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You seem to like a nice series, so here’s a new one Fraser and Pamela have been thinking about. Over the course of the next 4 weeks, they’re going to cover each of the basic forces in the Universe. And this week, they’re going to start with gravity; the force you’re most familiar with. Gravity happens when masses attract one another, and we can calculate its effect with exquisite precision. But you might be surprised to know that scientists have no idea why gravity happens
A debate today between astronomer Neil deGrasse Tyson and planetary scientist Mark Sykes, moderated by NPR’s Ira Flatow, addressed the issue of Pluto’s planetary status. There was lots of arm-waving and finger-pointing, endless interruptions, disagreements on details big and small, and battling one-liners. The two scientists sat at a table with the moderator between them and Flatow was often obscured by Tyson and Sykes getting in each other’s faces in eye-to-eye confrontation. At one point, Flatow was hit by Tyson’s ebullient arm motions. Yes, it was heated. But it was fun, too. It ended up being not so much a debate between the Pluto-huggers and the Pluto-haters as a disagreement over the lexicon of astronomy and planetary science and, primarily, the definition of a planet. Pluto’s planetary status was definitely not decided here, and the debate concluded with an amicable agree-to-disagree concurrence that the scientific process is an ongoing, evolving practice. But it wasn’t without fireworks.
At the start of the Great Planet Debate, Flatow laid down the ground rules, which included no throwing of perishable items, but that was about the only rule that didn’t get disregarded. Tyson, director of the Hayden Planetarium in New York and host of Nova ScienceNow, and who is in the camp that Pluto is not a planet, began his opening statements with “It’s simple. The word ‘planet’ has lost all scientific value.” He went on, saying “planet” doesn’t tell you much and you have to ask all sorts of questions such as is it big or small, rocky or gaseous, in the habitable zone or not, etc. “If you have to ask twenty questions after I say I’ve discovered a planet, the word has lost its utility.” Tyson said “planet” had utility far back in time when there wasn’t much else we knew about, but we know so much more now. “If we’re going rely on one word and put them all in one pot, what are we doing as scientists and educators? The time has come to discard the useless words and invent a whole new system to respect the level of science we have achieved…We’re in desperate need of a new lexicon to accommodate this knowledge,” he said.
Sykes, director of the Planetary Science Institute, and who believes Pluto should be reinstated as a planet, began, “How we categorize things is part of the science process. It is natural for humans to group things together with common characteristics as a tool to better understand and how they work. This applies to biology and astronomy as well.” He continued that we have discovered planets around other stars and continue to find Kuiper Belt objects that will need to be classified, so classifying objects is not a useless task. The IAU (International Astronomical Union) bit the bullet and decided on a classification, but unfortunately, Sykes said, what they came up with was not very useful.
That was the end of decorum, as Tyson interrupted with, “You wanted a definition. They gave you a definition and now you’re complaining about it!”
“Absolutely,” said Sykes, wanting to continue, but Tyson quickly chimed in, “And let me add…”, where Sykes butted in with “You have to let me start before you add!”
Flatow looked around and said, “I think I’m in a danger zone here.”
Thus began the debate. Mark Sykes
Sykes said that any definition has to have a reason, or a purpose. According to the IAU’s definition, planets have to orbit the sun, they have to be round, and they have to have cleared their orbits, among other things. There was immediate confusion with this definition, which Sykes said was a little “goofy.” In order to be a planet, an object has be bigger the farther away it is from the sun, and it ignores the physical characteristics. He believes it’s useful to group things together that are similar and then have subcategories. So, you have planets, under which are terrestrial, gas giants, ice planets, etc.
Tyson said that even for him, the IAU’s definition falls short of taking the total amount of information to task. “If you only want to call round things planets, that puts Pluto in the same class as Jupiter. I happen to like round things. But what other lexicon might be available to group similar things together?”
“That’s why god made subcategories,” said Sykes. “It’s good to have a good general starting point for classifying things.” Neil de Grasse Tyson
Tyson humorously pointed out this debate is big only in the US, which he attributed to Disney’s creation of the lovable, dimwitted cartoon bloodhound named Pluto. School kids, grownups, op-ed writers all say Pluto is their favorite planet. “I am certain that the word ‘plutocracy’ is traceable to what Disney has done, so it’s hard to extricate the sentiment we have for the planet from the dog.”
Sykes said the IAU didn’t expand our perspective on planets, but narrow it. “The planet count went down, and what was the justification of that? The proponents have never given a good explanation of what was motivating that perspective.”
Tyson said numbers aren’t important, but words and definitions are, and we definitely need new ones.
Both scientists gave good arguments for their cause, and since I’m decidedly on the fence with this issue, I found myself leaning towards one option or the other, as each one spoke. Sykes, who wants to see Pluto reinstated as a planet, wants to take what we have and make it better, while Tyson, who thinks Pluto is a comet, wants to start over with new and better words and definitions.
It was an entertaining and educational debate with two well-spoken and intelligent scientists who sometimes weren’t very polite, however. (Sykes said, “When were’ not fighting we get along fine.”) The most important thing, they both agreed though, was that scientists are actually talking about this issue in the public eye and people are interested. But more importantly, the public is seeing the scientific process in action. They said this debate shouldn’t be about making things easy, or worrying about “not confusing the public.” Learning science shouldn’t be rote memorization of lists of objects, but a discussion of how objects are similar and different. “My recommendation to school teachers,” said Tyson “is to get the notion of counting things out of your system and comb the solar system for the richness of objects. Ask about different ways to combine the different objects in our solar system and have a discussion about their different properties.”
The debate will be available online, and we’ll post a link to it here when it is.
Sykes ended with his closing argument: “We both have issues with what happened with the IAU, its part of an ongoing presentation, but the important things is that the public gets to see the debate, and it’s not a battle over what list and what numbers you have, but the debate of the issues. That’s more important whether either of us have convinced you of one perspective. Science in this country is too much memorizing lists promulgated by those in authority. This is helping to expose the messy side of science. This debate is good and positive.”
Tyson ended by saying how charmed he is at the level of public interest in this subject. “How many sciences get to have their issues debated in the op-ed pages and comics?” He said he was happy with the word “planet” until all the data started pouring in from our explorations. “There should be a way to celebrate a new way to think about things. There ought to be a way to capture that” he said.
Obviously, this is not the last word on the subject from either scientist, or either side of the debate.
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Former NASA astronaut and Rocketplane test pilot John Herrington has a new state-of-the-art vehicle of choice: a bike. But it’s a touring bike fully loaded with a GPS, laptop, broadband phone, and digital and video cameras. Herrington is embarking on a cross country bike trek to promote and encourage student participation in science, technology, engineering and mathematics (STEM). Herrington, once a college dropout who went on to fly in space in 2002 on the STS-113 mission, hopes he can help make a difference and impact on children by sharing his experiences and providing web-based, hands-on activities using STEM skills to solve problems while following his journey. Herrington also wants to encourage children to pursue their dreams and seek out exciting opportunities. “The generation that grew up in the age of the Apollo program and the journey to the moon was motivated by the excitement of space and the possibilities that it brought to the nation,” said Herrington. “Those kinds of possibilities to explore the unknown and make new discoveries still exist, but we must motivate students to learn and have a way to connect what they learn to what they do on a daily basis.”
Herrington began his coast-to-coast tour yesterday (August 13) from Cape Flattery in Washington state and will finish at Cape Canaveral in Florida. The trip is expected to take three months, and Herrington will stop at schools along the way to talk about his “journey to the space program, the wonders of flying in space and the need for students to realize their potential that lies within,” he said.
Students can log into Herrington’s blog for daily updates and new problem solving challenges. Herrington, the first Native American in space will be especially focusing on Native students, hoping to kindle imagination and motivation. “I was once an unmotivated student, looking for something that sparked my fire,” he said. “I found it as a rock-climber on a survey crew, learning the application of mathematics from the side of a cliff. That experience inspired me to return to school and ultimately led to my career as an astronaut.”
As part of the crew of the space shuttle Endeavour in November of 2002, Herrington conducted three spacewalks to help in construction of the International Space Station, logging just under 20 hours of EVAs. He left NASA in 2005 to join Rocketplane Global as a test pilot. He left Rocketplane in December 2007 to pursue other opportunities, which obviously, includes biking.
“Sometimes it takes someone outside of our normal circle of friends and family to shine a light in our direction and help us along,” Herrington continued. “As I set out on this bike ride and try to make the learning practical and fun, I hope to also show students that it takes commitment and effort, both mental and physical, to accomplish your goals.” Herrington getting his bike ready for takeoff. Credit: Rocketrek
Here are the topics Herrington will be focusing on in his educational endeavors:
Science:
Caloric intake and heart rate in relation to overall health
Hydration, dehydration, hypothermia
Weather, wind velocity, ground and air speed, relative motion Technology:
Bike composition and weight/ comparison to space shuttle/station
Bike maintenance and repair
Getting power to electronics (i.e. batteries, solar)
Global Positioning System (GPS)
Digital camera technology Engineering:
Velocity and torque
Mass and weight
Friction and measurements Math:
Basic math
Addition and subtraction
Geometry, trigonometry and physics
The space-time bubble. Unfortunately, quantum physics may have the final word (Michael Alcubierre)
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Standard in almost every Star Trek episode are warp drives and cloaking devices. But in reality these science fiction gadgets defy the laws of physics. Or do they? Different scientists have been working on developing these two devices and they say they are getting closer to actually creating working prototypes. While warp drive won’t be available anytime soon, scientists are gaining a better understanding of how faster-than-light speed could possibly be achieved. And as for cloaking devices, don’t look now, but researchers recently cloaked three-dimensional objects using specially engineered materials that redirects light around objects.
Previously, scientists at the University of California, Berkley were only able to cloak very thin, two dimensional objects. But now, using meta-materials, which are mixtures of metal and circuit board materials such as ceramic, Teflon or fiber composite, scientists have deflected light waves around an object, like water flowing around a smooth rock in a stream. Objects are visible because they scatter the light that strikes them, reflecting some of it back to the eye. But the meta-materials would ward off light, radar or other waves. In effect, it would be a type of optical camouflage.
The research group, led by Xiang Zhang say they are a step closer to being able to render people and objects invisible. Their findings will be released later this week in the journals Nature and Science. The path that light rays would take through a theoretical cloaking device. Credit: John Pendry
Another scientist and one of the leaders in cloaking research is John Pendry, a theoretical physicist at Imperial College, London. It was he who first worked out how a cloak could be built in theory, and then he helped build the first working cloak. Pendry recently submitted an abstract that discusses what he says is a new type of cloak, one that gives all cloaked objects the appearance of a flat conducting sheet. Pendry says this type of cloak has the advantage in that nothing remarkable is required to create the cloak. Pendry said the device could be “made isotropic. It makes broadband cloaking in the optical frequencies one step closer.” This type of cloak seemingly creates a mirage to render an object invisible to the eye. Pendry’s own website says information on his new cloak will be available soon.
While cloaking devices would have military applications, a group of scientists researching warp drives say they just want to have the ability to travel to Earth-like exoplanets, like Gliese 581c to better understand the origin and development of life. “The only way we could realistically visit these worlds in time-frames on the order of a human lifespan would be to develop what has been popularly termed a `warp drive,'” said researchers Gerald Cleaver and Richard Obousy from Baylor University in Texas.
Their work expands on research done by theoretical physicist Michael Alcubierre from the University of Mexico, who in 1994 demonstrated space could be made to move around a spacecraft by `stretching’ space so that space itself would expand behind a hypothetical spacecraft, while contracting in front of the craft, creating the effect of motion. So, the ship itself doesn’t move, but space moves around it.
Their new research tries to take advantage of advances in understanding dark energy and why our universe is ever-expanding in every direction. Comprehending that might give us a leg up in being able to generate an asymmetric bubble around a spacecraft. “If we can understand why spacetime is already expanding, we may be able to use this knowledge to artificially generate an expansion (and contraction) of spacetime,” said Cleaver and Obousy in their abstract.
They propose manipulating the 11th dimension, a special theoretical part of an offshoot of string theory called the “m-theory” to create a bubble of dark energy by shrinking the 11th dimension in front of the ship and expanding it behind.
Obviously, this is highly theoretical, but if it leads researchers to a better understanding of dark energy, so much the better.
There’s one hitch, however. Cleaver and Obousy calculated that the energy needed to distort the space around a spacecraft-sized object is about 10^45 Joules or the total energy of an object the size of Jupiter if all its mass were converted into energy.
This creates a chicken and the egg type of conundrum. Which comes first: understanding dark energy or having the ability to create huge amounts of energy?
But Cleaver and Obousy are upbeat about it all. “This is a hypothetical propulsion device that could theoretically circumvent the traditional limitations of special relativity which restricts spacecraft to sub-light velocities. Any breakthrough in this field would revolutionize space exploration and open the doorway to interstellar travel.”
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The Aurora Borealis or Northern Lights are stunningly beautiful. But they can also disrupt radio communications and GPS signals, and even cause power outages. What’s behind the ethereal Northern Lights that causes them to shimmer and dance with colorful lights while sometimes wreaking havoc with electrical systems here on Earth? Using a fleet of five satellites, NASA researchers have discovered that explosions of magnetic energy a third of the way to the moon power substorms that cause sudden brightenings and rapid movements of the aurora borealis, called the Northern Lights. “We discovered what makes the Northern Lights dance,” said Dr. Vassilis Angelopoulos of the University of California, Los Angeles. Angelopoulos is the principal investigator for the Time History of Events and Macroscale Interactions during Substorms mission, or THEMIS.
The cause of the shimmering in Northern Lights is magnetic reconnection, a common process that occurs throughout the universe when stressed magnetic field lines suddenly snap to a new shape, like a rubber band that’s been stretched too far.
“As they capture and store energy from the solar wind, the Earth’s magnetic field lines stretch far out into space. Magnetic reconnection releases the energy stored within these stretched magnetic field lines, flinging charged particles back toward the Earth’s atmosphere,” said David Sibeck, THEMIS project scientist at NASA’s Goddard Space Flight Center. “They create halos of shimmering aurora circling the northern and southern poles.” An explosion of energy increases in the brightness and movement of Northern Lights. Credit: NASA/Goddard Space Flight Center
The data was gathered by five strategically positioned Themis satellites, combined with information from 20 ground-based observatories located throughout Canada and Alaska. Launched in February 2007, the five identical satellites line up once every four days along the equator and take observations synchronized with the ground observatories. Each ground station uses a magnetometer and a camera pointed upward to determine where and when an auroral substorm will begin. Instruments measure the auroral light from particles flowing along Earth’s magnetic field and the electrical currents these particles generate.
During each alignment, the satellites capture data that allow scientists to precisely pinpoint where, when, and how substorms measured on the ground develop in space. On Feb. 26, 2008, during one such THEMIS lineup, the satellites observed an isolated substorm begin in space, while the ground-based observatories recorded the intense auroral brightening and space currents over North America.
These observations confirm for the first time that magnetic reconnection triggers the onset of substorms. The discovery supports the reconnection model of substorms, which asserts a substorm starting to occur follows a particular pattern. This pattern consists of a period of reconnection, followed by rapid auroral brightening and rapid expansion of the aurora toward the poles. This culminates in a redistribution of the electrical currents flowing in space around Earth.
Solving the mystery of where, when, and how substorms occur will allow scientists to construct more realistic substorm models and better predict a magnetic storm’s intensity and effects.
Rendering of the Phoenix Mars Lander with robotic arm working on the Mars surface (NASA)
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All the best sci-fi films have them, and they may become our future automated space explorers. Currently, one of the biggest drawbacks for using robots in space is that they depend on human input (i.e. commands need to be sent for every robotic arm motion and every rover wheel rotation). This means that, especially with missions operating far from Earth (such as the Phoenix Mars Lander and Mars Expedition Rovers), very simple and mundane tasks can take hours or even days to complete. One of the main reasons supporting manned exploration of space is that very complex science can be carried out very rapidly (after all, astronauts are human and many robotic operations that take weeks can be completed in seconds). But say if our robotic explorers had a high degree of automation? Say if they could sever the requirement for human input and carry out tasks with intelligent reasoning? As robotic and computer technology increases in sophistication, one Caltech scientist believes space exploration by artificial intelligence is closer than we think…
I remember watching the start of Star Wars: The Empire Strikes Back thinking it was so unfair that Darth Vader and his ilk had access to intelligent space exploration droids that could fly around the galaxy, land on alien worlds and automatically seek out the rebels on Hoth (directing the battle fleet to the icy moon, creating one of the most famous and atmospheric sci-fi battle sequences in movie history. In my opinion at least). But say if we were able to build such “droids” (in fact, droid is a good description of these space explorers, defined as ‘self-aware robots’) that could be sent out into space to explore and report back to mission control without depending on instruction from Earth?
Wolfgang Fink, physicist and researcher at Caltech, believes robotic exploration of space will always take the lead, and even reverse the need for manned missions. “Robotic exploration probably will always be the trail blazer for human exploration of far space,” he says in an interview with Sharon Gaudin. “We haven’t yet landed a human being on Mars but we have a robot there now. In that sense, it’s much easier to send a robotic explorer. When you can take the human out of the loop, that is becoming very exciting.”
While Fink is encouraged by the progress made by missions such as Phoenix and its robotic arm, he is keen to emphasize that the link between human and robot needs to be removed, thus allowing robots to make their own decisions on what science needs to be carried out. In reference to Phoenix’s robotic arm he said, “The arms are the tools, but it’s about the intent to move the arms. That’s what we’re after. To [have the robot] know that something there is interesting and that’s where it needs to go and then to go get a sample from it. That’s what we’ve after. You want to get rid of the joystick, in other words. You want the system to take control of itself and then basically use its own tools to explore.”
An Imperial probe droid from the film Star Wars: Empire Strikes Back (Lucasfilm)
The key attribute robots need to possess is the ability to recognize something of interest, such as a rock or crater, something that a human mind would see as a scientific opportunity. At Caltech, Fink and others are working on programs that use images for robots to distinguish colours, textures, shapes and obstacles. Once artificial intelligence has the ability to do this, if the programming is complex enough, the robot can notice something that is out of place, or a region worth investigating (such as a strangely coloured patch of Mars regolith that a Mars robot will decide to dig into).
As you’d expect, software is being tested and Caltech scientists are beginning to try it out on a rover’s navigation functions. However, the robotic decision-making is very basic presently, but NASA has taken a keen interest in Fink’s work. For example, in 2017 NASA intends to send a robotic mission to Titan, one of Saturn’s moons. In all likelihood the moon will be explored by a balloon-type vehicle. However, it would be impractical for such a vehicle to depend on commands being sent from Earth (as it would take more than an hour for communications to transmit over that distance), so there would need to be a certain degree of automation built into the craft so fast decisions can be made in a dynamic environment such as Titan’s atmosphere.
Although this is all interesting and necessary, there will still be a basic human desire to explore space via manned missions, although a certain degree of self-awareness may be required of our robotic explorers as they carry out reconnaissance trips before we make the trip…
NASA’s Marshall and Ames Research Centers will team up with the commercial space company SpaceX to launch and deploy a solar sail this summer. A bread-box sized payload called NanoSail-D will travel to space onboard a SpaceX Falcon 1 Rocket and if all goes well, it will be the first fully deployed solar sail in space, and the first spacecraft to use a solar sail as a primary means of orbital maneuvering. The first launch window is from July 29th to August 6th, with a back-up window extending from August 29th to September 5th. Weighing less than 4.5 kilograms (10 pounds) the aluminum and plastic sail has about 9.3 m² (100 square feet) of light-catching surface which researchers hope will successfully propel the spacecraft.
Solar sails have been the stuff of dreams for years. Because there’s no friction in space, once a solar sail starts moving, it can go on forever. While rockets would run out of gas and begin to coast, a spaceship powered by solar sails would continue accelerating as long as there is a solar wind, reaching faster speeds and covering distances far greater than any rocket. No rocket has been invented that could carry enough fuel to reach the outer solar system in as short a time. And like a marine sail, a solar sail could also bring you home. You could use the solar sail to travel “against the wind,” back to Earth.
“It’s not so much about how far a sail will go compared to a rocket; the key is how fast,” says Edward “Sandy” Montgomery of NASA’s Marshall Space Flight Center. “The Voyagers have escaped the solar system, and they were sent by rockets, but it’s taken more than three decades to do it. A sail launched today would probably catch up with them in a single decade. Sails are slower to get started though. So, for example, between the Earth and the moon, rockets might be preferred for missions with a short timeline. It’s a trip of days for rockets, but months for a solar sail. The rule of thumb, therefore, would be to use rockets for short hops and solar sails for the long hauls.”
Previous attempts to launch and deploy a solar sail in space have met limited success. In 2004 Japan launched prototype solar sails that deployed, but they weren’t used for propulsion. The Planetary Society attempted a solar sail launch in 2005, called Cosmos 1, but the Russian launch vehicle failed to reach orbit. NASA did successfully deploy a solar sail in a vacuum chamber in 2004, but of course, its propulsive capability wasn’t able to be tested.
Montgomery believes a successful mission would be huge for the future of spaceflight. If successful, solar sails could potentially help with a growing problem of space debris.
“Currently, micro-satellites in orbit above a few hundred kilometers can stay in orbit for decades after completing their mission,” Montgomery said. “This creates an orbital debris collision risk for other spacecraft. NanoSail-D will demonstrate the feasibility of using a drag sail to decrease the time satellites clutter up Earth’s orbit. Although our sail looks like a kite, it will act like a parachute (or like a drag sail) in the very thin upper atmosphere around Earth. It will slow the spacecraft and make it lose altitude, re-enter the Earth’s atmosphere and burn off in a relatively short period of time. A drag sail is a lighter alternative to carrying a propulsion system to de-orbit a satellite.”
Astronomers and cosmologists endeavor to solve some of the great mysteries of the universe. One mystery scientists here at the AAS meeting in St. Louis are seriously trying to address is how to make science more interesting and accessible to the general public. While this issue has little cosmic implications, having a science literate population in our ever-growing technology-based civilization is not just an advantage, but becoming an absolute necessity. In attempt to tackle this concern, a group of astronomers are encouraging others to follow the lead of a concept that seems to be working: Invite the public out for a beer.
Science Cafes, or “Cafe Scientifique,” are billed as places where, for the price of glass of beer or a cup of coffee, anyone can come to explore the latest ideas in science and technology. The people leading these groups are committed to promoting public engagement with science, as well as helping scientists improve their communication skills.
“Beer and science are two things a lot of us love,” said Randy Landsberg, Director of the Kavli Institute of Cosmological Science in Chicago. “We started a Science Cafe just because we thought it would be fun. We wanted to get people engaged to understand the research we’re doing, and researchers to be better at conveying the science. The drinks help.”
Meetings take place in cafes, bars, restaurants but always outside a traditional scientific or academic context.
“We want to provide a fun place to hear about science,” said Landsberg.
The group in Chicago meets at a local establishment that supports the effort by offering free appetizers. Their format is a brief introduction to the topic, (15-20 minutes) with limited visual aids (detailed PowerPoint’s are frowned upon). Then they take a break, get some beer and follow with a question and answer session for about 90 minutes. People can leave anytime they want, and the scientists are monitored. “If the speaker starts talking about derivatives, we try to rein him in,” Landsberg said.
They try to vary the topics. “It’s not all cosmology all the time. We’ve done global warming, flying snakes, biology of gender, and one entitled ‘The Dark Side: from dark energy and dark matter to Washington and science policy.'”
Ben Wiehe, the Outreach Coordinator at WGBH Educational Foundation in Boston, has been instrumental promoting Science Cafes with PBS’s NOVAscienceNOW. “Science Cafes are taking place in a lot of bars, coffeehouses, bookstores, churches, and even hardware stores. You want to go where your audience is naturally gathering anyway,” he said. “If you want teens to show up, you may have to consider whether you want to meet at a bar. But you can choose a library or some other place. Where and when you have your meetings will help determine the demographics.”
Wiehe said “field research” (i.e., checking out the local bars) is necessary to help choose a location. But the main goal of Science Cafes is to reach out to new audiences of people who don’t normally talk about science.
Surveys of Science Cafe attendees are overwhelmingly positive about the experience, with comments like, “I love coming to these. Please do this more!” and “Beer + Intellectual Stimulation = Fun.”
To keep the size intimate, the Chicago group has resorted to requiring tickets (free) to attend. They have 385 people registered on their email list, but want to limit attendance at any one event to 50-70 people.
R. J. Wyatt from the Southern California Academy of Sciences says for their Science Cafes, he likes to get people to consider alternate possibilities. “Sometimes we want to cover topics that are edgy and confrontational,” he said. “If we can assuage anyone’s fears, and get them fascinated about science you can shift people’s thinking in how they think about themselves and their world.”
Venerable cosmologist Michael Turner offered a speaker’s perspective on how to best choose a speaker.
“It’s a theorem that someone who gives a good public lecture is not necessarily a good Cafe Scientifique choice,” he said. “You’re not doing a lecture. It has to be spontaneous and extraordinarily flexible. Shorter is better, and if you’re talking about astronomy you can just show astronomical pictures, and do a four star presentation.”
Turner added, “Loose ends are really important. If you’ve explained everything and its absolutely perfect, then there will be no questions and no follow up. There has to be some ‘hanging chads’ to get people engaged.”
There are many possible “geo-engineering” solutions open to scientists in the aim to stave off global warming. One of the main candidates to dim the solar energy input to the atmosphere is to inject huge quantities of sulphate particles high in the atmosphere. This mimics the emissions from a large volcanic explosion proven to cool the Earth’s atmosphere in the past. But, you guessed it, there’s a problem. New research suggests that tampering with the atmosphere in this way will have serious repercussions for the ozone layer… Now there’s a surprise!
On writing this week’s Carnival of Space, I came across an interesting discussion about the damage that can be caused by scientists tampering with weather. Nancy L. Young-Houser takes the strong view that under no circumstance is it OK to alter natural weather processes, even if the purpose is to advert a catastrophic hurricane or bring rain to drought-ridden regions. Looking at historic examples of cloud seeding for example, Nancy concludes that weather manipulation is not only morally but ethically wrong. There will always be a loser.
Then today, the BBC ran an article on the perils of using high altitude particles to block sunlight from entering our atmosphere. The effect of such a large-scale measure could emulate the ejected particles from a huge volcanic explosion. Sulphide particles are known to be a highly efficient means to deflect sunlight, thus cooling our atmosphere, possibly saving us from the ravages of our self-inflicted global warming. (This effect was observed in the 1991 eruption of Mount Pinatubo, pictured.) But there is a big flaw in this plan according to new research published in Science. Sulphide particles can damage the ozone layer, possibly creating another hole in the ozone over the Arctic and undo the recovery of the Antarctic ozone hole, setting it back decades.
Dr Simone Tilmes of the National Center for Atmospheric Research (NCar) in Boulder, Colorado, and her team analysed data and ran simulations of the sulphide effect on the atmosphere. Their conclusion? Injecting sulphide particles into the high atmosphere may lessen the effects of global warming, but it will also set back Antarctic ozone layer recovery 30 to 70 years. Sulphates are ideal particles on which atmospheric chlorine gases held in polar clouds will attach themselves to (pictured top). A chemical reaction between sulphate particle and chlorine destroys ozone molecules (O3). The effects of this chemical reaction may cause accelerated damage in troubled polar regions. This ozone depletion was also recorded after the Mount Pinatubo eruption.
Attempting to “repair” the global damage we are causing to the atmosphere by injecting even more particles at high altitudes may not be the best way forward. After all, as outlined in Nancy’s article, there are many hidden risks when geo-engineering our atmospheric dynamics. Perhaps working on the reduction in greenhouse gas emissions may be a better idea, sooner rather than later.
One thing is certain, Wolf-Rayet stars produce some interesting
science. In this week’s portrait we see a distorted bubble produced
by a moving star blowing a strong stellar wind into a surrounding
uniform interstellar medium – yet is isn’t uniform. What exactly is
going on here?
Hanging out some 11,736 light years away in the southern constellation
of Carina (RA 10:17:24.0 Dec -57:55:18), NGC 3199 is classed as a
diffuse nebula or supernova remnant. Discovered by John Herschel in
1834, it has been known throughout historic astronomy observations as
bright, large, crescent-shaped nebula with embedded stars, but modern
astronomy shows it as much more. It’s being pushed along by
Wolf-Rayet star 18.
Says Dr. Michael Corcoran: “Wolf-Rayet stars (named for their
discoverers) are very large, massive stars (stars which are about 20
times bigger than the sun) nearly at the end of their stellar lives.
As these stars age, material which the stars have cooked up in their
central nuclear furnaces (like carbon and oxygen) gradually reach the
surface of the star. When enough material reaches the surface, it
absorbs so much of the intense light from the star that an enormously
strong wind starts to blow from the star’s surface. This wind becomes
so thick that it totally obscures the star – so when we look at a
Wolf-Rayet star, we’re really just seeing this thick wind. The amount
of material which the wind carries away is very large – typically, a
mass equivalent to that of the entire earth is lost from the star each
year. The mass loss is so large that it significantly shortens the
star’s life, and as you can imagine has important effects on the space
surrounding the star too. We think that very massive stars become Wolf-Rayet stars just before they explode as supernova (though no one
has yet seen such a star explode).
At magnitude 11, NGC 3199 is observable with larger amateur
telescopes, but the crescent shape is cause for study by some of the
finest research telescopes and astronomers in the world. Through
optical observations, the ring nebula and cavities around WF stars have
painted a history of mass loss in these highly evolved stellar
curiosities. By studying molecular gases associated with Wolf-Rayet
stars, it appears that some materials seem to be avoiding optical
emission.
In reading scientific reports submitted by A. P. Marston, molecular
gas has already been observed around Wolf-Rayet Star 18 – the first to
confirm the presence of HCN, HCO+, CN, and HNC and molecules. This
makes the Wolf-Rayet ring nebula NGC 3199 very unique and filled
associated molecular gas that took the form clumpy ejecta and
interstellar material. At one time, NGC 3199’s formation was believed
to be caused by bow shock, but current data now shows the associated Wolf Rayet star is moving at a right angle to its enveloping
environment. Could this be an indication that something else is at
work here? Astronomers seem to think so.
According to their information, it is possible the northern area of
the optically bright nebula is being torn apart by a possible blowout
of Wolf Rayet wind. This, in turn, affects the surrounding ejecta and
could very well account for the observed velocity. By modeling
molecular abundances, the central Wolf Rayet star could be contributing a
portion of its material to this nebula as ejecta. Despite its still
unsolved mysteries, NGC 3199 is a stunning portrait. J.E. Dyson and
Ghanbari summed it up best when they described it as an “interstellar
snow plough”.
Says Ken: “This image was taken using an Apogee CCD Camera that uses primarily Narrow Band data which is color mapped mixed with RGB for natural star colors and back ground balancing. The bright blue area shows lots of OIII (ionized oxygen) signal which really shows the direction of the star movement well. The star is said to be moving at about 60 km/s through the interstellar gas.”
