[meteorite-list] AD: For Sale - 73 Remaining Collection Specimens

From: Dave Ribeca <davior_at_meteoritecentral.com>
Date: Sat, 9 Jan 2016 09:43:35 -0500
Message-ID: <F59687319563446CAC79F7EE69778276_at_UserPC>

Hi All,
I have 73 remaining collection specimens up for sale on ebay. Once these are
gone I will have sold the portion of my collection that I had planned. I
have reduced the prices of many for the last time. From late January on, all
remaining specimens will be available on ebay at a "Buy Now" offer only. If
you see something you like, without a bid, contact me off ebay. Also, hold
deposits are welcome.

~1 Day and 16 Hours left - 73 remaining collection specimens as of 1/9/16,
9:30am, ET.

-
http://www.ebay.com/sch/i.html?_from=R40&_trksid=p3984.m570.l1313.TR0.TRC0.A0.H0.XRibeca.TRS2&_nkw=Ribeca&_sacat=0

Thank you to all the meteorite people who have purchased the majority of my
collection over the past five months, or so. You people are the BEST! Please
take good care of my specimens....

David L. Ribeca
IMCA Member 4050



-----Original Message-----
From: meteorite-list-request at meteoritecentral.com
Sent: Saturday, January 09, 2016 1:25 AM
To: meteorite-list at meteoritecentral.com
Subject: Meteorite-list Digest, Vol 155, Issue 9

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Today's Topics:

   1. Mining Asteroids (ian macleod)
   2. Meteorite Picture of the Day (valparint at aol.com)
   3. Re: Happy New Year to the World (Peter Davidson)
   4. Re: Mining Asteroids (Walter Paleski)
   5. AD: Deal of the Day (valparint at aol.com)
   6. Mars Odyssey THEMIS Images: December 28, 2015 - January 8,
      2016 (Ron Baalke)
   7. Curiosoty Rover Rounds Martian Dune to Get to the Other Side
      (Ron Baalke)
   8. NASA Office to Coordinate Asteroid Detection, Hazard
      Mitigation (Ron Baalke)
   9. Dawn Journal - December 31, 2015 (Ron Baalke)


----------------------------------------------------------------------

Message: 1
Date: Fri, 8 Jan 2016 06:38:49 +0000
From: ian macleod <ianmacca81 at hotmail.com>
To: "meteorite-list at meteoritecentral.com"
<meteorite-list at meteoritecentral.com>
Subject: [meteorite-list] Mining Asteroids
Message-ID:
<MEXPR01MB0070B85E53BE0090EAEE4469CDF60 at MEXPR01MB0070.ausprd01.prod.outlook.com>

Content-Type: text/plain; charset="iso-8859-1"

Hi List, I love the romantic idea that asteroids will be mined one day.
However considering that on Earth whole terrestrial?mines are shut down that
contain ore or oil cheaper to?obtain than sending a space x rocket and crew
(or robot) to an asteroid. I hardly think mining asteroids will eventuate
anytime soon.


Even if we used space x re-usable rockets....... It just would not be cost
effective at the moment!


Mining water or low scale mining as we explore space might be the first
step, this saves a re-fuelling or a?water trip.


look at China and the world markets, massive slowing down (and disappearing)
?of capital.........


-Apple just lost like 20% or so, that equivalent to the size of Pepsi in $
-China down at least 3 trillion!
-Australia down 40 billion at least
-Oil companies writing off reserves that cannot or?will not?be explored
within 5 years (and this stuff is cheap compared to asteroid mining)


So in all REALITY it is just a pipe dream for now


Cheers


Ian










------------------------------

Message: 2
Date: Fri, 8 Jan 2016 00:00:21 -0700
From: <valparint at aol.com>
To: <meteorite-list at meteoritecentral.com>
Subject: [meteorite-list] Meteorite Picture of the Day
Message-ID: <258D84B54981472A94AFD032539FE10A at Seuthopolis>
Content-Type: text/plain

Today's Meteorite Picture of the Day: NWA 10256

Contributed by: Geoff Notkin/Aerolite Meteorites

http://www.tucsonmeteorites.com/mpodmain.asp?DD=01/08/2016


------------------------------

Message: 3
Date: Fri, 8 Jan 2016 09:56:11 +0000
From: Peter Davidson <P.Davidson at nms.ac.uk>
To: "Impactika at aol.com" <Impactika at aol.com>, "Meteorite List
(meteorite-list at meteoritecentral.com)"
<meteorite-list at meteoritecentral.com>
Subject: Re: [meteorite-list] Happy New Year to the World
Message-ID:
<576F2B74A34E584AA173B40D1A8914C336D127A7 at NMSMAIL01.nms2k.int>
Content-Type: text/plain; charset="us-ascii"

Anne and all the Meteorite Community

Wishing all my friends and acquaintances around the globe a very happy and
successful New Year from bonnie Scotland. I hope to see a few of you in
Tucson again.

A guid New Year tae yin an' a'.

Good hunting

Peter Davidson
Senior Curator of Mineralogy

Natural Sciences Department
National Museums Collection Centre
242 West Granton Road
Edinburgh
EH5 1JA
TEL: 0131 247 4283
E-mail: p.davidson at nms.ac.uk

-----Original Message-----
From: Meteorite-list [mailto:meteorite-list-bounces at meteoritecentral.com] On
Behalf Of Anne Black via Meteorite-list
Sent: 31 December 2015 22:27
To: mikestang at gmail.com; jl at lutzon.com
Cc: meteorite-list at meteoritecentral.com
Subject: Re: [meteorite-list] Happy New Year to the World

OK, Michael,


HAPPY NEW YEAR TO MOST OF THE WORLD!!!

Lets hope that 2016 will be kinder to all than 2015.


Anne M. Black
www.IMPACTIKA.com
IMPACTIKA at aol.com


-----Original Message-----
From: Michael Mulgrew via Meteorite-list
<meteorite-list at meteoritecentral.com>
To: John Lutzon <jl at lutzon.com>
Cc: Meteorite List <meteorite-list at meteoritecentral.com>
Sent: Thu, Dec 31, 2015 3:19 pm
Subject: Re: [meteorite-list] Happy New Year to the World

Not quite everyone everywhere, John. It's often easy to assume the whole
world does everything like we do, but there are a multitude of cultures and
belief systems to take into account. Here's a small list of countries and
people who do not follow the Gregorian New Year (from
wikipedia):

Ethiopian New Year called Enkutatash. It is celebrated on September 11
(September 12 in leap years).

The Odunde Festival is also called the "African New Year" is celebrated in
Philadelphia, Pennsylvania in the United States on the second Sunday of
June.

Cambodian New Year (Chaul Chnam Thmey) is celebrated on April 13 or April
14.

Chinese New Year is celebrated in many countries around the world. It is the
first day of the lunar calendar and is corrected for the solar every three
years.

Korean New Year, called Seollal, is the first day of the lunar calendar.

Thai New Year is celebrated on April 13 or April 14 and is called Songkran
in the local language.

Vietnamese New Year normally falls between 20 January and 20 February.

In the Gwaun Valley, Pembrokeshire, Wales the new year is celebrated on
January 13, based on the Julian calendar.

Hijri New Year in the Islamic culture is also known as Islamic new year is
the day that marks the beginning of a new Islamic calendar year. New Year
moves from year to year because the Islamic calendar is a lunar calendar.

Nowruz marks the first day of spring and the beginning of the year in
Iranian calendar. It is celebrated on the day of the astronomical vernal
equinox.
Rosh Hashanah, the Jewish new year, falls during September or October.

Hindu in Assam, Bengal, Kerala, Nepal, Orissa, Punjab and Tamil Nadu
celebrate the new year when the Sun enters Aries on the Hindu calendar. This
is normally on April 14 or April 15.

Unlike most other calendar systems in India, the New Year's Day on the
Malayalam Calendar is not based on any astronomical event. It is just the
first day of the first of the twelve months on the Malayalam Calendar.

The Sikh New Year is celebrated as per the Nanakshahi calendar. The epoch of
this calendar is the birth of the first Sikh Guru, Guru Nanak in 1469. New
Year's Day falls annually on what is March 14 in the Gregorian Western
calendar.

Sinhalese New Year is celebrated in Sri Lankan culture predominantly by the
Sri Lankan Sinhalese, while the Tamil New Year on the same day is celebrated
by Sri Lankan Tamils. The Sinhalese New Year marks the end of harvest
season, by the month of Bak (April) between April 13 and April 14.

Telugu New Year (Ugadi), Kannada New Year (Yugadi) is celebrated in March
(generally), April (occasionally).


Globally yours,
Michael in so. Cal.

Hippy Nude Year!

On Thu, Dec 31, 2015 at 9:28 AM, John Lutzon via Meteorite-list
<meteorite-list at meteoritecentral.com> wrote:
> Everyone, Everywhere,
>
> Happy New Year !!!!!!!
>
> Happiness and Good Health to everyone.
>
> John Lutzon
> IMCA#1896
> ______________________________________________
>
> Visit our Facebook page https://www.facebook.com/meteoritecentral and
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Archives at http://www.meteorite-list-archives.com
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Join us for BUILD IT! Adventures with LEGO(R) Bricks. A free display and
family activities from 29 January?17 April 2016. www.nms.ac.uk/buildit
(http://www.nms.ac.uk/buildit)

National Museums Scotland, Scottish Charity, No. SC 011130
This communication is intended for the addressee(s) only. If you are not the
addressee please inform the sender and delete the email from your system.
The statements and opinions expressed in this message are those of the
author and do not necessarily reflect those of National Museums Scotland.
This message is subject to the Data Protection Act 1998 and Freedom of
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may be caused to your systems or data by this message.


------------------------------

Message: 4
Date: Fri, 8 Jan 2016 08:20:38 -0500
From: Walter Paleski <paleskiw at gmail.com>
To: "meteorite-list at meteoritecentral.com"
<meteorite-list at meteoritecentral.com>
Subject: Re: [meteorite-list] Mining Asteroids
Message-ID: <8AC650A6-5E82-4C25-B436-C0DBDE534F11 at gmail.com>
Content-Type: text/plain; charset=us-ascii

>From what I read they don't anticipate that to start happening until 2035

Walter J Paleski

> On Jan 8, 2016, at 1:38 AM, ian macleod via Meteorite-list
> <meteorite-list at meteoritecentral.com> wrote:
>
> Hi List, I love the romantic idea that asteroids will be mined one day.
> However considering that on Earth whole terrestrial mines are shut down
> that contain ore or oil cheaper to obtain than sending a space x rocket
> and crew (or robot) to an asteroid. I hardly think mining asteroids will
> eventuate anytime soon.
>
>
> Even if we used space x re-usable rockets....... It just would not be cost
> effective at the moment!
>
>
> Mining water or low scale mining as we explore space might be the first
> step, this saves a re-fuelling or a water trip.
>
>
> look at China and the world markets, massive slowing down (and
> disappearing) of capital.........
>
>
> -Apple just lost like 20% or so, that equivalent to the size of Pepsi in $
> -China down at least 3 trillion!
> -Australia down 40 billion at least
> -Oil companies writing off reserves that cannot or will not be explored
> within 5 years (and this stuff is cheap compared to asteroid mining)
>
>
> So in all REALITY it is just a pipe dream for now
>
>
> Cheers
>
>
> Ian
>
>
>
>
>
>
>
>
> ______________________________________________
>
> Visit our Facebook page https://www.facebook.com/meteoritecentral and the
> Archives at http://www.meteorite-list-archives.com
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> https://pairlist3.pair.net/mailman/listinfo/meteorite-list


------------------------------

Message: 5
Date: Fri, 8 Jan 2016 06:34:54 -0700
From: <valparint at aol.com>
To: <meteorite-list at meteoritecentral.com>
Subject: [meteorite-list] AD: Deal of the Day
Message-ID: <69B84BFD2ECD4454850A3F26CC7A27CA at Seuthopolis>
Content-Type: text/plain

Greetings Listees.

The Deal of the Day at Tucson Meteorites is active again after resting for
the holidays. Check it out at

tinyurl.com/TucMet

Look for the Deal of the Day fireball, and check out the new stuff on the
main web site, too.

Thanks for looking.

Paul Swartz
IMCA 5204
Meteorite Picture of the Day Web Master

ad 3 of 12


------------------------------

Message: 6
Date: Fri, 8 Jan 2016 14:02:09 -0800 (PST)
From: Ron Baalke <baalke at zagami.jpl.nasa.gov>
To: meteorite-list at meteoritecentral.com (Meteorite Mailing List)
Subject: [meteorite-list] Mars Odyssey THEMIS Images: December 28,
2015 - January 8, 2016
Message-ID: <201601082202.u08M29dd014308 at zagami.jpl.nasa.gov>
Content-Type: text/plain; charset=us-ascii


MARS ODYSSEY THEMIS IMAGES
December 28, 2015 - January 8, 2016

o Nili Fossae - False Color (28 December 2015)
  http://themis.asu.edu/zoom-20151228a

o Hebes Mensa - False Color (29 December 2015)
  http://themis.asu.edu/zoom-20151229a

o Noachis Terra - False Color (30 December 2015)
  http://themis.asu.edu/zoom-20151230a

o Ophir Planum - False Color (31 December 2015)
  http://themis.asu.edu/zoom-20151231a

o Eos Chasma - False Color (01 January 2016)
  http://themis.asu.edu/zoom-20160101a

o Iani Chaos - False Color (04 January 2016)
  http://themis.asu.edu/zoom-20160104a

o Nili Fossae - False Color (05 January 2016)
  http://themis.asu.edu/zoom-20160105a

o Nili Patera - False Color (06 January 2016)
  http://themis.asu.edu/zoom-20160106a

o Crater - False Color (07 January 2016)
  http://themis.asu.edu/zoom-20160107a

o Arabia Terra Plains - False Color (08 January 2016)
  http://themis.asu.edu/zoom-20160108a


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.





------------------------------

Message: 7
Date: Fri, 8 Jan 2016 14:19:11 -0800 (PST)
From: Ron Baalke <baalke at zagami.jpl.nasa.gov>
To: meteorite-list at meteoritecentral.com (Meteorite Mailing List)
Subject: [meteorite-list] Curiosoty Rover Rounds Martian Dune to Get
to the Other Side
Message-ID: <201601082219.u08MJBhc016326 at zagami.jpl.nasa.gov>
Content-Type: text/plain; charset=us-ascii



http://www.jpl.nasa.gov/news/news.php?feature=4810

Rover Rounds Martian Dune to Get to the Other Side
Jet Propulsion Laboratory
January 4, 2016

NASA's Curiosity Mars rover, partway through the first up-close study
ever conducted of extraterrestrial sand dunes, is providing dramatic views
of a dune's steep face, where cascading sand has sculpted very different
textures than the wavy ripples visible on the dune's windward slope.

Panoramic scenes dominated by the steep face of a dune called "Namib Dune"
are online at these sites:

http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA20284

http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA20281

Researchers are using Curiosity to examine examples of the Bagnold Dunes,
a band of dark sand dunes lining the northwestern flank of Mt. Sharp,
the layered mountain the rover is climbing. A characteristic that sets
true dunes apart from other wind-shaped bodies of sand, such as drifts
and ripples previously visited by Mars rovers, is a steep, downwind slope
known as the slip face. Here, sand blowing across the windward side of
the dune suddenly becomes sheltered from the wind by the dune itself.
The sand falls out of the air and builds up on the slope until it becomes
steepened and flows in mini-avalanches down the face.

The mission's dune-investigation campaign is designed to increase
understanding
about how wind moves and sorts grains of sand, in an environment with
less gravity and much less atmosphere than well-studied dune fields on
Earth. The Bagnold Dunes are active. Sequential images taken from orbit
over the course of multiple years show that some of these dunes are
migrating
by as much as a yard, or meter, per Earth year.

Curiosity has not caught a sand slide in action, but the rover's images
of the Namib Dune slip face show where such slides have occurred recently.
These dunes likely are most active in Mars' southern summer, rather than
in the current late-fall season.

A few days of rover operations were affected in December due to an
arm-motion
fault, diagnosed as a minor software issue. Normal use of the arm resumed
Dec. 23.

Curiosity has been working on Mars since early August 2012. It reached
the base of Mount Sharp in 2014 after fruitfully investigating outcrops
closer to its landing site and then trekking to the mountain. The main
mission objective now is to examine successively higher layers of Mount
Sharp.

For more information about Curiosity, visit:

http://mars.jpl.nasa.gov/msl


Media Contact

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
guy.webster at jpl.nasa.gov

Dwayne Brown / Laurie Cantillo
NASA Headquarters, Washington
202-358-1726 / 202-358-1077
dwayne.c.brown at nasa.gov / laura.l.cantillo at nasa.gov

2016-001



------------------------------

Message: 8
Date: Fri, 8 Jan 2016 14:20:34 -0800 (PST)
From: Ron Baalke <baalke at zagami.jpl.nasa.gov>
To: meteorite-list at meteoritecentral.com (Meteorite Mailing List)
Subject: [meteorite-list] NASA Office to Coordinate Asteroid
Detection, Hazard Mitigation
Message-ID: <201601082220.u08MKYUC017280 at zagami.jpl.nasa.gov>
Content-Type: text/plain; charset=us-ascii



http://www.jpl.nasa.gov/news/news.php?feature=4816

NASA Office to Coordinate Asteroid Detection, Hazard Mitigation
Jet Propulsion Laboratory
January 7, 2016

NASA has formalized its ongoing program for detecting and tracking
near-Earth
objects (NEOs) as the Planetary Defense Coordination Office (PDCO). The
office remains within NASA's Planetary Science Division, in the agency's
Science Mission Directorate in Washington. The office will be responsible
for supervision of all NASA-funded projects to find and characterize
asteroids
and comets that pass near Earth's orbit around the sun. It will also take
a leading role in coordinating interagency and intergovernmental efforts
in response to any potential impact threats.

More than 13,500 near-Earth objects of all sizes have been discovered
to date -- more than 95 percent of them since NASA-funded surveys began
in 1998. About 1,500 NEOs are now detected each year.

"Asteroid detection, tracking and defense of our planet is something that
NASA, its interagency partners, and the global community take very
seriously,"
said John Grunsfeld, associate administrator for NASA's Science Mission
Directorate in Washington. "While there are no known impact threats at
this time, the 2013 Chelyabinsk super-fireball and the recent 'Halloween
Asteroid' close approach remind us of why we need to remain vigilant and
keep our eyes to the sky."

NASA has been engaged in worldwide planning for planetary defense for
some time, and this office will improve and expand on those efforts, working
with the Federal Emergency Management Agency (FEMA) and other federal
agencies and departments.

In addition to detecting and tracking potentially hazardous objects, the
office will issue notices of close passes and warnings of any detected
potential impacts, based on credible science data. The office also will
continue to assist with coordination across the U.S. government,
participating
in the planning for response to an actual impact threat, working in
conjunction
with FEMA, the Department of Defense, other U.S. agencies and international
counterparts.

"The formal establishment of the Planetary Defense Coordination Office
makes it evident that the agency is committed to perform a leadership
role in national and international efforts for detection of these natural
impact hazards, and to be engaged in planning if there is a need for
planetary
defense," said Lindley Johnson, longtime NEO program executive and now
lead program executive for the office, with the title of Planetary Defense
Officer.

Astronomers detect near-Earth objects using ground-based telescopes around
the world as well as NASA's space-based NEOWISE infrared telescope. Tracking
data are provided to a global database maintained by the Minor Planet
Center, sanctioned by the International Astronomical Union. Once detected,
orbits are precisely predicted and monitored by the Center for NEO Studies
(CNEOS) at NASA's Jet Propulsion Laboratory in Pasadena, California.
Select NEOs are further characterized by assets such as NASA's InfraRed
Telescope Facility, Spitzer Space Telescope and interplanetary radars
operated by NASA and the National Science Foundation. Such efforts are
coordinated and funded by NASA's longtime NEO Observations Program, which
will continue as a research program under the office.

The Planetary Defense Coordination Office is being applauded by the National
Science Foundation (NSF), which supports research and education in science
and engineering. "NSF welcomes the increased visibility afforded to this
critical activity," said Nigel Sharp, program director in the agency's
Division of Astronomical Sciences. "We look forward to continuing the
fruitful collaboration across the agencies to bring all of our resources
-- both ground-based and space-based -- to the study of this important
problem."

With more than 90 percent of NEOs larger than 3,000 feet (1 kilometer)
already discovered, NASA is now focused on finding objects that are slightly
bigger than a football field -- 450 feet (140 meters) or larger. In 2005,
NASA was tasked with finding 90 percent of this class of NEOs by the end
of 2020. NASA-funded surveys have detected an estimated 25 percent of
these mid-sized but still potentially hazardous objects to date.

NASA's long-term planetary defense goals include developing technology
and techniques for deflecting or redirecting objects that are determined
to be on an impact course with Earth. NASA's Asteroid Redirect Mission
concept would demonstrate the effectiveness of the gravity tractor method
of planetary defense, using the mass of another object to pull an asteroid
slightly from its original orbital path. The joint NASA-European Space
Agency Asteroid Impact and Deflection Assessment (AIDA) mission concept,
if pursued, would demonstrate an impact deflection method of planetary
defense.

Even if intervention is not possible, NASA would provide expert input
to FEMA about impact timing, location and effects to inform emergency
response operations. In turn, FEMA would handle the preparations and
response
planning related to the consequences of atmospheric entry or impact to
U.S. communities.

"FEMA is dedicated to protecting against all hazards, and the launch of
the coordination office will ensure early detection and warning capability,
and will further enhance FEMA's collaborative relationship with NASA,"
said FEMA Administrator Craig Fugate.

The concept of a central office to coordinate asteroid detection and
mitigation
has been under consideration since 2010, when an Ad-Hoc Task Force on
Planetary Defense of the NASA Advisory Council recommended that NASA
"organize
for effective action on planetary defense and prepare to respond to impact
threats," and should "lead U.S. planetary defense efforts in national
and international forums." In addition, a NASA Office of Inspector General
2014 report concluded that the NEO Observations Program would be more
"efficient, effective and transparent" if it were organized and managed
in accordance with standard NASA research program requirements.

The NEO Observations Program operated on a budget of $4 million as recently
as fiscal year 2010. That same year, the President announced a new goal
for NASA -- a human mission to an asteroid. The President's fiscal year
2012 budget included, and Congress appropriated, $20.4 million for an
expanded NASA NEO Observations Program. The agency's Asteroid Grand
Challenge
to find all asteroid threats also launched in 2012. Funding for the NEO
program doubled to $40 million in 2014, which increased the rate of
detection
of new NEOs by 40 percent and jump-started research into potential asteroid
deflection techniques.

In 2015, NASA's NEO Observations Program supported 54 ongoing projects,
including detection and tracking campaigns, asteroid characterization
efforts and radar projects. Nine studies were funded to explore techniques
for impact mitigation.

The recently passed federal budget for fiscal year 2016 includes $50 million
for NEO observations and planetary defense, representing a more than
ten-fold
increase since the beginning of the current administration.

For regular updates on passing asteroids, NASA has an asteroid widget
that lists the next five close approaches to Earth; it links to the CNEOS
website with a complete list of recent and upcoming close approaches,
as well as all other data on the orbits of known NEOs, so scientists and
members of the media and public can track information on known objects.

For more information on NASA's Planetary Defense Coordination Office,
visit:

http://www.nasa.gov/planetarydefense


Media Contact

Dwayne Brown / Laurie Cantillo
NASA Headquarters, Washington
202-358-1726 / 202-358-1077
dwayne.c.brown at nasa.gov / laura.l.cantillo at nasa.gov

DC Agle
Jet Propulsion Laboratory, Pasadena, California
818-393-9011
agle at jpl.nasa.gov

2016-007



------------------------------

Message: 9
Date: Fri, 8 Jan 2016 14:41:41 -0800 (PST)
From: Ron Baalke <baalke at zagami.jpl.nasa.gov>
To: meteorite-list at meteoritecentral.com (Meteorite Mailing List)
Subject: [meteorite-list] Dawn Journal - December 31, 2015
Message-ID: <201601082241.u08MffxY019335 at zagami.jpl.nasa.gov>
Content-Type: text/plain; charset=us-ascii


http://dawnblog.jpl.nasa.gov/2015/12/31/dawn-journal-december-31/

Dawn Journal
by Dr. Marc Rayman
December 31, 2015

Dear Transcendawnts,

Dawn is now performing the final act of its remarkable celestial
choreography,
held close in Ceres' firm gravitational embrace. The distant explorer
is developing humankind's most intimate portrait ever of a dwarf planet,
and it likely will be a long, long time before the level of detail is
surpassed.

The spacecraft is concluding an outstandingly successful year 1,500 times
nearer to Ceres than it began. More important, it is more than 1.4 million
times closer to Ceres than Earth is today. From its uniquely favorable
vantage point, Dawn can relay to us spectacular views that would otherwise
be unattainable. At an average altitude of only 240 miles (385 kilometers),
the spacecraft is closer to Ceres than the International Space Station
is to Earth. From that tight orbit, the dwarf planet looks the same size
as a soccer ball seen from only 3.5 inches (9.0 centimeters) away. This
is in-your-face exploration.

The spacecraft has returned more than 16,000 pictures of Ceres this year
(including more than 2,000 since descending to its low orbit this month).
One of your correspondent's favorites (below) was taken on Dec. 10 when
Dawn was verifying the condition of its backup camera. Not only did the
camera pass its tests, but it yielded a wonderful, dramatic view not far
from the south pole. It is southern hemisphere winter on Ceres now, with
the sun north of the equator. From the perspective of the photographed
location, the sun is near the horizon, creating the long shadows that
add depth and character to the scene. And usually in close-in orbits,
we look nearly straight down. Unlike such overhead pictures typical of
planetary spacecraft (including Dawn), this view is mostly forward and
shows a richly detailed landscape ahead, one you can imagine being in
- a real place, albeit an exotic one. This may be like the breathtaking
panorama you could enjoy with your face pressed to the porthole of your
spaceship as you are approaching your landing sight. You are right there.
It looks - it feels! - so real and physical. You might actually plan a
hike across some of the terrain. And it may be that a visiting explorer
or even a colonist someday will have this same view before setting off
on a trek through the Cerean countryside.

Of course, Dawn's objectives include much more than taking incredibly
neat pictures, a task at which it excels. It is designed to collect
scientifically
meaningful photos and other valuable measurements. We'll see more below
about what some of the images and spectra from higher altitudes have
revealed
about Ceres, but first let's take a look at the three highest priority
investigations Dawn is conducting now in its final orbit, sometimes known
as the low altitude mapping orbit (LAMO). While the camera, visible mapping
spectrometer and infrared mapping spectrometer show the surface, these
other measurements probe beneath.

With the spacecraft this close to the ground, it can measure two kinds
of nuclear radiation that come from as much as a yard (meter) deep. The
radiation carries the signatures of the atoms there, allowing scientists
to inventory some of the key chemical elements of geological interest.
One component of this radiation is gamma ray photons, a high energy form
of electromagnetic radiation with a frequency beyond visible light, beyond
ultraviolet, even beyond X-rays. Neutrons in the radiation are entirely
different from gamma rays. They are particles usually found in the nuclei
of atoms (for those of you who happen to look there). Indeed, outweighing
protons, and outnumbering them in most kinds of atoms, they constitute
most of the mass of atoms other than hydrogen in Ceres (and everywhere
else in the universe, including in your correspondent).

To tell us what members of the periodic table of the elements are present,
Dawn's gamma ray and neutron detector (GRaND) does more than detect those
two kinds of radiation. Despite its name, GRaND is not at all pretentious,
but its capabilities are quite impressive. Consisting of 21 sensors, the
device measures the energy of each gamma ray photon and of each neutron.
(That doesn't lend itself to as engaging an acronym.) It is these gamma
ray spectra and neutron spectra that reveal the identities of the atomic
species in the ground.

Some of the gamma rays are produced by radioactive elements, but most
of them and the neutrons are generated as byproducts of cosmic rays
impinging
on Ceres. Space is pervaded by cosmic radiation, composed of a variety
of subatomic particles that originate outside our solar system. Earth's
atmosphere and magnetic field protect the surface (and those who dwell
there) from cosmic rays, but Ceres lacks such defenses. The cosmic rays
interact with nuclei of atoms, and some of the gamma rays and neutrons
that are released escape back into space where they are intercepted by
GRaND on the orbiting Dawn.

Unlike the relatively bright light reflected from Ceres's surface that
the camera, infrared spectrometer and visible spectrometer record, the
radiation GRaND measures is very faint. Just as a picture of a dim object
requires a longer exposure than for a bright subject, GRaND's "pictures"
of Ceres require very long exposures, lasting weeks, but mission planners
have provided Dawn with the necessary time. Because the equivalent of
the illumination for the gamma ray and neutron pictures is cosmic rays,
not sunlight, regions in darkness are no fainter than those illuminated
by the sun. GRaND works on both the day side and the night side of Ceres.

In addition to the gamma ray spectra and neutron spectra, Dawn's other
top priority now is measuring Ceres' gravity field. The results will help
scientists infer the interior structure of the dwarf planet. The
measurements
made in the higher altitude orbits turned out to be even more accurate
than the team had expected, but now that the probe is as close to Ceres
as it will ever go, and so the gravitational pull is the strongest, they
can obtain still better measurements.

Gravity is one of four fundamental forces in nature, and its extreme
weakness
is one of the fascinating mysteries of how the universe works. It feels
strong to us (well, most of us) because we don't so easily sense the two
kinds of nuclear forces, both of which extend only over extremely short
distances, and we generally don't recognize the electromagnetic force.
With both positive and negative electrical charges, attractive and repulsive
electromagnetic forces often cancel. Not so with gravity. All matter exerts
attractive gravity, and it can all add up. The reason gravity -- by far
the weakest of the four forces -- is so salient for those of you on or
near Earth is that there is such a vast amount of matter in the planet
and it all pulls together to hold you down. Dawn overcame that pull with
its powerful Delta rocket. Now the principal gravitational force acting
on it is the cumulative effect of all the matter in Ceres, and that is
what determines its orbital motion.

The spacecraft experiences a changing force both as the inhomogeneous
dwarf planet beneath it rotates on its axis and as the craft circles that
massive orb. When Dawn is closer to locations within Ceres with greater
density (i.e., more matter), the ship feels a stronger tug, and when it
is near regions with lower density, and hence less powerful gravity, the
attraction is weaker. The spacecraft accelerates and decelerates very
slightly as its orbit carries it closer to and farther from the volumes
of different density. By carefully and systematically plotting the
exquisitely
small variations in the probe's motion, navigators can calculate how the
mass is distributed inside Ceres, essentially creating an interior map.
This technique allowed scientists to establish that Vesta, the protoplanet
Dawn explored in 2011-2012, has a dense core (composed principally of
iron and nickel) surrounded by a less dense mantle and crust. (That is
one of the reasons scientists now consider Vesta to be more closely related
to Earth and the other terrestrial planets than to typical asteroids.)

Mapping the orbit requires systems both on Dawn and on Earth. Using the
large and exquisitely sensitive antennas of NASA's Deep Space Network
(DSN), navigators measure tiny changes in the frequency, or pitch, of
the spacecraft's radio signal, and that reveals changes in the craft's
velocity. This technique relies on the Doppler effect, which is familiar
to most terrestrial readers as they hear the pitch of a siren rise as
it approaches and fall as it recedes. Other readers who more commonly
travel at speeds closer to that of light recognize that the well-known
blueshift and redshift are manifestations of the same principle, applied
to light waves rather than sound waves. Even as Dawn orbits Ceres at 610
mph (980 kilometers per hour), engineers can detect changes in its speed
of only one foot (0.3 meters) per hour, or one five-thousandth of a mph
(one three-thousandth of a kilometer per hour). Another way to track the
spacecraft is to measure the distance very accurately as it revolves around
Ceres. The DSN times a radio signal that goes from Earth to Dawn and back.
As you are reminded at the end of every Dawn Journal, those signals travel
at the universal limit of the speed of light, which is known with
exceptional
accuracy. Combining the speed of light with the time allows the distance
to be pinpointed. These measurements with Dawn's radio, along with other
data, enable scientists to peer deep into the dwarf planet

Although it is not among the highest scientific priorities, the flight
team is every bit as interested in the photography as you are. We are
visual creatures, so photographs have a special appeal. They transport
us to mysterious, faraway worlds more effectively than any propulsion
system. Even as Dawn is bringing the alien surface into sharper focus
now, the pictures taken in higher orbits have allowed scientists to gain
new insights into this ancient world. Geologists have located more than
130 bright regions, none being more striking than the mesmerizing luster
in Occator crater. The pictures taken in visible and infrared wavelengths
have helped them determine that the highly reflective material is a type
of salt.

It is very difficult to pin down the specific composition with the
measurements
that have been analyzed so far. Scientists compare how reflective the
scene is at different wavelengths with the reflective properties of likely
candidate materials studied in laboratories. So far, magnesium sulfate
yields the best match (although it is not definitive). That isn't the
kind of salt you normally put on your food (or if it is, I'll be wary
about accepting the kind invitation to dine in your home), but it is very
similar (albeit not identical) to Epsom salts, which have many other
familiar
uses.

Scientists' best explanation now for the deposits of salt is that when
asteroids crash into Ceres, they excavate underground briny water-ice.
Once on the surface and exposed to the vacuum of space, even in the freezing
cold so far from the sun, the ice sublimes, the water molecules going
directly from the solid ice to gas without an intermediate liquid stage.
Left behind are the materials that had been dissolved in the water. The
size and brightness of the different regions depend in part on how long
ago the impact occurred. A very preliminary estimate is that Occator was
formed by a powerful collision around 80 million years ago, which is
relatively
recent in geological times. (We will see in a future Dawn Journal how
scientists estimate the age and why the pictures in this low altitude
mapping orbit will help refine the value.)

As soon as Dawn's pictures of Ceres arrived early this year, many people
referred to the bright regions as "white spots," although as we opined
then, such a description was premature. The black and white pictures
revealed
nothing about the color, only the brightness. Now we know that most have
a very slight blue tint. For reasons not yet clear, the central bright
area of Occator is tinged with more red. Nevertheless, the coloration
is subtle, and our eyes would register white.

Measurements with both finer wavelength discrimination and broader
wavelength
coverage in the infrared have revealed still more about the nature of
Ceres. Scientists using data from one of the two spectrometers in the
visible and infrared mapping spectrometer instrument (VIR) have found
that a class of minerals known as phyllosilicates is common on Ceres.
As with the magnesium sulfate, the identification is made by comparing
Dawn's detailed spectral measurements with laboratory spectra of a great
many different kinds of minerals. This technique is a mainstay of astronomy
(with both spacecraft and telescopic observations) and has a solid
foundation
of research that dates to the nineteenth century, but given the tremendous
variety of minerals that occur in nature, the results generally are neither
absolutely conclusive nor extremely specific.

There are dozens of phyllosilicates on Earth (one well known group is
mica). Ceres too likely contains a mixture of at least several. Other
compounds are evident as well, but what is most striking is the signature
of ammonia in the minerals. This chemical is manufactured extensively
on Earth, but few industries have invested in production plants so far
from their home offices. (Any corporations considering establishing Cerean
chemical plants are invited to contact the Dawn project. Perhaps, however,
mining would be a more appropriate first step in a long-term business
plan.)

Ammonia's presence on Ceres is important. This simple molecule would have
been common in the material swirling around the young sun almost 4.6 billion
years ago when planets were forming. (Last year we discussed this period
at the dawn of the solar system.) But at Ceres' present distance from
the sun, it would have been too warm for ammonia to be caught up in the
planet-forming process, just as it was even closer to the sun where Earth
resides. There are at least two possible explanations for how Ceres acquired
its large inventory of ammonia. One is that it formed much farther from
the sun, perhaps even beyond Neptune, where conditions were cool enough
for ammonia to condense. In that case, it could easily have incorporated
ammonia. Subsequent gravitational jostling among the new residents of
the solar system could have propelled Ceres into its present orbit between
Mars and Jupiter. Another possibility is that Ceres formed closer to where
it is now but that debris containing ammonia from the outer solar system
drifted inward and some of it ultimately fell onto the dwarf planet. If
enough made its way to Ceres, the ground would be covered with the chemical,
just as VIR observed.

Scientists continue to analyze the thousands of photos and millions of
infrared and visible spectra even as Dawn is now collecting more precious
data. Next month, we will summarize the intricate plan that apportions
time among pointing the spacecraft's sensors at Ceres to perform
measurements,
its main antenna at Earth to transmit its findings and receive new
instructions
and its ion engine in the direction needed to adjust its orbit.

The plans described last month for getting started in this fourth and
final mapping orbit worked out extremely well. You can follow Dawn's
activities
with the status reports posted at least twice a week here. And you can
see new pictures regularly in the Ceres image gallery.

We will be treated to many more marvelous sights on Ceres now that Dawn's
pictures will display four times the detail of the views from its third
mapping orbit. The mapping orbits are summarized in the following table,
updated from what we have presented before. (This fourth orbit is listed
here as beginning on Dec. 16. In fact, the highest priority work, which
is obtaining the gamma ray spectra, neutron spectra and gravity
measurements,
began on Dec. 7, as explained last month. But Dec. 16 is when the spacecraft
started its bonus campaign of measuring infrared spectra and taking
pictures.
Recognizing that what most readers care about is the photography, regardless
of the scientific priorities, that is the date we use here.

Mapping orbit Dawn code name Dates Altitude in miles (kilometers) Resolution
in feet (meters) per pixel Resolution compared to Hubble Orbit period
Equivalent
distance of a soccer ball
1 RC3 April 23 - May 9 8,400 (13,600) 4,200 (1,300) 24 15 days 10 feet
(3.2 meters)
2 Survey June 6-30 2,700 (4,400) 1,400 (410) 73 3.1 days 3.4 feet (1.0
meters)
3 HAMO Aug 17 - Oct 23 915 (1,470) 450 (140) 217 19 hours 14 inches (34
cm)
4 LAMO Dec 16 - end of mission 240 (385) 120 (35) 830 5.4 hours 3.5 inches
(9.0 cm)

Dawn is now well-positioned to make many more discoveries on the first
dwarf planet discovered. Jan. 1 will be the 215th anniversary of Giuseppe
Piazzi's first glimpse of that dot of light from his observatory in Sicily.
Even to that experienced astronomer, Ceres looked like nothing other than
a star, except that it moved a little bit from night to night like a planet,
whereas the stars were stationary. (For more than a generation after,
it was called a planet.) He could not imagine that more than two centuries
later, humankind would dispatch a machine on a cosmic journey of more
than seven years and three billion miles (five billion kilometers) to
reach the distant, uncharted world he descried. Dawn can resolve details
more than 60 thousand times finer than Piazzi's telescope would allow.
Our knowledge, our capabilities, our reach and even our ambition all are
far beyond what he could have conceived, and yet we can apply them to
his discovery to learn more, not only about Ceres itself, but also about
the dawn of the solar system.

On a personal note, I first saw Ceres through a telescope even smaller
than Piazzi's when I was 12 years old. As a much less experienced observer
of the stars than he was, and with the benefit of nearly two centuries
of astronomical studies between us, I was thrilled! I knew that what I
was seeing was the behemoth of the main asteroid belt. But it never occurred
to me when I was only a starry-eyed youth that I would be lucky enough
to follow up on Piazzi's discovery as a starry-eyed adult, responsible
for humankind's first visitor to that fascinating alien world, answering
a celestial invitation that was more than 200 years old.

Dawn is 240 miles (385 kilometers) from Ceres. It is also 3.66 AU (340
million miles, or 547 million kilometers) from Earth, or 1,360 times as
far as the moon and 3.72 times as far as the sun today. Radio signals,
traveling at the universal limit of the speed of light, take one hour
and one minute to make the round trip.



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End of Meteorite-list Digest, Vol 155, Issue 9
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Received on Sat 09 Jan 2016 09:43:35 AM PST