latest
from nasa
- water
on mars - images suggest recent surface flows
Comparing water phenomena on Earth with recent
traces on Mars.
Image credit: NASA/JPL/MSSS
- “Water is the chief agent of weathering and erosion on Earth.
Mars is a much drier, colder planet on which liquid water cannot exist
very long at the surface because it will immediately begin to boil,
evaporate, and freeze--all at the same time. However, new pictures from
the Mars Orbiter Camera (MOC) onboard the Mars Global Surveyor (MGS)
have provided an astonishing observation which suggests that liquid
water may have played a role in shaping some recent gully-like features
found on the slopes of various craters, troughs, and other depressions
on the red planet.
These pictures introduce the basic features of a martian gully. The
figure on the left is an example from Mars, the figure on the right
is a gully on Earth. In the Earth picture, rain water flowing under
and seeping along the base of a recently-deposited volcanic ash layer
has created the gully. For Mars, water is not actually seen but is
inferred from the landforms and their similarity to examples on Earth.”
[Quoted from msss.com]
Martian gully in 1999 and again in 2005 with
new deposit.
Image credit: NASA
“Malin and his colleagues used images from NASA’s now-silent
Mars Global Surveyor to revisit regions earlier this year where gullies,
depressionlike landforms on the Red Planet’s surface, were found
in 2000.
“What they found were new, light-colored deposits that do not
appear to have formed from Martian landslides, but could be the work
of frost, salt deposits or long-sought evidence that water flowed recently
on Mars.
“ “Our level of certainty [with] which we can address the
question of whether the gully features that we’re reporting on
were formed by water is high, but not extremely high,” said Malin
[...]” [Quoted from msnbc.msn.com]
- nasa’s
lunar base plans
“The Shackleton Crater rim near the moon's south pole will
likely be the future home of a lunar human outpost, NASA officials
said yesterday. A team of senior space agency managers laid out the
blueprint for returning astronauts to the lunar surface by 2020. But
this time, instead of a series of short, Apollo-like missions, NASA
envisions setting up a base--initially with four astronauts--that
would be fully functioning by 2024.
—
“[...] the entire plan hinges on NASA's ability to build and
fly a new launch vehicle early in the next decade.
—
“[NASA exploration chief ] Horowitz says that NASA isn't expecting
any major budget boosts to cover the as-yet-undetermined cost of the
venture, whereas [NASA's deputy administrator] Dale says that "we
go as we can afford to pay." ” [Quoted from sciencemag.org]
“NASA planners used the international group's deliberations as
well as input from academia, private sector and private citizens as
the basis for sketching a U.S. blueprint for a return to the moon. NASA's
Lunar Architecture Team, chartered in May 2006, concluded that the most
advantageous approach is to develop a solar-powered lunar base and to
locate it near one of the poles of the moon. With such an outpost, NASA
can learn to use the moon's natural resources to live off the land,
make preparations for a journey to Mars, conduct a wide range of scientific
investigations and encourage international participation.
—
“As currently envisioned, an incremental buildup would begin with
four-person crews making several seven-day visits to the moon until
their power supplies, rovers and living quarters are operational. The
first mission would begin by 2020. These would be followed by 180-day
missions to prepare for journeys to Mars.” [Quoted from nasa.gov]
I wish they’d get a move on with this. It’s
about time they properly prioritised the moon base project.
the web address for the article above is
https://www.abelard.org/news/science0610.php#nasa_061206 |
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leonid
meteorites: probably last chance in our lifetimes
- xavier
what are the Leonids?
“The Leonids are composed of the dusty debris that has been shed
by the comet Temple-Tuttle, a small celestial body that orbits the Sun
at 33-year intervals. In those years during [its passing the Sun] and
then for several years after the comet has swept through the inner solar
system, it has had a propensity for producing spectacular meteor displays;
meteors falling by the hundreds, if not thousands per hour.” [quoted
from space.com]
why “last chance”?
“In 2002 the gravitational field of the planet Jupiter shifted
much of the cometary material away from the Earth, so no more outbursts
are expected for nearly 100 years.” [Quoted from nmm.ac.uk]
when is this last chance?
“On November 19, the Earth is due to pass through a trail of
debris left by the Leonids' parent comet on one of its previous returns.
A sharp peak of perhaps 100 Leonids/hour is expected, although there
is a bit of uncertainty. If it occurs very near the predicted time of
4:45 UT, Europe and Western Africa will see the display during the favored
morning hours. The East Coast of North America will see a bit of the
display (maybe up to 25 per hour) as earthgrazing Leonids starting when
the radiant rises at around 11pm. Depending on just how short and sharp
this peak is, most of North America may be out of luck.” [Quoted
from skytour.homestead.com]
So, set your alarm for 04:30 UT (currently, this also
4.30am GMT), wrap up very warmly, position your deckchairs
to point towards the south east - that’s where the Leonids appear
to come from, from the constellation of Leo. Then if Leo is above the
horizon wherever you might be (or technically, the radiant is above the
horizon), you may see a short burst of small meteorites. Remember, this
shower is from the tail-end of the comet Tempel-Tuttle, so the display
will be ‘tailing off’ in comparision to previous displays.
the web address for the article above is
https://www.abelard.org/news/science0610.php#leonids_171106 |
responsibility
rather than rules improves road safety -
the auroran sunset
A small Dutch town, Drachten, is testing some new traffic
planning theories. Has Monderman theorises that removing traffic lights
and road markings will reduce accidents. The experiment suggests that
Monderman is correct:-
“ "There have been a few small collisions, but these are
almost to be encouraged, Mr Monderman explained. "We want small
accidents, in order to prevent serious ones in which people get hurt,"
he said yesterday.
“ "It works well because it is dangerous, which is exactly
what we want. But it shifts the emphasis away from the Government taking
the risk, to the driver being responsible for his or her own risk."
”
—
“ Mr Monderman, 61, compared his philosophy of motoring to an
ice rink. "Skaters work out things for themselves and it works
wonderfully well. I am not an anarchist, but I don't like rules which
are ineffective and street furniture tells people how to behave."
”
—
“In the days of traffic lights, progress across the junction was
slow as cars stopped and started. Now [in the Drachten experiment] tailbacks
are almost unheard of —and almost nobody toots a horn.
“However, it is not the cars which seem to be involved in the
greatest conflict, it is the cyclists and pedestrians who seem to jostle
for space. Driving around Drachten, vehicles approach roundabouts with
considerable caution—traffic approaches from the left, but cyclists
come from either side.
“Cyclists, almost none of whom bother with helmets, signal clearly
at junctions making sure motorists are aware of them.”
This looks like a good example of the advantages of
allowing evolution in action. Note that each person tends to have a personal
‘acceptable risk level’ - when they start to feel safer they
just take more risks to ‘compensate’. Monderman’s experiment
seems to playing on that instinct in the opposite direction: he decreases
the perception of safety, so that people must be more cautious in order
to keep themselves at their desired risk level.
the web address for the article above is
https://www.abelard.org/news/science0610.php#responsibility_rules_111106 |
keeping
up: wearable computers for the military -
the auroran sunset
“A high-tech collection of soldier gear, 15 years and half a billion
dollars in the making, will finally make it into battle. The 4th Battalion,
9th Infantry has adopted the Land Warrior suite of wearable electronics,
and will take it with them to Iraq when they deploy next year. It's the
first time a large group of infantrymen will be tied to the combat network
that's connecting so much of the military.”
—
“Radios and GPS locators come standard. A helmet-mounted monocle
lets the soldier know he and his buddies are on a satellite-powered map.
That same monocle is connected to the weapon sight, so the infantryman
can, in effect, shoot around corners. The sight also serves as a long-range
zoom, with twelve times amplification.”
[Image credit: defensetech.org]
The systems are not perfected, but as with any technology
it will improve little step by little step and reasonably quickly. As
a comment-maker points out, that the military are making this public makes
it likely that they have more advanced wearable technology already in
use with special ops forces.
the web address for the article above is
https://www.abelard.org/news/science0610.php#wearable_computers_261006 |
| silent
crickets avoid deadly parasite, but how to attract a mate? -
xavier
Changing their behaviour not being enough, oceanic field crickets (teleogryllus
oceanicus) on Kauai Island, Hawaii, have evolved to minimise attacks
from a local small parasite fly, ormia ochracea.
Male crickets rub their legs against their wings to make noise to attract
the attention of potential mates. Trouble is, the crick-cricking also
attracts a parasite fly that deposits a larva on the cricket’s back.
The larva burrows into the cricket and eats it from the inside out. A
week later, the cricket is dead.
Previously, it had been found that many of crickets avoided the problem
by keeping quiet during daylight, or when they heard flies. Now, a more
radical solution to the crickets’s problem has been observed. About
90% of the oceanic field crickets on Kauai having evolved to have flat
(not rounded) wings so they make no noise.
But, of course, that means that the crickets also cannot call for new
girlfriends, and no girlfriends would mean no new crickets. Except …
10% of crickets still make a noise despite the potential parasite fly
danger. Silent crickets now crowd round the noise-making ones and benefit
from the girl-crickets that the noisy crickets attract.
With 90% of crickets flat-winged and so silent, being dependent on the
10% that can attract females (and the killer parasitic flies) means that
there is a possibility of extinction.
However, there is another possibility - that the proportions of flat-wings
and normal-wings cycle. First, the normal-wings are at an advantage because
they can get more mates. This would provide more noisy incubators for
the parasite flies so their population would increase. In turn, this would
put the silent flat-wings at an advantage. Then the parasite flies do
not find victims so easily, allowing the normal-wings to breed more, and
so on.
“This kind of oscillation has been predicted for other host-parasite
or predator-prey systems, but seldom demonstrated [...] ”
the web address for the article above is
https://www.abelard.org/news/science0610.php#silent_crickets_021006
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