A 'rainbow' appears on this image from the Lunar Reconnaissance Oribiter
[/caption]
Even though it is not the mind-blowing experience of a double rainbow all the way across the sky, seeing a rainbow on the Moon is pretty unusual. This curious image from the Lunar Reconnaissance Orbiter shows a rainbow effect across 120 km of the lunar surface. And although water has recently been found on the Moon, water droplets have nothing to do with this rainbow. It comes from illumination conditions and viewing angles with having the Sun directly overhead of the LRO and the Moon.
“This image was acquired as the Sun was exactly overhead, allowing us to observe the ‘opposition surge,’said Brent Denevi, writing on the LRO Camera website. “This is a surge in brightness that occurs when the Sun is directly behind the observer because of two effects. First, there are no shadows seen on the surface, because each boulder and grain of soil’s shadow is hidden directly beneath it. Second, as the light reflects back to the observer it constructively interferes with itself.”
It is a very cool effect, giving the Moon a look having some unexpected color. Denevi said images that contain this type of effect are not just pretty, but useful, too. “They provide a huge new dataset for studying how light interacts with a particulate surface at different wavelengths,” he said. “Perhaps an esoteric-sounding field of study, but this data can help us understand the reflectance images and spectra we have of the Moon and other bodies throughout the Solar System.”
And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, let Fraser know if you can be a host, and he’ll schedule you into the calendar.
X-47B conducting a midair refueling run in the Atlantic Test Ranges. Credit: US Navy
The field of aviation has produced some interesting designs over the course of its century-long history. In addition to monoplanes, jet-aircraft, rocket-propelled planes, and high-altitude interceptors and spy craft, there is also the variety of airplanes that do away with such things as tails, sections and fuselages. These are what is known as Flying Wings, a type of fixed-wing aircraft that consists of a single wing.
While this concept has been investigated for almost as long as flying machines have existed, it is only within the past few decades that its true potential has been realized. And when it comes to the future of aerospace, it is one concept that is expected to see a great deal more in the way of research and development.
Description:
By definition, a flying wing is an aircraft which has no definite fuselage, with most of the crew, payload and equipment being housed inside the main wing structure. From the top, a flying wing looks like a chevron, with the wings constituting its outer edges and the front middle serving as the cockpit or pilot’s seat. They come in many varieties, ranging from the jet fighter/bomber to hand gliders and sailplanes.
A clean flying wing is theoretically the most aerodynamically efficient (lowest drag) design configuration for a fixed wing aircraft. It also offers high structural efficiency for a given wing depth, leading to light weight and high fuel efficiency.
A Junkers G 38, in service with Lufthansa. Credit: SDASM Archives
History of Development:
Tailless craft have been around since the time of the Wright Brothers. But it was not until after World War I, thanks to extensive wartime developments with monoplanes, that a craft with no true fuselage became feasible. An early enthusiast was Hugo Junkers who patented the idea for a wing-only air transport in 1910.
Unfortunately, restrictions imposed by the Treaty of Versailles on German aviation meant that his vision wasn’t realized until 1931 with the Junker’s G38. This design, though revolutionary, still required a short fuselage and a tail section in order to be aerodynamically possible.
A restored Horten Ho 229 at Steven F. Udvar-Hazy Center. Credits: Cynrik de Decker
Flying wing designs were experimented with extensively in the 30’s and 40’s, especially in the US and Germany. In France, Britain and the US, many designs were produced, though most were gliders. However, there were exceptions, like the Northrop N1M, a prototype all-wing plane and the far more impressive Horten Ho 229, the first jet-powered flying wing that served as a fighter/bomber for the German air force in WWII.
This aircraft was part of a long series of experimental aircraft produced by Nazi Germany, and was also the first craft to incorporate technology that made it harder to detect on radar – aka. Stealth technology. However, whether this was intentional or an unintended consequence of its design remains the subject of speculation.
After WWII, this plane inspired several generations of experimental aircraft. The most notable of these are the YB-49 long-range bomber, the A-12 Avenger II, the B-2 Stealth Bomber (otherwise known as the Spirit), and a host of delta-winged aircraft, such as Canada’s own Avro-105, also known as the Avro Arrow.
Recent Developments:
More recent examples of aircraft that incorporate the flying wing design include the X-47B, a demonstration unmanned combat air vehicle (UCAV) currently in development by Northrop Grumman. Designed for carrier-based operations, the X-47B is a result of collaboration between the Defense Advanced Research Projects Agency (DARPA) and the US Navy’s Unmanned Combat Air System Demonstration (UCAS-D) program.
The X-47B first flew in 2011, and as of 2015, its two active demonstrators successfully performed a series of airstrip and carrier-based landings. Eventually, Northrop Grumman hopes to develop the prototype X-47B into a battlefield-ready aircraft known the Unmanned Carrier-Launched Airborne Surveillance and Strike (UCLASS) system, which is expected to enter service in the 2020s.
Another take on the concept comes in the form of the bidirectional flying wing. This type of design consists of a long-span, low speed wing and a short-span, high speed wing joined in a single airframe in the shape of an uneven cross. The proposed craft would take off and land with the low-speed wing across the airflow, then rotate a quarter-turn so that the high-speed wing faces the airflow for supersonic travel.
The design is claimed to feature low wave drag, high subsonic efficiency and little or no sonic boom. The low-speed wings have likely a thick, rounded airfoil able to contain the payload and a wide span for high efficiency, while the high-speed wing would have a thin, sharp-edged airfoil and a shorter span for low drag at supersonic speed.
In 2012, NASA announced that it was in the process of funding the development of such a concept, known as the Supersonic Bi-Directional Flying Wing (SBiDir-FW). This came in the form of the Office of the Chief Technologist awarding a grant of $100,000 to a research group at the University of Miami (led by Professor Gecheng Zha) who were already working on such a plane.
Since the Wright Brothers first took to the air in a plane made of canvas and wood over a century ago, aeronautical engineers have thought long and hard about how we can improve upon the science of flight. Every once in awhile, there are those who will attempt to “reinvent the wheel”, throwing out the old paradigm and producing something truly revolutionary.
Before man ever set foot on the moon or achieved the dream of breaking the Earth’s gravity and going into space, a dog did it first! Really, a dog? Well… yes, if the topic is the first animal to go into space, then it was a dog that beat man to the punch by about four years. The dog’s name was Laika, a member (after a fashion) of the Russian cosmonaut program. She was the first animal to go into space, to orbit the Earth, and, as an added – though dubious – honor, was also the first animal to die in space. Laika’s sacrifice paved the way for human spaceflight and also taught the Russians a few things about what would be needed in order for a human to survive a spaceflight.
Part of the Sputnik program, Laika’s was launched with the Sputnik 2 craft, the second spacecraft launched into Earth orbit. The satellite contained two cabins, one for its “crew”, the other for its various scientific instruments, which included radio transmitters, a telemetry system, temperature controls for the cabin, a programming unit, and two photometers for measuring solar radiation (ultraviolent and x-ray emissions) and cosmic rays. Like Sputnik 1, the satellite’s launch vehicle the R-7 Semyorka rocket, a ballistic missile that was responsible for placing the satellite into the upper atmosphere.
The mission began on November 3rd, 1957 and lasted 162 days before the orbit finally decayed and it fell back to Earth. No provisions were made for getting Laika safely back to Earth so it was expected ahead of time that she would die after ten days. However, it is now known that Laika died within a matter of hours after deployment from the R-7. At the time, the Soviet Union said she died painlessly while in orbit. More recent evidence however, suggests that she died as a result of overheating and panic. This was due to a series of technical problems which resulted from a botched deployment. The first was the damage that was done to the thermal system during separation, the second was some of the satellite’s thermal insulation being torn loose. As a result of these two mishaps, temperatures in the cabin reached over 40º C.
In spite of her untimely death, Laika’s flight astonished the world and outraged many animal rights activists. Her accomplishment was honored by many countries through a series of commemorative stamps. The mission itself also taught the Russians a great deal about the behavior of a living organism in space and brought back data about Earth’s outer radiation belt, which would be the subject of interests for future missions.
Planets form by accreting material from a protoplanetary disk. New research suggests it can happen quickly, and that Earth may have formed in only a few million years. Credit: NASA/NASA/JPL-Caltech
[/caption]
Wanna build celestial objects? I mean it sounds easy – you just start with a big cloud of dust and give it a nudge so that it starts to spin and accrete and you end up with a star with a few wisps of dust left in orbit that continue to accrete to form planets.
Trouble is, this process doesn’t seem to be physically possible – or at least nothing like it can be replicated in standard theoretical models and laboratory simulations. There’s a problem with the initial small scale accretion steps.
Dust particles seem to stick readily together when they are very small – through van der Waals and electrostatic forces – steadily building up to form millimeter and even centimeter sized aggregates. But once they get to this size those sticky forces become less influential – and the objects are still too small to generate a meaningful amount of gravitational attraction. What interaction they do have is more in the nature of bouncing collisions – which most often result in pieces being chipped off the bouncing objects, so that they start getting smaller again.
This is an astrophysics problem known as the meter barrier.
But increasingly, theorists are coming up with ways to get around the meter barrier. Firstly, it may be a mistake to assume that you start with a uniform dust cloud, in which spontaneous accretion happens everywhere throughout the cloud.
Current thinking is that it may take a nearby supernova or a closely migrating star to trigger the evolution of a dust cloud into a stellar nursery. It’s possible that turbulence in a dust cloud creates whirlpools and eddies that favor the local aggregation of small particles into larger particles. So rather than going from a uniform dust cloud to a uniform collection of very small rocks – there is just a chance formation of accreted objects here and there.
Or we can just assume a certain stochastic inevitability about anything that has the faintest chance of happening – eventually happening. Over several million years, within a huge dust cloud that might be several hundred astronomical units in diameter, a huge variety of interactions becomes possible – and even with a 99.99% likelihood that no object can ever aggregate to a size bigger than a meter, it’s still entirely likely that this is going to happen somewhere in that vast area.
Either way, once you have a few seed objects, it’s hypothesised that the snowball process takes over. Once an aggregated object achieves a certain mass, its inertia will mean it becomes less engaged in turbulent flow. In other words, the object will begin to move through, rather than move with, the turbulent dust. Under these circumstances, it will behave like a snowball rolling down a snow covered hill, collecting a covering of dust as it plows through the dust cloud – increasing its diameter as it goes.
An artist's impression of HD 98800. The snowball process works even faster in protoplanetary disks around binary stars (at least on paper). Well, Tatooine must have formed somehow... Credit: JPL, NASA.
The time span required to build such snowballed planetesimals from a radius (Rsnow) of 100 meters up to 1000 kilometers is long. The modelling used suggests a time span (Tsnow) of between 1 and 10 million years is required.
It’s also possible to model planet formation around binary stars. Using orbital parameters equivalent to those of the binary system Alpha Centauri A and B, the snowball process is calculated to work more efficiently so that Tsnow is probably no more than 1 million years.
Once hundred kilometer-sized planetesimals have formed, they would still engage in collisions. But at this size, the objects generate substantial self-gravity and collisions are more likely to be constructive – eventually resulting in planets with their own orbiting debris, which then forms rings and moons.
There is evidence that some stars can form planets (at least gas giants) within 1 million years – such as GM Aurigae – while our solar system may have taken a more leisurely 100 million years from the Sun’s birth until the current collection of rocky, gassy and icy planets fully accreted out of the dust.
So, there’s more than a snowball’s chance in hell that that this theory may contribute to a better understanding of planet formation.
Artists impression of the Glory satellite at work. Credit: NASA
[/caption]
A satellite mission to study climate change on Earth has been delayed due to problems with its solar arrays. The Glory mission was scheduled for a November 22, 2010 launch, but it now has been tentatively pushed back to February 23, 2011. Reportedly, ground testing revealed a problem with a mechanism in one of the two solar panels on the Glory satellite. “The new launch date provides the necessary additional time required to complete preparations for the rocket and the spacecraft,” said a NASA status report issued on Friday. The mission is slated to launch on an Orbital Sciences Taurus XL rocket from Vandenberg Air Force Base in California.
The $424 million Glory mission will gather data to help scientists to better understand the Earth’s energy budget. It will look at the properties of aerosols, including black carbon, in the Earth’s atmosphere and climate system, and enable a greater understanding of the seasonal variability of aerosol properties.
It will also collect data on solar irradiance for the long-term effects on the Earth climate record, helping to help in our understanding whether the temperature increase and climate changes are by-products of natural events or whether the changes are caused by man-made sources is of primary importance.
On the last Taurus XL launch in February 2009 — for the Orbiting Carbon Observatory, another NASA climate change research satellite — a fairing failed to separate, and the mission failed.
The plumes of Enceladus are highlighted in this Cassini image. Credit: NASA/JPL/Space Science Institute
[/caption]
What an astonishing view of Saturn’s moon Enceladus, as seen by Cassini! At least four different plumes of water ice are spewing out from the south polar region, highlighted because of the black space behind the Moon. On Twitter, Carolyn Porco said that we see four jets because we’re looking down the four tiger stripe fractures crossing the south pole. “How lovely it is to know!” she added.
Cassini was about 617,000 kilometers (383,000 miles) away from Enceladus when it captured this image.
China successfully launched their second robotic mission, Chang’E-2, to the Moon. A Long March 3C rocket blasted off from Xichang launch center just before 1100 GMT on October 1. The satellite is scheduled to reach the Moon in five days, and so far, all the telemetry shows everything to be working as planned. It will take some time for Chang’E-2 to settle into its 100-km (60-mile) orbit above the lunar surfaces, although the China space agency also said the spacecraft will come as close as 15km above the surface during its mission in order to take high-resolution imagery of potential landing sites for Chang’E-3, China’s next lunar mission that will send a rover to the Moon’s surface, scheduled for 2013. Continue reading “China Launches Second Moon Mission”
Tornado at Union City, Oklahoma. Credit: NOAA Photo Library
[/caption]
Everyone knows about tornadoes. You may have seen them in movies or heard about them in the news. However one of the most important facts for a person to know is where Tornadoes are likely to occur. This makes simple sense. If you want to avoid hurricanes you know that you should likely not live in the Gulf Coast or Florida. If you want to avoid the chance of mudslides you wouldn’t live in Oregon. Knowing where and how tornadoes can appear can help you stay safer and better prepared in case such a storm happens.
For the most part we know that Tornadoes as they are known in the United States are largely a North American phenomenon. The unique position and composition of North America’s topography gives thunderstorms enough space, time, and energy to form tornadoes. The traditional red zone for tornadoes is the Great Plains region of the United States called Tornado Alley. This region is known for spawning several tornadoes a year and in this region tracking storms and preparing for tornadoes is a way of life. The flat grasslands are perfect place for pressure systems to collide, creating powerful storms and in turn powerful tornadoes.
Interesting enough Tornado Alley is not the only area where tornadoes can happen. Tornadoes can occur anywhere in continental United States if the conditions for tornado formation are met. That means if you have a particularly strong thunderstorm system in your area with high winds there is a strong possibility of a Tornado happening.
The frequency of tornadoes happening outside the Tornado alley have increased with powerful storms ripping up areas that would be by conventional wisdom considered safe such as the Southeast or the Atlantic Seaboard.
One type of location that is generally safe from Tornadoes is the city. However recent events have proven that not likely doesn’t mean never. Two years ago a powerful tornado ripped through downtown Atlanta and doing major damage to the CNN headquarters. The other major tornado in a major city happened recently in New York City. A twister touched down in the Bronx in September of this year in the early morning hours also did serious property damage.
The danger of tornadoes in unlikely locations is that they are harder to spot. The tornado that struck Piedmont, Alabama became one of the deadliest on record because the area was hilly and full of trees. This made it impossible for residents to see the storm funnel approaching. This is why it is important for local news to have good weather tracking systems to properly warn residents in case of unusual weather conditions.
We have written many articles about tornadoes for Universe Today. Here’s an article about the Tornado Alley, and here’s an article about how tornadoes are formed.
Have you ever wondered where stars are born? Stars are formed in nebulas, interstellar clouds of dust and gas. Nebulas are either remnants of matter from the original big bang or the result of stars either collapsing or going supernova. Nebulas have long been noted and observed by astronomers but very little was known about them until the 21st century.
Galaxies because of their similar appearance were once thought of as nebulas. It was later determined that they were actually larger grouping of stars a great distance away from the Earth. So how are Nebulas star forming regions? The answers lie in the gravitational force and nuclear fusion.
Most nebulas are disparate clouds of gas and cosmic dust floating in the interstellar medium. Nebulas are the more dense parts of the gas and dust that exist in the space between stars and galaxies. We know due to the law of universal gravitation that every particle in the universe exerts an attractive force on every other particle. This happens over times with nebulas as the particles that make up the interstellar medium start to gather together.
Since gases have mass it is inevitable that the process will continue as great mass will create a stronger gravitational field. At some undefined point in time a tipping point between the gas pressure and the gravity of the nebula is crossed and the nebula collapses under its own gravity. Since molecular hydrogen is the most abundant element in the nebula the pressure from the collapse causes the nebula to undergo nuclear fusion. This starts the birth of a star.
As evidenced by how many stars and galaxies are in the universe you can see that is process that happens just about everywhere. More recently scientists have started become interested in how common it is for stars to from planets, especially those that are likely to support life. Scientists have recently discovered one such planet Gliese 581-g. This planet while closer to it star than Earth is well with in habitable zone necessary for liquid water and the right temperatures for life to occur.
The study of nebulas and the interstellar medium have yielded a lot important information about the formation and stars. As better telescopes and probes are created we will get a clearer picture about our universe and how it was formed and continues to grow over time.
We have written many articles about the birth of stars for Universe Today. Here’s an article about the star birth myth, and here’s an article about the birth of the biggest stars.
