Confusing Signals: Does this make you feel safer?

THE FOLLOWING RELEASE WAS RECEIVED FROM THE UNIVERSITY OF WASHINGTON IN SEATTLE, AND IS FORWARDED FOR YOUR INFORMATION. (FORWARDING DOES NOT IMPLY ENDORSEMENT BY THE AMERICAN ASTRONOMICAL SOCIETY.) Steve Maran, American Astronomical Society: steve.maran@aas.org, 1-202-328-2010 x116.

PIO Source:

Vince Stricherz

1-206-543-2580 vinces@u.washington.edu

(NOTE: researcher contact information at end)

For immediate release July 30, 2009

NOTE: An image may be downloaded at

http://uwnews.org/images/newsreleases/2009/July/20090730_pid51189_aid51186_c

omet2001rx14linear_sourceimage.jpg

CRASHING COMETS NOT LIKELY THE

CAUSE OF EARTH'S MASS EXTINCTIONS

Scientists have debated how many mass extinction events in Earth's

history were triggered by a space body crashing into the planet's surface.

Most agree that an asteroid collision 65 million years ago brought an end to

the age of dinosaurs, but there is uncertainty about how many other

extinctions might have resulted from asteroid or comet collisions with

Earth.

In fact, astronomers know the inner solar system has been protected

at least to some degree by Saturn and Jupiter, whose gravitational fields

can eject comets into interstellar space or sometimes send them crashing

into the giant planets. That point was reinforced last week (July 20) when a

huge scar appeared on Jupiter's surface, likely evidence of a comet impact.

New University of Washington research indicates it is highly

unlikely that comets have caused any mass extinctions or have been

responsible for more than one minor extinction event. The work also shows

that many long-period comets that end up in Earth-crossing orbits likely

originate from a region astronomers have long believed could not produce

observable comets. A long-period comet takes from 200 years to tens of

millions of years to make a single orbit of the sun.

"It was thought the long-period comets we see just tell us about the

outer Oort Cloud, but they really give us a murky picture of the entire Oort

Cloud," said Nathan Kaib, a University of Washington doctoral student in

astronomy and lead author of a paper on the work being published July 30 in

Science Express, the online edition of the journal Science. NASA and the

National Science Foundation funded the work.

The Oort Cloud is a remnant of the nebula from which the solar

system formed 4.5 billion years ago. It begins about 93 billion miles from

the sun (1,000 times Earth's distance from the sun) and stretches to about

three light years away (a light year is about 5.9 trillion miles). The Oort

Cloud could contain billions of comets, most so small and distant as to

never be observed.

There are about 3,200 known long-period comets. Among the

best-remembered is Hale-Bopp, which was easily visible to the naked eye for

much of 1996 and 1997 and was one of the brightest comets of the 20th

century. By comparison, Halley's comet, which reappears about every 75

years, is perhaps the best-known comet, but it is a short-period comet, most

of which are believed to originate in a different part of the solar system

called the Kuiper Belt.

It has been believed that nearly all long-period comets that move

inside Jupiter to Earth-crossing trajectories originated in the outer Oort

Cloud. Their orbits can change when they are nudged by the gravity of a

neighboring star as it passes close to the solar system, and it was thought

such encounters only affect very distant outer Oort Cloud bodies.

It also was believed that inner Oort Cloud bodies could reach

Earth-crossing orbits only during the rare close passage of a star, which

would cause a comet shower. But it turns out that even without a star

encounter, long-period comets from the inner Oort Cloud can slip past the

protective barrier posed by the presence of Jupiter and Saturn and travel a

path that crosses Earth's orbit.

In the new research, Kaib and co-author Thomas Quinn, a UW astronomy

professor and Kaib's doctoral adviser, used computer models to simulate the

evolution of comet clouds in the solar system for 1.2 billion years. They

found that even outside the periods of comet showers, the inner Oort Cloud

was a major source of long-period comets that eventually cross Earth's path.

By assuming the inner Oort Cloud as the only source of long-period

comets, they were able to estimate the highest possible number of comets in

the inner Oort Cloud. The actual number is not known. But by using the

maximum number possible, they determined that no more than two or three

comets could have struck Earth during what is believed to be the most

powerful comet shower of the last 500 million years.

"For the past 25 years, the inner Oort Cloud has been considered a

mysterious, unobserved region of the solar system capable of providing

bursts of bodies that occasionally wipe out life on Earth," Quinn said. "We

have shown that comets already discovered can actually be used to estimate

an upper limit on the number of bodies in this reservoir."

With three major impacts taking place nearly simultaneously, it had

been proposed that the minor extinction event about 40 million years ago

resulted from a comet shower. Kaib and Quinn's research implies that if that

relatively minor extinction event was caused by a comet shower, then that

was probably the most-intense comet shower since the fossil record began.

"That tells you that the most powerful comet showers caused minor

extinctions and other showers should have been less sev ere, so comet showers

are probably not likely causes of mass extinction events," Kaib said.

He noted that the work assumes the area surrounding the solar system

has remained relatively unchanged for the last 500 million years, but it is

unclear whether that is really the case. It is clear, though, that Earth has

benefitted from having Jupiter and Saturn standing guard like giant catchers

mitts, deflecting or absorbing comets that might otherwise strike Earth.

"We show that Jupiter and Saturn are not perfect and some of the

comets from the inner Oort Cloud are able to leak through. But most don't,"

Kaib said.

For more information, contact Kaib at 1-206-616-4549, 1-206-375-1048 or

kaib@astro.washington.edu; or Quinn at 1-206-685-9009 or

trq@astro.washington.edu.

Top 10 Ways to Destroy Earth

Holes in the Earth: 170 and Counting

Catastrophe Calculator

[Is the estimate correct using only visible comets? Do Dark Comets (see earlier post) affect this calculus?]

New Comet Modeling

http://uwnews.org/images/newsreleases/2009/July/20090730_pid51189_aid51186_comet2001rx14linear_sourceimage.jpg

CRASHING COMETS NOT LIKELY THE

CAUSE OF EARTH'S MASS EXTINCTIONS

Scientists have debated how many mass extinction events in Earth's

history were triggered by a space body crashing into the planet's surface.

Most agree that an asteroid collision 65 million years ago brought an end to

the age of dinosaurs, but there is uncertainty about how many other

extinctions might have resulted from asteroid or comet collisions with

Earth.

In fact, astronomers know the inner solar system has been protected

at least to some degree by Saturn and Jupiter, whose gravitational fields

can eject comets into interstellar space or sometimes send them crashing

into the giant planets. That point was reinforced last week (July 20) when a

huge scar appeared on Jupiter's surface, likely evidence of a comet impact.

New University of Washington research indicates it is highly

unlikely that comets have caused any mass extinctions or have been

responsible for more than one minor extinction event. The work also shows

that many long-period comets that end up in Earth-crossing orbits likely

originate from a region astronomers have long believed could not produce

observable comets. A long-period comet takes from 200 years to tens of

millions of years to make a single orbit of the sun.

"It was thought the long-period comets we see just tell us about the

outer Oort Cloud, but they really give us a murky picture of the entire Oort

Cloud," said Nathan Kaib, a University of Washington doctoral student in

astronomy and lead author of a paper on the work being published July 30 in

Science Express, the online edition of the journal Science. NASA and the

National Science Foundation funded the work.

The Oort Cloud is a remnant of the nebula from which the solar

system formed 4.5 billion years ago. It begins about 93 billion miles from

the sun (1,000 times Earth's distance from the sun) and stretches to about

three light years away (a light year is about 5.9 trillion miles). The Oort

Cloud could contain billions of comets, most so small and distant as to

never be observed.

There are about 3,200 known long-period comets. Among the

best-remembered is Hale-Bopp, which was easily visible to the naked eye for

much of 1996 and 1997 and was one of the brightest comets of the 20th

century. By comparison, Halley's comet, which reappears about every 75

years, is perhaps the best-known comet, but it is a short-period comet, most

of which are believed to originate in a different part of the solar system

called the Kuiper Belt.

It has been believed that nearly all long-period comets that move

inside Jupiter to Earth-crossing trajectories originated in the outer Oort

Cloud. Their orbits can change when they are nudged by the gravity of a

neighboring star as it passes close to the solar system, and it was thought

such encounters only affect very distant outer Oort Cloud bodies.

It also was believed that inner Oort Cloud bodies could reach

Earth-crossing orbits only during the rare close passage of a star, which

would cause a comet shower. But it turns out that even without a star

encounter, long-period comets from the inner Oort Cloud can slip past the

protective barrier posed by the presence of Jupiter and Saturn and travel a

path that crosses Earth's orbit.

In the new research, Kaib and co-author Thomas Quinn, a UW astronomy

professor and Kaib's doctoral adviser, used computer models to simulate the

evolution of comet clouds in the solar system for 1.2 billion years. They

found that even outside the periods of comet showers, the inner Oort Cloud

was a major source of long-period comets that eventually cross E arth's path.

By assuming the inner Oort Cloud as the only source of long-period

comets, they were able to estimate the highest possible number of comets in

the inner Oort Cloud. The actual number is not known. But by using the

maximum number possible, they determined that no more than two or three

comets could have struck Earth during what is believed to be the most

powerful comet shower of the last 500 million years.

"For the past 25 years, the inner Oort Cloud has been considered a

mysterious, unobserved region of the solar system capable of providing

bursts of bodies that occasionally wipe out life on Earth," Quinn said. "We

have shown that comets already discovered can actually be used to estimate

an upper limit on the number of bodies in this reservoir."

With three major impacts taking place nearly simultaneously, it had

been proposed that the minor extinction event about 40 million years ago

resulted from a comet shower. Kaib and Quinn's research implies that if that

relatively minor extinction event was caused by a comet shower, then that

was probably the most-intense comet shower since the fossil record began.

"That tells you that the most powerful comet showers caused minor

extinctions and other showers should have been less severe, so comet showers

are probably not likely causes of mass extinction events," Kaib said.

He noted that the work assumes the area surrounding the solar system

has remained relatively unchanged for the last 500 million years, but it is

unclear whether that is really the case. It is clear, though, that Earth has

benefitted from having Jupiter and Saturn standing guard like giant catchers

mitts, deflecting or absorbing comets that might otherwise strike Earth.

"We show that Jupiter and Saturn are not perfect and some of the

comets from the inner Oort Cloud are able to leak through. But most don't,"

Kaib said.

For more information, contact Kaib at 1-206-616-4549, 1-206-375-1048 or

kaib@astro.washington.edu; or Quinn at 1-206-685-9009 or

trq@astro.washington.edu.

Laser Propulsion

From: http://news.yahoo.com/s/space/20090729/sc_space/laserpropulsionwildideamayfinallyshine

Laser Propulsion: Wild Idea May Finally Shine

Leonard David
SPACE.com's Space Insider Columnist
SPACE.com – Wed Jul 29, 1:00 pm ET

New laser propulsion experiments are throwing light on how to build future hypersonic aircraft and beam spacecraft into Earth orbit.

Indeed, a "Lightcraft revolution" could replace today's commercial jet travel. Passengers would be whisked from one side of the planet to the other in less than an hour - just enough time to get those impenetrable bags of peanuts open. Furthermore, beamed energy propulsion can make flight to orbit easy, instead of tenuous and dangerous.

That's the belief of Leik Myrabo an aerospace engineering professor at Rensselaer Polytechnic Institute in Troy, NY. He's an expert in directed energy applications, aerospace systems, space prime power, and advanced propulsion.

For the past three decades, Myrabo's burning desire has been to create and demonstrate viable concepts for non-chemical propulsion of future flight vehicles through his research and company Lightcraft Technologies, Inc., of Bennington, Vt.

"Typically, a new propulsion technology takes 25 years to mature...to the point where you can actually field it. Well, that time is now," Myrabo told SPACE.com.

Real hardware...real physics

The brightest new news in beamed energy propulsion is that experiments are now underway at the Henry T. Nagamatsu Laboratory of Hypersonics and Aerothermodynamics at the IEAv-CTA in Sao Jose dos Campos, Brazil.

The work is being sponsored under international collaboration between the United States Air Force Office of Scientific Research and the Brazilian Air Force.

Basic research experiments using high-powered lasers are underway in Brazil, with experts investigating the central physics of laser-heated airspikes and pulsed laser propulsion engines for future ultra-energetic craft.

At the Brazil-based lab, a hypersonic shock tunnel is linked to two pulsed infrared lasers with peak powers reaching the gigawatt range - the highest power laser propulsion experiments performed to date, Myrabo said.

"In the lab we're doing full-size engine segment tests for vehicles that will revolutionize access to space," Myrabo emphasized. "It's real hardware. It's real physics. We're getting real data...and it's not paper studies."

"Right now, we're chasing the data," Myrabo said. "When you fire into the engine, it's a real wallop. It sounds like a shotgun going off inside the lab. It's really loud."

The laser propulsion experiments, Myrabo added, are also relevant to launching nanosatellites (weighing 1 to 10 kilograms) and microsatellites (10 to 100 kilograms) into low Earth orbit.

Highways of light

Creating and flying Myrabo's "highways of light" has been a methodical and step by step undertaking.

Back in 1996 through 1999, he flew Lightcraft prototypes via a 10 kilowatt high-power infrared laser at White Sands Missile Range in New Mexico. In 2000 - sponsored under a grant to his company - he established a new world altitude record of over 230 feet (71 meters) for laser-boosted vehicles in free fight.

Myrabo points to his new book "Lightcraft Flight Handbook, LTI-20," co-authored with John Lewis and recently published by Apogee books, to explain his quest for low-cost, safe space access with beamed-powered Lightcraft.

"The physics of high-power beamed energy propagation through the atmosphere...there's not a lot of expertise out there to make this stuff real. It's completely out of the conventional box," Myrabo said. "I've been working on it for 30 years. I know how to do it."

For decades, Myrabo said, what laser propulsion physicists have been hungry to achieve is a couple of dollars per watt of laser energy. "We're here now. It's a matter of will and do we want to do it. This technology is now at the cusp of commercial reality."

• Video - Star Trek's Warp Drive: Are We There Yet?
• Looking to Lasers, Microwaves and Anti-Matter for Space Travel
• Video - Promising New Space Engines

Leonard David has been reporting on the space industry for more than four decades. He is past editor-in-chief of the National Space Society's Ad Astra and Space World magazines and has written for SPACE.com since 1999.

The money is there for big energy!

Sahara Solar Project to Move Forward at Munich Meeting

Reuters Jul 9, 2009

Desertec aims to establish 6,500 square miles of renewable thermal solar power plants in the Sahara Desert. (DESERTEC Foundation)

BERLIN—A group of companies from Europe and northern Africa will meet in Munich on Monday to map out concrete steps for a series of large-scale renewable energy projects worth 400 billion euros ($560 billion) over 40 years.

They will launch a venture to explore the feasibility of harvesting solar thermal energy from the deserts of northern Africa and the Middle East to be used within the next decade or so in those regions and Europe.

Invited by German reinsurer Munich Re, executives from blue chip companies such as Siemens, E.ON, RWE and Switzerland's ABB along with firms from southern Europe and northern Africa will be at the inaugural meeting.

About 10 companies are expected to sign a memorandum of understanding setting up the Desertec Industrial Initiative.

Despite uncertainties associated with such vast multinational projects and concerns about political stability in the Mediterranean region, host Munich Re said the companies were eager to move forward with the next concrete steps.

"We believe the time is ripe for projects like this," said Alexander Mohanty, a Munich Re spokesman. "It's a great vision for the future. But we're not dreamers. This is the start of an industry initiative and we're looking for results.

"We're not just setting up a 'working group' to meet from time to time. The focus is on concrete results. The initiative will be doing lobby work, getting a dialogue going. The issue of the power price is important to be able to raise capital."

The European Union and German government are also firmly behind the projects. EU Commission President Jose Manuel Barroso and Chancellor Angela Merkel both expressly praised the idea behind Desertec at a recent Berlinmeeting of energy executives.

Growing global efforts to slow climate change by reducing greenhouse gas emissions along with a projected increase in energy demand in the Middle East and northern Africa make the projects all the more attractive, its proponents say.

Analysts are eagerly waiting for details.

"I think it's a serious project, but it will take a very long time until there will be concrete news," said Commerzbankanalyst Robert Schramm.

"The time schedule seems a bit overambitious. The technology is certainly there and it makes sense but there are political factors that need to be taken into consideration regarding the Sahara region."

Harnessing Sun's Power

The Desertec Foundation has noted in six hours the world's deserts receive more energy than mankind consumes in a year.

The projects would use concentrated solar power (CSP)—a technology that uses mirrors to harness the sun's rays to produce steam and drive turbines to produce electricity—from the Sahara and deliver to markets locally and in Europe.

Using high-voltage direct current transmission lines there is only a minimal power loss of 3 percent per 1,000 kilometres.

Solar thermal is a well-tested technology from operation since the 1980s of an installation in the U.S. Mojave Desert as well as in Spain, but it is a more expensive source of electricity than fossil fuels.

Desertec officials hope the Sahara could be supplying 20 gigawatts of power—the equivalent of 20 large conventional power plants -- by 2020 and one day deliver 15 percent of Europe's electricity, helping the EU meet CO2 reduction targets.

"After the founding we're planning to invite more companies to join in," said Michael Straub, head of marketing at the Desertec Foundation in Hamburg.

"At first we'll be studying which countries and which areas could be used for the first plants, and we'll also be studying the costs, the financing and other fundamental questions."

Straub said one project is already moving ahead; it would link power produced in Tunisia with users in southern Italy. He said it was possible it could be on line within five years.

Germany's Solar Millennium, which helped develop Spain's Andasol 1 solar thermal project, will also be at the Desertec meeting as is German solar technology company Schott Solar.

Could Earth Be Hit, Like Jupiter Just Was?

From: http://news.yahoo.com/s/space/20090728/sc_space/couldearthbehitlikejupiterjustwas

AP – This image provided by NASA's Hubble Space Telescope taken with it's Wide Field Camera 3 on Thursday …

Could Earth Be Hit, Like Jupiter Just Was?

Charles Q. Choi

Special to SPACE.com

SPACE.com

Tue Jul 28, 10:45 am ET

The recent bruising Jupiter received from a cosmic impact is a violent reminder that our solar system is a shooting gallery that sometimes blasts Earth.

Still, what are the odds of a cosmic impact threatening our planet?

So far 784 near-Earth objects (NEOs) more than a half-mile wide (1 km) have been found.

"If an object of about the same size that just hit Jupiter also hit Earth — it was probably a typical cometary object of a kilometer or so in size (0.6 miles) — it would have been fairly catastrophic," explained astronomer Donald Yeomans, manager of NASA's Near-Earth Object program office at the Jet Propulsion Laboratory in Pasadena, Calif.

Scientists have ruled out the chances of an Earth impact for all of these 784 large NEOs. Still, lesser objects also pose a risk, and researchers estimate more than 100 large NEOS remain to be found.

Small risk

Billions of years ago, impacts were far more common. Our moon retains a record of the pummeling it and Earth took: the moon's craters remain, while on Earth, most scars of ancient impacts have been folded back into the planet or weathered away.

Today's solar system is far less crowded, and in fact Jupiter, having more mass and gravity, scoops up a lot of the dangerous objects, as does the sun.

Currently just one NEO of all the objects scientists are tracking poses any significant chance of hitting the Earth — 2007 VK184. If this roughly 425-foot-wide (130 meters) asteroid hit our planet, it would strike with an energy of roughly 150 million tons of TNT, or more than 10,000 times that of the atom bomb dropped on Hiroshima.

Roughly 100 telescopic observations made so far suggest that 2007 VK184 has a 1-in-2,940 chance of hitting Earth 40 to 50 years from now. However, if the past is any guide, further observations to refine computations of its orbit very likely will downgrade its probability of hitting Earth to virtually nothing, Yeomans said.

Of remaining concern are the NEOs that we do not see. Researchers suspect about 156 large NEOs 1 kilometer in diameter or larger remain to be found, and when it comes to dangerous NEOs in general, "when we get down to 140 meters (460 feet) or larger diameter objects, we think we've discovered about 15 percent of them, and with 50 meters (164 feet) or larger diameter, we've discovered less than 5 percent of them," Yeomans explained.

On average, an NEO roughly a half-mile wide or larger hits the Earth roughly every 500,000 years, "so we're not expecting one anytime soon," Yeomans explained.

"For 500 meters (1,640 feet), we're talking a mean interval of about 100,000 years," he added. "When you get down to 50 meters, the mean interval is about 700 years, and for 30 meters (98 feet), about 140 years or so, but by then you're getting down to a size where you won't expect any ground damage, as they burn up in the atmosphere at about 25 meters (82 feet) in diameter and smaller, probably for an impressive fireball event."

When it comes to truly monstrous NEOs some 10 kilometers (6.2 miles) or larger, of the size thought to have helped kill off the dinosaurs, "that's a 100 million year event, and in fact, I don't think there is anything like that we see right now," Yeomans said. "The largest near-Earth object that can actually cross the Earth's path, Sisyphus, has a diameter of 8 kilometers (5 miles), and the largest that is termed a potential hazard is Toutatis, which has a diameter of approximately 5.4 km (3.35 miles)."

Keeping watch

There are currently four teams worldwide actively looking for both large and small NEOs, Yeomans said. "We're concentrating on the large ones for now, but hopefully with the next generation of search, we'll be more efficient in finding the smaller objects, to find 90 percent of the total population of potential hazards larger than 140 meters," he added.

Keeping an eye on NEOs might not just be healthy for humanity, but also help lead us out into space.

"They're easy objectives to get to, and asteroids have significant metal resources that can be mined, while comets have significant water resources for space habitats or travel," Yeomans said. "If you want to build a habitat in space, you're not going to build it all on the ground and launch it up, since that's too expensive — you want to go up and look for resources instead."

Furthermore, asteroids and comets are among the objects that have changed the least since the birth of the solar system roughly 4.6 billion years ago, and might reveal vital clues behind the mysterious process.

"They may well have delivered the water and carbon-based molecules to Earth that allowed life to form, so they're extremely important for study in that direction," Yeomans added.

Note from Blogger: The IAA is expected to release its White Paper on Planetary Defense from the 1st International Planetary Defense Conference any day now. The conference was held in April.

Solaren Video Clip

The Science Channel Reviews Solaren's plans to supply Green Power to 150,000 California homes by 2016:

http://science.discovery.com/videos/brink-news-solar-power-in-space.html

Discusses Asimov's advocacy role in the 40's, and features Senior Science Advisor, Department of Energy, Dwight Williams--"Really its been engineering.

Also:

And STRATFOR reports that the US and China have signed a Clean Energy Memorandum of Understanding on 28 July for working together to reverse climate change and for cooperating on clean energy technology. Sec Clinton said the agreement “highlights the importance of climate change in our bilateral relationship by creating a platform for climate policy, dialogue and cooperation.” That comes just one day after U.S. President Barack Obama called for for mutual development of clean energy with China.

Secure World in the News

From: http://news.cnet.com/8301-13772_3-10294333-52.html

Secure World is interested in the following:

SUPERIOR, Colo.--If you remember the scene from Pixar's "Wall-E," in which a rocket ship on its way to humankind's space station blasts through a debris field of abandoned satellites, you may have wondered if anyone on Earth is working to prevent that from becoming reality.

The answer is yes.

Here in this small town not far from Boulder, Colo., the Secure World Foundation (SWF), a nonprofit unassociated with any government, is thinking about that kind of issue, as well as several others related to the fair use of space, and succeeding at getting its analysis and recommendations heard by decision makers around the world.

The Secure World Foundation is a nonprofit that is advocating for the fair use of outer space.

(Credit: Secure World Foundation)

"We promote the need for space governance," said Phil Smith, the Secure World Foundation's communications director, and help "establish effective systems of governance in outer space."

ISecure world is primarily interested in the following:

Space traffic management

Space weapons

Orbital debris

Planetary defense

Another main area of SWF's focus is on planetary defense, or the protection of Earth against asteroids, or comets, or other space junk that could appear out of nowhere, impact the planet and cause serious problems, up to and including massive species extinction.

The Association of Space Explorers, a group of former astronauts, is one group that is focusing on this issue, and has produced a report on how to deal with this issue at a policy level.

But again, the SWF gets involved at the international policy level, weighing in when asked by the U.N. about what to do with the astronauts' report. The idea is to prepare a plan so that if a hazardous space object is detected, we know what to do about it, rather than having to create a plan on the fly.

And that leads to a final area of the SWF's main focus: data sharing.

The SWF wants to ensure, Smith said, that everyone has access to data that can be collected by satellites about global vegetation growth, about the effects of global warming, as well as many of the issues discussed above.

While a small organization without major funding or direct involvement in any of the issues it studies, the SWF would seem to have limited power. But because it is consulted regularly by the United Nations and has contacts throughout the world, we can all hope that having a non-governmental nonprofit looking out for the fair use of space will help further that goal. After all, who else is going to argue for space?

Jupiter deserves a medal for doing its job of sucking up dangerous rocks

From:http://www.space.com/scienceastronomy/090721-jupiter-impact.html

The dark bruise that appeared suddenly near the south pole of Jupiter several days ago, likely as the result of an impact by a comet or asteroid, is as big as the Pacific Ocean, astronomers report.

The dark spot was first noticed by chance by amateur astronomer Anthony Wesley in Australia on Sunday, July 19.

The blemish is thought to be the result of an impact similar to that ofComet Shoemaker-Levy 9, which pummeled the gas giant 15 years ago.

After he was convinced the spot was not just another storm or the shadow of one of Jupiter's moons, Wesley alerted other astronomers around the world to the scar's appearance.

University of California, Berkeley, astronomer Paul Kalas took advantage of previously scheduled observing time on the Keck II telescope in Hawaii to image the blemish in the early morning hours of Monday, July 20. The near-infrared image showed a bright spot in the clouds of Jupiter's southern hemisphere, where the impact had propelled reflective particles high into the relatively clear stratosphere.

In visible light, the bruise appears dark against the bright surface of Jupiter.

These observations mark only the second time that astronomers have been able to see the results of an impact on the planet, the first being Comet Shoemaker-Levy 9's collision. Many theories were formed after that collision.

"Now we have a chance to test these ideas on a brand new impact event," Kalas, said.

Kalas and his colleagues hope their observations will shed light on the nature of the impact.

"The analysis of the shape and brightness of the feature will help in determining the energy and the origin of the impactor," said Marchis. "We don't see other bright features along the same latitude, so this was most likely the result of a single asteroid, not a chain of fragments like for SL9 [Comet Shoemaker-Levy 9]."

http://pajamasmedia.com/richardfernandez/

An Australian amateur astronomer detected the first indications that a comet had slammed into Jupiter only fifteen years after the Shoemaker-Levy impacts. It left an impact signature on the giant planet the size of earth. William Harwood writes:

“We’re not sure how large this fragment could have been,” Leigh Fletcher, a researcher at the Jet Propulsion Laboratory in Pasadena, Calif., told CNET. …”We’ve compared it in size to the little red spot on Jupiter, you can see the two are roughly a similar order of magnitude in size,” he said. “It’s smaller than Earth-sized, but it’s certainly gargantuan by earthly proportions.”

Over the next few days and weeks, the Hubble Space Telescope, other space-based telescopes, and observatories around the world will focus on the impact site to learn as much as possible about what might have hit Jupiter and how the impact affected the planet’s atmosphere.

This is the second large hit on Jupiter we’ve observed in fifteen years. Does it tell us anything about the likelihood of an impact on earth? The answer is we don’t really know because we don’t have the detection systems in place to gather the data. Glenn Reynolds, writing in TCS notes that politicians have devoted a relative pittance to watching the skies. And even if an incoming object were detected, there are no established protocols to respond to the event, nor any realistic defenses against a massive incoming. This is probably a function of politics more than anything else, I think. Its deemed essential to spend trillions to prevent “climate change” in the name of the precautionary principle, but the ranging shots of the artillerist of the Solar System are left to amateur astronomers from Australia to observe.

But the most interesting issue that Glenn Reynolds raises in his TCS article is that, without a planetary defense and with an inadequate detection system, then humanity will at most have a short time between the detection of a life-ending incoming space projectile and impact. In that case, he asks, would we want to know? Should governments keep it secret from us?

Quite some time ago, I wrote about scientists’ questions on whether to deliver bad news. The news in question had to do with a potential life-ending asteroid strike. Perhaps, I suggested, it might be best not to deliver that news, if things were bad enough that nothing could be done. I also noted that this was an active question within the astronomical community.

Personally, I would want to know if the end were imminent. In the case Reynolds cites, the panic spawned by a sighting was premature. Further observations by astronomers showed the feared object was going to miss. Somebody should do a disaster movie like that one day, when everybody closes his eyes at the anticipated moment, only to look up to see, blazoned in flaming letters across the sky, “Nyah, nyah! Fooled you! Fooled you!”

Holst looked up at Jupiter and heard laughter. Here’s’s his Jupiter, Bringer of Jollity, from The Planets. On winter nights, after the last bus down Trapelo road had gone, I used to run the distance from Harvard Square to Belmont with a Walkman in my pocket. And the everything after 2:38 was my favorite on the track.