SPACE
& SCIENCE NEWS: December 2001
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& science news > space & science news: December 2001
Signs of an asteroid belt around Zeta
Leporis
(Dec. 31, 2001)
A decade ago, measurements by the Infrared
Astronomy Satellite (IRAS) showed the presence of warm dust around
Zeta Leporis, a star 70 light years away, twice as massive as the
Sun, but only about 100 million years old (one fiftieth the Sun's
age). Now, astronomers Catherine Chen and Michael Jura at UCLA report
that not only may dust be present but also asteroids
and possibly planets as well. Chen and Jura found that some of the
dust around Zeta Lep basks at a toasty 77 °C, revealing that the
dust belt's inner margin is a mere 6 astronomical units from the central
star. They estimate that the entire belt has a mass comparable to
that of Earth, or about 1,000 times more than the Sun's asteroid belt.
The point is that the dust couldn't possibly exist unless it were
being constantly replenished – it would long ago have spiralled
into the star – and the only way it can be being regenerated
is through the collision of larger rocky bodies. This strongly suggests
the presence of asteroids. And if asteroids are present, then it may
be that Zeta Leporis harbors planets as well. The next step will be
to obtain an infrared spectrum of the disk to learn more about its
composition.
For more, go here. |
"Alien" species of squid discovered
(Dec. 26, 2001)
The difficulty in predicting what type of creatures might evolve on
another planet, under a different set of environmental circumstances,
has been underlined by the discovery of a previously unknown type
of squid in the oceans here on Earth. The new cephalopod is equipped
with 10 spidery, seven-meter-long arms, held in an unusual position:
spread outward from the body and then bent anteriorly (i.e. at a kind
of elbow). It has been spotted independently by eight different scientists
in the Pacific, Atlantic, and Indian Oceans, and in the Gulf of Mexico.
One sighting was made at a depth of almost five km in the western
Atlantic, off the coast of Brazil. Researchers speculate that the
squid may be an adult member of the recently identified family called
Magnapinnidae of which only juvenile specimens had previously been
seen. According to one of the scientists involved, the squid might
use its long arms "like a living spider web" to catch its prey. "I
think it dangles those arms until small organisms bump into them."
Apparently, in a one recent encounter with a submersible, the squid
seemed to have problems dislodging its arms from the vessel's hull.
(NOAA). |
The sweet taste of – meteorites?
(Dec. 20, 2001)
A team of NASA researchers writing in this week's Nature claim
to have found a variety of extraterrestrial sugar molecules in the
Murchison and Murray
meteorites – two well-known carbonaceous
chondrites. They believe there is little chance that these molecules
are Earthly contaminants. If the claim holds up this is a key discovery
because, together with amino acids, which have already been shown
to arrive here from space, sugars are an important building block
of life. The meteoritic sugars may predate the Solar System, having
formed by the action of starlight on molecules resting on cold grains
of interstellar dust. Indeed, a primitive sugar molecule has already
been detected in one of the giant molecular clouds near the galactic
center.
For more, go here. |
Astrobiology: a big joke
(Dec. 20, 2001)
UK psychologist Richard Wiseman has been up to some funny business
– trying to find what kind of jokes make people laugh most.
Having reviewed 10,000 gags with the help of 100,000 surfers from
more than 70 countries, the winner was this:
Sherlock
Holmes and Dr Watson are going camping. They pitch their tent under
the stars and go to sleep. Some time in the middle of the night, Holmes
wakes Watson up. "Watson, look up at the stars, and tell me what you
deduce."
Watson says: "I see millions of stars and even if a few of those have
planets, it's quite likely there are some planets like Earth; and
if there are a few planets like Earth out there, there might also
be life."
Holmes replies: "Watson, you idiot, somebody stole our tent!" |
Cassini's eye waters while Odyssey eyes
water
(Dec. 16, 2001)
The Cassini probe
en route to Saturn
has developed partially blurred vision in its narrow-angle camera;
specifically, it appears to have picked up some contamination which
is making images from the instrument hazy around the edges. However,
engineers are working to remedy the problem by turning on and off
the camera's built-in heater. One cycle of warming has already brought
some improvement. Another in January, it's hoped, will sharpen the
camera's vision further. A similar but much worse problem with Stardust
was cured in the same way.
Meanwhile, Odyssey
has returned its first scientific results from Martian orbit. The
spacecraft's neutron spectrometer has detected the presence of large
amounts of hydrogen in soil and rock near the planet's poles. The
hydrogen very likely indicates the presence of water-ice in large
quantities. Scientists had been hoping for such a discovery but are
surprised that it has come so early, with the probe still tightening
its orbit for a mapping mission that will begin in January.
For more on this, go here. |
Astrobiology in San Francisco (Dec. meeting
of the AGU
(Dec. 8, 2001)
The American Geophysical Union's 2001 Fall Meeting takes place Dec.
10-14 in San Francisco and includes numerous presentations and sessions
related to the search for life and water in the solar system. Just
to mention two of the items, Jonathan Lunine, professor of Planetary
Science and Physics at the University of Arizona, will be talking
on Monday about "Oceans on Titan Past, Present and Future". His abstract
reads:
Titan is Saturn's largest moon, and
the second largest natural satellite in the solar system. Composed
of half rock by mass, the satellite probably contains enough radiogenic
material so that, when combined with accretional heating, differentiation
into a rocky deep mantle and icy upper mantle is likely. Unlike its
near twins in size and density, Jupiter's Ganymede and Callisto, Titan
is endowed with a dense atmosphere, mostly nitrogen but with an admixture
of methane. The methane is photolyzed in the upper atmosphere to make,
with the participation of nitrogen, a complex mixture of hydrocarbons
and nitriles. This in turn forms aerosols which descend to the surface,
and have accumulated over time as solids and liquids. If photochemistry
has occurred in a steady state fashion over Titan's history, perhaps
hundreds of meters of liquid hydrocarbons (expressed as equivalent
depth of the layer) reside in the upper crust and on the surface.
The Cassini-Huygens mission will search for such liquids and assess
the extent of photochemistry through time. Titan's overall history
with respect to surface liquids may be complex. In the distant past
accretional heating could have sustained a deep layer of mixed water-ammonia
liquid as a kind of cryogenic magma ocean. Liquid hydrocarbons have
come and gone on the surface through time to the present. In the distant
future, when the Sun becomes a red giant star, Titan could once again
possess a water-ammonia surface ocean.
Dirk Schulze-Makuch and Louis Irwin of the University of Texas at
El Paso will talk on "Gravitational Flexing and the Potential for
Life on the Outer Icy Satellites." Their abstract reads:
Though water is abundant on many satellites of the
solar system, the potential sources of energy for dynamic geophysical
activity and possible biological processes are less well known. Gravitational
flexing and the presence of a liquid medium could have provided biologically
favorable conditions early in the history of the solar system when
many of the satellites most likely held a water vapor atmosphere.
Gravitational attraction between numerous satellites and their parent
planets exceeds that between the Earth and the Moon (G(Earth x Moon)).
They include (for G(Earth × Moon =1) Io (× 321), Ganymede
(× 86), Europa (× 68), Callisto (× 19), Titan (×
17), and Triton (× 6). Perhaps more relevant is the flexing to
which a satellite is exposed between maximum and minimum gravitational
interactions among its sibling moons. Flexing is greatest by far on
Io (13.7%), but appreciable on Oberon (0.071%), Europa (0.058%), Callisto
(0.054%), Titania (0.046%), Ganymede (0.042%), Rhea (0.018%), Dione
(0.010%), Tethys (0.007%), and Enceladus (0.005%). Tidal flats on
Earth typically have high biological productivity, and may have provided
an environment for the origin of life. Similar conditions followed
by subsequent cooling in the outer solar system could have replaced
the atmosphere of distant satellites with an ice shield, leaving liquid
water with living organisms beneath the frozen crust. Such ecosystems
conceivably could still be supported by kinetic energy due to tidal
flexing within the liquid subsurface. |
Waterworld Mars: past and future
(Dec. 8, 2001)
Long-term changes, possibly related to a global shift in climate,
have been detected on the surface of Mars. High-resolution images
of Mars' south pole by
Mars Global Surveyor show
dramatic erosion in its year-round frosty upper layers. Scientists
have also identified a reservoir of carbon dioxide that, if released,
could alter the planet completely. The size of the reservoir, still
unknown, could also influence the presence of liquid water on the
Martian surface through a combination of increased atmospheric pressure
and greenhouse warming. For more on this, go here
(space.com).
Meanwhile, results from NASA's Far
Ultraviolet Spectroscopic Explorer (FUSE) suggest that, although
covered by frozen deserts today, Mars may have been born with more
water in proportion to its mass than the Earth. The new measurements
suggest that if this early Martian water had been spread evenly across
the planet, it could have created a global ocean at least 1.25 km
deep. For more on this, go here
(Spaceflight Now). |
Europa's red tinge due to bacteria?
(Dec. 5, 2001)
Europa's
unusual spectrum matches some of the features of the spectra of bacteria,
according to astrogeologist Brad Dalton. One of the bacterial specimens
he matched to the Jovian moon's light characteristics was Deinoccus
radiodurans (literally "strange berry that withstands radiation").
This microbial oddball, which smells of rotten cabbage, also happens
to be pinky-red in color – similar to the hue of parts of Europa's
surface. Although the idea seems far-fetched – and reminiscent
of Hoyle and Wickramasinghe's claims that the spectrum of interstellar
dust grains matches those of bacteria – it certainly isn't out
of the question. If the putative sub-ice ocean on Europa does harbor
primitive life, the frozen remains of those microorganisms may well
have found their way to the surface through cracks and fissures. An
interesting possibility at least.
For more, go here
(New Scientist). |
Evidence builds for an ocean on Callisto
(Dec. 2, 2001)
Suspicions are growing that the outermost of Jupiter's four big moons,
Callisto, may have
a sub-ice ocean of the type believed to exist on Europa.
The latest clue to the presence of subterranean liquid is the absence
of any major feature on Callisto on the opposite side to the great
Valhalla impact basin. Such antipodean features have been noted on
the Moon and Mercury
but the fact that the impact which created Valhalla failed to generate
some structure at the opposition point suggests the shock waves were
absorbed by a subsurface fluid layer. Magnetometer data from Galileo
had already hinted at underground oceans on Europa, Callisto, and
the biggest of the Galilean moons – Ganymede.
For more, go here. |
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