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Nature’s Spectacular Show – the Northern Lights

Most people have heard of the aurora borealis  more commonly known as the northern lights – even if they have never actually seen them. And if you have been lucky enough to observe this truly spectacular natural phenomenon, you will probably agree that it is one of the most dramatic sights that Mother Nature can offer putting most firework displays to shame.The Northern Lights have been occurring for thousands of years  long before anybody had a scientific explanation for them. Many primitive people regarded the lights as an omen of war or misfortune; some Eskimo groups believed the lights were the spirits of children who had died at birth, or animal spirits dancing. The Algonquin Indians even believed that the lights were reflections of huge fires, constructed by the creator of the earth, Nanahbozho. In medieval Europe, the lights were said to foretell of famine, war or other disaster.

The lights are actually caused by the earth’s magnetic field interacting with solar winds, creating a type of light known as an aurora. As well as emitting heat and light, the sun also emits gas, sometimes known as solar wind. Upon reaching the earth, this gas will collide with the earth’s magnetic field and create energy. The excess energy created by these collisions is given off in the form of light emissions what we call the northern lights.One of the fascinating things about seeing the northern lights is that the patterns and colors are constantly changing no two nights are exactly the same. The most common color is green, although just about any color red, blue, yellow or purple  can occur in more intense light displays, making the experience even more dramatic. The green color is created by oxygen molecules that are found about 60 miles above the earth; different types of gas particles help to create the other colors. Many people claim that the lights resemble a spectacular sunset or sunrise.

The lights actually occur during the day as well, although it’s virtually impossible to see them. The northern lights do occur year round, but the best time of year to observer them is during the equinoxes  March/April and September/October. They also follow a cycle of about 11 years and scientists have determined they will be at their peak in 2013. At night, the best view of the lights is enjoyed with a clear sky, and no street lighting or other bright lights nearby. In general, if the sky is clear enough to see the Milky Way, your chances of seeing the northern lights are good.

The northern lights occur most frequently in the areas around both the North and South Poles, due to the strong magnetic fields found here. For this reason, the further north you travel, the better your chances of seeing the lights, although they have been seen as far south as Texas and Georgia. In Europe, Iceland and Scandinavia are ideal places to see them; and in North America, the best view is from Alaska and parts of Northern Canada. There are actually southern lights as well  known as aurora australis  although they can only be seen from parts of  Australia, Antarctica and South America

Solar Sailing Comes of Age With IKAROS and Lightsail I

This is an article about lightsails, an idea that has been around for a long time, and is now approaching reality.  Both the Japan Aerospace Exploration Agency and America’s Planetary Society have plans underway to launch and test prototype lightsails.  The two projects are not in competition with each other, but are working together in a complementary effort to initiate and explore this new lightsail technology, which ultimately promises to be one of the most revolutionary concepts in space exploration.For space kids who grew up reading science fiction, this idea requires no explanation.  For those unfortunate readers who did not have this experience, we offer this quick summary:

The warm, gentle sunlight that we feel here on Earth is really only a tiny fraction of the sun’s full output.  Even the hottest places on Earth- say, Death Valley or the Sahara Desert- are only receiving a small percentage of the solar radiation that hits the atmosphere above them.  Luckily for us, we are protected from most of it by that thick blanket of air.  Outside of that protection, the wind from the sun is a blasting torrent, a constant tsunami of radiation and particles.And of course, sunlight exerts a certain amount of pressure.  The pressure is very weak down here on Earth, but if you get off the Earth and move into the full blast of the solar wind, everything changes.  Suddenly you’re in the full tsunami, and the pressure exerted by it is much greater.

Consider what you’ve got here.  It’s a stream of propulsive force which, in human terms, is inexhaustible- and unlike the intermittent thrust of rockets, this is constant propulsion, which allows you to build up enormous speed over time.  In the world of space exploration, this is the Holy Grail.  It is the thing that can finally free us from that necessary evil of space flight: fuel.  The sad fact is that when you’re using conventional rockets, the fuel is the biggest part of the weight.Now, we’ll always need a big push to get out of the atmosphere and attain orbital velocity, and chemical rockets are still the only way to get that (though other ideas have been discussed- more on this in future articles).  However, once you get into orbit and you’ve got all that sunlight,  why not use it?  Throw out a kite and ride

That’s the definition of a lightsail: a kite that uses the solar wind to move a spacecraft.  In the old days, this was pure sci-fi, because we didn’t have any materials that were strong and light enough to do the job, but recent advances in materials science have provided lightweight plastics that are bringing the goal within reach.   Not only that, but we now have a couple of possible embellishments that build on the basic concept and use the power of light in different ways.As mentioned above, there are actual prototypes being readied for launch this year.  The Japan Aerospace Exploration Agency, a rising power in the field of space exploration, is planning to send up a craft called IKAROS in May.  In an effort to cut costs, the craft will be launched aboard the same rocket with Japan’s Venus Climate Orbiter, the partner to the European Space Agency’s Venus Express which we discussed a few weeks ago.

IKAROS takes the idea of a lightsail a step or two further.  Here, the plastic membrane is not only used for propulsion, but also contains three other systems: a thin-film electrical power generation system, a set of steering devices and a dust-counter.  They do all this on a layer of polyimide that is only .0075 mm thick.  When fully deployed, IKAROS will be a square with a diagonal length of 20 m.  Its mission will be in two stages. In the first stage, the sail will be deployed and used to generate electricity. This will be the first time a lightsail has been used for this purpose, and if the mission ended right there, it would have already started a revolution in the field of space electronics.

But hopefully, IKAROS will keep on going. The second phase of its mission is to actually use solar power to navigate the craft.   The destination of IKAROS is uncertain, but it will be steered toward Venus.  As mentioned above, it will be sent into orbit on the same rocket with the Venus Climate Orbiter, and hopefully both craft will eventually arrive at that planet.IKAROS is the first of two proposed Japanese missions.  The second one will take place in the late 2010’s, and will consist of a hybrid craft which combines all of the technology of IKAROS with an ion propulsion system.

The ion drive uses electricity generated by solar power to excite xenon fuel.  The excited fuel is focused into a jet by passing it between two powerful magnetic fields, and leaves the engine at high velocity.  The advantage of an ion engine is that the xenon fuel is capable of delivering a large amount of thrust in proportion to its weight, which means that a spacecraft can carry enough fuel to keep going for years.When you combine this system with the lightsail idea, you get a hybrid craft that can use both systems to maximum advantage.   For instance, such a craft might use its lightsail while it’s near the sun, riding the solar wind and storing up electricity.  Later, when it gets farther out where the sunlight is weaker, it might fold up its sail and use the stored electricity to run the ion drive.

Here in the US, the Planetary Society is making its second attempt at testing a lightsail.  Their first one, Cosmos I, was tragically lost when its launch rocket crashed, but now the Society has embarked on an ambitious project to deploy three sails over the next few years.   While the Japanese project is focused on broad technologies that will be used for multiple projects in the future, the Planetary Society is focusing more on practical and specific jobs, such as monitoring the sun for solar storms and providing stable Earth observation platforms.

Their first sail, Lightsail I, will be launched this year and will demonstrate the deployment of the sail and its use for propulsion.  The second sail will do the same, but will move to a much higher Earth orbit.  The third sail in the Planetary Society’s program will leave Earth orbit and navigate to the Earth-Sun libration point, L1.  This will be an ideal location for weather-sensing satellites and other devices, which in the future will hopefully be propelled into their positions by lightsails.

The Planetary Society’s ambitions are set on greater goals someday.  Louis Friedman, the Society’s executive director, recently posted an article on their website about the glowing possibilities offered by this line of research.  One possibility that he brought up is the idea of using a lightsail with an Earth-based laser for propulsion instead of sunlight.  With something like that, you could send a beam of coherent light at another star and ride it all the way there.  When you arrived, you could set up another laser and point it back at Earth, then ride the beam back home.  Whereas the basic solar sail idea only allows travel within the solar system, the laser idea could give us access to the stars.


It’s a long way off, but someday it could happen. In the meantime, we need to do the basic groundwork, and that’s what’s about to happen.  Both the JAXA craft and Lightsail 1 will go up this year, and the results of those projects will show the way to the future.In 1964, Arthur C. Clarke wrote a short story called “The Sunjammer,” which was about a race between solar-propelled spacecraft.  It was published in a popular boys’ magazine, and was read by a whole generation of kids in love with space.  Some of those kids are probably working on these projects today- and some of them are also reading and writing about them.Stick with us, and you won’t miss a thing.ESA’s Venus Express Is Answering Questions
 About the Sun’s Second Planet
This is the second of our articles about the recent achievements of the European Space Agency. Since 2003, the ESA has launched three similar missions: the Mars Express probe in June 2003, the Rosetta comet mission in March 2004 and the Venus Express mission in November 2005. Last week, we took a look at Mars Express, which has provided us with stunning pictures and science from the red planet. In this article, we will look at Venus Express, which has been equally successful in sending back data on that planet. Next week, we will discuss the Rosetta comet mission.


These three missions are really just variations on the same theme. The probes themselves are very similar to each other, using many of the same kinds of equipment and ground facilities and even some of the same personnel, which made the design and preparatory phases much quicker and easier than if each mission had started from scratch. The word “Express” in the names of the Mars and Venus probes refers to the fact that they were constructed and launched in record time, and with relatively low cost. Besides being stellar achievements in space science (pun intended!) they are also models of the kind of faster and more efficient missions that have become the norm in recent years. These missions prove the point that while space exploration will always be an expensive and lengthy undertaking, there are ways to greatly limit the cost and the amount of time needed for preparation.

Venus Express was launched from Baikonur, Kazakhstan on November 9, 2005 aboard a Soyuz-Fregat launcher. It traveled through space for 155 days, arriving at Venus in April 2006. Its mission was primarily to study the atmosphere and weather patterns on Venus, which are quite different from the kinds of patterns that we see here on Earth, despite the basic physical similarity of the two planets. The mission’s assignments included several firsts on Venus:
1. First global monitoring of the composition of the lower atmosphere in near-infrared transparency “windows.”
2. First coherent study of atmospheric temperature and dynamics at different levels of atmosphere, from the surface up to 200 km.
3. First measurements from orbit of global surface temperature distribution.
4. First study of middle and upper atmosphere dynamics from oxygen and nitrogen oxide emissions.
5. First measurements of non-thermal atmospheric escape.
6. First cohereionospheric structure.nt observations of Venus in the spectral range from ultraviolet to thermal infrared.
7. First application of solar/stellar occultation technique at Venus to analyse how light is absorbed by the atmosphere, revealing atmospheric characteristics.
8. First use of 3D ion mass analyser, high-energy resolution electron spectrometer and energetic neutral atom imager.
9. First sounding of top-side
Venus Express was designed to address several open questions suggested by previous research. One of the most baffling mysteries is the cause of the super-fast atmospheric rotation and hurricane-force winds that have been observed on Venus. The Venusian atmosphere is whipping around the planet in a vast, global motion that is more than 60 times the speed of the planet’s rotation. This is a mystery, since such rapid motion cannot be explained by any conventional theory of atmospheric dynamics. Venus Express was designed to study the atmosphere in an effort to discover where all that energy is coming from. Another mystery is the double atmospheric vortex that has been observed at both Venusian poles, and has persisted for the entire observation period. The fact that similar features exist at both of the Venusian poles indicates a global symmetry that has so far eluded explanation. Scientists do not know how these features maintain their shape, and will be observing them closely in an attempt to figure out their dynamics.

Another part of Venus Express’ mission was the study of certain mysterious ultraviolet markings that have been seen at the tops of Venusian clouds. The upper clouds have areas visible in the ultraviolet that mysteriously absorb half of the solar energy received by the planet. The origin of these markings, and their remarkable absorption power, were among the questions being asked by Venus Express.

While the probe was designed to study the composition and dynamics of the Venusian atmosphere, it is also able to gain some information about the surface underneath that atmosphere. For instance, one of the questions regarding Venus is the nature and extent of volcanic activity on the planet, and how recently that activity occurred. Because it is capable of compiling detailed data on the temperature distribution and chemical composition of the atmosphere, Venus Express is capable of sensing both the heat of a volcanic eruption, and the chemicals that such an eruption would release into the air. By doing this, the probe should be able to spot places where eruptions have happened recently and determine how frequently they have occurred. In addition, Venus Express should be able to obtain valuable data on surface temperature, mineralogy, chemical weathering and the occurrence of earthquakes.

 
Since Venus Express has been in orbit around Venus for some time now, it has been able to obtain preliminary data on some of these questions. The picture that is emerging is of a planet that has changed radically from its earlier days. While Venus is hot and dry today, there is growing evidence that it may have been much more earthlike in its infancy.

For instance, Venus Express has observed that there is a color difference between the highland regions of Venus and the lowlands. On Earth, such a color difference would indicate that the highlands are composed primarily of granite. Granite is a relatively light rock formed by the action of water on basalt. In order for large amounts of granite to be present on the planet today, there must have been a lot of water sometime in the past.In fact, theories of planetary formation would lead us to think that Venus and Earth started out with similar amounts of water. The two planets were formed from the same protoplanetary material, and were subjected to the same cometary bombardment in the early history of the solar system. Because of this, there is every reason to think that the two planets were once much more similar than they are today.

On Earth, granite literally floats on the heavier molten rock underneath, and forms the basis of the continents. So, when we look at Venus today and see highland regions that resemble the continental masses of Earth, the obvious conclusion is that these are the ancient continents of Venus, and that they were once surrounded by oceans as extensive as those on Earth. We are looking back billions of years, to a time when Venus, once called “Earth’s twin,” may have really deserved that title.The question is unavoidable: was there life? Given the data that we have at the moment, we can’t answer that question- but it certainly is an intriguing possibility.

There is also some new data on the UV markings at the polar regions. It has been determined that these are caused by plumes of UV-absorbing material that has been brought up from deep in the atmosphere by convection currents. In other words, these UV-absorbing regions are really just the tops of tall columns of material. Where they well up, areas of high absorption are created, and the areas where they do not appear remain UV bright. That’s the phenomenon that is taking place, but the reason for it, and the exact nature of the absorbing material, are still unknown.

In regard to the vortexes at the north and south poles, we now know that they are much more variable than was originally thought. Observations on successive orbits have shown that the formations change their shape quickly and extensively, sometimes forming two separate “eyes” and sometimes a single oval or circular formation. A classic “eye of the hurricane” shape has been observed at the center of the south polar vortex. The dynamics of these features seem to be very complex, and will warrant much observation in the future.

Venus Express has also seen an eerie infrared glow in the night-time atmosphere of Venus, caused by nitric oxide which is produced when the sun’s radiation bombards the atmosphere and breaks up molecules, which recombine and release energy in the form of infrared light. This night glow can tell us much about the composition and movement of the atmosphere.

These are only a few of the things being learned from Venus Express. A full discussion of the data is far beyond the scope of this humble article. (For those who want more detail, the ESA website provides fascinating reading.) The probe continues to function well, and its mission has now been extended through December of 2012. Considering the huge success of the mission so far, we can only expect more great things in the future.As new data comes in, it will be covered here. Watch this site for updates.

Sources:Space Topics: Venus Express at website of the Planetary Society: planetary.org/explore/topics/venus_express/

NASA’s EPOXI Probe: Deep Impact Is Reborn

This is another one of our articles about the new things we’re learning regarding comets.  It’s also about the amazing ingenuity of the folks at NASA, who have taken the “faster, better, cheaper” ethic to heart in ways that are truly impressive.  The Deep Impact mission made history when it impacted the comet Tempel 1, and the information yielded by that encounter  will be analyzed for years to come.  Now Deep Impact has been given new life and renamed EPOXI, beginning a whole new chapter in the mission.  The probe is already giving us valuable data from beyond the solar system, and after that, there’s another comet waiting for it.

Deep Impact started out as a neat, straightforward mission.  The idea was to get close to a comet, hit it with a projectile, and observe the ensuing dust cloud for scientific data.  The spacecraft was launched on January 12, 2005, from Cape Canaveral.  After about seven months in flight, it reached its destination, the comet Tempel 1.  On July 2, Deep Impact released its “impactor,” which had its own power source and was designed to operate autonomously for just one day, long enough to move itself into the path of the comet and hit it.  About 24 hours later, the impactor successfully performed this maneuver, taking some spectacular pictures during the approach.  The actual moment of impact was recorded by the larger Deep Impact probe, which was watching from about 300 miles away.

The impact caused a brilliant flash of light, illuminating the side of the comet facing the probe: a battered little world covered with craters and other scars.  The cloud of debris was bright and larger than anticipated.  While planetary scientists were expecting the collision to throw up some liquid water with chunks of rock and ice, what they actually saw was more fine and powdery.  Because of this, it was not possible to see the resulting crater, and its exact size remained a mystery.But it certainly made a nice plume, and this was observed by the Deep Impact probe itself and by the Spitzer Space Telescope, which is in an Earth-trailing solar orbit.  Scientists will be mining information out of this data for a long time, but already they have gotten some interesting facts.  Spitzer obtained spectrographic information, and analysis of this has revealed the signatures of a list of chemicals- they’re calling it “comet soup.”

Some of the ingredients are not surprising: silicates (sand) which were already known to be standard comet components.  But here’s a real head-scratcher: the plume from Tempel 1 also contained clay and carbonates.  What’s strange about them is that they are only supposed to form in water.Commenting on this, Dr. Carey Lisse of Johns Hopkins University’s Applied Physics Laboratory said, “How did clay and carbonates form in frozen comets?  We don’t know, but their presence may imply that the primordial solar system was thoroughly mixed together, allowing material formed near the sun where water is liquid, and frozen material from out by Uranus and Neptune, to be included in the same body.”

This goes along with findings from the Stardust probe featured in one of our earlier articles, which took samples of dust from comet Wild 2,  in which materials that could only have formed in extreme heat were found.  Since these particles were encased in the ice of the comet, it is obvious that the different components of the comet were formed in different places, and then somehow combined.Spitzer also spotted some substances that have never been seen in a comet before, such as iron-bearing compounds and aromatic hydrocarbons, which can be found more commonly in car exhaust and barbecue pits.

We will certainly hear more from the ongoing analysis of that data, but meanwhile, Deep Impact is moving on to bigger and better things.The probe is still operational, and NASA has big plans for it.  It has been renamed EPOXI, and is actually two missions combined: a search for extrasolar planets and another comet investigation.
In July 2007, NASA announced that the Deep Impact mission would be extended to include a second encounter, this time with the comet Boethin.  That would be an impressive accomplishment, but there might be a problem: the orbit of this comet was not known with absolute certainty.  It had only been seen twice ever, and the most recent sighting was more than twenty years ago.  To make the necessary course alteration, the probe was going to make a flyby of Earth and use the planet’s gravity to bend its path.  In order do this accurately, it would have to make its approach to Earth at exactly the right angle, so that it would emerge from the maneuver headed in the right direction.  The probe was in hibernation following its encounter with Tempel 1, and would only wake up when it was close to Earth.  The NASA scientists would have to find the comet quickly and calculate exactly what the angle of the flyby should be.

Unfortunately, it didn’t work.  When the probe came out of hibernation, the ground crew looked for comet Boethin, and it wasn’t there.  The approximate orbit of the comet had been calculated from the two sightings that had been made, but the calculations were obviously off.Time was wasting; the flyby of Earth was approaching, and NASA couldn’t find its target.  A desperate decision was made: pick another comet, quick!

They picked a comet called Hartley 2.  This was actually a better target because it had been extensively observed, and its orbit was known accurately.  However, the new course would take two years more than the mission to Boethin would have, and the cost would be correspondingly higher.  That cost had not been taken into account when the original budget was drawn up, so the extension would require new funding.

There was no time for a budget meeting.  The mission team made the Earth flyby and sent the probe off toward Hartley 2, thus obligating NASA to pay for two more years of mission time.  Luckily, their bosses were understanding, and NASA increased the mission’s funding to include the extra expense.That encounter will happen in November of this year.  Until then, EPOXI has its work cut out for it- and here we get into the other part of the extended mission.  In a complete departure from its original purpose, the probe is going to do some searching for planets around other stars.
It all came out of an earlier exercise in the Deep Impact itinerary.  When the probe was near Earth, it performed a series of observations of this planet.  As much as we know about our home world, there’s always room for more knowledge, and it was thought that Deep Impact might be able to yield some interesting science.It certainly did.  The NASA scientists found that by analyzing the sunlight glinting off the Earth, they could tell what kind of terrain was passing by.  Not surprisingly, the oceans reflected a lot more sunlight than the land did, and water, soil, vegetation etc., all reflect different wavelengths.  By analyzing the light, it was possible to tell whether land or water was passing underneath the probe.  It was also easy to detect the presence of vegetation, as this caused a bright glow in the infrared just above the visible light range.

This was something new.  Reading the accounts at the NASA website, you get the feeling that the space boys were really surprised at the degree of detail and accuracy that they were able to achieve, and it suggested a whole new purpose for this mission.  On the way out to comet Hartley 2, EPOXI can stay busy by scanning stars and looking for glints of sunlight from them.  A brilliant gleam can only mean one thing: water.  In nature, only water, either in its solid or liquid form, is smooth and reflective enough to do that.  Even if we don’t see that, slight changes in the light reflecting from an extrasolar planet may tell us what kind of terrain it has, or maybe even reveal the presence of vegetation.

This research has already yielded some interesting results.  The probe has scanned seven stars, and while it hasn’t found the telltale glint of oceans, it has found a new planet.  It’s a “hot Neptune,” a planet roughly comparable to Neptune in size, but orbiting very close to its parent star.  While extrasolar planets aren’t the big news that they once were, there is always the chance that EPOXI will turn up something really big.  An extrasolar planet with water oceans would be a revolutionary discovery, and this could be the way we find one.

Considering the fact that this angle of research had not even been thought of when the mission started, the NASA folks certainly deserve high marks for resourcefulness and ingenuity.Check back here for updates.  When EPOXI encounters Hartley 2 in November, we will cover it, of course.  Stick with us, and you won’t miss a thing.

Sources:
Deep Impact: MIssion to a Comet at NASA website:  nasa.gov/mission_pages/deepimpact/media/spitzer-di-090705.html

 

 

 

Russia Considering Asteroid Apophis Mission

It is known that the planet Earth has suffered collision events in its past history and is generally accepted that this will happen again at some time in the future. One of the most serious events in recent history occurred in 1908 when a 100 foot asteroid crashed into a remote area of Siberia and devastated an area 1,200 square miles in size. However there are a number of known asteroids which are far greater than 100 foot in size and these include one known as Apophis which was first identified in 2004. This asteroid is expected to pass earth again in 2029 with the chances that it will collide with Earth being estimated at 1 in 250,000. However the Russian Space Agency take the threat from this seriously enough that they recently announced they are considering launching a mission to deflect the asteroid.

When it was first identified in 2004 Apophis caused some concern as initial observations indicated a small chance that it would collide with Earth during its 2029 pass of the planet. At an estimated size of around 1000 feet this had the potential to be a serious impact event. However additional observations discounted the possibility of a collision in 2029 although they showed that the course of the asteroid could possibly take it through a gravitational keyhole at this time. These are small regions in space that can alter an asteroids course in such a way that on its subsequent pass it could collide with the Earth. If Apophis passed through such a region it was considered that it could set up an impact event in 2036.

This threat was taken seriously enough that Apophis remained on the Torino impact Hazard scale until 2006. This scale is a method of categorizing the potential danger of an asteroid and runs from 0 to 10. An asteroid classified with a 0 rating has a negligible chance of colliding with Earth while a classification of 10 means that a collision is certain. Asteroid Apophis was classified as a 4 for a short time although further study showed that it was unlikely that it would pass through a gravitational keyhole and it was subsequently downgraded to a 0.However a number of scientists still consider that Apophis warrants further study to assess its threat. In 2008 the Planetary Society organized a competition to design a space probe which could be used to track the asteroid and awarded $50,000 in prize money to the winners. The European Space Agency, NASA and other research groups have also studied ways in which Apophis or other similar asteroids could be deflected from an Earth bound course.

The latest view of the threat that Apophis poses came from the Russian Space Agency at the end of December 2009. Anatoly Perminov currently heads this organization and in a radio interview he indicated that they were planning a meeting to discuss the possibility of a mission to Apophis. Although no detailed information was given, Perminov indicated that other agencies such as NASA and the Chinese and European Space Agencies may be invited to join any subsequent project that the Russian Space Agency plans. Whether this comes to fruition remains to be seen.

Whatever the outcome of the latest discussions regarding Apophis, it is generally accepted that at some point in the future an asteroid is likely to be found that is on a collision course with Earth. Recent advances in technology such as the WISE telescope and projects such as NASA’s Near-Earth Object Program are likely to identify many new asteroids in coming years. While the majority of these will pose no threat to Earth it cannot be discounted that a number of dangerous asteroids will be identified. Studying strategies for dealing with such a threat is best done as early as possible and while Apophis itself may not turn out to be dangerous it may help to spur agencies and research groups into taking action which could prove to be beneficial in the long run.

WISE Opens Its Eyes and Gives Us a
New Window on the Universe

On December 29, 2009, the world got a new window on the cosmos. That was the day that NASA’s WISE Wide-field Infrared Survey Explorer, in orbit around Earth, shed its protective cover and began its mission: compiling the most complete and accurate map of the sky at mid-range infrared wavelengths to date. WISE will be able to detect objects that are too dark to emit visible light, but which do emit heat. This will include everything from galaxies billions of lightyears away, to near-earth objects (NEOs) such as asteroids and comets.

In addition to adding enormously to our scientific knowledge, some of this information may be of vital interest, since it will be our best survey of NEOs so far. If one of these objects is heading for Earth, WISE will probably be the instrument that detects it.WISE was launched on a Delta rocket on December 14, and after a few weeks of prepping the satellite, NASA jettisoned the cover that had kept the sensitive instrument cold. Since WISE sees in the infrared, it could pick up its own heat, which would ruin the data being collected. To guard against this, it was cooled with frozen hydrogen and sealed in a vacuum container similar in principal to a Thermos bottle.

Now that it is in orbit and without its cover, the vacuum of space will serve the same purpose, but even better. At the moment, the instruments on the satellite are being calibrated, and observations will begin shortly. WISE will spend eighteen months surveying the sky, at which time it should have exhausted its supply of internal coolant. At that time, the mission will be over.
What are some of the things that WISE might find? Scientists have high expectations.

This mission will build on the findings of two earlier infrared missions, COBE and IRAS. To get an idea of how big an improvement WISE is over its predecessors, consider this: while IRAS, which went up in the 1980’s, had only 62 pixels in its cameras, each of WISE’s four cameras has over a million. With eyes like that, it should be able to see a lot.
You can get an idea of the kind of science that will be done with WISE by considering the things it can see. The wavelengths that the satellite can detect fall into four bands:

Band 1: 3.4 microns- This is a broad filter to detect stars and galaxies.Band 2: 4.6 microns- This is radiation from things that are too cool to be stars, but have some internal heat- in other words, brown dwarfs.Band 3: 12 microns- This is the wavelength at which asteroids radiate in the infrared.Band 4: 22 microns- At this wavelength, relatively cold things will be revealed, such as the dust of star-forming regions.

WISE will orbit Earth from pole to pole, surveying strips of the sky with each passage.

This will allow each spot in the sky to be imaged many times, and by comparing the images, NASA scientists will be able to detect any that show visible movement over a short period of time. By doing, this, they will identify asteroids within the solar system, most of which are in the main asteroid belt between Mars and Jupiter. This will give us our first really accurate map of the asteroids in our system.
In addition to these nearer objects,

WISE will be able to pick up the faint warmth of brown dwarfs. As stated above, these are bodies that are almost massive enough to become stars, but not quite. They never achieve nuclear fusion, the fundamental characteristic of stars, but they do emit some infrared radiation. It is possible that one or more brown dwarfs exist close to the solar system, but have remained undetected before now. WISE will find these objects, if they’re out there, and should even be able to pick up the glow from any planets that orbit them.

There is no reason why a brown dwarf should not have planets, though it is unclear whether they could support life.
It is also hoped that WISE will show us the brightest galaxies in the universe. In addition to the faint objects that it will detect, the telescope will pick up infrared radiation from brighter sources, such as galaxies bursting with the heat of trillions of suns.

These ultraluminous infrared galaxies, or ULIRGs, are almost undetectable in visible light surveys, and may not have been found before.
Other things that WISE is expected to see include young stars and the discs of planetary debris that surround them, clusters of galaxies in the distant, early universe, and a detailed view of our own Milky Way galaxy. In doing this, it will give the best view yet of the evolution of stars, protoplanetary discs, galaxies and clusters of galaxies- in other words, the universe from the bottom up.

The WISE mission promises to be a gold mine, providing enough data to keep the worthy scientists of NASA working for years. Unfortunately, we will have to wait a little while to see any results. The WISE data will be released in two stages. A preliminary release is scheduled to take place six months after the end of the mission, or about 16 months after launch, and a final release is scheduled for 17 months after mission’s end, or about 27 months after launch.

Study of the Sun to Take a Leap Forward in 2010

The study of the Sun has long been an important part of astronomy and the recent successful launch of the Sunrise Telescope helped to move this forward by producing stunning images of the Sun’s surface. The Sunrise Telescope is launched into the stratosphere carried by a giant helium balloon and will only spend a limited time observing the Sun. However NASA is also planning a more permanent observatory which will be launched into orbit around Earth.

This new mission is known as the Solar Dynamics Observatory (SDO) and the design and build phase of the instrument is nearing completion. With a launch date for the mission currently planned for early 2010, our knowledge of the Sun is about to take a giant leap forward.
The SDO mission is the first in NASA’s scientific program called Living With a Star (LWS).

This program is being put in place to further our knowledge of solar variability and the impacts that this has on our planet. The SDO mission itself was designed with the aim of studying the solar atmosphere in an attempt to understand its influence on Earth and near-Earth space.
The planning and development of the project is being undertaken by NASA’s Goddard Space Flight Centre and they will also be responsible for managing the operational phase of the mission once its gets underway. Important milestones in recent months have included moving the instrument to Kennedy Space Centre where it is undergoing final testing to ensure it can withstand the rigors of being launched into space and also the conditions it will face during its life orbiting the Earth.

A launch date is expected in early 2010 with the mission planned to run for an initial 5 year period.
The aim of the SDO mission is to study how the magnetic field of the Sun is generated and converted into solar activity which comprises solar flares, solar wind and coronal mass ejections. Solar flares and coronal mass ejections can discharge millions of tons of charged particles and solar material into interplanetary space at millions of miles per hour and this can stream towards Earth on the solar wind. This is generally known as space weather and can be potentially dangerous to astronauts in outer space as well as posing problems for technology on and around Earth including satellite communications, electricity supply and navigation systems.

The observatory will be put into an orbit where it can monitor the Sun continuously during its 5 year mission and the three scientific instruments on board will be capable of taking a range of measurements. These instruments will work simultaneously and they include the Extreme Ultraviolet Variability Experiment (EVE) which will measure the Sun’s ultraviolet brightness as often as every ten seconds to record changes in this. The Helioseismic and Magnetic Imager (HMI) will measure sound waves bouncing around the interior of the Sun and also the strength and direction of magnetic fields on its surface which should allow a picture of the Sun’s interior to be built up.

The Atmospheric Imaging Assembly (AIA) will take pictures of the various layers in the Sun’s atmosphere in an effort to understand how changing magnetic fields release the energy which leads to solar flares and coronal mass ejections.
Together the suite of instruments on SDO will result in observations that should help scientists gain a much fuller understanding of the complex solar dynamics which impact on Earth and the near-Earth environment. Ultimately this should lead to the development of a capability for assessing and predicting solar variations and this should help to provide an early warning to any potential problems heading our way as a result of solar activity. 2010 should be an exciting year in the continued study of the Sun and with the recent success of the Sunrise Telescope and the operational capabilities of the Solar Dynamics Observatory our knowledge of the Sun could take a giant leap forward in the near future.

Sources:
WISE mission page at NASA website: wise.ssl.berkeley.edu/

 

    


 

 
 

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