[meteorite-list] Meteorite Picture of the Day

[Paul Swartz via Meteorite-list]

Today's Meteorite Picture of the Day: ET Winner

Contributed by: Twink Monrad

http://www.tucsonmeteorites.com/mpodmain.asp?DD=02/06/2016
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[meteorite-list] Dawn Journal - January 31, 2016

[Ron Baalke via Meteorite-list]

http://dawnblog.jpl.nasa.gov/2016/01/31/dawn-journal-january-31/

Dawn Journal 
by Dr. Marc Rayman
January 31, 2016

Dear Spellbindawngs,

A veteran interplanetary traveler is writing the closing chapter in its 
long and storied expedition. In its final orbit, where it will remain 
even beyond the end of its mission, at its lowest altitude, Dawn is circling 
dwarf planet Ceres, gathering an album of spellbinding pictures and other 
data to reveal the nature of this mysterious world of rock and ice.

[Image]
Dawn captured this view of Kupalo crater on Dec. 20, shortly after beginning 
the observations from its current low altitude mapping orbit at 240 miles 
(385 kilometers). (Kupalo is a Slavic harvest deity associated with love 
and fertility.) This is a relatively young crater, as seen by its sharp, 
clear features and the paucity of overlying smaller impact craters which 
would have formed later. Bright material on the rim and walls may be salts, 
as explained last month. The crater is 16 miles (26 kilometers) across. 
Full image and caption. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Ceres turns on its axis in a little more than nine hours (one Cerean day). 
Meanwhile, its new permanent companion, a robotic emissary from Earth, 
revolves in a polar orbit, completing a loop in slightly under 5.5 hours. 
It flies from the north pole to the south over the side of Ceres facing 
the sun. Then when it heads north, the ground beneath it is cloaked in 
the deep dark of night on a world without a moon (save Dawn itself). As 
we discussed last month, Dawn's primary measurements do not depend on 
illumination. It can sense the nuclear radiation (specifically, gamma 
rays and neutrons) and the gravity field regardless of the lighting. This 
month, let's take a look at the other measurements our explorer is performing, 
most of which do depend on sunlight.

Of course the photographs do. Dawn had already mapped Ceres quite thoroughly 
from higher altitudes. The spacecraft acquired an extensive set of stereo 
and color pictures in its third mapping orbit. But now that Dawn is only 
about 240 miles (385 kilometers) high, its images are four times as sharp, 
revealing new details of the strange and beautiful landscapes.

[Image]
This is an excerpt from a much more extensive animation providing a colorful 
tour of some of the highlights on Ceres. It is made with the color and 
stereo pictures Dawn collected in its third mapping orbit 915 miles (1,470 
kilometers) above the dwarf planet. Here we see Occator crater, with its 
famous bright regions. The full animation (in which both color and sound 
are exaggerated) also shows the strange, conical mountain Ahuna Mons plus 
Urvara, Haulani and Dantu (seen in more detail below) craters and more. 
The colors indicate different compositions, which may include salts and 
phyllosilicates, as explained last month. Full animation and caption. 
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Our spaceship is closer to Ceres than the International Space Station 
is to Earth. At that short range, it takes a long time to capture all 
of the vast territory, because each picture covers a relatively small 
area. Dawn's camera sees a square about 23 miles (37 kilometers) on a 
side, less than one twentieth of one percent of the more than one million 
square miles (nearly 2.8 million square kilometers). In an ideal world 
(which is not the one Dawn is in or at), it would take just over two thousand 
photos from this altitude to see all the sights. However, as we will discuss 
in more detail next month, it is not possible to control the orbital motion 
and the pointing of the camera accurately enough to manage without more 
photos than that.

Most of the time, Dawn is programmed to turn at just the right rate to 
keep looking at the ground beneath it as it travels, synchronizing its 
rotation with its revolution around Ceres. It photographs the passing 
scenery, storing the pictures for later transmission to Earth. But some 
of the time, it cannot take pictures, because to send its bounty of data, 
it needs to point its main antenna at that distant planet, home not only 
to its controllers but also to many others (including you, loyal reader) 
who share in the thrill of a bold cosmic adventure. Dawn spends about 
three and a half days (nine Cerean days) with its camera and other sensors 
pointed at Ceres. Then it radioes its findings home for a little more 
than one day (almost three Cerean days). During these communications sessions, 
even when it soars over lit terrain, it does not observe the sights below.

Mission planners have devised an intricate plan that should allow nearly 
complete coverage in about six weeks. To accomplish this, they guided 
Dawn to a carefully chosen orbit, and it has been doing an exceptionally 
good job there executing its complex activities.

[Image]
On Dec. 21, in its lowest orbit at about 240 miles (385 kilometers), Dawn 
flew over Dantu crater and obtained 

[meteorite-list] Pluto's Mysterious, Floating Hills

[Ron Baalke via Meteorite-list]

http://pluto.jhuapl.edu/Multimedia/Science-Photos/image.php?page=1_id=2_id=408

Pluto's Mysterious, Floating Hills

Release Date: February 4, 2016

The nitrogen ice glaciers on Pluto appear to carry an intriguing cargo:
numerous, isolated hills that may be fragments of water ice from Pluto's
surrounding uplands. These hills individually measure one to several
miles or kilometers across, according to images and data from NASA's New
Horizons mission.

The hills, which are in the vast ice plain informally named Sputnik
Planum within Pluto's "heart," are likely miniature versions of the
larger, jumbled mountains on Sputnik Planum's western border. They are
yet another example of Pluto's fascinating and abundant geological
activity.

Because water ice is less dense than nitrogen-dominated ice, scientists
believe these water ice hills are floating in a sea of frozen nitrogen
and move over time like icebergs in Earth's Arctic Ocean. The hills are
likely fragments of the rugged uplands that have broken away and are
being carried by the nitrogen glaciers into Sputnik Planum. "Chains" of
the drifting hills are formed along the flow paths of the glaciers. When
the hills enter the cellular terrain of central Sputnik Planum, they
become subject to the convective motions of the nitrogen ice, and are
pushed to the edges of the cells, where the hills cluster in groups
reaching up to 12 miles (20 kilometers) across.

At the northern end of the image, the feature informally named
Challenger Colles - honoring the crew of the lost space shuttle
Challenger - appears to be an especially large accumulation of these
hills, measuring 37 by 22 miles (60 by 35 kilometers). This feature is
located near the boundary with the uplands, away from the cellular
terrain, and may represent a location where hills have been "beached"
due to the nitrogen ice being especially shallow.

The image shows the inset in context next to a larger view that covers
most of Pluto's encounter hemisphere. The inset was obtained by New
Horizons' Multispectral Visible Imaging Camera (MVIC) instrument. North
is up; illumination is from the top-left of the image. The image
resolution is about 1050 feet (320 meters) per pixel. The image measures
a little over 300 miles (almost 500 kilometers) long and about 210 miles
(340 kilometers) wide. It was obtained at a range of approximately 9,950
miles (16,000 kilometers) from Pluto, about 12 minutes before New
Horizons' closest approach to Pluto on July 14, 2015.

Credit: NASA/Johns Hopkins University Applied Physics
Laboratory/Southwest Research Institute

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[meteorite-list] Inside Rosetta's Comet

[Ron Baalke via Meteorite-list]

http://sci.esa.int/rosetta/57307-inside-rosetta-s-comet/

Inside Rosetta's comet
European Space Agency
04 February 2016

There are no large caverns inside Comet 67P/Churyumov-Gerasimenko. 
ESA's Rosetta mission has made measurements that clearly demonstrate 
this, solving a long-standing mystery. 

Comets are the icy remnants left over from the formation of the
planets 4.6 billion years ago. A total of eight comets have now
been visited by spacecraft and, thanks to these missions, we have
built up a picture of the basic properties of these cosmic time
capsules. While some questions have been answered, others have
been raised.

Comets are known to be a mixture of dust and ice, and if fully
compact, they would be heavier than water. However, previous
measurements have shown that some of them have extremely low
densities, much lower than that of water ice. The low density
implies that comets must be highly porous.

But is the porosity because of huge empty caves in the comet's
interior or it is a more homogeneous low-density structure?

In a new study, published in this week's issue of the journal
Nature, a team led by Martin Pätzold, from Rheinische Institut
für Umweltforschung an der Universität zu Köln, Germany, have
shown that Comet 67P/Churyumov-Gerasimenko is also a low-density
object, but they have also been able to rule out a cavernous interior.

This result is consistent with earlier results from Rosetta's
CONSERT radar experiment showing that the double-lobed comet's
'head' is fairly homogenous on spatial scales of a few tens of metres.

The most reasonable explanation then is that the comet's porosity
must be an intrinsic property of dust particles mixed with the ice
that make up the interior. In fact, earlier spacecraft
measurements had shown that comet dust is typically not a
compacted solid, but rather a 'fluffy' aggregate, giving the dust
particles high porosity and low density, and Rosetta's COSIMA and
GIADA instruments have shown that the same kinds of dust grains
are also found at 67P/Churyumov-Gerasimenko
.

Pätzold's team made their discovery by using the Radio Science
Experiment (RSI) to study the way the Rosetta orbiter is pulled by
the gravity of the comet, which is generated by its mass.

The effect of the gravity on the movement of Rosetta is measured
by changes in the frequency of the spacecraft's signals when they
are received at Earth. It is a manifestation of the Doppler
effect, produced whenever there is movement between a source and
an observer, and is the same effect that causes emergency vehicle
sirens to change pitch as they pass by.

In this case, Rosetta was being pulled by the gravity of the
comet, which changed the frequency of the radio link to Earth.
ESA's 35-metre antenna at the New Norcia ground station in
Australia is used to communicate with Rosetta during routine
operations. The variations in the signals it received were
analysed to give a picture of the gravity field across the comet.
Large internal caverns would have been noticeable by a tell-tale
drop in acceleration.

ESA's Rosetta mission is the first to perform this difficult
measurement for a comet.

"Newton's law of gravity tells us that the Rosetta spacecraft is
basically pulled by everything," says Martin Pätzold, the
principal investigator of the RSI experiment.

"In practical terms, this means that we had to remove the
influence of the Sun, all the planets – from giant Jupiter to the
dwarf planets – as well as large asteroids in the inner asteroid
belt, on Rosetta's motion, to leave just the influence of the
comet. Thankfully, these effects are well understood and this is a
standard procedure nowadays for spacecraft operations."

Next, the pressure of the solar radiation and the comet's escaping
gas tail has to be subtracted. Both of these 'blow' the spacecraft
off course. In this case, Rosetta's ROSINA instrument is extremely
helpful as it measures the gas that is streaming past the
spacecraft. This allowed Pätzold and his colleagues to calculate
and remove those effects too.

Whatever motion is left is due to the comet's mass. For Comet
67P/Churyumov-Gerasimenko, this gives a mass slightly less than 10
billion tonnes. Images from the OSIRIS camera have been used to
develop models of the comet's shape and these give the volume as
around 18.7 km^3 , meaning that the density is 533 kg/m^3 .

Extracting the details of the interior was only possible through a
piece of cosmic good luck.

Given the lack of knowledge of the comet's activity, a cautious
approach trajectory had been designed to ensure the spacecraft's
safety
.
Even in the best scenario, this would bring Rosetta no closer than
10 km.

Unfortunately, prior to 2014, the RSI team predicted that they
needed to get closer than 10 km to measure the internal
distribution of the 

[meteorite-list] NASA's James Webb Space Telescope Primary Mirror Fully Assembled

[Ron Baalke via Meteorite-list]

February 04, 2016

RELEASE 16-013

NASA's James Webb Space Telescope Primary Mirror Fully Assembled

The 18th and final primary mirror segment is installed on what will be the 
biggest and most powerful space telescope ever launched. The final mirror 
installation Wednesday at NASA's Goddard Space Flight Center in Greenbelt, 
Maryland marks an important milestone in the assembly of the agency's James 
Webb Space Telescope.

"Scientists and engineers have been working tirelessly to install these 
incredible, nearly perfect mirrors that will focus light from previously 
hidden realms of planetary atmospheres, star forming regions and the very 
beginnings of the Universe," said John Grunsfeld, associate administrator 
for NASA's Science Mission Directorate in Washington. "With the mirrors 
finally complete, we are one step closer to the audacious observations that 
will unravel the mysteries of the Universe."

Using a robotic arm reminiscent of a claw machine, the team meticulously 
installed all of Webb's primary mirror segments onto the telescope structure. 
Each of the hexagonal-shaped mirror segments measures just over 4.2 feet (1.3 
meters) across -- about the size of a coffee table -- and weighs 
approximately 88 pounds (40 kilograms). Once in space and fully deployed, the 
18 primary mirror segments will work together as one large 21.3-foot diameter 
(6.5-meter) mirror.

"Completing the assembly of the primary mirror is a very significant 
milestone and the culmination of over a decade of design, manufacturing, 
testing and now assembly of the primary mirror system," said Lee Feinberg, 
optical telescope element manager at Goddard. "There is a huge team across 
the country who contributed to this achievement."

While the primary mirror installation may be finished on the tennis 
court-sized infrared observatory, there still is much work to be done.

"Now that the mirror is complete, we look forward to installing the other 
optics and conducting tests on all the components to make sure the telescope 
can withstand a rocket launch," said Bill Ochs, James Webb Space Telescope 
project manager. "This is a great way to start 2016!"

The mirrors were built by Ball Aerospace & Technologies Corp., in Boulder, 
Colorado. Ball is the principal subcontractor to Northrop Grumman for the 
optical technology and optical system design. The installation of the mirrors 
onto the telescope structure is performed by Harris Corporation, a 
subcontractor to Northrop Grumman. Harris Corporation leads integration and 
testing for the telescope.

"The Harris team will be installing the aft optics assembly and the 
secondary mirror in order to finish the actual telescope," said Gary 
Matthews, director of Universe Exploration at Harris Corporation. "The 
heart of the telescope, the Integrated Science Instrument Module, will then 
be integrated into the telescope. After acoustic, vibration, and other tests 
at Goddard, we will ship the system down to Johnson Space Center in Houston 
for an intensive cryogenic optical test to ensure everything is working 
properly."

The James Webb Space Telescope is the scientific successor to NASA's Hubble 
Space Telescope. It will be the most powerful space telescope ever built. 
Webb will study many phases in the history of our universe, including the 
formation of solar systems capable of supporting life on planets similar to 
Earth, as well as the evolution of our own solar system. It's targeted to 
launch from French Guiana aboard an Ariane 5 rocket in 2018. Webb is an 
international project led by NASA with its partners, ESA (European Space 
Agency) and the Canadian Space Agency.

To watch the Webb telescope being built at Goddard, visit the "Webb-cam" page 
at:

http://www.jwst.nasa.gov/webcam.html


-end-

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[meteorite-list] Mars Odyssey THEMIS Images: January 25 - February 5, 2016

[Ron Baalke via Meteorite-list]

MARS ODYSSEY THEMIS IMAGES
January 25 - February 5, 2016

o Crater - False Color (25 January 2016)
  http://themis.asu.edu/zoom-20160125a

o Gale Crater - False Color (26 January 2016)
  http://themis.asu.edu/zoom-20160126a

o Crater - False Color (27 January 2016)
  http://themis.asu.edu/zoom-20160127a

o Windstreaks - False Color (28 January 2016)
  http://themis.asu.edu/zoom-20160128a

o Sand Dunes - False Color (29 January 2016)
  http://themis.asu.edu/zoom-20160129a

o Terra Sabaea - False Color (01 February 2016)
  http://themis.asu.edu/zoom-20160201a

o Ophir Chasma - False Color (02 February 2016)
  http://themis.asu.edu/zoom-20160202a

o Ophir Chasma - False Color (03 February 2016)
  http://themis.asu.edu/zoom-20160203a

o Craters - False Color (04 February 2016)
  http://themis.asu.edu/zoom-20160204a

o Terra Sabaea - False Color (05 February 2016)
  http://themis.asu.edu/zoom-20160205a




All of the THEMIS images are archive here:

http://themis.asu.edu/latest.html

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission 
for NASA's Office of Space Science, Washington, D.C. The Thermal Emission 
Imaging System (THEMIS) was developed by Arizona State University,
Tempe, in co.oration with Raytheon Santa Barbara Remote Sensing. 
The THEMIS investigation is led by Dr. Philip Christensen at Arizona State 
University. Lockheed Martin Astronautics, Denver, is the prime contractor 
for the Odyssey project, and developed and built the orbiter. Mission 
operations are conducted jointly from Lockheed Martin and from JPL, a 
division of the California Institute of Technology in Pasadena. 



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[meteorite-list] Mars Rover Opportunity Update: January 26 - February 2, 2016

[Ron Baalke via Meteorite-list]

http://mars.nasa.gov/mer/mission/status.html#opportunity

OPPORTUNITY UPDATE:  Climbing Steeper Slopes to Reach Science Targets 
 - sols 4269-4275, January 26, 2016-February 02, 2016:

Opportunity is exploring 'Marathon Valley' on the rim of Endeavour crater. 
The rover is climbing up steep slopes to reach high-value science targets 
up on 'Knudsen Ridge.'

Opportunity performed the first of two steep climbs on Sol 4269 (Jan. 
26, 2016), with just less than 16 feet (5 meters) for progress on slopes 
nearing 30 degrees. On the next sol, the rover ascended further up slope 
about 14 feet (4.4 meters) reaching tilts just under 30 degrees. For the 
next fives sols Opportunity conducted extensive Navigation Camera (Navcam) 
and Panoramic Camera (Pancam) imaging surveys of the potential rock targets 
and ridge outcrop in front of the rover in preparation for extensive in-situ 
(contact) science campaigns on the geologic units high up on this ridge 
line.

As of Sol 4275 (Feb. 2, 2016), the solar array energy production was 498 
watt-hours with an atmospheric opacity (Tau) of 0.459 and a solar array 
dust factor of 0.683.

Total odometry is 26.51 miles (42.66 kilometers), more than a marathon.
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