NASA Investigating Deep-Space Hibernation Technology

Manned missions to deep space present numerous challenges. In addition to the sheer amount of food, water and air necessary to keep a crew alive for months (or years) at a time, there’s also the question of keeping them busy for the entirety of a long-duration flight. Exercise is certainly an option, but the necessary equipment will take up space and be a drain on power.

In addition, they’ll need room to move around, places to sleep, eat, work, and relax during their down time. Otherwise, they will be at risk of succumbing to feelings of claustrophobia, anxiety, insomnia, and depression – among other things.

NASA has been looking at a few options and one proposed solution is to put these crews into an induced state of hypothermia resulting in torpor – a kind of hibernation. Rather than being awake for months or years on end, astronauts could enter a state of deep sleep at the beginning of their mission and then wake up near the end. This way, they would arrive refreshed and ready to work, rather than haggard and maybe even insane.

If this is starting to sound familiar, it’s probably because the concept has been explored extensively by science fiction. Though it goes by different names – cryosleep, reefersleep, cryostasis, etc. – the notion of space explorers preserving their bodies through cryogenic suspension has been touched upon by numerous sci-fi authors, movies and franchises.

But NASA’s plan is a little different than what you might remember from 2001: A Space Odyssey or Aliens. Instead of astronauts stepping into a tube and having their temperature lowered, torpor would be induced via the RhinoChill – a device that uses invasive tubes to shoot cooling liquid up the nose and into the base of the brain.

Artist's concept of "sleeping to Mars". Photo Credit: SpaceWorks Enterprising
Artist’s concept of “sleeping to Mars”. Photo Credit: SpaceWorks Enterprising

To research the technology, NASA has teamed up with SpaceWorks, an Atlanta-based aerospace company that is investigating procedures for putting space crews into hibernation. During this year’s International Astronomical Congress – which took place from Sept. 29th to Oct. 3rd  in Toronto – representatives from SpaceWorks shared their vision.

According to the company, inducing torpor in a crew of astronauts would eliminate the need for accommodations like galleys, exercise equipment, and large living quarters. Instead, robots could electrically stimulate key muscle groups and intravenously deliver sustenance to ensure the health and well being of the astronauts while in transit.

As Dr. Bradford, President of SpaceWorks Enterprises Inc., told Universe Today via email:

“We have completed the initial evaluation of our concept which demonstrated significant benefits against non-torpor Mars mission approaches and established the medical plausibility of torpor. We have expanded our team and put together a development plan that we are in the process of executing. While the longer term goal of enabling access to Mars is our ultimate objective, we have a number of near-term, commercial applications for this technology that we will develop along the way.”

In addition to cutting down on the need for room and supplies, keeping crews in hibernation would also save on another all-important factor: costs. With a crew in stasis, ships could be built smaller or have more room to accommodate safety features like radiation shields. At the same time, smaller, lighter ships would mean that material, construction, and fuel costs would be lower.

According to SpaceWorks’ mockups, the size of a crew living quarters for a Mars mission could be reduced from the currently-proposed dimensions of 8.2×9 meters to just 4.3×7.5. Also, current projections indicate that a Mars ready-habitat for a 4-person crew would weight roughly 31 tons. But the company claims that a torpor-stasis habitat could weigh as little as 15.

Image Credit: SpaceWorks
Artist’s concept for Mars-ready habitat. Image Credit: SpaceWorks

Of course, SpaceWorks also emphasized the psychological benefits. Rather than being awake for the entire 180 day journey, the crew would be able to go to sleep and wake up upon arrival. This would ensure that no one succumbs to “space madness” during the months-long journey and does something terrible – like take their own life or those of the crew!

Naturally, there is still plenty of research and development that needs to be done before a torpor hibernation system can be considered a feasible option for space travel. RhinoChill has so far only been used in therapeutic scenarios here on Earth. The next step will be to test it in orbit.

Luckily, the potential savings during a trip to Mars or somewhere in the outer Solar System could be just the incentive to make it happen. And no matter what, it seems that some form of induced-hibernation will be necessary if ever humanity is ever to explore the depths of space.

“We are at the dawn of a new era in space and my company is excited to be working at the forefront,” Bradford said. “I believe our technology will be required to support human missions to Mars. It offers an affordable solution by leveraging ongoing medical research to address challenges spanning engineering, human health, and psychology for which we do not have alternate solutions. This can be ready for the first Mars mission and we are talking with partners to make this happen.”

Further reading: SpaceWorks Enterprises

Bigelow Inflatable Module to be Added to Space Station in 2015

Astronauts aboard the International Space Station are going to be getting an addition in the near future, and in the form of an inflatable room no less. The Bigelow Expandable Activity Module (BEAM) is the first privately-built space habitat that will added to the ISS, and it will be transported into orbit aboard a Space X Falcon 9 rocket sometime next year.

“The BEAM is one small step for Bigelow Aerospace,” Bigelow representative Michael Gold told Universe Today, “but is also one giant leap for private sector space activities since the BEAM will be the first privately owned and developed module ever to be part of a crewed system in space.”

NASA and Bigelow Aerospace announced the $17.8 million contract in 2013, and on October 2, 2014, Gold announced at the International Astronautical Congress that the launch would take place next year on a SpaceX resupply flight. Gold said BEAM provides an example of what the company, and private firms in general, can do in low-Earth orbit (LEO).

Upon arrival, the BEAM will be installed by the robotic Canadarm2 onto the Tranquility node’s aft docking port. Once it’s expanded, an ISS crew member will enter the module and become the first astronaut to step inside an expandable habitat system. The plan is to have the module remain in place for a few years to test and demonstrate the feasibility of the company’s inflatable space habitat technology.

The BEAM, which weighs approximately 1,360 kg (3000 lbs), will travel aboard the unpressurized cargo hold of a Dragon capsule. Once it is successfully transferred to the station, ISS astronauts will activate the deployment sequence, and the module will expand out to its full size – approx. 4 meters (13 feet) in length and 3 meters (10.5 feet) in diameter.

Bigelow currently has two stand-alone autonomous spacecraft in orbit, the Genesis I and the Genesis II – both of which are collecting data about LEO conditions and how well the technology performs in practice in space. In turn, NASA will use BEAM to measure the radiation levels inside the module as compared to other areas of the ISS to determine how safe it is for habitation.

“Through the flight of the Bigelow module on the International Space Station, we expect to learn critical technical performance data related to non-metallic structures in space,” said Jason Crusan, director of Advanced Exploration Systems Division at NASA Human Exploration and Operations Mission Directorate, in an email to Universe Today. “Data about things such as radiation, thermal, and overall operations of non-metallic structures in space has multiple benefits both to NASA and to the commercial sector.”

Bigelow station
Artist concept of the Bigelow space station. Credit: Bigelow Aerospace.

The BEAM module will also allow for further data collection for the company, which is planning on launching its own space station, named Bigelow Aerospace Alpha Station, to be at least partially operational as early as next year. This station will be initially made up of two BA 330 expandable habitats, which are designed to function either as an independent space station or as modular components that can be connected to create a larger apparatus.

Bigelow hopes that such stations will allow for greater participation in space exploration and research, both by nations and private companies. But looking to the future, Bigelow also sees BEAM and its other long-term projects for space habitation as a crucial step in the commercialization of Low-Earth Orbit.

Already, the company is planing on getaways that will take tourists into orbit – for a modest price, of course. Beginning in 2012, the company began offering space travel packages, including the trip to and from LEO aboard a SpaceX craft,  starting at $26.25 million and a two-month stay package aboard the Alpha Station for $25 million – bringing the grand total  to just $51.25 million, compared to the $40 million it currently costs members of the public to stay on the ISS for a week.

Further reading: Bigelow Aerospace

What is the Milky Way?

Artist's conception of the Milky Way galaxy. Credit: Nick Risinger

When you look up at the night sky, assuming conditions are just right, you might just catch a glimpse of a faint, white band reaching across the heavens. This band, upon closer observation, looks speckled and dusty, filled with a million tiny points of light and halos of glowing matter. What you are seeing is the Milky Way, something that astronomers and stargazers alike have been staring up at since the beginning of time.

But just what is the Milky Way? Well, simply put, it is the name of the barred spiral galaxy in which our solar system is located. The Earth orbits the Sun in the Solar System, and the Solar System is embedded within this vast galaxy of stars. It is just one of hundreds of billions of galaxies in the Universe, and ours is called the Milky Way because the disk of the galaxy appears to be spanning the night sky like a hazy band of glowing white light.

Discovery and Naming:

Our galaxy was named because of the way the haze it casts in the night sky resembled spilled milk. This name is also quite ancient. It is translation from the Latin “Via Lactea“, which in turn was translated from the Greek for Galaxias, referring to the pale band of light formed by stars in the galactic plane as seen from Earth.

Persian astronomer Nasir al-Din al-Tusi (1201–1274) even spelled it out in his book Tadhkira: “The Milky Way, i.e. the Galaxy, is made up of a very large number of small, tightly clustered stars, which, on account of their concentration and smallness, seem to be cloudy patches. Because of this, it was likened to milk in color.”

The Milky Way Galaxy. Astronomer Michael Hart, and cosmologist Frank Tipler propose that extraterrestrials would colonize every available planet. Since they aren't here, they have proposed that extraterrestrials don't exist. Sagan was able to imagine a broader range of possibilities. Credit: NASA
Artist’s impression of the Milky Way Galaxy, as seen from above the galactic “North pole”. Credit: NASA

Astronomers had long suspected the Milky Way was made up of stars, but it wasn’t proven until 1610, when Galileo Galilei turned his rudimentary telescope towards the heavens and resolved individual stars in the band across the sky. With the help of telescopes, astronomers realized that there were many, many more stars in the sky, and that all of the ones that we can see are a part of the Milky Way.

In 1755, Immanuel Kant proposed that the Milky Way was a large collection of stars held together by mutual gravity. Just like the Solar System, this collection of stars would be rotating and flattened out as a disk, with the Solar System embedded within it. Astronomer William Herschel (who discovered Uranus) attempted to actually map out the shape of the Milky Way in 1785, but he didn’t realize that large portions of the galaxy are obscured by gas and dust, which hide its true shape.

It wasn’t until the 1920s, when Edwin Hubble provided conclusive evidence that the spiral nebulae in the sky were actually whole other galaxies, that the true shape of our galaxy was known. Thenceforth, astronomers came to understand that the Milky Way is a barred, spiral galaxy, and also came to appreciate how big the Universe truly is.

Structure and Composition:

The Milky Way looks brightest toward the galactic center, in the direction of Sagittarius. The fact that the Milky Way divides the night sky into two roughly equal hemispheres indicates that the Solar System lies near the galactic plane. The Milky Way has a relatively low surface brightness due to the gases and dust that fills the galactic disk. That prevents us from seeing the bright galactic center or from observing clearly what is on the other side of it.

a mosaic of the images covering the entire sky as observed by the Wide-field Infrared Survey Explorer (WISE), part of its All-Sky Data Release.
A mosaic of the images covering the entire sky as observed by the Wide-field Infrared Survey Explorer (WISE), part of its All-Sky Data Release. Credit: NASA/JPL

If you could travel outside the galaxy and look down on it from above, you’d see that the Milky Way is a barred spiral galaxy measuring about 120,000 light-years across and about 1,000 light-years thick. For the longest time, the Milky Way was thought to have 4 spiral arms, but newer surveys have determined that it actually seems to just have two spiral arms, called Scutum–Centaurus and Carina–Sagittarius.

The spiral arms are formed from density waves that orbit around the Milky Way. As these density waves move through an area, they compress the gas and dust, leading to a period of active star formation for the region. However, the existence of these arms has been determined from observing parts of the Milky Way – as well as other galaxies in our universe – and are not the result of seeing our galaxy as a whole.

In truth, all pictures that depict our galaxy are either artist’s renditions or pictures of other spiral galaxies. Until recently, it was very difficult for scientists to gauge what the Milky Way looks like, mainly because we’re embedded inside it. If you had never been outside of your own house, you wouldn’t know what it looked like from outside. But you’d get a sense by looking at the interior and comparing it to other houses in the neighborhood.

From ongoing surveys of the night sky with ground-based telescopes, and more recent missions involving space telescopes, astronomers now estimate that there are between 100 and 400 billion stars in the Milky Way. They also think that each star has at least one planet, which means there are likely to be hundreds of billions of planets in the Milky Way – and at least 17 billion of those are believed to be the size and mass of the Earth.

Illustris simulation, showing the distribution of dark matter in 350 million by 300,000 light years. Galaxies are shown as high-density white dots (left) and as normal, baryonic matter (right). Credit: Markus Haider/Illustris
Illustris simulation, showing the distribution of dark matter in 350 million by 300,000 light years. Galaxies are shown as high-density white dots (left) and as normal, baryonic matter (right). Credit: Markus Haider/Illustris

The Milky Way, like all galaxies, is surrounded by a vast halo of dark matter, which accounts for some 90% of its mass. Nobody knows precisely what dark matter is, but its mass has been inferred by observations of how fast the galaxy rotates and other general behaviors. More importantly, it is believed that this mass helps keep the galaxy from tearing itself apart as it rotates.

Location of our Sun:

Our Sun is located in the Orion Arm, a region of space in between the two major arms of the Milky Way, and about 27,000 light years from the galactic core. At the heart of the Milky Way is a super-massive black hole, just like all of the other galaxies, known as Sagittarius A*. This monster is more than 4 million times

Our Sun takes about 240 million years to orbit the Milky Way once, in what is known as a galactic year (or cosmic year). Just imagine, the last time the Sun was at this region of the galaxy, dinosaurs roamed the Earth, and the Sun has only made an estimated 18-20 trips around in its entire life. By this reckoning, the birth of our Sun took place 18.4 galactic years ago, and the Universe itself was created approximately 61 galactic years ago.

Future of the Milky Way:

It is further believed that our galaxy formed through the collisions of smaller galaxies, early in the Universe. These mergers are still going on, and the Milky Way is expected to collide with the Andromeda galaxy in 3-4 billion years. The two galaxies will combine to form a giant elliptical galaxy, and their super-massive black holes might even merge.

A mosaic of telescopic images showing the galaxies of the Virgo Supercluster. Credit: NASA/Rogelio Bernal Andreo
A mosaic of telescopic images showing the galaxies of the Virgo Supercluster. Credit: NASA/Rogelio Bernal Andreo

The Milky Way and Andromeda are part of a larger collection of galaxies known as the Local Group. And these are contained within an even larger region called the Virgo Supercluster – a mass concentration of galaxies that contains at least 100 galaxy groups and clusters within its diameter of 33 megaparsecs (110 million light-years).

You might be amazed to know that dung beetles actually navigate at night using the Milky Way. If you’ve never seen the Milky Way with your own eyes, you should take the chance when you can. Go to a place with nice dark skies, free from light pollution, and look up and appreciate the Milky Way. And be sure to wave hello to all the neighboring stars who share our galaxy with us.

Those are just a few of the interesting facts, figures, and images that you will find among the links below.

What is the Difference Between Speed and Velocity?

What is the Difference Between Speed and Velocity?

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When it comes to measuring motion, that is the relative passage of an object through space at a certain rate of time, several different things need to be taken into account. For example, it is not enough to know the rate of change (i.e. the speed) of the object. Scientists must also be able to assign a vector quantity; or in other words, to know the direction as well as the rate of change of that object. In the end, this is major difference between Speed and Velocity. Though both are calculated using the same units (km/h, m/s, mph, etc.), the two are different in that one is described using numerical values alone (i.e. a scalar quantity) whereas the other describes both magnitude and direction (a vector quantity).

By definition, the speed of an object is the magnitude of its velocity, or the rate of change of its position. The average speed of an object in an interval of time is the distance traveled by the object divided by the duration of the interval. Represented mathematically, it looks like this: ν=[v]=[?] = [dr/dt]•, where speed ν is defined as the magnitude of the velocity v, that is the derivative of the position r with respect to time. The fastest possible speed at which energy or information can travel, according to special relativity, is the speed of light in vacuum (a.k.a. c = 299,792,458 meters per second, which is approximately 1079 million kilometers per hour or 671,000,000 mph).

Velocity, on the other hand, is the measurement of the rate and direction of change in the position of an object. Since it is a vector physical quantity, both magnitude and direction are required to define it. The scalar absolute value (magnitude) of velocity is speed, a quantity that is measured in metres per second (m/s) when using the SI (metric) system. Mathematically, this is represented as: v = Δx/Δt, where v is the average velocity of an object, (Δx) is the displacement and (Δt) is the time interval. Add to this a vector (i.e. Δx/Δt→, ←, or what have you), and you’ve got velocity!

As an example, consider the case of a bullet being fired from a gun. If we divide the overall distance it travels within a set period of time (say, one minute), than we have successfully calculated its speed. On the other hand, if we want to determine its velocity, we must consider the direction of the bullet after it’s been fired. Whereas the average speed of the object would be rendered as simple meters per second, the velocity would be meters per second east, north, or at a specific angle.

We have written many articles about speed and velocity for Universe Today. Here’s an article about formula for velocity, and here’s an article about escape velocity.

If you’d like more info on speed and velocity, check out these articles:
Speed and Velocity
Angular and Linear Velocity

We’ve also recorded an episode of Astronomy Cast about the space shuttle. Listen here, Episode 127: The US Space Shuttle.

Sources:
http://physics.info/velocity
http://en.wikipedia.org/wiki/Speed
http://en.wikipedia.org/wiki/Velocity
http://www.physicsclassroom.com/class/1dkin/u1l1d.cfm
http://www.edinformatics.com/math_science/acceleration.htm

Dispersion of Light

Dispersion of Light

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Look up into the rainy sky! What do you see? Well, if its just rained and the sun is once again shining, chances are you see a rainbow. Always a lovely sight isn’t it? But why is it that after a rainstorm, the air seems to catch the light in just the right way to produce this magnificent natural phenomenon? Much like stars, galaxies, and the flight of a bumblebee, some complicated physics underlie this beautiful act of nature. For starters, this effect, where light is broken into the visible spectrum of colors, is known as the Dispersion of Light. Another name for it is the prismatic effect, since the effect is the same as if one looked at light through a prism.

To put it simply, light is transmitted on several different frequencies or wavelengths. What we know as “color” is in reality the visible wavelengths of light, all of which travel at different speeds through different media. In other words, light moves at different speed through the vacuum of space than it does through air, water, glass or crystal. And when it comes into contact with a different medium, the different color wavelengths are refracted at different angles. Those frequencies which travel faster are refracted at a lower angle while those that travel slower are refracted at a sharper angle. In other words, they are dispersed based on their frequency and wavelength, as well as the materials Index of Refraction (i.e. how sharply it refracts light).

The overall effect of this – different frequencies of light being refracted at different angles as they pass through a medium – is that they appear as a spectrum of color to the naked eye. In the case of the rainbow, this occurs as a result of light passing through air that is saturated with water. Sunlight is often referred to as “white light” since it is a combination of all the visible colors. However, when the light strikes the water molecules, which have a stronger index of refraction than air, it disperses into the visible spectrum, thus creating the illusion of a colored arc in the sky.

Now consider a window pane and a prism. When light passes through glass that has parallel sides, the light will return in the same direction that it entered the material. But if the material is shaped like a prism, the angles for each color will be exaggerated, and the colors will be displayed as a spectrum of light. Red, since it has the longest wavelength (700 nanometers) appears at the top of the spectrum, being refracted the least. It is followed shortly thereafter by Orange, Yellow, Green, Blue, Indigo and Violet (or ROY G. GIV, as some like to say). These colors, it should be noted, do not appear as perfectly distinct, but blend at the edges. It is only through ongoing experimentation and measurement that scientists were able to determine the distinct colors and their particular frequencies/wavelengths.

We have written many articles about dispersion of light for Universe Today. Here’s an article about the refractor telescope, and here’s an article about visible light.

If you’d like more info on the dispersion of light, check out these articles:
dispersion of Light by Prisms
Q & A: Dispersion of Light

We’ve also recorded an episode of Astronomy Cast all about the Hubble Space Telescope. Listen here, Episode 88: The Hubble Space Telescope.

Sources:
http://en.wikipedia.org/wiki/Refractive_index
http://en.wikipedia.org/wiki/Dispersion_%28optics%29
http://www.physicsclassroom.com/class/refrn/u14l4a.cfm
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=415.0
http://www.school-for-champions.com/science/light_dispersion.htm

Diffraction of Light

Diffraction of Light

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For some time, the behavior of light has baffled scientists. Initially, and in accordance with classic physics, light was thought to be a wave, an indefinable form of energy that simply flowed from a heated source. However, with the advent of quantum physics, scientists came to realize that photons, a tiny elementary particle responsible for all forms of electromagnetic radiation, was in fact the source. So you can imagine how confounded they were when, in the course of performing experiments, they discovered that it exhibited the behavior of both a particle and a wave! This rather unique behavior, the ability of light to behave as a wave, even though it is made up of tiny particles, is known as the Diffraction of Light.

By definition, diffraction refers to the apparent bending of waves around small obstacles and the spreading out of waves past small openings. It had long been understood that this is what happens when a wave encounters an obstacle, and by the 17th and 18th centuries, this behavior was observed through experiments involving light. One such physicist who observed this at work was Thomas Young (1773 – 1829), an English polymath who is credited devised the double-slit experiment. In this experiment, Young shone a monochromatic light source (i.e. light of a single color) through an aperture (in this case, a wall with a horizontal slits cut in it) and measured the results on a screen located on the other side. The results were interesting, to say the least. Instead of appearing in the same relative shape as the aperture, the light appeared to be diffracting, implying that it was made up of waves. The experiment was even more interesting when a second slit was cut into the screen (hence the name double-slit). Young, and those who repeated the experiment, found that interference waves resulted, meaning that two propagation waves occurred which then began to interfere with one another.

A more common example comes to us in the form of shadows. Ever notice how the outer edges do not appear solid, but slightly fuzzy instead? This occurs as a result of light bending slightly as it passes around the edge of an object, again, consistent with the behavior of a wave. Similar effects occur when light waves travel through a medium with a varying refractive index, resulting in a spectrum of color or a distorted image. Since all physical objects have wave-like properties at the atomic level, diffraction can be studied in accordance with the principles of quantum mechanics.

We have written many articles about diffraction of light for Universe Today. Here’s an article about visible light, and here’s an article about telescope resolution.

If you’d like more info on diffraction of light, check out these articles:
The Physics of Light: Diffraction
Experiments on Diffraction of Light

We’ve also recorded an episode of Astronomy Cast all about the Hubble Space Telescope. Listen here, Episode 88: The Hubble Space Telescope.

Sources:
http://en.wikipedia.org/wiki/Photon
http://en.wikipedia.org/wiki/Diffraction
http://en.wikipedia.org/wiki/Double-slit_experiment
http://library.thinkquest.org/27356/p_diffraction.htm
http://en.wikipedia.org/wiki/Thomas_Young_%28scientist%29
http://ww2010.atmos.uiuc.edu/%28Gh%29/guides/mtr/opt/mch/diff.rxml

Angular Velocity of Earth

Angular Velocity of Earth

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The planet Earth has three motions: it rotates about its axis, which gives us day and night; it revolves around the sun, giving us the seasons of the year, and through the Milky Way along with the rest of the Solar System. In each case, scientists have striven to calculate not only the time it takes, but the relative velocities involved. When it comes to the Earth rotating on its axis, a process which takes 23 hours, 56 minutes and 4.09 seconds, the process is known as a sidereal day, and the speed at which it moves is known as the Earth’s Angular Velocity. This applies equally to the Earth rotating around the axis of the Sun and the center of the Milky Way Galaxy.

In physics, the angular velocity is a vector quantity which specifies the angular speed of an object and the axis about which the object is rotating. The SI unit of angular velocity is radians per second, although it may be measured in other units such as degrees per second, revolutions per second, etc. and is usually represented by the symbol omega (ω, rarely Ω). A radian, by definition, is a unit which connects the radius of an arc, the length of the arc and the angle subtended by the arc. A full radian is 360 degrees, hence we know that the Earth performs two radians when performing a full rotation around an axis. However, it is sometimes also called the rotational velocity and its magnitude – the rotational speed – is typically measured in cycles or rotations per unit time (e.g. revolutions per minute). In addition, when an object rotating about an axis, every point on the object has the same angular velocity.

Mathematically, the average angular velocity of an object can be represented by the following equation: ωaverage= Δθ/Δt, where ω is the radians/revolutions per second (on average), Δ is the change in quantity, θ is the velocity, and t is time. When calculating the angular velocity of the Earth as it completes a full rotation on its own axis (a solar day), this equation is represented as: ωavg = 2πrad/1day (86400 seconds), which works out to a moderate angular velocity of 7.2921159 × 10-5 radians/second. In the case of a Solar Year, where ωavg = 2πrad/1year (3.2×107 seconds), we see that the angular velocity works out to 2.0×10-7 rad/s.

We have written many articles about the angular velocity of Earth for Universe Today. Here’s an article about angular velocity, and here’s an article about why the Earth rotates.

If you’d like more info on angular velocity of Earth, check out the following articles:
Angular Speed of Earth
Earth’s Rotation

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

Sources:
http://en.wikipedia.org/wiki/Angular_velocity
http://hyperphysics.phy-astr.gsu.edu/hbase/rotq.html
http://hypertextbook.com/facts/2002/JasonAtkins.shtml
http://en.wikipedia.org/wiki/Earth%27s_rotation#Rotation_period
http://www.livephysics.com/tables-of-physical-data/mechanical/angular-speed-of-earth.html

Beaufort Scale

Beaufort Scale

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The high seas. Tankers, fishing trawlers and naval craft watch the horizon with eager anticipation. The wind is high and the waves are rising. The ship’s anemometer (wind speed detector) reads sixty-five kilometers per hour. The perfect storm is coming! Back on land, people are observing much of the same. The high winds are picking up debris, throwing it around and causing much damage. The waves are high and crashing all along the coast and even further inland. Power lines are destroyed, trees uprooted, and houses looking out to sea pelted by seawater and hard rain. In the aftermath of all this, this storm would been classified as 12 on the Beaufort Scale. Alternately known as the Beaufort Wind Force Scale, this is an empirical measure that relates wind speed to observed conditions at sea or on land.

Officially devised in 1805 by an Irish-born Royal Navy Officer named Sir Francis Beaufort (apparently while serving on the HMS Woolwich), this scale has a long and complicated history. It began with Daniel Defoe, the English novelist who, after witnessing of the Great Storm of 1703, suggested that a scale of winds be developed based on 11 points and used words common to the English language. By the early 19th century, there was renewed demand for such a scale, as naval officers were hard pressed to make accurate weather observations that weren’t tainted by partiality. Beaufort’s scale was therefore the first standardized scale to be introduced, and has gone through a number of variations since.

The initial scale of thirteen classes (zero to twelve) did not reference wind speed but related to qualitative wind conditions based on the effects it had on the sails of a British man-of-war. At zero, all the sails would be up; at six, half of the sails would have been taken down; and at twelve, all sails would have to be stowed away. In the late 1830’s, the scale was made standard for all Royal Navy vessels and used for all ship’s logs. In the 1850’s it was adapted to non-naval use, with scale numbers corresponding to cup anemometer rotations. By 1916, to accommodate the growth of steam power, the descriptions were changed to how the sea, not the sails, behaved and extended to land observations. It was extended once again in 1946 when Forces 13 to 17 were added, but only for special cases such as tropical cyclones.

Today, many countries have abandoned the scale and use the metric-based units m/s or km/h instead, but the severe weather warnings given to public are still approximately the same as when using the Beaufort scale. For example, wind speeds on the 1946 Beaufort scale are based on the empirical formula: v = 0.836 B3/2 m/s, where v is the equivalent wind speed at 10 meters above the sea surface and B is the Beaufort scale number. Oftentimes, hurricane force winds are described using the Beaufort scales 12 through 16 in conjunction with the Saffir-Simpson Hurricane Scale, by which actual hurricanes are measured.

We have written a few related articles for Universe Today. Here’s an article about, and here’s an article about the F5 tornado. Also, here are some extreme weather pictures.

If you’d like more info on the Beaufort Scale, check out this Wikipedia entry about the Beaufort Scale. Also, check out the NOAA Beaufort Wind Scale.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

Sources:
http://en.wikipedia.org/wiki/Anemometer
http://en.wikipedia.org/wiki/Beaufort_scale
http://www.tc.gc.ca/eng/marinesafety/tp-tp10038-80-wi-beaufort-scale-324.htm
http://weather.mailasail.com/Franks-Weather/Historical-And-Contemporay-Versions-Of-Beaufort-Scales

What is Galactic Cannibalism?

Galactic Cannibalism

Seattle, January, 2003. Two prestigious astronomers: Puragra GuhaThakurta of UCSC and David Reitzel of UCLA present some new findings to the American Astronomical Society that would seem to indicate that large spiral galaxies grow by gobbling up smaller satellite galaxies. Their evidence, a faint trail of stars in the nearby Andromeda galaxy that are thought to be a vast trail of debris left over from an ancient merger of Andromeda with another, smaller galaxy. This process, known as Galactic Cannibalism is a process whereby a large galaxy, through tidal gravitational interactions with a companion galaxy, merges with that companion, resulting in a larger galaxy.

The most common result of this process is an irregular galaxy of one form or another, although elliptical galaxies may also result. Several examples of this have been observed with the help of the Hubble telescope, which include the Whirlpool Galaxy, the Mice Galaxies, and the Antennae Galaxies, all of which appear to be in one phase or another of merging and cannibalising. However, this process is not to be confused with Galactic Collision which is a similar process where galaxies collide, but retain much of their original shape. In these cases, a smaller degree of momentum or a considerable discrepancy in the size of the two galaxies is responsible. In the former case, the galaxies cease moving after merging because they have no more momentum to spare; in the latter, the larger galaxies shape overtakes the smaller one and their appears to be little in the way of change.

All of this is consistent with the most current, hierarchical models of galaxy formation used by NASA, other space agencies and astronomers. In this model, galaxies are believed to grow by ingesting smaller, dwarf galaxies and the minihalos of dark matter that envelop them. In the process, some of these dwarf galaxies are shredded by the gravitational tidal forces when they travel too close to the center of the “host” galaxy’s enormous halo. This, in turn, leaves streams of stars behind, relics of the original event and one of the main pieces of evidence for this theory. It has also been suggested that galactic cannibalism is currently occurring between the Milky Way and the Large and Small Magellanic Clouds that exist beyond its borders. Streams of gravitationally-attracted hydrogen arcing from these dwarf galaxies to the Milky Way is taken as evidence for this theory.

As interesting as all of these finds are, they don’t exactly bode well for those of us who call the Milky Way galaxy, or any other galaxy for that matter, home! Given our proximity to the Andromeda Galaxy and its size – the largest galaxy of the Local Group, boasting over a trillion stars to our measly half a trillion – it is likely that our galaxy will someday collide with it. Given the sheer scale of the tidal gravitational forces involved, this process could prove disastrous for any and all life forms and planets that are currently occupy it!

We have written many articles about galactic cannibalism for Universe Today. Here’s an article about ancient galaxies feeding on gas, and here’s an article about an article, Galactic Ghosts Haunt Their Killers.

If you’d like more info on galaxies, check out Hubblesite’s News Releases on Galaxies, and here’s NASA’s Science Page on Galaxies.

We’ve also recorded an episode of Astronomy Cast about galaxies. Listen here, Episode 97: Galaxies.

Sources:
http://en.wikipedia.org/wiki/Interacting_galaxy
http://en.wikipedia.org/wiki/Andromeda_Galaxy
http://www1.ucsc.edu/currents/02-03/01-13/debris.html
http://blogs.physicstoday.org/update/2009/10/galactic-cannibalism.html
http://news.discovery.com/space/hubble-spiesz-aftermath-of-galactic-cannibalism.html

What are Active Optics?

Active Optics

For astronomers and physicists alike, the depths of space are a treasure trove that may provide us with the answers to some of the most profound questions of existence. Where we come from, how we came to be, how it all began, etc. However, observing deep space presents its share of challenges, not the least of which is visual accuracy.

In this case, scientists use what is known as Active Optics in order to compensate for external influences. The technique was first developed during the 1980’s and relied on actively shaping a telescope’s mirrors to prevent deformation. This is necessary with telescopes that are in excess of 8 metres in diameter and have segmented mirrors.

Definition:

The name Active Optics refers to a system that keeps a mirror (usually the primary) in its optimal shape against all environmental factors. The technique corrects for distortion factors, such as gravity (at different telescope inclinations), wind, temperature changes, telescope axis deformation, and others.

The twin Keck telescopes shooting their laser guide stars into the heart of the Milky Way on a beautifully clear night on the summit on Mauna Kea. Credit: keckobservatory.org/Ethan Tweedie
The twin Keck telescopes shooting their laser guide stars into the heart of the Milky Way on a beautifully clear night on the summit on Mauna Kea. Credit: keckobservatory.org/Ethan

Adaptive Optics actively shapes a telescope’s mirrors to prevent deformation due to external influences (like wind, temperature, and mechanical stress) while keeping the telescope actively still and in its optimal shape. The technique has allowed for the construction of 8-meter telescopes and those with segmented mirrors.

Use in Astronomy:

Historically, a telescope’s mirrors have had to be very thick to hold their shape and to ensure accurate observations as they searched across the sky. However, this soon became unfeasible as the size and weight requirements became impractical. New generations of telescopes built since the 1980s have relied on very thin mirrors instead.

But since these were too thin to keep themselves in the correct shape, two methods were introduced to compensate. One was the use of actuators which would hold the mirrors rigid and in an optimal shape, the other was the use of small, segmented mirrors which would prevent most of the gravitational distortion that occur in large, thick mirrors.

This technique is used by the largest telescopes that have been built in the last decade. This includes the Keck Telescopes (Hawaii), the Nordic Optical Telescope (Canary Islands), the New Technology Telescope (Chile), and the Telescopio Nazionale Galileo (Canary Islands), among others.

The New Technology Telescope (NTT) pioneered the Active Optics. Credit: ESO/C.Madsen. Bacon
The New Technology Telescope (NTT) pioneered the Active Optics. Credit: ESO/C.Madsen. Bacon

Other Applications:

In addition to astronomy, Active Optics is used for a number of other purposes as well. These include laser set-ups, where lenses and mirrors are used to steer the course of a focused beam. Interferometres, devices which are used to emit interfering electromagnetic waves, also relies on Active Optics.

These inferometers are used the purposes of astronomy, quantum mechanics, nuclear physics, fiber optics, and other fields of scientific research. Active optics are also being investigated for use in X-ray imaging, where actively deformable grazing incidence mirrors would be employed.

Adaptive Optics:

Active Optics are not to be confused with Adaptive Optics, a technique which operates on a much shorter timescale to compensate for atmospheric effects. The influences that active optics compensate for (temperature, gravity) are intrinsically slower, and have a larger amplitude in aberration.

. Credit: ESO/L. Calçada/N. Risinger
Artist’s impression of the European Extremly Large Telescope deploying lasers for adaptive optics. Credit: ESO/L. Calçada/N. Risinger

On the other hand, Adaptive Optics corrects for atmospheric distortions that affect the image. These corrections need to be much faster, but also have smaller amplitude. Because of this, adaptive optics uses smaller corrective mirrors (often the second, third or fourth mirror in a telescope).

We have written many articles about optics for Universe Today. Here’s The Photon Sieve Could Revolutionize Optics, What did Galileo Invent?, What did Isaac Newton Invent?, What are the Biggest Telescopes in the World?

We’ve also recorded an entire episode of Astronomy Cast all about Adaptive Optics. Listen here, Episode 89: Adaptive Optics, Episode 133: Optical Astronomy, and Episode 380: The Limits of Optics.

Sources: