOC) High Resolution Images
>      Early SPO-2 High Resolution Imaging: The Challenge of Cloudy Skies
> 
> 
> 
>
----------------------------------------------------------------------------

> 
>                             June 19, 1998, Update:
>           First Two Weeks of Science Phasing Orbit II Observations
> 
> The first two weeks of June 1998 saw cloudy mornings on Mars. This is
normal
> for this time of the Martian year, and the cloudiness is expected to
> continue for the next several months, especially in the northern
hemisphere
> and especially at low elevations.
> 
> Mars Global Surveyor resumed photographing the Red Planet on June 1,
1998,
> after being off for a month while Mars moved behind the sun as seen from
the
> Earth. At the beginning of June, the orbit of MGS was crossing the
equator
> at approximately 9:30 a.m. -- this means that the local time on the
ground
> underneath the spacecraft was about 9:30 in the morning.
> 
> As the closest point to the planet slowly moves north under the influence
of
> subtle variations of the gravity field of Mars, the latitude range over
> which the camera can photograph also migrates. During the early part of
the
> mission, the camera could observe mostly in the southern hemisphere; now,
> the camera mostly views the northern hemisphere. The southernmost
latitude
> also varies now from orbit to orbit as the pointing of the spacecraft and
> the time when pictures can be taken are changed to accommodate the
observing
> requests of other experiments aboard the spacecraft. Unfortunately, most
of
> the remaining areas accessible for imaging by the Mars Orbiter Camera
(MOC)
> have been found to be socked-in by morning clouds, fog, and haze.
> 
> Taking pictures during the second Science Phasing Orbit period (SPO-2)
has
> become a considerable challenge for the MOC science team. Not only must
each
> picture be carefully planned and targeted by one or more Mars scientists,
> but commanding and retrieving the observations from the spacecraft now
takes
> several days because MGS is being tracked from Earth only 8-10 hours per
day
> (between September and May, the spacecraft was tracked 24 hr/day).
Targeting
> takes place a few days before the data are acquired, often using position
> predictions several days old, and the results of the targeting aren't
known
> until several days after the images are taken. Thus, variations on Mars
that
> occur on timescales of less than a few days, such as changes in weather,
> cannot be anticipated in planning.
> 
> For example, between May 30 and June 9, a total of 22 orbits were
targeted--
> Orbits 336 through 357. The first images from these orbits were received
on
> June 2 (from Orbit 338, as the data planned for orbits 336 and 337 were
> never received). The last of these images--Orbit 357--were received on
June
> 13th. The time elapsed between targeting an orbit until the images are
> received on Earth varied from 3 to 5 days (6 to 10 orbits). During these
3
> to 5 day intervals, additional orbits are targeted with no knowledge of
the
> success or failure of recently-targeted pictures.
> 
> The first two weeks of SPO-2 had a spotty record for MOC high resolution
> images. On any given orbit, the MOC team might select as many as 5 or as
few
> as 2 places to take a high resolution picture. Under SPO-2 orbital
> conditions, these images vary from about 3 meters (10 feet) to 12 meters
(39
> feet) per pixel. For Orbits 336 to 357, about 30% of the high resolution
> images were never received back from Mars owing to factors beyond the
> control of the camera team and 20% were completely cloudy. This means
that
> about 50% of the targeted high resolution pictures for Orbits 336-357
were
> essentially "lost" to science. Another 25% of the images were hazy--owing
to
> the clouds--and thus were of reduced resolution and contrast.
> 
> The good news is that about 25% of the images received from Orbits 336 to
> 357 were not hazy. A fair number of these good images were acquired
during
> the last three orbits of this period--Orbits 355, 356, and 357--the first
> orbits targeted after the team had received sufficient images to tell
just
> how cloudy Mars had become. By changing the targeting strategy to observe
> higher elevations (such as the Tharsis volcanoes and the heavily-cratered
> Arabia Terra) rather than lower elevations (such as the canyons of the
> Valles Marineris), and favoring southernly areas over those farther to
the
> north, it is possible to target images that avoid the clouds.
> 
> The MOC team now has a complete set of wide angle (low resolution) images
> that cover the northern hemisphere as it appeared during the first two
weeks
> of June. The team uses these images to find cloud-free areas to target
new
> high resolution images for the orbits occurring since Orbit 357.
(Examples
> of these wide angle images were released June 12, 1998: (A) Northern
Tharsis
> and (B) Tempe Terra/Kasei Vallis).
> 
>
----------------------------------------------------------------------------

> 
>                         June 19, 1998, Image Releases
> 
> Every MOC image is targeted by one or more Mars scientists. Each orbit
that
> is targeted takes 2 to 5 hours to plan. Mars Global Surveyor conducts two
> orbits per day. This means approximately 28 to 70 hours per week are
spent
> planning these observations. This week's MOC image release shows two
> pictures--one that is cloudy (to show how much of the data presently
> appears), and one that is not cloudy.
> 
> [Image]  Release #MOC2-53: Cloudy Image of Cerberus Rupes Dark Lineation
> 
> The first, "Cloudy Image of Cerberus Rupes Dark Lineation," shows the
> difficulty that clouds have posed for the MOC team. The image was
targeted
> on June 5, 1998. The image was obtained by MOC during orbit 350 on June
7,
> 1998, and it was received and processed at Malin Space Science Systems on
> June 9, 1998.
> 
> [Image]  Release #MOC2-54: Eroded Crater Adjacent to Huygens Impact Basin
> 
> The second, "Eroded Crater Adjacent to Huygens Impact Basin," shows a
> successful image acquisition. This picture was targeted on June 9, 1998,
> hours after the images from orbit 350 were received. The image was
obtained
> by MOC during orbit 357 on June 10, 1998, and it was received and
processed
> at Malin Space Science Systems on June 13, 1998.
> 
>
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>
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> 
> Malin Space Science Systems and the California Institute of Technology
built
> the MOC using spare hardware from the Mars Observer mission. MSSS
operates
> the camera from its facilities in San Diego, CA. The Jet Propulsion
> Laboratory's Mars Surveyor Operations Project operates the Mars Global
> Surveyor spacecraft with its industrial partner, Lockheed Martin
> Astronautics, from facilities in Pasadena, CA and Denver, CO.