SETI bioastro: FW: SPA ENB No.76

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From: Larry Klaes (larry.klaes@incent.com)
Date: Mon Jun 11 2001 - 14:37:22 PDT


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From: SPA Electronic News Bulletin [mailto:SPAstronomy@aol.com]
Sent: Sunday, June 10, 2001 9:40 AM
To: List Member
Subject: SPA ENB No.76

SPA Electronic News Bulletin - http://www.popastro.com

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The SOCIETY for POPULAR ASTRONOMY
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Electronic News Bulletin
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Issue No 76 2001, June 10th

NO METEORS FROM COMET SW3 - YET

By Alastair McBeath, SPA Meteor Section Director

Alerts in late May suggested meteor activity might be seen associated with
the Earth's closest pass to the orbit of Comet 73P/Schwassmann-Wachmann 3
(SW3) on May 29-30. The comet's current orbital period is around 5.3
years, and its perihelion distance is roughly 1 astronomical unit (a.u.;
the Earth's mean distance from the Sun). At its 1995 return, SW3 underwent
a massive disruption, and broke up into at least four main pieces,
liberating huge amounts of gas and dust. Three active SW3 fragments were
recovered at the comet's late 2000 return. Calculations showed the Earth
would miss the dust trail laid down by the comet in 1941 by 0.0026 a.u. at
~ 10h UT on 2001 May 30.

This is quite a large distance in meteoric terms. For instance, the 1999
Leonid storm occurred with a miss distance of just 0.00066 a.u. between
the Leonid stream and Earth's orbit, so the chances for any significant
SW3 meteor rates were not ideal, but needed to be checked-for. The
proposed radiant was in western Bootes, about 5 to 6 degrees south-west of
the stars Rho and Sigma Bootis, and the meteors were expected to be
extremely slow. Observations submitted to the International Meteor
Organization (IMO) by May 31 showed no activity had been detected at all
this year. However, an article in the February-April issue of the IMO's
journal "WGN" indicates other potential SW3-associated showers might
happen in 2011, 2017 and, most interestingly of all, 2022, when the Earth
will pass just 0.0004 a.u. from the trail laid down in 1995, the year the
comet broke up! For more details, see the IMO's Website:
http://www.imo.net.

METEOR ACTIVITY FOR MID JUNE 2001

By Alastair McBeath, SPA Meteor Section Director

June's waning crescent Moon should allow checking for any possible June
Lyrids between June 11-21, perhaps at maximum on June 16. Their radiant on
June 16 should be near Vega, at RA 18h32m, Dec +35 degrees, and low rates
of slow-medium speed meteors may be seen. The clearest and best-confirmed
June Lyrid return was in 1969, when British observers made a significant
contribution to the data-pool, despite the all-night twilight. Zenithal
Hourly Rates (ZHRs) then reached 9-10 at best, although subsequent returns
produced lower activity, which dwindled to nothing significant by the late
1970s. Independent reports of weak activity by several observers were last
made in 1996, though nothing was seen from them in moonless skies in 1999.
The source may not be active every year, however.

The minor Sagittarid showers continue throughout June, producing very low
activity now, with ZHRs of ~ 1-3, barely detectable, perhaps rising to a
still-meagre ~ 4 in a final "peak" towards the end of the month. By then,
the Moon will be becoming a nuisance again. Numerous individual radiants
in Ophiuchus, Serpens, Sagittarius and Scorpius have been proposed, but we
recommend visual observers should treat this source as having a single,
very large, diffuse radiant two hours across in RA by 20 degrees in Dec,
centred at RA 18h00m, Dec -23 degrees on June 15, roughly 30m in RA and 3
degrees in Dec north-east of Mars.

Remember to send copies of all your meteor watch observations to the SPA
Meteor Section for analysis. Details of what to report and where to send
your sightings can be found on the Meteor Section pages of the SPA's
Website at http://www.popastro.com. Good luck, and clear skies!

BRIGHT COMET IN MORNING SKY

Comet C/2001 A2 (LINEAR) will be making an appearance in the pre-dawn sky
during the next couple of weeks. Observers in the UK will have to wait
until the end of the month before it becomes high enough to be observed.

  2001 TT R. A. (2000) Decl. Delta r Elong. Phase m1

      14 3 37.87 -25 40.3 0.334 0.873 55.9 105.7 4.0

     16 3 21.13 -24 32.8 0.315 0.891 58.2 104.2 4.0

     18 3 03.04 -23 05.2 0.299 0.910 61.1 102.2 4.0

     20 2 43.65 -21 15.6 0.284 0.930 64.5 99.6 4.0

     22 2 23.02 -19 02.7 0.271 0.951 68.4 96.3 3.9

     24 2 01.30 -16 26.3 0.260 0.972 72.9 92.3 4.0

     26 1 38.70 -13 27.9 0.252 0.994 77.9 87.8 4.0

     28 1 15.52 -10 11.2 0.246 1.017 83.3 82.8 4.0

     30 0 52.10 - 6 42.0 0.244 1.041 89.0 77.5 4.1

 NASA APPROVES COMET MISSION

 NASA has approved the development of a robotic spacecraft mission that
will attempt to use a probe to collide with a comet in an attempt to peer
beneath its surface. Scheduled for launch in January 2004, the unique
spacecraft is expected to arrive at comet Tempel 1 in July 2005. In a
space-exploration first, NASA's Deep Impact Mission researchers hope the
impact will allow them to measure freshly exposed material and study
samples hidden deep below the surface of the comet, which could yield
dramatic scientific breakthroughs. NASA's Discovery Program emphasizes
lower-cost, highly focused scientific missions within the Space Science
enterprise. NASA has developed six other Discovery Program missions.
Three have completed their missions, one is operational and two others, in
addition to Deep Impact, are under development:

 * In 1997, the Mars Pathfinder lander, carrying a small robotic rover
named Sojourner, landed successfully on Mars and returned hundreds of
images and thousands of measurements of the Martian environment.

 * The Near Earth Asteroid Rendezvous (NEAR) spacecraft orbited the
asteroid Eros for a year, ending with a successful landing on 2001
February 12.

 * The Lunar Prospector orbiter mapped the Moon's composition and gravity
field and completed its highly successful mission in July 1999.

 * The Stardust mission to gather samples of comet dust and return them to
Earth was launched in 1999 February, and is on its way to comet Wild-2.

 * The Genesis mission to gather samples of the solar wind and return them
to Earth is scheduled for launch on 2001 July 30.

 MARS SAMPLES QUARANTINE PLANS

A report by the National Research Council's Committee on Planetary and
Lunar Exploration (COMPLEX), urges NASA to begin planning a system to
quarantine Martian samples even though missions to return such samples are
at least a decade in the future. The report "The Quarantine and
Certification of Mars Samples", expanded on a 1997 report that recommended
creating a quarantine system to protect from the chance, however small,
that Martian organisms could infect the Earth.

BROWN DWARFS MAY HAVE PLANETS

  The cool, dim cosmic objects known as brown dwarfs form more like stars
than planets, and might even have planets of their own, astronomers have
reported. Brown dwarfs have variously been called failed stars and super
planets, but an international team of astronomers has detected a tell-tale
sign of a star-like accessory: dusty disks circling about 60 brown dwarfs
in the Orion Nebula. Dust disks are the precursors to planetary systems
when they surround stars like our Sun, with rocky planets coming together
as dust particles in the disk collide and stick. The same thing might
occur around brown dwarfs, the scientists reported.

QUASAR CAUGHT IN THE ACT

 A new image of a distant quasar shows that it is engaged in a
gravitational battle with its neighbouring galaxies. It also provides
information on how supermassive black holes thought to be present in the
centres of quasars are fed. Using the FORS2 multi-mode instrument at the
ESO 8.2-m VLT KUEYEN telescope on Paranal (Chile), a team of German
astronomers obtained a spectacular image of the close and complex
environment of the distant quasar "HE 1013-2136", located some 10 billion
light-years away. The remarkable structures revealed in the photo lend
support to the hypothesis that quasar activity is connected to
gravitational interaction between galaxies, already at that early epoch of
the Universe (about 5 billion years after the Big Bang).

 MARS COLONISTS

 The first colonists on Mars probably won't be humans. More likely,
they'll be plants, and the prototypes of these leafy pioneers are under
development right now. As part of a proposed mission that could put
plants on Mars as soon as 2007, University of Florida professor Rob Ferl
is bio-engineering tiny mustard plants. He's not altering these plants so
that they can adapt more easily to Martian conditions. Instead, he's
adding reporter genes: part plant, part glowing jellyfish -- so that these
diminutive explorers can send messages back to Earth about how they are
faring on another planet.

 GALAXY SURVEY

Redshift data and spectra from the first 100,000 galaxies measured by the
2dF (Two-degree-Field) Galaxy Redshift Survey have been released to the
world astronomical community. Thirty-two researchers from 13 institutions
have been carrying out the survey with the Anglo-Australian Telescope near
Coonabarabran in eastern Australia. They have now netted more than 175,000
redshifts and will reach the survey target of 250,000 by the end of 2001.
Redshift data can be converted to positions in space and so the survey has
created the most comprehensive three-dimensional map of the local Universe
yet made.

As well as providing by far the largest available set of galaxy spectra
for mapping the Universe, the 2dFGRS database is a gold-mine of
interesting and unusual objects. The 2dF dataset is a free gift of
100,000 redshifts to astronomers world-wide. They can apply it
immediately to improving our understanding of galaxy evolution and the
structure of the Universe. For many rare types of objects, we need to
have large samples before we can understand the objects' properties and
how they are related to their environments.

For instance, radio telescopes are extremely good at detecting extremely
powerful, 'active' galaxies in the very distant universe. But to
understand how those galaxies evolve over time, we need also a large
sample of such galaxies nearby. That can only be achieved with an optical
telescope. Cross-matching the 2dF survey data with large-area radio
surveys will give a sample of up to 4,000 radio-emitting galaxies in the
local Universe. The 2dF survey covers a total area of about 2,000 square
degrees, selected from both northern and southern skies.

EXTRASOLAR ASTEROID BELT

 Astronomers at UCLA have found evidence for what could be a belt of
asteroids forming around the star Zeta Leporis. The presence of a dust
disk of some kind around the star had been known since 1983, when it was
detected by the Infrared Astronomy Satellite (IRAS). Follow-up
observations ten years ago found that the disk was unusually warm,
suggesting that either the disk was closer to its parent star than
expected or that some other energy source was generating infrared
radiation.

 They were able to estimate the temperature of the disk by observing it at
two different wavelengths. They found the average temperature of the disk
to be about 70 degrees Celsius, which they consider to be a relatively
high temperature: it would mean that particles in the disk could be as
close as 2.5 AU (375 million kilometres) to the star. The size and
temperature observations can be best explained, the astronomers said, if
the disk was composed not just of dust grains but of larger objects, like
asteroids or even protoplanets. There must be objects larger than dust
around Zeta Lep, which may resemble asteroids in our own solar system,
that are creating the infrared-emitting dust by violently colliding with
each other.

 If confirmed, this discovery would mark the first time an asteroid belt
was discovered around another star. Astronomers have detected several
dozen extrasolar planets and many protoplanetary disks of dust, but had
yet to find evidence of intermediate-sized bodies like asteroids. Zeta
Leporis may not be the most hospitable locale in the galaxy, though. The
young star -- about 100 million years old -- is about twice the mass of
the Sun and 20 times as bright. It is about 70 light-years from the Earth.

 BLACK HOLES IN STAR FORMING GALAXIES

NASA's Chandra X-ray Observatory has found new populations of suspected
mid-mass black holes in several starburst galaxies, where stars form and
explode at an unusually high rate. Although a few such objects had been
found previously, this is the first time they have been detected in such
large numbers and could help explain their relationship to star formation
and the production of even more massive black holes. The X-ray objects
appear point-like and are ten to a thousand times more luminous in X-rays
than similar sources found in our Milky Way and the M81 galaxy.

Kimberly Weaver, of NASA's Goddard Space Flight Center, lead scientist of
the team that studied the starburst galaxy NGC 253, discussed the
importance of the unusual concentration of very luminous X-ray sources
near the centre of that galaxy. Four sources, which are tens to thousands
of times more massive than the Sun, are located within 3,000 light years
of the galaxy core. "This may imply that these black holes are
gravitating toward the centre of the galaxy where they could coalesce to
form a single supermassive black hole," Weaver suggested. "It could be
that this starburst galaxy is transforming itself into a quasar-like
galaxy as we watch. In NGC 253, Chandra may have found the causal
connection between starburst activity and quasars."

 MOST DISTANT OBJECTS

 Astronomers have detected the most distant objects ever observed -- two
quasars billions of light-years from Earth -- as part of a five-year
international plan to make a digital map of the universe. The quasars,
celestial objects believed to be among the universe's oldest and
brightest, were found by scientists working on the Sloan Digital Sky
Survey. The faraway quasars could now be as much as 80 billion
light-years away, according to Donald York of the University of Chicago,
one of the key researchers on the project.

 That may seem hard to fathom, because astronomers believe the universe
itself is only about 10 billion to 20 billion years old. But light from
the record-breaking quasars started its journey toward Earth when the
universe was about 800 million years old and about one-seventh the size it
is now. "The light you're seeing from those objects actually left the
objects when they were much closer to Earth," York said in an interview.
Using current theories about how fast the universe is expanding, he gave
his estimate of 80 billion light-years for the quasars' distance. The two
quasars break records for distance set by earlier readings from the Sloan
survey, and more records are expected to fall as research continues.
Scientists want to capture data on 100,000 quasars for the universe map,
and have so far discovered more than 13,000.

 MERCURY MISSION

NASA has given the first Mercury orbiter mission the go-ahead to move into
full-scale spacecraft development -- setting up the first trip to the
Sun's closest neighbour in more than a generation. MESSENGER, short for
MErcury Surface, Space ENvironment, GEochemistry, and Ranging, will launch
in March 2004 and orbit Mercury for one Earth-year beginning in April
2009.

 PLUTO MISSION

NASA has selected two proposals for possible fly-by missions to Pluto,
keeping alive the possibility it will launch a spacecraft to the
yet-unexplored planet. The National Aeronautics and Space Administration
scrapped plans for a Pluto mission last year when the cost soared to $1.5
billion from $650 million. That decision angered scientists and led NASA
to seek proposals for innovative ways to explore the planet at about
one-third that cost. The two proposals detail missions that would launch
by 2006 and fly by the distant planet by 2020. NASA may select one for
development if funding becomes available.

 PIONEER 10

The Geiger Tube Telescope instrument data have been analysed from NASA's
Pioneer 10 space probe. James Van Allen reports that the successful DSS63
reception total of two hours of clean data from the GTT instrument from
the 28 April and 19 May tracks. The cosmic ray intensity has continued to
decrease since 6 August 2000 and is now 77 percent of its maximum value in
late 1998-early 1999.

Hence, Pioneer 10 at ~78 AU is still under the delayed influence of solar
activity and has not yet reached the cosmic ray modulation boundary of the
heliosphere. At GMT 17:27:30, Saturday, 4/28/01, the signal from Pioneer
10 was received at station 63 in Madrid, the first time since August 5/6
of last year. So it appears that Pioneer 10 has life, albeit in another
mode - i.e., only in a two-way coherent mode.

We have been listening for the Pioneer 10 signal in a one way downlink
non-coherent transmission mode since last summer with no success. We
therefore conclude that in order [for Pioneer 10] to talk to us, we need
to talk to it. This means from now on, we need two-way round-trip light
time (RTLT) passes to allow the Deep Space Network (DSN) to send up a
strong stable signal to lock up with a coherent downlink signal.

After the last attempted pointing manoeuvre in July of last year, the
operations centre lost the capability to command the spacecraft. Our
command capability has now been re-established. We can now repoint the
spacecraft towards Earth when that becomes necessary. Pioneer 10
distance from Sun: 77.86 AU. Speed relative to the Sun: 12.24 km/sec
(27,380 mph). Distance from Earth: 11.81 billion kilometres (7.34 billion
miles). Round-trip Light Time: 21 hours 52 minutes

 Bulletin compiled by Clive Down

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(c) 2001 the Society for Popular Astronomy

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