PLEASE NOTE:
*
CCNet, 33/2003 - 21 March 2003
-------------------------------
Historical records of solar activity indicate that solar
radiation has been increasing
since the late 19th century. If a trend, comparable to the one
found in this study,
persisted throughout the 20th century, it would have provided a
significant component of
the global warming the Intergovernmental Panel on Climate Change
reports to have occurred
over the past 100 years."
--Richard Willson, NASA Goddard Institute for Space Studies
"Fear and hope are the two great motivators of human action,
and neither untempered by the other leads to wise
decision-making. Paralysis by unreasonable fear is as much to be
avoided as the foolhardiness induced by groundless hope; but, of
the two, fear is the more easily generated. It is certainly more
common nowadays than unbounded optimism."
--The Spectator, 22 March 2003
(1) NASA STUDY FINDS INCREASING SOLAR TREND THAT CAN CHANGE
CLIMATE
NASANews@hq.nasa.gov
(2) SUN'S OUTPUT INCREASING IN POSSIBLE TREND FUELING GLOBAL
WARMING
Space.com, 20 March 2003
(3) POSSIBLE BOLIDE SPOTTED OVER NEW ZEALAND
Stuff.com, 21 March 2003
(4) ONE MARTIAN METEORITE PER MONTH: 100 MILLION YEARS TO ARRIVE
ON EARTH
NEO Information Centre, 20 March 2003
(5) ESA'S ROSETTA MISSION: THREE OPTIONS, TWO COMETS
ESA, 21 March 2003
(6) GETTING TO DAWN
SpaceDaily, 19 March 2003
(7) ASTEROID/COMET EMERGENCY (ACE) MAGNITUDE SCALE PROGRESS
Andy Smith <astrosafe22000@yahoo.com>
(8) AND FINALLY: WAR, FEAR AND RISK ANALYSIS
The Spectator, 21 March 2003
========
(1) NASA STUDY FINDS INCREASING SOLAR TREND THAT CAN CHANGE
CLIMATE
>From NASANews@hq.nasa.gov
Elvia H. Thompson
Headquarters,
Washington
March 20, 2003
(Phone: 202/358-1696)
Krishna Ramanujan
Goddard Space Flight Center, Greenbelt, Md.
(Phone: 301/286-3026)
RELEASE: 03-106
NASA STUDY FINDS INCREASING SOLAR TREND THAT CAN CHANGE CLIMATE
Since the late 1970s, the amount of solar radiation the sun
emits, during times of quiet sunspot activity, has increased by
nearly .05 percent per decade, according to a NASA funded study.
"This trend is important because, if sustained over many
decades, it could cause significant climate change," said
Richard Willson, a researcher affiliated with NASA's Goddard
Institute for Space Studies and Columbia University's Earth
Institute, New York. He is the lead author of the study recently
published in Geophysical Research Letters.
"Historical records of solar activity indicate that solar
radiation has been increasing since the late 19th century. If a
trend, comparable to the one found in this study, persisted
throughout the 20th century, it would have provided a significant
component of the global warming the Intergovernmental Panel on
Climate Change reports to have occurred over the past 100
years," he said.
NASA's Earth Science Enterprise funded this research as part of
its mission to understand and protect our home planet by studying
the primary causes of climate variability, including trends in
solar radiation that may be a factor in global climate change.
The solar cycle occurs approximately every 11 years when the sun
undergoes a period of increased magnetic and sunspot activity
called the "solar maximum," followed by a quiet period
called the "solar minimum."
Although the inferred increase of solar irradiance in 24 years,
about 0.1 percent, is not enough to cause notable climate change,
the trend would be important if maintained for a century or more.
Satellite observations of total solar irradiance have obtained a
long enough record (over 24 years) to begin looking for this
effect.
Total Solar Irradiance (TSI) is the radiant energy received by
the Earth from the sun, over all wavelengths, outside the
atmosphere. TSI interaction with the Earth's atmosphere, oceans
and landmasses is the biggest factor determining our climate. To
put it into perspective, decreases in TSI of 0.2 percent occur
during the weeklong passage of large sunspot groups across our
side of the sun. These changes are relatively insignificant
compared to the sun's total output of energy, yet equivalent to
all the energy that mankind uses in a year. According to Willson,
small variations, like the one found in this study, if sustained
over many decades, could have significant climate effects.
In order to investigate the possibility of a solar trend, Willson
needed to put together a long-term dataset of the sun's total
output. Six overlapping satellite experiments have monitored TSI
since late 1978. The first record came from the National Oceanic
and Atmospheric Administration's
(NOAA) Nimbus7 Earth Radiation Budget (ERB) experiment (1978 -
1993). Other records came from NASA's Active Cavity Radiometer
Irradiance Monitors: ACRIM1 on the Solar Maximum Mission (1980 -
1989), ACRIM2 on the Upper Atmosphere Research Satellite (1991 -
2001) and ACRIM3 on the ACRIMSAT satellite (2000 to present).
Also, NASA launched its own Earth Radiation Budget Experiment on
its Earth Radiation Budget Satellite (ERBS) in 1984. The European
Space Agency's (ESA) SOHO/VIRGO experiment also provided an
independent data set (1996 to 1998).
In this study, Willson, who is also Principal Investigator of
NASA's ACRIM experiments, compiled a TSI record of over 24 years
by carefully piecing together the overlapping records. In order
to construct a long-term dataset, he needed to bridge a two-year
gap (1989 to 1991) between
ACRIM1 and ACRIM2. Both the Nimbus7/ERB and ERBS measurements
overlapped the ACRIM 'gap.' Using Nimbus7/ERB results produced a
0.05 percent per decade upward trend between solar minima, while
ERBS results produced no trend. Until this study, the cause of
this difference, and hence the validity of the TSI trend, was
uncertain. Willson has identified specific errors in the ERBS
data responsible for the difference. The accurate long-term
dataset, therefore, shows a significant positive trend (.05
percent per decade) in TSI between the solar minima of solar
cycles 21 to 23 (1978 to present). This major finding may help
climatologists to distinguish between solar and man-made
influences on climate.
NASA's ACRIMSAT/ACRIM3 experiment began in 2000 and will extend
the long-term solar observations into the future for at least a
five-year minimum mission.
For more information on the Internet, visit:
http://www.gsfc.nasa.gov/topstory/2003/0313irradiance.html
For more information about ACRIM on the Internet, visit:
http://www.acrim.com
===========
(2) SUN'S OUTPUT INCREASING IN POSSIBLE TREND FUELING GLOBAL
WARMING
>From Space.com, 20 March 2003
http://www.space.com/scienceastronomy/sun_output_030320.html
By Robert Roy Britt
In what could be the simplest explanation for one component of
global warming, a new study shows the Sun's radiation has
increased by .05 percent per decade since the late 1970s.
The increase would only be significant to Earth's climate if it
has been going on for a century or more, said study leader
Richard Willson, a Columbia University researcher also affiliated
with NASA's Goddard Institute for Space Studies.
The Sun's increasing output has only been monitored with
precision since satellite technology allowed necessary
observations. Willson is not sure if the trend extends further
back in time, but other studies suggest it does.
The recent trend of a .05 percent per decade increase in Total
Solar Irradiance (TSI) in watts per meter squared, or the amount
of solar energy that falls upon a square meter outside the
Earth's atmosphere. The trend was measured between successive
solar minima that occur approximately every 11 years. At the
bottom, the timeline of the many different datasets that
contributed to this finding, from 1978 to present.
"This trend is important because, if sustained over many
decades, it could cause significant climate change," Willson
said.
In a NASA-funded study recently published in Geophysical Research
Letters, Willson and his colleagues speculate on the possible
history of the trend based on data collected in the pre-satellite
era.
"Solar activity has apparently been going upward for a
century or more," Willson told SPACE.com today.
Significant component
Further satellite observations may eventually show the trend to
be short-term. But if the change has indeed persisted at the
present rate through the 20th Century, "it would have
provided a significant component of the global warming the
Intergovernmental Panel on Climate Change reports to have
occurred over the past 100 years," he said.
That does not mean industrial pollution has not been a
significant factor, Willson cautioned.
Scientists, industry leaders and environmentalists have argued
for years whether humans have contributed to global warming, and
to what extent. The average surface temperature around the globe
has risen by about 1 degree Fahrenheit since 1880. Some
scientists say the increase could be part of natural climate
cycles. Others argue that greenhouse gases produced by
automobiles and industry are largely to blame.
Willson said the Sun's possible influence has been largely
ignored because it is so difficult to quantify over long periods.
Confounding efforts to determine the Sun's role is the fact that
its energy output waxes and wanes every 11 years. This solar
cycle, as it is called, reached maximum in the middle of 2000 and
achieved a second peak in 2002. It is now ramping down toward a
solar minimum that will arrive in about three years.
Connections
Changes in the solar cycle -- and solar output -- are known to
cause short-term climate change on Earth. At solar max, Earth's
thin upper atmosphere can see a doubling of temperature. It
swells, and denser air can puff up to the region of space where
the International Space Station orbits, causing increased drag on
the ship and forcing more frequent boosts from space shuttles.
Changing Sun
Solar max has also been tied to a 2 percent increase in clouds
over much of the United States.
It might seem logical to assume tie climate to solar output, but
firm connections are few. Other studies looking further back in
time have suggested a connection between longer variations in
solar activity and temperatures on Earth.
Examinations of ancient tree rings and other data show
temperatures declined starting in the 13th Century, bottomed out
at 2 degrees below the long-term average during the 17th Century,
and did not climb back to previous levels until the late 19th
Century. Separate records of sunspots, auroral activity (the
Northern Lights) and terrestrial deposits of certain substances
generated in atmospheric reactions triggered by solar output,
suggest the Sun was persistently active prior to the onset of
this Little Ice Age, as scientists call the event.
Solar activity was lowest during the 17th Century, when Earth was
most frigid.
Large-scale ocean and climate variations on Earth can also mask
long-term trends and can make it difficult to sort out what is
normal, what is unusual, and which effects might or might not
result from shifts in solar radiation.
To get above all this, scientists rely on measurements of total
solar energy, at all wavelengths, outside Earth's atmosphere. The
figure they derive is called Total Solar Irradiance (TSI).
Heating up
The new study shows that the TSI has increased by about 0.1
percent over 24 years. That is not enough to cause notable
climate change, Willson and his colleagues say, unless the rate
of change were maintained for a century or more.
On time scales as short as several days, the TSI can vary by 0.2
percent due to the number and size of sunspots crossing the face
of the Sun. That shift, said to be insignificant to weather, is
however equal to the total amount of energy used by humans,
globally, for a year, the researchers estimate.
The study analyzed data from six satellites orbiting Earth at
different times over the 24 years. Willson ferreted out errors in
one of the datasets that had prevented previous studies from
discovering the trend.
A separate recent study of Sun-induced magnetic activity near
Earth, going back to 1868, provides compelling evidence that the
Sun's current increase in output goes back more than a century,
Willson said.
He said firm conclusions about whether the present changes
involve a long-term trend or a relatively brief aberration should
come with continued monitoring into the next solar minimum,
expected around 2006.
Copyright 2003, Space.com
============
(3) POSSIBLE BOLIDE SPOTTED OVER NEW ZEALAND
>From Stuff.com, 21 March 2003
http://www.stuff.co.nz/stuff/0,2106,2346810a11,00.html
Space junk or big meteor? Whatever it was, the big, bright light
that hurtled northward over an area from Nelson to Palmerston
North in the early morning light of Wednesday was according to
witnesses "really honking".
Fifteen sightings were reported to the Carter Observatory and
astronomer Brian Carter said the object was probably man-made
space junk.
But Noel Munford, of the Manawatu Astronomical Society, said the
international astronomical website that reliably tracks bigger
pieces of space debris had given no warning of a significant
object coming in.
Witnesses had reported the object was travelling at great speed
across the sky and did not break up, as space debris usually did.
That suggested the object was a "bolide" - a meteor far
bigger that the usual pea- or pebble-sized "shooting
star". And it might have disappeared because it came in at a
low angle and skimmed off the upper atmosphere back into space.
============
(4) ONE MARTIAN METEORITE PER MONTH: 100 MILLION YEARS TO ARRIVE
ON EARTH
>From NEO Information Centre, 20 March 2003
http://www.nearearthobjects.co.uk/news_display.cfm?code=news_intro&itemID=164
Today at the Lunar and Planetary Science Conference in Houston Dr
Jim Head presented new results to suggest that about one rock
from Mars falls on Earth each month. Head's work involves
calculating exactly how often asteroids and comets impact with
the planet Mars and how many martian rocks these collisions blast
up into space. He then models the paths of these little fragments
of the red planet, under the influence of the combined gravity of
the planets and Sun to see how many and how often such martian
meteorites fall to Earth.
The results of the new research suggest that martian meteorites
come from craters larger than 3 km on the red planet and take up
to 100 million years to make the 45 million kilometre journey to
the Earth. Head's work implies that the currently known martian
meteorites, of which there are just over 20, come from around 6
craters on the martian surface and so some are samples of closely
related rocks that can give additional clues to the geological
history of the red planet.
Martian meteorites are our only samples of another planet and
they provide us with the opportunity of to investigate how
planets form and evolve in general. It is only because of the
collision of asteroids and comets with Mars, every few hundred
thousand years, that we can study the red planet in such detail.
============
(5) ESA'S ROSETTA MISSION: THREE OPTIONS, TWO COMETS
>From ESA, 21 March 2003
http://sci.esa.int/content/news/index.cfm?aid=13&cid=36&oid=32001
ESA INFO 06-2003. Following the decision not to launch Europe's
comet chaser Rosetta in January, scientists and engineers in the
programme have been examining several alternative mission
scenarios.
Each has been looked at on the basis of the expected scientific
return, the technical risks related to using the Rosetta design
in the new mission, and the containment of costs. Of the nine
mission scenarios studied by the Rosetta Science Working Team,
three have survived to this point and were presented to the
delegations of the ESA Member States through the Science
Programme Committee at its meeting on 25/26 February. Two mission
scenarios (in February 2004 and 2005 respectively) would take
Rosetta to a new target comet, Churyumov-Gerasimenko, while
another (in January 2004) would take it to its original target,
Comet Wirtanen.
All three options are now being studied in detail so that the
final decision can be made. A campaign of observations using both
the NASA/ESA Hubble Space Telescope and the instruments of the
European Southern Observatory is under way to study Comet
Churyumov-Gerasimenko. In this way, astronomers will be able to
characterise the comet and perform a mission analysis, also to
identify landing scenarios and make a thorough assessment of any
hardware modification that would be necessary.
In parallel, ESA is assessing the launch requirements for the
various mission scenarios. This will include looking at
alternatives to Ariane as back-up options, such as the Russian
Proton rocket.
The final decision on Rosetta's new mission scenario will be made
by the ESA Science Programme Committee in May.
Note to editors
Following the failure of Ariane Flight 157 in December with the
loss of two spacecraft, ESA and Arianespace took the joint
decision not to launch Rosetta during its January launch window.
This meant that Rosetta's originally intended mission to Comet
Wirtanen had to be abandoned.
For more information please contact:
ESA Communication Department
Media Relations Service, Paris, France
Tel: +33(0)15369 7155
Fax: +33(0)1 5369 7690
============
(6) GETTING TO DAWN
>From SpaceDaily, 19 March 2003
http://www.spacedaily.com/news/dawn-03a2.html
by Marc D. Rayman
Dawn Project Engineering Team
Jet Propulsion Laboratory
Pasadena - Mar 19, 2003
The design of Dawn's trajectory is difficult, unusual, and
interesting because of the use of solar electric propulsion,
implemented on Dawn as an ion propulsion system (IPS).
While providing performance far in excess of what conventional
chemical propulsion would deliver, the IPS necessitates the use
of design tools and methods quite different from what has been
used for the development of trajectories since the dawn of the
solar system (or, at least, since the dawn of space exploration).
Rather than finding a few points at which impulsive maneuvers are
required, this problem involves the determination of IPS thrust
vectors over years of continuous thrusting.
Unlike trajectories for ballistic missions, Dawn's depends
sensitively on the spacecraft's power system (because power
translates directly into IPS thrust). The tools that generate the
trajectories require much more coaxing and cajoling (and
sometimes pleading) than the tools that have been used for
conventional missions.
In addition to the different underlying mathematical problem, the
use of the IPS necessitates unfamiliar constraints on the
mission. For example, because IPS thrusting is needed for years
at a time, the mission could be vulnerable to an unexpected loss
of thrust.
Therefore, a substantial effort is devoted to designing a
trajectory with enough "mission margin" that most
spacecraft problems that interfere with IPS thrusting do not
jeopardize reaching both Vesta and Ceres. (Missions relying on
chemical propulsion tend to have greater vulnerability for
shorter times.)
The initial work is focused on obtaining an understanding of the
sensitivity of the trajectory to parameters that we can control.
Ultimately we will develop a baseline trajectory that accounts
for constraints such as the finite launch period, launch window,
Vesta arrival window (to ensure good lighting for framing camera
and mapping spectrometer observations of the south pole), Ceres
arrival window (for lighting at one of the poles), mission
margin, periods in which spacecraft activities preclude thrusting
in the optimal direction, spacecraft power characteristics,
flybys of other asteroids during the interplanetary cruise, and
others.
We separately analyze the orbit insertion, departure, and orbit
transfers at each primary science target, where the complexity of
spiraling around the bodies requires different analytical
techniques.
Steve Williams and Dr. Greg Whiffen of JPL are the principal
trajectory analysts on Dawn. Steve designed the trajectory for
Deep Space 1 (DS1), the mission that tested the IPS design Dawn
uses. Many issues that an operational IPS flight would face were
revealed during that work; prior analyses had rarely, if ever,
exceeded the depth necessary for conceptual studies.
Greg has written a powerful new trajectory design tool that
complements the one used for DS1. With his new software, Greg has
generated our first looks at the Vesta orbit transfers. The first
baseline trajectory will be completed by early April. Although
preliminary, it will be significantly more accurate than previous
calculations.
============================
* LETTERS TO THE MODERATOR *
============================
(7) ASTEROID/COMET EMERGENCY (ACE) MAGNITUDE SCALE PROGRESS
>From Andy Smith <astrosafe22000@yahoo.com>
Hello Benny and CCNet,
This note is to announce that we are expanding our ACE scale to
add objects smaller than Tunguska (ACE#1) and larger than
Hale-Bopp (ACE#10). Our scale is an exponential step-scale, which
doubles the NEO diameter with each increasing step. The log. of
the released destructive impact energy (megatons of TNT) is about
the same as the step number and the log. of the interval between
impacts (years) is approximately the same as the step number plus
one.
The extension, on the low-end of the scale, will go down to
slightly under a meter (ACE#-5). On the high end, it will
increase to an NEO width of about 100 kilometers (ACE#12).
We are also adding comparison scales, to include the Richter
Scale(RS) and the Volcanic Explosivity Index (VEI). All three are
exponential magnitude step-scales. Our pivotal event, the
Tunguska/Arizona/Mt. St. Helens level event (ACE#1) is about
equal to #6.5 on the RS and #5, on the VEI. The level #10 events,
on the other two scales, are about the same as our ACE#6 (impact
of a 1.6 kilometer ball).
We find crater-size a useful basis for comparison, between the
ACE and the VEI.
We are also re-examining the energy level associated with the
ACE#1 event, because the Arizona
(Barringer)crater seems much too large for a 10-20 megaton
explosion. The energy level of this event, we think, may have
been well in excess of 50 megatons.
We still think a short regional winter (like the one associated
with the Tambora volcanic explosion)could result from an ACE#3-#4
impact (200-400 meters) and that the duration and severity would
increase, with increasing NEO size.
Fortunately, most of the NEO threat population is smaller than
ACE#4 (about abs.magnitude 19.5) . It is for this reason, that we
feel the next generation of NEO telescopes is so important and we
are still urging the larger, more advanced available survey
units/teams (like the SLOAN and the NEWTON) to help more, with
the search.
Cheers,
Andy Smith/IPPA
astrosafe22000@yahoo.com
============
(8) AND FINALLY: WAR, FEAR AND RISK ANALYSIS
>From The Spectator, 21 March 2003
http://www.spectator.co.uk/article.php3?table=old§ion=current&issue=2003-03-22&id=2912
Fear and hope are the two great motivators of human action, and
neither untempered by the other leads to wise decision-making.
Paralysis by unreasonable fear is as much to be avoided as the
foolhardiness induced by groundless hope; but, of the two, fear
is the more easily generated. It is certainly more common
nowadays than unbounded optimism.
How easily unfounded fear is provoked has been demonstrated this
week by the appearance of a new disease in China of unknown
causation. No sooner had nine people died of it, out of a global
population of six billion, than the end of the world, or at least
of humanity, was deemed in certain quarters to be nigh: and this
despite the fact that the great majority of the people who have
contracted the disease have survived it, not died from it.
Nothing is easier to conjure up from the unknowability of the
future than panic. There is no difficulty in imagining the most
terrible of consequences from the most banal of actions, let
alone from genuinely dangerous ones. Certain minds take pleasure
in predicting apocalypses, and the failure of the last predicted
apocalypse to make its appearance at the duly appointed time
never reduces the certainty with which the next apocalypse is
envisioned.
Because the future is inherently unknowable, and because dramatic
predictions are so much more vivid in our minds than undramatic
ones, the Cassandras of the world enjoy a certain natural
advantage, which has nothing to do with their accuracy or
clairvoyance. A book predicting disaster will always sell more
than one which predicts that the world will continue in its
chronically unsatisfactory but nevertheless survivable way.
This should be borne in mind when the possible consequences of
the war with Iraq are discussed. The person who says that it will
result in eternal enmity between the Middle East and the West,
and in ever more terrorism directed at Western cities, will be
paid more attention than one who predicts less fraught
consequences, simply because what the former says is more
arresting. Our desire to be entertained is generally greater than
our thirst for truth; and apocalypses are nothing if not
entertaining.
Eventually, decisions have to be made and risks taken. The risks
involved in making war on Iraq are now slight because the armed
forces arrayed against it are so formidable. Moreover, it is
unlikely that many Iraqis will wish to go to their deaths to
fight for Saddam Hussein and his small clique of thugs. No one
can be absolutely sure of this, of course, and perhaps Iraqi
civilians will turn out to be ferocious urban guerrillas. But if
we seriously entertained such outside possibilities in our daily
lives, we would make Hamlet seem impulsive and unreflective.
As for the undying enmity that making war on Iraq will supposedly
generate, it assumes not only that, uniquely among large
populations of human beings, unanimity of opinion exists in the
Middle East, but also that those in the Middle East who do indeed
hate us will hate us less than they do if we refrain from making
war on Iraq. This is highly doubtful, to say the least; it
assumes that we are hated for what we do rather than for what we
are and what we represent. A withdrawal from war would not now
make us more loved, or even less hated; it would simply make us
ridiculous.
For every fearful vision of the future, there is an equal and
opposite fearful vision. The epidemic in China could, if it
evoked an exaggerated response, bring about a collapse in world
trade, as China and South-east Asia were sealed off or
quarantined from the rest of the world. If Saddam were not
checked now, his successful defiance of the most powerful country
in the world would set an example for many aspiring regional
despots to follow, and in the end would result in many small
nuclear wars.
One of the problems with pre-emptive action is that what has been
pre-empted can never be known for certain, while the undesired
effects - what the Americans call collateral damage - can be
assessed retrospectively with some degree of accuracy. On this
view, pre-emptive action is never justified; for only collateral
damage is certain.
Prudence, the greatest of all political virtues, shades
imperceptibly into timidity and outright cowardice. Fearful
imaginings can always be made a reason for doing nothing, or for
retreating into a world of one's own. The agoraphobic refuses to
go out because he is prey to fears of what might happen to him
once he leaves the safety of his domestic cocoon, though of
course sometimes unpleasant things do happen to people who leave
their homes. But if everyone were agoraphobic, the human race
would soon die out, for no one would produce or distribute
anything. The world needs nations, as well as men, who are
unafraid.
The choice before humans is never between risk and no risk; it is
always between different risks. The risks of making war are now
far outweighed by those of not making war. And the only thing we
have to fear is fear itself.
Copyright 2003, The Spectator
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