Home' Position : Position Dec Jan 2015 Contents Upcoming Events
8-10 December 2014: European
LiDAR Mapping Forum; Amsterdam,
The Netherlands. www.sparpointgroup.
10-12 March 2015: Locate15;
Brisbane, Qld. www.locateconference.com.
16-18 March 2015: Association
of Public Authority Surveyors
Conference; Coffs Harbour, NSW.
4-5 May 2015: ANZ Emergency &
Disaster Management Conference;
Gold Coast, Qld. www.anzdmc.com.au.
11-15 May 2015: 36th International
Symposium on Remote Sensing of
Environment (ISRSE); Berlin, Germany.
27-28 May 2015: GeoBusiness 2015;
London, UK. http://geobusinessshow.com.
29 June - 10 July 2015: Pivotal
Master Class; Brisbane, Qld.
14-16 July 2015: IGNSS 2015; Gold
Coast, Qld. http://ignss.org.
19 August 2015: GeoNext 2015;
Melbourne, Vic. www.geonext.com.au.
This is a high-resolution geological map
is of Vesta -- one of the largest aster-
oids in the Solar System -- and is de-
rived from data captured by NASA's Dawn
spacecraft in 2011-2012. The map unifies
15 individual quadrangle maps published
November in a special issue of Icarus (see
http://bit.ly/1xTUsIJ), and spans the entire
equatorial diameter of approx. 572 km.
Vesta -- the fourth discovered asteroid in
the cosmos -- has a surface area approxi-
mately the same as that of Pakistan (about
800,000 square kilometres). The most
prominent features on the surface are two
enormous craters: the 500 kilometre wide
Rheasilvia crater, at most 1 billion years
old, and home to the Solar System's tallest
mountain at 22 km from its base (for com-
parison, Mt Everest reaches 8.8 km above
sea level); and the 400 kilometre wide
Veneneia crater -- about 2 billion years old.
The brown colours seen on the map rep-
resent the oldest, most heavily cratered sur-
face. Purple colours in the north and light
blue represent terrains modified by the
Veneneia and Rheasilvia impacts, respec-
tively. Light purples and dark blue colours
below the equator represent the interior of
the Rheasilvia and Veneneia basins. Greens
and yellows represent relatively young
landslides or other downhill movement and
crater impact materials, respectively.
The legend shows formations and
features highlighted on the map. The
geological units mapped on Vesta are
identified by their appearance in high-
resolution images. The place of each unit
in Vesta's geologic history comes from
careful study of the relative relationship
of features. In the legend, Marcian units
are younger than Rheasilvian units, which
are younger than Veneneian units. The
oldest identifiable unit is Vestalia Terra.
The map uses a Mollweide projection,
centred on 180 degrees longitude using
the Dawn Claudia coordinate system.
The Mollweide projection is often used
for global maps or for the night sky, as
it trades accuracy of angle and shape
for accuracy of the area proportions. It
is also known as the Babinet projection,
homalographic projection, homolographic
projection and elliptical projection, and
was first published by mathematician
and astronomer Karl (or Carl) Brandan
Mollweide (1774 -- 1825) of Leipzig in
1805. It was reinvented and popularised
by Jacques Babinet in 1857, who gave it
the name homalographic projection.
The Dawn spacecraft that captured the
imagery used to create the map entered
orbit around Vesta on 16 July 2011 for a
one-year exploration, and left orbit on 5
September 2012, heading for the dwarf
planet Ceres -- the largest object in the
asteroid belt -- which it is due to arrive at
in February 2015.
The Jet Propulsion Laboratory
manages the Dawn mission for
NASA's Science Mission Directorate
in Washington. Dawn is a project of
the directorate's Discovery Program,
managed by NASA's Marshall Space
Flight Centre in Huntsville, Alabama. The
University of California at Los Angeles
(UCLA) is responsible for overall Dawn
mission science. Orbital Sciences Corp.
in Dulles, Virginia, designed and built
the spacecraft. The German Aerospace
Centre, the Max Planck Institute for
Solar System Research, the Italian
Space Agency and the Italian National
Astrophysical Institute are international
partners on the mission team.
More information about Dawn is
online at www.nasa.gov/dawn.■
A geological map of Vesta
Image credit: NASA/JPL-Caltech/ASU.
4 position December/January 2015
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