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                  The SOCIETY for POPULAR ASTRONOMY
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        Electronic News Bulletin No. 253     2008 September 28
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Here is the latest round-up of news from the Society for Popular
Astronomy.  The SPA is Britain's liveliest astronomical society, with
members all over the world.  We accept subscription payments online
at our secure site and can take credit and debit cards.  You can join
or renew via a secure server or just see how much we have to offer by
visiting  http://www.popastro.com/



MAJOR FIREBALL OVER NORTHERN BRITAIN, SEPTEMBER 22
By Alastair McBeath, SPA Meteor Section Director

At 20:31 UT on September 22-23, a brilliant fireball, estimated as 
brighter than full Moon by several witnesses, appeared over northern 
Britain. Reports are in to the SPA so far from twelve sites from near 
Newburgh on the coast north of Aberdeen, south to Accrington in 
Lancashire, and west as far as Co Antrim in Northern Ireland. 
Suggestions are the object peaked perhaps in the range magnitudes 
-14 to -18, lighting up the whole sky from some places, as the very 
slow-moving meteor crossed on a general westerly to easterly track, 
probably across southern Scotland and perhaps the far north of 
England. The fireball was visible for around 5 or 6 seconds judging by 
the better estimates, with colours suggested as orange-yellow for the 
head of the object, and a blue-green tail following. Several people saw 
it fragment, maybe into 3 or 4 pieces, towards its end, and it may have 
left a persistent train for some seconds too. There was one report of 
simultaneous sounds which may have been associated with the event, 
but curiously this was from one of the most distant observers. No other 
reports of sounds simultaneous or some time later (due to normal 
sound waves from a sonic boom) have yet come through. Further 
details to try to refine the possible track are still being sought from the 
lucky observers. Thanks are due especially to the witnesses, and 
Darren Moody, President of Aberdeen AS, for rounding-up and 
forwarding many of the Scottish sightings.

Ten days earlier, on September 12-13 at around 19:02 UT, so still in 
daylight, three witnesses in Kent, Hampshire and Dorset, reported a 
magnitude -4/-6 or brighter fireball probably out over the Channel or 
northern France. No further information has been established for this 
meteor as yet however, nor have any sightings from the Continent 
been recovered on it.

Anyone else who spotted either event, or any other fireballs - meteors 
of magnitude -3 or brighter - from the British Isles or nearby is welcome 
to send a full report to the Meteor Section as soon as possible. The 
minimum details I need from you are:

1) Exactly where you were (name of the nearest town or large village 
and county if in Britain, or your geographic latitude and longitude if 
elsewhere in the world);

2) The date and timing of the event (please be sure to state whether this 
was in clock time, currently BST in Britain, or GMT/UT, which is BST 
minus one hour); and

3) Where the fireball started and ended in the sky, as accurately as 
possible, or where the first and last points you could see of the trail 
were if you didn't see the whole flight.

More advice and a fuller set of details to send are outlined on the 
"Fireball Observing" page of the SPA website, at: http://snipurl.com/3wyh4 .


UNEXPECTED BRIGHT-METEOR OUTBURST, SEPTEMBER 9
By Alastair McBeath, SPA Meteor Section Director

A wholly unexpected meteor outburst happened for at least a few hours 
centred around 08h UT on September 9. It was observed and recorded 
by several video systems and visual observers across North America, 
and by radio meteor observers in Europe and North America. Reports 
indicate the event produced a high proportion of magnitude +1 and 
brighter meteors. The brightest so far seem to have been about 
magnitude -8. Initial claims that this was due to the usually-minor 
September Perseid meteor shower (SPE), which peaks around 
September 9, remain unconfirmed, because estimates of the radiant 
position for the outburst meteors suggest it was some way from the 
expected SPE radiant, and the meteors, although swift-moving, may 
have been somewhat slower than the typical 66 km/sec SPE velocity. 
Further investigations have suggested the shower was active in video 
results over Europe on the previous two nights, September 7-8 and 
8-9, and it may have been detected previously, as International Meteor 
Organization (IMO) results originally presented to the 2006 International 
Meteor Conference, found a minor radiant centred at 03h08m RA, +39 
deg Dec active around September 8 or 9, with an atmospheric velocity 
of 61 km/sec. This position seems quite close to the details as 
currently estimated.

Please bear in mind the following data are all very preliminary still, and 
are subject to confirmation and change, but there does seem a growing 
consensus. The first information was from 25 video meteors caught on 
camera by the Marshall Spaceflight Center in the USA. These 
suggested the outburst radiant was around 03h20m RA, +43 deg Dec. 
Next, regular Section contributor and video observer Enrico Stomeo in 
Italy imaged seven meteors on September 8-9 which gave a radiant 
near 03h13m RA, +38 deg Dec, with a mean atmospheric velocity of 
56 km/sec. Another regular Section contributor, video and radio meteor 
observer, Jeff Brower in British Columbia, Canada was well-placed to 
catch the main event. Working tirelessly and closely with Finnish 
meteoricist Esko Lyytinen in the weeks since the event, using Jeff's 
results, plus trying to analyse additional details from fellow North 
American video observers Tom Ashcraft and Ken Tapping, has now 
suggested a radiant close to 03h10m RA, +39 deg Dec, with a 
suspected mean atmospheric velocity of ~64 km/sec. Interestingly, 
Esko also caught unusual bright-meteor activity probably from this 
radiant on September 7-8 in his video observations. Other showers 
have been suspected of producing activity from near this location in 
past years too, going back to the 1950s, so it may be this is an 
occasional, perhaps periodic, source. By contrast to all these positions, 
the SPE radiant for September 9 as found in IMO visual and video 
results in recent years has been closer to 04h00m RA, +47 deg Dec.

As for the outburst itself, Jeff Brower's all-sky video fireball camera 
recorded 13 meteors brighter than magnitude +1 between 04:12-12:26 
UT on September 9. Eleven of those happened between 07:26-09:21 
UT, and there is a suggestion in Jeff's results alone that the peak may 
have been within a few minutes of 08:01 UT. The mean centre timing 
for all the meteors like this he recorded was 08:25 UT. The IAU reported 
the peak as at 08:20 UT ± 20 mins, with activity lasting for about four 
hours overall away from this time in their Electronic Telegram No. 
1501. The Marshall camera's meteors were recorded between 06:20-
10:30 UT.

IAU ET 1501 also indicated no unusual visual activity was seen by 
experienced observer Paul Martsching in Iowa, USA from 05h-06h UT, 
but he caught increased rates thereafter, with many negative magnitude 
events. Clear peaks in radio meteor echo-counts roughly coincident 
with the video outburst timings have been mentioned from their own 
results so far by Jeff, Esko and our own Assistant Director David 
Entwistle in England. Jeff mentioned Ken Tapping also recorded the 
event by radio (Ken is a professional radio astronomer), but 
investigations of this aspect are still on-going.

More comments, including copies of David's radio graphs and links to 
other Internet sites with initial details, can be found on the SPA's 
Observing Forum topic at: http://snipurl.com/3wyik.  Particular thanks 
are due to all the named observers, and especially to Jeff Brower who 
provided a series of daily updates on the latest findings to David and 
myself in mid September. Anyone else who was observing on nights 
around September 9, whether in the UK or elsewhere in the world, and 
who recorded notes on meteor activity they have not submitted yet, is 
welcome to do so as soon as possible, please.


PERSEIDS 2008 UPDATE
By Alastair McBeath, SPA Meteor Section Director

Further to the most recent Perseid comments in ENB 251 (see: 
http://snipurl.com/3wyjj, the latest IMO preliminary visual findings from 
this year's Perseids now suggest a minor peak around 05:00 UT on 
August 11-12, when Zenithal Hourly Rates (ZHRs) reached ~80, 
apparently near-coincident with that peak found in the initial SPA radio 
results by David Entwistle. The main peak remains that on August 
12-13 however, with IMO results showing ZHRs of ~120 or so from 
about 01:30-02:30 UT that morning. The maximum ZHR was attained 
near 02:00 UT, at 125 ± 4.

The full set of Radio Meteor Observation Bulletin data from August is 
now available too (RMOB 181 for August 2008, available at: 
http://www.rmob.org ; check this for the full list of all contributing 
observers' details, and their radio systems), results from which across 
the shower's maximum have been analysed this week. Quite a few 
observers had severe interference problems in August, including right 
across the expected best from the Perseids, and seven of the fifteen 
observers were either prevented from covering the shower's maximum 
because of that, or found no sign of a definite peak in radio counts 
during the Perseids at all, which could also be indicative of unidentified 
interference.

Those systems that were active and unaffected by this during much of 
the shower found signs of a minor maximum between 05h-08h UT on 
August 12, apparently peaking close to 06h UT. Most of the systems to 
report this were in Europe however, and as this interval coincided both 
with one of the best times of day for meteor activity generally, and 
when the Perseid radiant can be well-observed by radio from this part 
of the world, its significance is less clear. It seems plausible there 
were more than just these fortunate elements at play even so, although 
the radio and IMO visual maximum timings were not identical. There is 
a suggestion that longer-duration echoes, often taken to be associated 
with brighter meteors, were somewhat more prevalent during this peak 
than at other times during the shower.

All the systems fully operational and well-placed to observe the 
Perseids around the 02h UT maximum on August 13, all in Europe, 
recorded it well, and the 02h UT interval produced the strongest and 
best-confirmed peak of any among the radio Perseids this year. The 
event lasted from about 01h-05h UT on that date.

Many thanks go to all the radio observers, and also David Entwistle 
and Jeff Brower for valuable discussions regarding the Perseids in 
recent weeks.


METEOR PROSPECTS FOR OCTOBER
By Alastair McBeath, SPA Meteor Section Director

No Draconid activity is expected this autumn, but that need not prevent 
some happening! If so, October 8 is most likely to bring it, perhaps at 
some stage between 02:30 to 19:30 UT. The waxing gibbous Moon 
then will set to leave the second half of the night suitably dark for meteor

watchers. Past outbursts have happened when their parent comet 
21P/Giacobini-Zinner is near perihelion and fairly close to Earth in 
early October, as last in 1998, when estimated ZHRs reached ~700 
briefly. The comet was at perihelion last in July 2005, and a relatively 
minor outburst happened that October (even so, with ZHRs about 
30-40). Another, but unanticipated, minor outburst happened over 
Japan in 1999 however, showing there may be features to watch out for 
in other years too. The radiant is circumpolar from Britain, near 
17h28m RA, +54 deg Dec, but is highest in the early evening and 
early morning skies. Draconids are very slow meteors.

The main Orionid maximum is expected on October 20-21, when the 
radiant is near Orion's "Club" asterism, usefully observable for meteor 
work after about 23h UT from the UK. It has been suggested this year 
may see a third consecutive return of the enhanced activity noted from 
the shower in 2006 and 2007, when ZHRs of 50-70 were seen on two 
or three dates across the predicted peak. Normal ZHRs should be 
about 25-30 this year otherwise. Regrettably, the waning Moon is at 
last quarter on October 21, so will be a severe problem right through 
the likely maximum period. However, as IMO investigations have 
suggested NO similarly enhanced activity is likely next year, hopeful 
Orionid observers may wish to brave the moonlight this year 
regardless. If you intend to join in, you should watch as much sky as 
comfortably possible, but facing away from the Moon (hiding the Moon 
behind a rooftop, wall, fence or trees can be helpful). Orionid meteors 
are fast, often bright, and frequently trained.

In 1995, 1998 and 2005, the normally minor, slow-meteor Taurid 
showers produced unusual activity in late October, persisting in some 
cases through into November. For example in 2005, combined ZHRs 
lasted at about the normal maximum level, or slightly above it, ~10-15, 
from October 29 to November 10 (including through the typical 
maximum period). Increased numbers of fireballs were reported from 
a similar interval, notably between October 25 to November 14, most 
of them probable Taurids. All three of these years were ones for which 
David Asher of Armagh Observatory had predicted returns of a 
theoretical "swarm" of more and somewhat larger Taurid meteoroids 
than usual, and he anticipates another such return this year. If it takes 
place, and shows a similar pattern of behaviour to the recent events 
(remembering nothing is guaranteed in meteor astronomy!), new Moon 
on October 28 should provide a near-perfect opportunity to observe 
whatever happens. Not all "swarm" returns are identical, but anything 
unusual that does chance-by is most likely to be present sometime 
between October 20 and November 15, perhaps for just a few days. 
Consequently, observers need to be alert to the possibilities - and 
hope for the best!

For more details on October's expected meteor activity, plus radiant 
charts for the Orionids and Taurids, see our monthly meteor page on 
the SPA website, at: http://snipurl.com/3wym3.  Good luck, and clear 
skies!


SOLAR WIND LOSES POWER
NASA
 
The Ulysses spacecraft has found that the average pressure of the
solar wind has dropped more than 20% since the mid-1990s, to the
weakest that it has been since monitoring began almost 50 years ago.
Curiously, the speed of the million-mph solar wind has decreased
only 3%; the change in pressure has come mainly from reductions in
temperature and density.  The solar wind is 13% less hot and 20% less
dense.  Ulysses has also found that the Sun's underlying magnetic field
has weakened by more than 30% since the mid-1990s.  Flagging solar
wind has repercussions across the entire Solar System, beginning with
the heliosphere.  The heliosphere is a bubble of magnetism springing
from the Sun and inflated to colossal proportions --to beyond Pluto --
by the solar wind.  The heliosphere shields the Solar System to some
extent from Galactic cosmic rays.  The degree of shielding is less now
than it was, owing to the reductions in both the magnetic field
strength and in the solar wind.  There is, however, no threat to
people on the Earth, as our thick atmosphere and planetary magnetic
field provide additional layers of protection that keep us safe.
But if the trend continues, astronauts on the Moon or en route to Mars
would get a higher dose of cosmic radiation, and space probes and
satellites in high Earth orbit are at an increased risk of instrument
malfunctions due to cosmic-ray strikes.


PHOENIX SEES DUST DEVILS
NASA

The Phoenix Mars lander has photographed several dust devils dancing
across the arctic plain on which it landed.  Pictures taken on Sept. 8
show at least six different dust devils, ranging from about 2 to 5
metres in diameter.  Images from spacecraft orbiting Mars had
previously indicated that dust devils occur in the region where
Phoenix landed.  The ones that Phoenix has observed so far are much
smaller than those that the 'Spirit' rover has photographed much
closer to the equator.  Phoenix monitors air pressure, and on the day
that the camera saw dust devils, the barometer recorded a sharper dip
than ever before.  The change was still less than the daily change in
air pressure from daytime to nighttime, but over a much shorter time.
Also on the same day, Phoenix's anemometer indicated wind speeds
exceeding 5 metres per second.


DIFFUSION CAUSED JUPITER'S WHITE SPOT TO TURN RED
RAS

A study has suggested how Oval BA, an anticyclone on Jupiter, suddenly
turned from white to red in a period of just a few months.  Oval BA
was formed in 2000 by the merger of smaller vortices called the White
Ovals, in a chain of collisions that started in 1998.  The apparent
reddening was first reported by amateur astronomers in early 2006, but
it was not until April that professional astronomers were able to
image the impressive alteration of the oval, which is the
second-largest storm in the Solar System after the Great Red Spot
(GRS).

Using computer models, researchers tried to identify causes for the
colour change, including alterations to dynamical, photochemical and
diffusion processes.  The most likely cause appears to be an upward
and inward diffusion of either a coloured compound or a substance
that may interact later with high-energy solar photons at the upper
levels of Oval BA.  Comparing Oval BA with the GRS, the group found
that the GRS is still redder than BA, most likely because it is higher
in Jupiter's atmosphere, thicker and contains a higher concentration
of the unidentified chemical agents that give Jupiter its browny-red
colour.

The group was able to rule out the possibility that the reddening was
caused by any dynamical process.  They found no change to the strength
of the 'hurricane' and, although some changes in the circulation
around the spot had taken place, the maximum wind speeds (up to 400
km/h or more) were consistent with measurements made before 2000 of
the Oval or its white predecessors.  The group modelled the wind flow
in detail with high-resolution simulations, to try to understand why
the red material may be confined to the annulus region and how the
colour change happened on the observed time-scale.  The model accounts
well for the temperature and wind structure inside Oval BA.


SATURN'S RINGS MAY BE MORE MASSIVE, OLDER
RAS

Saturn's rings may be more massive than previously thought, and
potentially much older.  Astronomers at the University of Colorado
tried to model a simplified version of the ring system, by computing
the gravitational attraction and collisions between more than 100,000
particles, representing a sample of those in Saturn's rings.  They
followed the orbit and history of each individual particle, and
calculated the amount of starlight that would pass through the ring.
Their results were compared to Cassini observations of starlight
blocked by the rings, a method that has long been used to estimate the
total amount of material in the ring system.  In 1983 that method led
to am estimate that the rings contain as much material as Saturn's
moon Mimas, which is about 250 miles across.  The new simulations
indicate that the ring particles aggregate into clumps, which would
lead to the previous estimate being low by a factor of 3 or more.

Calculations suggest that meteorites slowly grind and shatter the
particles in the ring.  Gradually, a layer of dust and fragments
builds up and covers each particle.  The layer includes both ice (from
the particle) and meteoritic dust.  As time passes, the ring system
becomes increasingly polluted and darkened by meteoritic dust.
Because the rings appear so clean and bright, it has been argued that
they are much younger than Saturn, which is some 4.5 billion years
old; in fact it was concluded from Voyager measurements that the rings
are only about 100 million years old.  The new calculations show that
if the rings are more massive, they appear less polluted, and thus
could be proportionately older.  Recycling of ring material extends
their lifetime and reduces the expected darkening.


5TH DWARF PLANET NAMED HAUMEA
The Register

The International Astronomical Union (IAU) has decreed that the object
formerly known as 2003 EL61 will henceforth be known as Haumea, and
joins Ceres, Eris, Makemake and Pluto in the Solar System's league of
dwarf planets.  The IAU describes trans-Neptunian Haumea as a
fast-spinning "bizarre object with a shape resembling a plump cigar",
with a diameter "approximately the same as that of the dwarf planet
Pluto".  The name is taken from the goddess of childbirth and
fertility in Hawaiian mythology, which the IAU considers particularly
appropriate since "Haumea also represents the element of stone, and
observations of Haumea hint that, unusually, it is almost entirely
composed of rock with a crust of pure ice".

The IAU notes that Haumea is joined in its orbit by two satellites
thought to have been created by debris knocked off its surface by
historic impacts.  The goddess Haumea's children "sprang from
different parts of her body", according to Hawaiian lore.  The larger
satellite has been christened Hi'iaka in honour of Hawaii's patron
goddess, who was born from the mouth of Haumea.  The second is 
Namaka, a water spirit who emerged from Haumea's body.


SUN COULD BE FAR FROM WHERE IT STARTED
University of Washington

It has long been believed that stars tend to remain in the same
general part of a galaxy where they originally formed.  Some astro-
physicists have recently questioned whether that is true, and now
new simulations show that, at least in galaxies similar to our own
Milky Way, stars such as the Sun can migrate great distances.  Using
ever such a lot of computer time, the scientists ran a simulation of
the formation and evolution of a galactic disc.  The simulations began
with conditions about 9 billion years ago, after material for the disc
of our Galaxy had largely come together but the actual disc formation
had not yet started.  The scientists set basic parameters to mimic the
development of the Milky Way to that point, but then let the simulated
galaxy evolve on its own.

It has previously been supposed that if a star, in an approximately
circular orbit around the centre of a galaxy, is intercepted by a
spiral arm, its orbit would become more eccentric.  However, in the
new simulations the orbits of some stars get larger or smaller but
still remain very circular after passing through the massive spiral
wave.  Our Sun has a nearly circular orbit, so the findings mean that
when it formed, more than 4 billion years ago, it could have been
either nearer to or farther from the centre of the galaxy, rather than
where it is now.  Migrating stars also help to explain a long-standing
problem in the chemical mix of stars in our neighbourhood, which has
been regarded as more mixed and diluted than would be expected if
stars spent their entire lives where they were born.  The researchers
claim that by containing stars from very different initial locations
the Sun's neighbourhood can be viewed as a more diverse and
interesting place.


1843 ERUPTION OF ETA CARINAE MAY BE NEW TYPE OF STELLAR EXPLOSION
University of California at Berkeley

The 1843 giant outburst of Eta Carinae, one of the brightest and most
massive stars in our Galaxy, now appears to have been driven by a
hitherto unrecognized type of stellar explosion that is not as
comprehensive as that of a typical supernova and does not destroy the
star.  It was probably related to a class of faint stellar explosions
seen in other galaxies in recent years by telescopes searching for
supernovae.

Eta Carinae is a massive, hot, variable star far down in the Southern
Hemisphere, and is located about 7,500 light-years from us in a
star-forming region called the Carina Nebula.  It was observed to
brighten immensely in 1843, becoming for a time second only to Sirius.
Astronomers now see the resulting cloud of gas and dust, known as the
Homunculus Nebula, wafting away from the star.  A faint shell of
debris from an earlier explosion is also visible, probably dating from
around 1,000 years ago.  Recent observations indicate that extremely
fast filaments of gas, moving five times faster than the debris in the
Homunculus Nebula, were propelled away from Eta Carinae in the 1843
event.  The amount of mass in the relatively slow-moving Homunculus
was already at the edge of plausibility in terms of what an extreme
stellar wind could do physically.  The much faster material now
discovered poses even harsher difficulties for current theories.
Instead, the speeds and energies involved are reminiscent of material
accelerated by the fast blast wave of a supernova explosion.

The high speeds in the blast wave could roughly double earlier
estimates of the energy released in the 1843 eruption of Eta Carinae,
an event that astronomers argue was not just a surface eruption
associated with the stellar wind but an actual explosion deep within
the star.  In fact, the fast-moving blast wave is now colliding with
the slow-moving cloud from the 1,000-year-old eruption and generating
X-rays that have been observed by the orbiting Chandra Observatory.
Eta Carinae probably once had a mass 150 times that of the Sun.  Such
large stars burn very brightly but only for only a few million years,
all the while shedding mass as their own intense radiation pushes the
outer layers of the star away in a stellar wind.  After 2 to 3 million
years of wind loss, and having shed about 10 solar masses in its most
recent 1843 eruption alone, Eta Carinae now probably has a mass of 90
to 100 solar masses.


LEAST LUMINOUS GALAXY
Yale University

A team of astronomers has discovered the least luminous galaxy yet
known to exist.  The galaxy, called Segue 1, is one of about two dozen
small satellite galaxies orbiting our own Milky Way galaxy.  It is a
billionth as bright as the Milky Way, according to the team's results.
But despite its small number of visible stars, Segue 1 is nearly a
thousand times more massive than it would be if it were made of
objects with the same ratio of mass to light as the Sun.  Segue 1 is
the most extreme example of a galaxy that contains only a few hundred
stars, yet has a relatively large mass.

The team has observed about half of the dwarf satellite galaxies that
orbit the Milky Way.  Those objects are so faint and contain so few
stars that at first they were thought to be globular clusters.  But by
spectroscopy with the Keck telescope in Hawaii, the astronomers showed
that the objects are actually galaxies themselves, albeit very dim
ones.  Finding ultra-faint galaxies like Segue 1 may provide clues as
to how galaxies form and evolve, especially at the smallest scales.

It is only recently that it has become apparent just how prevalent
such dwarf satellite galaxies are, thanks to projects like the Sloan
Digital Sky Survey, which imaged large areas of the sky in greater
detail than before.  In the past two years alone, the number of known
dwarf galaxies orbiting the Milky Way has doubled from the dozen or so
brightest that were discovered during the first half of the twentieth
century.


FARTHEST GAMMA-RAY BURST
NASA

The Swift satellite has observed the most distant gamma-ray burst so
far detected.  The event, designated GRB 080913, arose from an
exploding star 12.8 billion light-years away -- less than a billion
years after the Universe began.  Gamma-rays from the explosion
triggered Swift's burst-alert telescope on Sept. 13.  The spacecraft
established the event's location in the constellation Eridanus and
quickly turned to examine the spot.  Less than two minutes after the
alert, Swift's X-ray telescope began observing the position, where it
found a fading, previously unknown X-ray source.  Astronomers on the
ground captured the burst's fading afterglow with the 2.2-m telescope
at ESO in Chile.  Analysis of the spectrum obtained with the VLT at
Paranal established the redshift at 6.7 -- among the most distant
objects known.


NEW MARS MISSION WILL STUDY PLANET'S ATMOSPHERE
NASA

NASA is to undertake a Mars mission that will provide information
about the planet's atmosphere and climate history in greater detail
than previous missions.  Called the Mars Atmosphere and Volatile
EvolutioN (MAVEN) spacecraft, the $485 million mission is scheduled
for launch in late 2013.  Among 20 proposals submitted in 2006, Maven
was selected as having the best scientific value and lowest
implementation risk.

Mars once had a denser atmosphere than it has now, one that allowed
liquid water to exist on the surface.  It seems that, as part of a
dramatic climate change, most of the atmosphere was lost.  MAVEN will
measure present-day atmospheric loss, which may offer clues about the
planet's history.



Owing to holidays, the next edition of the ENB will be issued on October
26.

The SPA Electronic News Bulletins are sponsored by the Open University.

Bulletin compiled by Clive Down


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