This time it is even more controversial than the connection between
the mass extinction 65 Myr ago and the Mexican impact event once was.
A geologist claims that the same shocked microscopic quartz crystals that
were crucial in proving that link are also present in sediments
from the late Permian period, which ended about 250 Myr ago. No
mechanism other than a tremendous impact (or a man-made explosion)
seems to be able to cause this kind of damage to quartz. The Perm/Trias
transition was marked by one of the greatest extinctions ever,
and palaeontologists had come up with many clever non-astronomical
explanations. Be prepared for more controversy in coming months...
(Science Now Oct. 30, 1996)
Another Martian Meteorite in the Headlines
This time it is EETA79001, another Antarctic meteorite that had
been the most famous one until 1/4 year ago. It was the first one
in which pockets of Martian air had been detected, which led to the
widespread acceptance of the Martian origin of the SNC meteorites
(Ad Astra July 1996). And it was again EETA79001 in which
British researchers claim to have found the first organic matter
from Mars in 1989 (Nature July 20, 1989, p. 220-222). Now the
same scientists have given a news conference in London, claiming
even stronger evidence for this result which was controversial
at the time. EETA79001 is much younger than ALH84001: Significant
traces of life from Mars in this rock would be strong evidence for
life enduring on that planet til the present time.
In 1989 there was suspicion that the organic matter could have
been terrestrial contamination, but now the sample was from a
part of the meteorite that had been sealed in a glasslike substance
before EETA79001 landed in Antarctica. The evidence apparently
is purely isotopic: Carbon atoms extracted from the rock have an
isotope ratio matching the C ratio in methane produced by bacteria.
The British geochemists applied the same test to the carbon
compounds in ALH84001 and found the same isotope ratio again -
but to claim that this is proof of present live on Mars (as one
of the scientists had said) is pretty bold... (Science Now
Oct. 31 + Boston Globe +
Florida Today Nov. 1, 1996)
China plans manned spaceflight for 1999
A secret project named "Project 921" has been described to members
of an internatiomnal delegation visiting Chinese space centers:
Apparently the are plans to launch one or two astronauts in a
Gemini-like capsule on a Long March rocket in 1999 - for purely
political reasons, namely to celebrate the 50th birthday of the
communist state. The development of the capsule must have been
under way for several years as should have been the training of the
astronauts - they will have watched the mixed success of Long
March launches in recent years with great interest...
For 1998, the visitors heard, an unmanned test
flight is planned. And there seem to be even vague plans for a
Chinese space station, to be launched around 2020. (AW&ST
Oct. 21, 1996, p.22)
Briefly noted:
The third Galileo encounter with a Jovian satellite begins
today: The highlight of "
C3
" will be a flight over
Callisto at an altitude of 1118 km).
This is going to happen exactly. Meanwhile the launch of the
Pegasus rocket with SAC-B and HETE has been halted until at least
Monday.
The HST images of the current dust storm on Mars (see Update
#7) have already become
available:
When watching them remember how small the Martian disk is a the
moment! Meanwhile a group of young students will take a virtual trip
to Mars this month when they remotely steer a Russian-built
robotic rover through a barren Arizona desert from
their classrooms. Using their computers and the Internet,
the students will control the rover as it
navigates through a sparsely-vegetated area during a NASA
field test to simulate future robotic exploration of the red
planet - and everybody can look on
here.
111 molecules in space are known to date: The largest one
is HC9N with 11 atoms (claims that HC11N has
been seen as well turned out to be
incorrect). Nearly all of the larger molecules are carbon chains;
only three of them are rings, and no ball-shaped fullerenes have
been found so far. The laboratory study of long carbon chains (a
somewhat dangerous pastime, as some of the compounds are explosive)
is now catching up with the astronomical observations.
(Talk by M. McCarthy in Cambridge, MA, on Oct. 31st, 1996).
Update #9 of Oct. 31, 1996 01:00 UTC
Posted from Cambridge, MA, U.S.A.
Pegasus launch delayed til Friday
The countdown for the winged rocket
carrying SAC-B and HETE (see Update #8) ran to t-5 seconds, but then the
countdown was stopped when one of the rudder pins did not retract from
the Pegasus rocket. Soon the battery power for the rocket's fins expired,
forcing the abort and scrub for Oct. 30th.The launch of Pegasus/HETE
and SAC-B, to occur off Wallops Island, Va., is now
scheduled for no earlier than Friday. Over the next 48 hours, controllers
will continue to troubleshoot yesterday's problem, and replace the
fin batteries for the next attempt. (Adapted from
Florida Today Online)
Meanwhile, learn more about the
history of the Gamma Ray Bursts which SAC-B and especially HETE
are to study - and about
Violence in the Cosmos in general!
Briefly noted:
Still no firm launch date set for STS-80: Only on Monday will
managers decide whether to launch Columbia on Nov. 8th - mysterious
damage found in the retrieved boosters from the last mission is
causing considerable concern. STS-80
will be a very special mission for one of the passengers: It's
mission number six for
Story Musgrave, who with 61 years is
also the oldest active astronaut. (Florida Today Oct. 30, and Boston
Globe Oct. 29, 1996)
Are the "DIBs" simple hydrogen molecules? It's one of the
oldest unsolved mysteries in astrophysics: What component of the
interstellar medium is causing widely observed
diffuse absorption bands in stellar spectra? Most astronomers were
betting on complicated molecules with many atoms (PAHs, e.g., or
fullerenes) - but now it seems possible that simple molecular
hydrogen is to blame, albeit in a specially excited state.
(Science Now
Oct. 29, 1996)
Spectacular new
image of the ocean floor: A dramatic geophysical data product
from the NOAO is visualizing the spreading of the sea floor and the
formation of new earth crust by color-coding is age. This image
can also be bought from the U.S. government. (CNN Online Oct.
30, 1996)
Update #8 of Oct. 29, 1996 18:45 UTC
Posted from Cambridge, MA, U.S.A. (includes DPS'96 wrap-up)
Launch of new High-Energy Astrophysics Spacecraft Approaches
Oct. 30 is the latest date set for the launch of HETE and
SAC-B, an American and an Argentinian small satellite with
instruments for x-ray and gamma astronomy. The launch window
opens around 17:30 UTC on that day. They are supposed to fly
on a
Pegasus-XL winged rocket, and the launch delay by one day was
apparently caused by problems in related small science satellites
due to fly on the Pegasus.
SAC-B
(Scientific Applications Satellite-B) is an international
cooperative project between
NASA and the Space Agency of Argentina,
CONAE. The spacecraft, which is
managed by the GSFC International Projects Office, will observe
solar flares, gamma ray bursts, the diffuse cosmic X-ray background
and energetic neutral atoms. Argentina has built the satellite
(total mass 181 kg) and one instrument, NASA built two others, and
Italy provided the solar arrays and yet another instrument.
HETE, the High Energy
Transient Experiment, weighs only a little more than 100 kg and was
built at the MIT in Cambridge, MA. It carries three instruments: a
gamma burst detector, an x-ray camera with a coded mask, and UV cameras.
Together these instruments will try to solve one of the greatest
mysteries of contemporary astrophysics: Where do the
Gamma Ray Bursts
(GRBs) originate? Not only will the satellite itself try to observe
the bursts and their possible aftereffects itself: It will broadcast
the detection of a burst in realtime over a freely
available
radio link to astronomers around the world. Any amateurs up to
the challenge?! (With NASA News Release # 213 Oct. 21, 1996)
Most of Earth's Oxygen Supply Produced by Geologic Events ?
Did global-scale geologic events produce the bulk of the Earth's
oxygen supply - and not the plant life in its early oceans, as
the traditional view sees it?
Research performed at the NASA Ames Research Center by David
DesMarais correlates oxygen "surges" in the
atmosphere 2.2 to 2.0 billion years ago with changes in the
amount of carbon stored in Earth's crust at that time
when several of Earth's "micro" continents
crashed together forming new, stable modern-sized continents.
As the continental fragments collided, towering mountain
ranges formed. Their steep slopes produced rapid erosion and
sedimentation, key to the new theory presented at a meeting in Denver.
Orgnic matter is normally consumed by bacteria and
animals, a process that utilizes oxygen (respiration),
producing energy and carbon dioxide and water as by-products.
According to DesMarais, when huge amounts of organic matter
were buried during cataclysmic collisions, oxygen was freed
to accumulate in Earth's early atmosphere.
"The cycle of photosynthesis (which produces oxygen)
and respiration (where oxygen is consumed) is an almost
break-even process," DesMarais said. Only when large amounts
of organic material are buried in ocean sediments during
tectonic upheavals can the amount of oxygen in the atmosphere
increase substantially, he added.
An independent recent study concludes that
approximately three large continental masses were assembled
between 2.5 and 1.9 billion years ago by the collision of
smaller land masses. Two of these were assembled between 2.2
and 1.9 billion years ago. These collisions formed
Himalayan-class mountains with high rates of sedimentation in
the ocean, burying organic matter. According to DesMarais, the formation of stable, large
continents also protects and stores larger amounts of organic
carbon for hundreds of millions of years, further allowing
the atmosphere to accumulate large amounts of free oxygen.
(Adapted from NASA News Release # 219 Oct. 29, 1996)
Strange double-meteor detected seismically
The unique meteoroid that flew through the Earth's atmosphere
twice on two subsequent orbits, before it went down somewhere in
California (see Update #3), has also been detected by a network
of 31 seismographs. During its final entry the meteor exploded in
midair at least twice, and soundwaves similar to sonic booms were
detected by the seismographs. From those signals the point of
impact of any remaining meteoritic particles could be narrowed
down further: It is the Rose Valley near Little Lake, a desert
region at the base of the southeastern flank of the Sierra Nevada.
All those heading out there now should be warned, though: The
$ 5000 reward for the first chunk of the meteorite recovered will
only be paid out for a piece weighing more han 4 ounces... (New
York Times Oct. 27, 1996)
Final Brief Notes from the 28th DPS Meeting in Tucson, AZ:
Water from the Rings is Raining onto Saturn! A remarkable hypothesis about the short lifetime of Saturn's
spectacular ring system has apparently been confirmed by UV
spectroscopy with the Hubble Space Telescope: At wavelengths below
180 nm there is an enormous water absorption feature in the clouds
of the planet which is due to water - which can be traced back to the
ring system. The latter is being eroded by micrometeorite hits, and
some of the chipped-off particles get negatively charged and follow
Saturn's magnetic field lines straight into its cloud deck. This fact
will allow to determine the erosion rate (and thus the age) of the
rings from the water abundance of Saturn's clouds.
Still Haze left from Shoemaker-Levy 9 on Jupiter! Both with
its spectrographs and with its cameras the Hubble Space Telescope
can still see hazy reminders of The Great Comet Crash more than two
years ago. The spectrographic data over the past 27 months
have tracked an ammonia enhancement after the impacts which was
slowly "eaten away" by solar photons but still hadn't returned to the
pre-impact level in June of 1996. To actually see the comet
haze, clever image processing is required, though: Pre-impact images
have to be carefully subtracted from current views. By doing just
that two teams had no trouble detecting the remaining material in the
UV, also this June: It has by now spread to between 15 and 80
degrees South.
Hale-Bopp's water production rises and rises: Radio astronomers
have confirmed the findings from the Hubble Space Telescope (see
Update #6) that this comet is producing more water each time it is
observed, with the value going up with the -5.8th power of the
distance from the sun; just now the value is approaching 10**30
water molecules per second. In contrast the production of carbon
monoxide is rising only with the -1.9th power of the heliocentric
distance: Water is clearly the dominant driver now.
Second, bigger SPACEWATCH telescope finally under construction:
With 1.8 meters aperture it will be the largest instrument in the
world dedicated to search for potentially Earth-threatening
asteroids. While the mirror was purchased already in 1969, it took
a lot of time and effort to
raise the money for the telescope and its
building (now under construction on Kitt Peak, AZ, next to the old
but
successful SPACEWATCH camera -
1/4 came from private donations! The new instrument should be able to
find 80 000 unknown asteroids each year, most of them in the main
belt, but a fraction will be Near-Earth Objects. Around the world
the search for them is intensifying now - check this
list from a competing
Arizona-based program.
More URL's from the Meeting (see Update #6.1) and a correction:
The Space Telescope-related online catalogs and sky survey data have
moved here
recently. An on-line Solar System Data and Ephemeris Computation
Service is
Horizons. Planetary-research interest groups worth a visit are the
Planetary Society and the
amateur
ALPO. Other places of interest advertised at the DPS'96 were
the new efforts for educational programs during NASA missions
(POETRY) and
SETI, the
SEDSAT-1 project and a
shop for Space Art.
Update #7 of Oct. 26, 1996 22:30 UTC
Posted from the 28th DPS Meeting in Tucson, AZ, U.S.A.
Stunning HST views: Dust storm on Mars continues
The public will see them only on November 4th, shortly before the
Mars Global Surveyor gets launched, but they were already shown at
the planet conference here in cold and rainy Tucson: color Hubble images
of the planet Mars that show the evolution of a dust storm at high
Northern latitudes. The storm was first discovered by Todd Clancy as a brown patch
somewhat overlapping the Northern polar cap on Sept. 16th. By October
15th the dusty cloud had mutated into a curly wave which had moved
completely onto the polar cap. This is only a minor dust storm which
did not affect the global temperature of the Martian atmosphere.
Planetwide duststorms, however, can raise the temperature by many
degrees, a phenomenon that was last measured in 1995 (only in the
radio spectrum, as the planet was virtually unobservable at the time).
For the coming months Mars will be a - relatively - frequent target
for the Hubble Space Telescope; 3 to 5 orbits per month will be
devoted, which is a lot for a planetary program. But the HST's (and
groundbased observers') support is needed for a safe landing o
the Mars Pathfinder:
It cannot take any close-up pictures of Mars
during its approach and requires detailled knowledge of the state
of the Martian atmosphere. No major dust storms are likely when it
arrives next July 4th, but when the Mars Global Surveyor enters the
Martian atmosphere in September, the storm season will have begun.
Unfortunately the HST cannot help then: Mars will already be quite
close to the sun. Check out
this site for
the 'use' of Mars in education!
The planet currently most distant from the Sun is also the most
dynamic one: No other major planet keeps changing its face as
frequently. When Voyager 2 came by in 1989, a Great Dark Spot was
the dominating feature, then it disappeared a few years later, and
around 1993 major activity erupted in the Northern hemisphere. When
Hubble took its first post-repair images in 1994, there were still
many clouds North of the equator, but in 1995 and 1996 the main
remaining features were two bands of bright clouds in the South.
The latest images
from August 13th confirm this pattern: From 1994 to 1996 the planet
has basically stayed the same, at least w.r.t. the band structure -
apparently a new stable situation, but markedly different from 1989.
In the years before 1989 crude groundbased images had shown yet another
distribution of the Neptunian clouds (and therefore apparently also
of its bands): One could speculate that the atmospheric pattern
switches every 5 years or so. For that reason some 9 HST orbits per
year are dedicated to this planet: It is well possible that the
Space Telescope will still be around when Neptune does it again...
Other News from the 28th DPS Meeting:
Neptune brighter than ever before! Within the last decades
the brightness of the planet has been going up all the time, from
7.82 to now 7.72 mag, while this secular trend was modulated in
rhythm with the solar cycle (the more sunspots the dimmer Neptune).
Whether both phenomena are really related to the sun is hard to say,
but quite a number of phenomena on the gas planets seem to react
to the sun, such as the Great White Storms on Saturn and the changes
on Uranus which has now much better visible clouds than 10 years ago.
Triton is boring - at least when you observe it with the
Hubble Space Telescope: This large moon of Neptune which showed
a stunningly complicated and active surface to Voyager 2 is just a
totally featureless disk for the HST. But on Pluto - which shares
many physical characteristics with Triton - the HST sees a lot (see
below): Imagine what this planet might look like for a visiting
spacecraft...
Does Pluto's surface change? Given that this planet is just
8 pixels in diameter even for Hubble, it is very difficult to turn
images into reliable maps and to compare maps from different
epochs.
Typical maps have a resolution of about 600 km (with a diameter
of the planet of 2300 km), and to obtain them reliably more than one
image is needed. The single orbit that was given to Pluto during the
Life from the HST program was thus basically useless: The new
image from early 1996 does show differences relative to the
1994 pictures, but it is impossible to say whether the pattern of
frost deposits has changed in the 2 years or not.
Charon's orbit is excentric: This is a very new discovery
coming from the monitoring of the orbit of Pluto's moon with the
HST. It is still to early to put a number on the orbital eccentricity,
but in the future it might be possible to deduce perturbations by
other members of the Kuiper belt.
Saturn's F ring is inclined: Observations of the occultation
of a star by this mysteriously warped narrow ring on Nov. 22, 1995,
have shown that it is inclined by 0.006 +/- 0.002 degrees against
the equator of Saturn. This is the first detection of an inclination
in Saturn's rings. The finding explains why the F ring changed its
brightness abruptly during the 1995 ring plane crossings.
Update #6.1 of Oct. 25, 1996 23:30 UTC (Oct. 26 16:30 UTC)
Posted from the 28th DPS Meeting in Tucson, AZ, U.S.A.
The "other" Planets: Why are some excentric?
With about 8
extrasolar planetary systems discovered, one can slowly start
to look for patterns. One criterion to sort the planets by is their
mass, but perhaps the excentricity of their orbits is more important.
That's at least what G. Marcy of Lick Observatory is proposing, one
of the particularly
successful planet hunters.
There seem to be three classes of planetary systems: Those like
our own, with a Jupiter-sized object in a Jupiter-like orbit (the
only "other" one of this category is the one of 47 UMa), those like
the one around 51 Peg, with Jupiter-like objects in very close orbit
around their star (in total 4 cases are known to date) - and those
like 70 Vir, HD 114762 and 16 Cyg B (see Update #4) with excentric
orbits. Tau Bootis is a particularly weird member of class #2, by the
way: It is not only very close to its "sun" but also pretty massive
(some 4 Jupiter masses). This system must be in total tidal lock,
with the star forcing the planet to show it always the same face -
and vice versa!
What causes the excentricity in some planetary systems is far from
clear, but theorists are busy at work right now. Meanwhile the planet hunt
with the most successful technique, looking for periodic patterns in
the radial velocities of stars, is continuing. The Lick group has
reached the greatest level of accuracy, 3 meters per second - an
impressive task, since this means looking for spectral lines moving
a mere 1/1000 of one pixel back and forth over weeks to years.
But only then can one reliably detect Jupiter-size planets in orbits
around other stars. And the hunt for the first other "Uranus" or
"Neptune" is already on...
Astronomers still optimistic about Hale-Bopp
While many in the amateur community are increasingly worried about
the "performance" of comet Hale-Bopp (which only a few days ago finally
broke the 'barrier' of 5.0 mag, according to current
observations),
comet professionals don't waiver in their excitement. Just
take Hal Weaver. The latest
spectrographic observations from the Hubble Space Telescope, for
example, taken in late September, show the all-important water
production rate well on a typical track which would reach 3 to 5 times
10**30 molecules per second at perihelion - almost 10 times the
figure that Halley had at the same distance from the sun.
Even more importantly for the visual observer, the dust production
which was more or less steady in the last 12 months, has finally
started to catch up with the water production - actually Hale-Bopp is
one of the most dust-rich comets ever studied in detail! So lets wait
and watch: This comet with its BIG nucleus (30 to 40 km in diameter,
according to Hubble images with the coma removed) will have more
surprises in store. There are for example the half-dozen dust jets
which appeared in its coma just when the main driver of the activity
switched from carbon monoxide (CO) to water this summer: They basically
don't move, which could indicate an outstandingly long rotation
period of the nucleus.
So scientists are already having lots of fun with
this cosmic visitor: There is the hypothesis, for example, that its
nucleus is composed of fragments of different chemical composition.
That could explain why the production of carbon monoxide is behaving
very differently from the water production (it is flattening out,
while the latter is rising and rising). Unfortunately Hubble won't be
able to watch, though: From now til next August - when everything
will be over (the best viewing window is next March to April) - the
comet is closer than 50 degrees to the sun. And that's the limit for
the HST...
One of the many unsolved questions that the Great Comet Crash of
1994 left behind was the nature of the amazing circular rings
that emanated from every impact spot and just moved on without
slowing down. This indicated that some wave phenomenon (and not the
actual transport of matter) was to blame - but what kind of wave?
Based on the models of the Jovian atmosphere available in 1994 and
1995, Andy Ingersoll had figured out that only one special kind of
wave at great depth could possible have the right speed (of 450
meters per second) - but only if Jupiter was extremely rich in water.
The Galileo Probe, of course, found the opposite, an extremely dry
Jupiter, at least in the Hot Spot region that it accidentally fell
into. While the debate is still raging on how global the dryness
of Jupiter really is (and whether the "missing" water can't be
hidden somewhere, e.g. in the thunderclouds Galileo has imaged North
of the Red Spot or other phenomena), a clever Japanese - working at
the National Research Center for Earth Science and Disaster
Prevention, of all places - may have solved the mystery.
Shingo Watada has taken the new atmospheric profile data that also
came out of the Galileo Probe mission and calculated the sound speed
at various heights. And there it was: a "trap" for soundwaves between
the 1 bar level of the atmosphere and 300 km above it that had
not existed in the pre-Galileo atmosphere model! Sound waves
from the impact explosions could have travelled inside this channel,
being reflected up and down and thus slowing their actual horizontal
speed to some 500 m/s: just right to explain the larger, outer
wave. Moreover these sound waves would have existed at the right
altitude where the dark material actually condensed that made the
rings visible in the first place.
Posted from the 28th DPS Meeting in Tucson, AZ, U.S.A.
Daylight Fireball over the Netherlands!
The following report has just come in from Casper ter Kuile from
the Netherlands: "Dear observers! As previously stated by Urjan Poerink
of the 'Dutch working group meteors'
a daylight fireball has been observed from the eastern and northern
part of the Netherlands.
Our well-known meteorologist Jacob Kuiper from the National Meteorological
Weather Service (KNMI) has gathered lots of observations regarding this event.
It might turn out that this fireball could well be a meteoritedropper!
From a number of observations we are able to conclude that this fireball
appeared above Germany (Niedersachsen, Schleswig-Holstein,
Mecklenburg-Vorpommeren), Denmark or the Baltic sea. The uncertainty is
rather big still.We urgently ask our German and Danisch colleagues to pay attention to this
special event! Dutch meteorobservers of the DMS and WGM will join efforts in an
interviewsession this weekend in the north-eastern part of the Netherlands
to gain more knowledge on the trajectory of this very special event.
Sorry, I forget to mention the date of this big bright daylightfireball.
October 17, 11:35 UT."(2 Circulars from late Oct. 23 and
early Oct. 24, 1996)
Meteorite-travel from Mars to Earth? No Problem!
It has been known for some time that meteoroids can travel between
the planets (see e.g. Gladman et al., Science March 8, p. 1387-92) -
and now there a full computer simulation of what can happen when an object
is "launched" from Mars (as the consequence of a large impact).
Several workstations around the world
integrated the highly chaotic trajectories of thousands of test
particles: First, they stay in the vicinity of Mars, then their
orbits get increasingly disturbed, and finally they crash into
Venus (7% of all cases), the Earth (another 7%), Mars (9%) or the
Sun (32%). About 10% reach Jupiter and get thrown out of the solar
system, and the remaining 35% 'survive' for millions of years.
The 'trip' from Mars to Earth can be very quick if the meteoroid
gets launched with a high speed and in the right direction: perhaps
one in 10**8 goes even on a direct 6-month trajectory to Earth.
Since some exobiological experiments have shown that primitive life
can withstands many months of exposure to space if it is protected
by some meteoritic crust, it is rather likely that any life which
may have arisen on Mars would sooner or later end up on Earth! The
other way around would be much rarer: The gravitational field of
the Earth is much greater than Mars', and there is also the atmosphere
which hampers any 'launch attempt'. (Talk by J. Burns at the
DPS-Meeting)
Io has a high-altitude ionosphere
Scientists participating in NASA's Galileo mission have
discovered that the Galileo spacecraft may have flown though
a dense, high-altitude ionosphere during its encounter with
Jupiter's volcanic moon Io last December. This discovery
suggests that Io's atmosphere is time variable and is made of
volcanic gas lofted to very high altitudes. Plasma Science sensors
on the spacecraft found a very dense region of
ionized oxygen, sulfur and sulfur dioxide at 555 miles on Io
that obviously was pumped into that region by Io's
volcanic activity. Instead of being swept away by Jupiter's
rotating magnetosphere as anticipated, the ionized gases
surprisingly remain with Io.
Passage of the Galileo spacecraft through an ionosphere
was not expected because images of the volcanic plumes
previously taken with the Voyager spacecraft indicated that
the plume heights extended only to a few hundred kilometers
or less. A radio occultation by the Pioneer 10
spacecraft in 1973 indicated ionospheric heights only about
30 to 60 miles above the surface. No one expected to see
this at 900 kilometers' altitude. The difference
between what Pioneer saw and what Galileo has observed
indicates that Io's atmosphere and ionosphere are variable
and may grow and shrink with more or less volcanic activity.
(adapted from NASA News # 216 Oct. 23, 1996)
Other News from the 28th DPS Meeting:
Lunar Transient Phenomena near edges of maria: A comparision
of these strange flashes on the moon (which have been reported for
at least 450 years) with the new geologic maps of the moon generated
from Clementine's images is indicating some possibly revealing
correlations. Not only is there a concentration of "LTP"s near the
edges of maria; the reported events also tend to be in craters with
rims of distinctly bluer composition. This compositional difference
may have resulted from recent slumping of the rim, accompanied by the
appearance of fresher underlying material. The LTPs may thus be
associated with outgassing of volatiles collected in mare basalts.
Clementine's Moon map delivers new quality: With the help
of this little lunar mission from early 1994 the cartographic control
net for the Moon has been improved from 1-2 km on the near and 10 km
on the far side to better than 200 meters globally. Several automated
procedures were developed to aid in finding matchpoints, with a
successrate exceeding 90%: This software is
available on the Internet.
Plans for a 4 meter coronagraph useful for both solar and
other astronomical studies are currently being drawn: CLEAR or the
Coronographic & Low Emissivity Astronomical Reflector would be an
obstruction-free off-axis Gregorian with 0.1 arc sec resolution and
probably some adaptive optics. It could revolutionize the study of
the exospheres (extremely thin outer atmospheres) of the Moon,
Mercury and Jupiter and could look for asteroidal satellites (which
some simulation say are frequent). And in the distant Universe
CLEAR would be ideal for imaging the halos of galaxies.
Update #4 of Oct. 23, 1996 23:55 UTC
Posted from the 28th Annual Meeting of the Division
for Planetary Sciences
of the American Astronomical Society (DPS)
in Tucson, AZ, U.S.A.
Yet another Planetary System - again no twin of our own
One year ago most astronomers would have proclaimed that our own
Solar System would be typical, and computer simulations had
underpinned that idea. But each and
every other planetary system that
has been discovered in the last 12 months looks different - and
the newest case is no exception. Announced just an hour ago here at the
world's largest planetary science conference, the
planet of 16 Cygni B has a mass of equal or greater than
1.5 times that of Jupiter and a semimajor axis of 1.7 AU. But unlike
other Jupiter-sized planets in near-circular orbits of the order of
one 1 AU that circle 47 UMa and Lalande 21185, this
one has a large excentricity of about 0.7!
The reason could be that 16 Cygni is a double (or even triple)
star, albeit a strange one: The components A and B move around
one another every few 100 000 years on a very excentric orbit
(e = 0.90...0.95) with a semimajor axis of some 4000 AU and a
periastron of a mere 200 AU. Right now the two stars (which are
about 70 light years away) are separated by 33 arc sec or 700 AU:
their last close approach took place just a few thousand years ago.
The third component, by the way, is 7 magnitudes fainter and stands
70 arc sec away.
It may well be the double nature of 16 Cygni that has 'pumped' up
the excentricity of the planet's orbit. On the other hand it might
be typical that planets born in double stars start out on
excentric orbits to begin with. Or there is yet another mechanism
at work that none has thought of yet. Whatever the reason: Although
16 Cyg B is a near-perfect twin of our Sun (with 1.00 +/- 0.05
solar masses and a temperature identical to the first 3 digits),
its planetary system clearly isn't. (Press conference by
W. Cochran on Oct. 23, 1996, at the 28th DPS Meeting, who is one of
four discoverers, working in two totally independent teams)
Other News from the 28th DPS Meeting:
The News from Mars is... No News: That's the state
of the quest for evidence for (past) life on Mars. Several members
of the Houston-based team that caused such a stir two months ago,
including Dave McKay, gave presentations today to both the media and
the scientific community - but no new evidence was presented. To the
contrary, actually: McKay all but retracted his earlier comments on
possible life traces in a 2nd Martian meteorite (see Update # 2) which
he now considers "so shaky we don't want to talk about it", and he
didn't elaborate on the evidence for cell walls in some of the
tiny structures in ALH84001 that he had mentioned in a
House hearing
on Sept. 12th.
The plan is now to get even thinner cuts of samples
of the meteorite for TEM analysis and to try looking for biogenic
traces with light fluorescence microscopy. Otherwise McKay et al.
have been busy responding to a flurry of critical letters Science
has received in recent weeks (which will be published soon) and to
study many samples of extremely tiny structures in terrestrial stones
that some interpret as nannofossils or nannobacteria. In his talks
McKay showed strikingly similar structures from the Earth and from
Mars - even if the "Martian fossils" might turn out to be some
inorganic artefacts in the end, the current activity would have
brought forward micropalaeontology on Earth a great deal.
The Great Red Spot's center is counterrotating! This is one
of the many puzzling findings from Galileo's early orbits around
Jupiter. The understanding how this gigantic storm is
structured in 3D has grown quite a bit, thanks to Galileo's visible
and especially IR images, but why it acts like it does,
remains to be studied. Meanwhile the first images from the 2nd
encounter (Ganymede-2) have become
available.
Can Hyakutake's X-rays be explained by dust? According to a
new model the strikingly bright X-ray emission that ROSAT saw from
this comet (and lots of others in the past) could be solar X-rays
scattered by extremely small dust particles of just 5 nm scale. This
can explain the intensity of the cometary x-rays quite well -
but how would one account for the fast variations of this
intensity that were measured and did not reflect variations
in the output of the sun?
Update #3 of Oct. 21, 1996 23:45 UTC
Posted from Tuscon, Arizona, U.S.A.
The Meteor(!) that came twice!
This could well be the most unusual meteoritic event that hit
the Earth since Tunguska: A meteoroid about the size of a car
first grazed the Earth's atmosphere, causing a spectacular fiery
display over much of the Western U.S., then left the atmosphere
again but reentered one orbit later and crashed into California.
At least that's the story that astronomers have figured out from
the available visual observations from Oct. 3rd: The interval
between the two sightings was 100 minutes, equal to one Keplerian
orbit of the Earth at low altitude, and the distance between the
original path across the sky in New Mexico and Texas and the later
track seen in California is 25 degrees of longitude, exactly the
amount the Earth has rotated onwards in these 100 minutes.
Now a reward of $U.S. 5000 is being offered for parts of the meteoroid that could
have reached the ground in California. This event, while unique,
somewhat resembles the famous fireball of Aug. 11, 1972, which was
also caused by a meteoroid grazing the outer atmosphere and
then returning into space. But this one never returned, although some
predict it might do so next summer. (The Arizona Republic Oct.
19, 1996)
Really Live Images from Mars on the Internet
That's what NASA is promising for the upcoming Mars Pathfinder
and Mars Global Surveyor missions. The old rule that the
data from space missions, including images, "belong" to the mission
scientists for some time, with only selected bits reaching the
public at their choosing, is being rapidly eroded these days. In
contrast to the on-going Galileo mission where the slow trickle of
bits from Jupiter hampers efforts to make full images available
right away, the new Mars mission images will be piped into the WWW
as soon as possible!
While there may still be some delay in the case of the orbiting
Surveyor, the images from the IMP (Imager for Mars Pathfinder)
instrument will reach "viewers" on the Internet at the very moment
they appear on the monitors of JPL - that is, if both the launch
on Dec. 2nd and the touchdown on July 4th, 1997, are successful. And
not only images but also daily weather reports will be available
from the lander: Together with efforts to bring the Mars news to
Earth big style (in the "
Life from Mars" program) this will be a completely new Martian
experience... (Mesa Tribune Oct. 17, 1996)
A Martian visit for Deep Space One?
The Deep Space One spacecraft, the first in the new New Millennium
series of NASA technology demonstrators, will not only visit an
asteroid and a comet but will also make a - moderately - close
flyby of Mars, which just happens to be in the right place. After
launch in July of 1998, DS1 will encounter asteroid McAuliffe on
Jan. 28, 1999, Mars on April 19, 2000 and comet West-Kohoutek-Ikemura
on June 6, 2000. Interestingly DS1 cannot approach Mars
arbitrarily close because there is a legal 'zone of avoidance': If you
want to get closer you have to sterilize your hardware, and New
Millennium doesn't want to pay for that.
The instrumentation of Deep Space One (which will travel with the
help of an ion engine, the first ever to go on an interplanetary
journey) has already been chosen. There will be a combined camera
and spectrograph as well as fields & particles instruments. But
science really isn't the main issue for this mission: Even if DS1
just flies but doesn't report one bit of science data, it would
still be considered a full success, technically. However, in order
to enhance the science output, there will be a team of small body
experts on hand to optimize the camera and operations. (On Location
at the Arizona company that builds DS1; with additional insights from
JPL: D. Fischer)
Update #2 of Oct. 15, 1996 12:50 UTC
Famous German Institute faces Closure!
It came as a shock to the space science community in Germany: One
of their most important institutes, the Max Planck Institute for Aeronomy
will most likely be closed within the next few years. Many past,
present and future endeavours of Europe's space science were and
are based here, e.g. the cameras of the comet spacecraft Giotto and
Rosetta or a major spectrograph of SOHO. Between 1994 and 2000 the
Max Planck Society has to lay off 11% of its staff in the Western
Bundeslaender, to make up for funding shortages and heavy investment
into the East (i.e. the former GDR). The policy of the society is
to kill whole institutes instead of laying off a few people everywhere:
This is supposed to keep the 'survivors' competitive. Fortunately the
MPAe is the only victim in the field of physics, chemistry and
technology. The decision to close it down has still to be confirmed
by the MPG senate in November; the future of the science programs
run from there is totally unclear at the moment. (DF,
based on an interview with a high-ranking MPG officer)
Rosetta loses one of its landers
Bad news galore for Europe's space scientists: A sudden decision by
the Jet Propulsion Lab to withdraw its funding for the
Champollion
comet lander has killed this joint venture between France and the U.S.
Champollion was supposed to accompany the German-led
RoLand
on the Rosetta spacecraft to comet Wirtanen. Now RoLand will be the
only surface science package of Rosetta, maybe a little bigger
than planned: The French are scrambling to get some of their
instruments aboard. The U.S. comet community, though, has been had
once more: First they don't get their Halley Intercept Mission,
then they loose CRAF, and now Champollion. The Deep Space-1 mission
to comet West-Kohoutek-Ikemura and the Stardust mission seem to
be healthy, though - and there is talk of a Deep Space-5 mission
which would basically be a Champollion without an orbiter. (DF,
based on interviews with various Rosetta people; see also
Nature of 10 October, page 469)
Suspected fossils in other Martian meteorites
The researcher who brought you the "evidence of past Martian biota"
in the famous meteorite ALH84001 from Mars have now found similar
microstructures resembling microfossils in at least one other
stone from Mars. If this is confirmed and the fossils in
both ALH84001 and the other Mars meteorite(s) turn out to be genuine,
the likelyhood of present life on Mars would rise
dramatically. This is because ALH84001 is 4 billions years old,
while the others all date back only some 1.3 billion years. So if
there was (microbial) life on the Read Planet in its infancy and
billions of years later, there would be every reason to believe
that it survived until today.
Dave McKay, who leads the investigation,
had already earlier expressed his belief in the power of Martian
life: Once started, he told the Space News it would always
find warm places to cling on. (CBS [Evening News] 11 October)
Later he somewhat
retracted his comments to CBS and is
now speaking of only "very preliminary evidence" for fossil
evidence in the younger Martian meteorites.[2: 96/10/15]
Briefly noted:
Solar eclipse major success: Many European countries
enjoyed their best partial solar eclipse in years, and public
observatories had a field day with 1000's of visitors. But the
media coverage of the eclipse was also a bleak reminder of the
staggering incompetence of average news people to deal with
astronomical events: The "recommendations" for safe observations
given by various German TV stations ranged from the bizarre to the
outright dangerous...
Mass of the Galactic Center nailed down: The clever use
of modern speckle imaging techniques in the near infrared has
finally allowed the measurement of proper stellar motions in the
vicinity of Sgr A*, the mysterious central object of our galaxy.
Combined with radial velocity measurements it is now clear that
the stars are on simple Keplerian orbits around a central
point mass of 2.5 +/- 0.4 million solar masses. The likelyhood that
Sgr A* is a massive black hole has thus increased, though the high
mass alone is not a definitive proof. (Nature 3 October,
page 415-7)
Update #1.3 of Oct. 10, 1996 19:00 UTC
Physics Nobel Prize with Cosmological Implications
This year's Nobel Prize in Physics for the discovery of superfluid
helium, i.e. events at extremely low temperatures in the laboratory,
is nonetheless something astronomers should take note of: There
are parallels to events which may have taken place in the
very early Universe and led to the formation of topological
defects such as cosmic strings. Find out more anout the Nobel Prize
in Physics 1996 from The Official Announcement
of the Swedish Academy, Lots of Pages
from the Cornell University, or A detailled directory
of physics laureates.
Anti-gravity engine working, held under wraps?
Apparently a Finnish experimental paper that describes a magnetic
engine which reduces the weight of everthing placed above it by 2%
was first accepted for publication by the prestigious Journal of
Physics D - and then withdrawn. Now everybody is wondering: Was
"Podkletnov's antigravity device" a joke from the beginning - or
was the paper withdrawn because it actually worked so well that it
was to be patented first? (New Scientist 21 Sept. 1996 7)
Some more notes
on these weird events can be found - albeit on a website from the
science fringe...
Why is there almost no mass beyond the orbit of the planet Neptune?
Even the planet Pluto, thousands of "Kuiper Belt Objects" in the
size range 100 to 400 km, and billions of cometary nuclei don't add
up to more than one earth mass - while some 50 earth masses might be
expected in the range 50 to 75 astronomical units beyond Neptune's
orbit. That there is so little mass in the range 30 - 50 AU is
easy to understand, given the strong gravitational influence of
Neptune. But beyond 50 AU observational data are pretty scarce and
any planet even of substantial size (comparable to Pluto or even
Mars) would be well hidden in the "twilight zone" - and could
nonetheless be discovered within the next few years, thanks to
advances in widefield imaging. (Talk by A. Stern, SWRI, in Bonn,
Germany, on Oct. 10, 1996)
Deep Partial Solar Eclipse coming to Europe!
The deepest partial eclipse of the sun (not a total one, unfortunately)
can be seen all over Europe on the afternoon of Saturday, Oct. 12th -
and the weather forecast, at least for Germany, is excellent. Detailled
information plus live pictures of the eclipse will be available from
the Society for Popular Astronomy
in the U.K., while the European Southern Observatory
has thought about didactial experiments the eclipse could be used for.
And there is always Sky & Telescope.
Briefly noted:
Still no Galileo images from the Ganymede-2 encounter more
than a month ago have been released by the JPL - it's about time!
Keep your watch on The Galileo Homepage
for any new developments.
Two comets of 5th magnitude can be seen in the sky, Hale-Bopp
in the evening at 5.2 to 5.6 mag (falling more and more behind even
conservative predictions...), and Tabur all night long in UMa at
5.0 to 5.6 mag (all estimates from Oct. 7 til 9th). Both comets have
faint tails: Follow their development in the sky and
on a special page
for comet observations.
Big planet conference ahead: The 28th Annual Meeting of
the Division for Planetary Sciences of the American Astronomical
Society will take place in Tucson, AZ, from Oct. 23-26 - expect
several important announcements (which I already have, but which are
embargoed until the 23rd - sorry). Abstracts are
available.
If technology permits, The Cosmic
Mirror will 'broadcast' live from the conference.
Compiled and written by
Daniel Fischer (send me a
mail to
[email protected]!),
Skyweek
