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Mission update
1: Mars comes into focus in this
enhanced-colour view of the
Terra Sirenum region of Mars.
These gullies in the sides of an
unnamed crater are further signs
of the erosive action of water in
martian geological history. This
image covers an area just 250 m
across, showing the potential of
the HiRISE camera on NASA’s
Mars Reconnaissance Orbiter. The
high signal-to-noise ratio of the
HiRISE camera allows colours to
be distinguished in shadows, so
that true albedo features can be
distinguished from topographical
features in dark areas. (NASA/JPL/
Univ. of Arizona)
As orbiters and rovers work
simultaneously on Mars, an Earth
orbiter shows the way forward for
planetary exploration; multiwavelength astronomy shows its power
in astrophycial investigations of the
oldest and most distant objects.
MRO makes
ready for work
NASA’s Mars Reconnaissance Orbiter
has made a series of observations
from a low orbit, producing detailed
environmental observations from
the present and past martian surface
(figure 1). The orbiter’s high-resolution camera, imaging spectrometer,
context camera, ground-penetrating
radar, atmo­spheric sounder, global
colour camera, radio and accelerometers were being checked out on
various parts of the planet’s surface
before the start of the primary mission in November this year. All the
instruments are working well, and
the High Resolution Imaging Science Experiment (HiRISE) camera
was even able to snap a picture of the
rover Opportunity as it sat in Victoria
Crater.
http://www.nasa.gov/mission_pages/
MRO/main/index.html
Dry ice and dust
geysers
An idea for the origin of an enigmatic
area near the southern martian pole
has been dismissed as a result of data
A&G • December 2006 • Vol. 47 from the European Space Agency’s
OMEGA instrument on Mars Express.
The “cryptic region” was detected by
orbiters in the 1970s, in the form of
a pattern of large areas that became
much darker than their surroundings
in the spring. Once the temperature
was measured at –135 °C, researchers knew that solid carbon dioxide
was likely, and suggested that a layer
of clear carbon dioxide ice might be
present that would allow the dark
surface below to show through. But
OMEGA’s infrared observations have
shown no significant carbon dioxide
ice signal in the cryptic region.
http://www.esa.int/SPECIALS/Mars_
Express/SEMMT0O7BTE_0.html
Spitzer shows
supernova
The supernova that formed Cassiopeia A exploded in such a way as
to keep intact much of its original
onion-like layering, astronomers
using NASA’s infrared Spitzer Space
Telescope have discovered. The
original star that exploded to form
Cas A, like all mature massive stars,
was once formed of concentric shells
with lighter elements in the outer skin,
middle layers lined with heavier elements such as neon, and the heaviest
elements, such as iron, in the core. A
fairly uniform explosion would send
these compositional layers outwards
in order, preserving the pattern in the
expanding debris. Observations had
shown some layering patterns, but
there were mysterious gaps.
Spitzer observations of X-ray emis-
sions arising from expelled material
heated by shock waves from the
explosion solved the riddle. It turns
out that parts of the Cas A star had
not been shot out as fast as others
when the star exploded. Material that
hit the shock wave sooner had more
time to heat up to temperatures that
radiate X-ray and visible light. Mat­
erial that is just now hitting the shock
wave is cooler and glowing with
infrared light. Consequently, previous
X-ray and visible-light observations
identified hot, deep-layer material
that had been flung out quickly, but
not the cooler missing chunks that
lagged behind. Spitzer’s infrared
detectors were able to find gas and
dust made from the middle-layer elements neon, oxygen and aluminum.
“Spitzer has essentially found key
missing pieces of the Cassiopeia A puzzle,” said Jessica Ennis of the University of Minnesota, Minneapolis, lead
author of a paper in the 20 November
issue of the Astrophysical Journal.
http://www.spitzer.caltech.edu/spitzer
Long ago and
far away
Astronomers have images – and
detailed physical properties – of two
of the most distant galaxies ever seen.
Carnegie Fellow Ivo Labbé, along
with Rychard Bouwens and Garth Illingworth of the UCO/Lick Observatory at the University of California,
Santa Cruz, and Marijn Franx of the
Leiden Observatory, examined galaxies in the Hubble Ultra Deep Field
(HUDF) using the sensitive Infrared
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Space Shorts
Sensorwebs show way
An Earth observation satellite
has shown the effectiveness of
artificial intelligence in making
use of a web of sensors, in this
case to start observing a newly
active volcano. Earth Observer 1
began watching the Indonesian
volcano Talang in September
2005 before volcanologists were
asked to examine it, thanks
to its intelligent response to
observations. EO-1 can tap
into networks of sensors on
Earth, in this case the USGS
volcano observatories in Hawaii,
Washington and Antarctica,
and is starting to use sensors
on other satellites, such as the
MODIS infrared spectrometers
on NASA satellites Terra and
Aqua, that can pick up heat
from forest fires and volcanoes.
In this case, EO-1 detected a
volcanic plume, but it can seek
out flash-floods, forest fires,
disintegrating sea-ice, and
anything unexpected.
http://science.nasa.gov/headlines/
y2006/26oct_sensorweb.
htm?list108954
Sunrise on Hinode
The Solar-B satellite, a joint
Japan/NASA/PPARC mission
which was launched on 22
September 2006 and renamed
Hinode, reported its first
observations of the Sun on 31
October. Hinode is Japanese for
sunrise, an appropriate name
given that the mission’s target is
to watch massive explosive solar
flares at close quarters as they
erupt from the Sun’s surface and
rise into interstellar space. All
three instruments are working
well: the Solar Optical Telescope,
the X-Ray Telescope, and the
EUV Imaging Spectrometer.
Researchers at University
College London’s Mullard Space
Science Laboratory have led
work on the EIS. “Waiting for the
first data from an instrument
that has taken years to design
and build is always a heartstopping moment,” said Prof.
Len Culhane, EIS Principal
Investigator. “We create incredibly
sensitive detectors such as EIS,
then strap them to a rocket and
hurl them into space under
extremely challenging conditions.
Finding out that it survived and is
working correctly is a huge relief
because the options are very
limited if it is not.”
http://www.pparc.ac.uk/Nw/Stereo_
launch.asp
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