Posted on by Nancy Atkinson

Vote for the Top 10 Stories on Universe Today in 2010

Vote for your favorite news stories of 2010 on Universe Today! Below is a survey of 17 news topics that we published this past year (some are single articles, some are a combination of articles, such as the X-37B space plane, which includes prelaunch, launch, on-orbit and landing articles.) The stories were chosen based on the “most viewed” articles this year. Below the survey is a review of the choices, with more information and links to articles. After reviewing the choices, rate each story topic, with 1 being the highest rating, and 10 the lowest rating. If you feel an article doesn’t deserve Top 10 honors, choose “Not in Top 10.” We’ll tally up the results and post the Top 10 list on Universe Today next week. Feel free to leave *short* comments either in the comment section or on the poll about why you chose as you did, and we’ll re-post some of the best. Make sure you click “Done” when finished. Thanks for taking part in this poll!

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Gliese 581 Photo: ESO Online Digitized Sky Survey

1. The Discovery (or not) of Exoplanet Gliese 581g

In September, astronomer Steven Vogt and his team announced what they claimed was the closest Earth-sized planet found so far that also exists in the habitable zone around its star. The planet, During a press conference, Vogt was quoted as saying, “Personally, given the ubiquity and propensity of life to flourish wherever it can, I would say, my own personal feeling is that the chances of life on this planet are 100 percent. I have almost no doubt about it.” Although the announcement created a lot of excitement, almost immediately after the announcement, another group of planet hunters said they could not find evidence of the planet in their data.

2. Radar Images Reveal Tons of Water Likely at the Lunar Poles

The Mini-SAR radar instrument on the Chandrayaan-1 spacecraft and the Mini-RF instrument on the Lunar Reconnaissance Orbiter are revealing there are likely massive amounts of water in the permanently shadowed craters at the poles, with over 600 million metric tons at the north pole alone. “If that was turned into rocket fuel, it would be enough to launch the equivalent of one Space Shuttle per day for over 2,000 years,” said Paul Spudis, principal investigator for the Mini-SAR.

Suspected Asteroid Collision Leaves Odd X-Pattern of Trailing Debris
Suspected Asteroid Collision Leaves Odd X-Pattern of Trailing Debris. Credit: NASA/Hubble team

3. Asteroid Collision Seen by Ground-Based Observatories and Hubble

We reported that on January 6, 2010, ground-based observatories spotted evidence of an asteroid collision in the asteroid belt. Then in February, the Hubble Space Telescope took a look at the mysterious X-shaped debris pattern and trailing streamers of dust. With Hubble’s sharp vision, astronomers believe a head-on collision between two asteroids actually occured. Astronomers have long thought the asteroid belt is being ground down through collisions, but such a smashup has never been seen before.

4. Thirteen Things That Saved Apollo 13

To celebrate the 40th anniversary of the Apollo 13 mission, Universe Today interviewed NASA engineer Jerry Woodfill, who was on console in NASA’s Mission Evaluation Room the night the explosion occured in the Command Module of Apollo 13. Jerry came up with “13 Things That Saved Apollo 13,” discussing different turning points and technicalities of the mission. Jerry also answered readers questions, and we also were able to publish exclusive, never-before-seen images of the Apollo 13 Crew on the aircraft carrier after they safely splashed down. This series was a Universe Today exclusive.

View of the Sun from August 18, 2010 from the Solar Dynamics Observatory. Credit: NASA/SDO

5. Solar Dynamics Observatory gives us a New View of the Sun

The Solar Dynamics Observatory launched in February of this year, and has been sending back a non-stop stream of data and images of the Sun like we’ve never seen before. SDO showed us almost up-to-the-minute views of a looping solar prominence, and have provided solar physicists with new details in helping them to understand the Sun.

SDO Soars To Study the Sun
SDO Wows with First Light Images
Near Synchronous Explosions Connect Across Vast Distances on the Sun

Lightning visible in the plume of the Eyjafjallajokull volcano in Iceland on April 17, 2010. Image courtesy of Snaevarr Gudmundsson.

6. Eyjafjallajokull Volcano In Iceland Erupts

Astronomer Snaevarr Gudmundsson from Iceland was able to travel to within just a few kilometers from the Eyjafjallajokull volcano, and shared his incredible close-up images exclusively with Universe Today. “I stayed near the volcano from about 16:00 hours to 22:00 hours on Saturday and watched its impressive eruption,” Gudmundsson said in an email. “Amazing event, awesome explosions of 1200 °C hot magma reaching ice and water. I shot more than 550 images during these hours of continuous enjoyment. Sounds ridiculous but its ever changing appearance was never boring.” The volcano ash disrupted flights across northern Europe for several days. This article was one of our “most viewed” in 2010.

7. Obama Budget Proposal for NASA Ends Constellation Program; Proposes Asteroid Mission

In what is still an evolving story, President Obama proposed a new budget and destination for NASA, which has received both praise and harsh criticism since first announced on Feb. 1, 2010. After the Augustine Commission found that Constellation program was “fundamentally un-executable,” Obama’s new plan canceled the Ares rockets but add $6 billion for NASA over the next five years, focusing more on science and technology development, as well as providing money for commercial space development. For human spaceflight, instead of returning to the Moon, an asteroid mission was proposed. There’s been no decision yet on a heavy lift program. Congress wrangled with varied versions and ultimately passed a bill similar to Obama’s original proposal, and Obama signed it, but Congress has yet to approve the overall budget.
NASA Budget Details: Constellation Canceled, But Where To Next?
Obama Compromises; Brings Back Orion, Heavy Lift Sooner
President Signs 2010 NASA Authorization Act

At least four distinct plumes of water ice spew out from the south polar region of Saturn's moon Enceladus. Credit: NASA/JPL/Space Science Institute

8. Enceladus and the Tiger Stripe Jets

2010 was the year we learned more about the geysers on Enceladus, and the Cassini spacecraft sent back more astonishing images of the geysers and the “tiger stripe” regions from which the geysers emanate. One new study even suggested that an exotic form of warm, bubbly mineral water could be what feeds the mysterious jets.

Warm Perrier Ocean Could be Powering Enceladus Geysers

Enceladus the Jet Powered Moon

SpaceX successfully launched its Falcon 9 rocket. Credit: Alan Walters (awaltersphot.com) for Universe Today.

9. SpaceX Makes Great Strides in Commercial Space Endeavours.

SpaceX’s launch of the Falcon 9 and Dragon capsule leads the way for commercial companies to bring cargo and crew the International Space Station.

The X-37B spaceplane sits on a runway at Vandenberg Air Force Base during prelaunch taxi tests. Credit: U.S. Air Force

10. The Air Force’s launches the X-37b mini space plane.

In April, the Air Force launched the X-37B Space Plane, an unmanned version of the space shuttle. It’s mission was top secret, although amateur skywatchers had no trouble keeping track of the object in orbit, and Universe Today posted pictures of several sightings. We also had an article where Brian Weeden from the Secure World Foundation speculated on what the mini space plane could be doing in orbit. The X37B landed on Dec. 3, and we posted several post landing images and videos. The Air Force has still not disclosed the purpose of the long-duration mission.

11. Bacteria Found that can Live on Arsenic

Despite the pre-announcement hype, NASA did not find life on another planet, but found life here on Earth that can live and grow almost entirely on a poison, arsenic, and incorporates it into its DNA. This announcement was soon met with opposition — not only for the science, but for how the hype got completely out of hand.

12. Exoplanets Galore!

2010 saw a plethora of new exoplanet discoveries, including the first four-planet system that was imaged, the Kepler mission which found 750 exoplanet candidates, the observation of the atmosphere of aso-called “Super-Earth“, and the discovery of what astronomers think is the “youngest” exoplanet.

Artist's impression of an anomalous X-ray pulsar. Credit: ESA

13. Faster Than Light Pulsars Discovered

Observational data from nine pulsars, including the Crab pulsar, suggest these rapidly spinning neutron stars emit the electromagnetic equivalent of a sonic boom, and a model created to understand this phenomenon shows that the source of the emissions could be traveling faster than the speed of light. Researchers say as the polarization currents in these emissions are whipped around with a mechanism likened to a synchrotron, the sources could be traveling up to six times light speed, or 1.8 million km per second. However, although the source of the radiation exceeds the speed of light, the emitted radiation travels at normal light speed once it leaves the source. “This is not science fiction, and no laws of physics were broken in this model,” said John Singleton of Los Alamos National Laboratory at a press briefing at the American Astronomical Society meeting in Washington, DC. “And Einstein’s theory of Special Relativity is not violated.”

Robonaut meets astronaut. Credit: NASA

14. NASA Prepares to Send Humanoid Robot to Space Station

Robonaut 2, NASA’s second generation of dexterous robots with a human-like torso, will be heading up to the International Space Station on space shuttle Discovery’s final mission (currently scheduled for Feb. 2011, delayed from Nov. 2010. R2 captured the imaginations of space and science fiction fans, as it can work with tools and be manipulated to do many human tasks. For now, RS will work indoors at the ISS, but is envisioned to be able to do EVA work outside the station. Also going up to the ISS on STS-133 is the Permanent Multipurpose Module (PMM) a former Multi Purpose Logistics Module (MPLM) known as Leonardo. It was transformed to become a storeroom for supplies on the station. But it might also become a haven to get away from it all, and one manager thought it might become a sort of “Man Cave” for the ISS.

15. Lunar Elevator Could be Built within a Decade

This article created quite a bit of buzz on Universe Today. Entrepreneur Michael Laine believes a lunar elevator – a space elevator from the surface of the Moon – could be created with materials that are available now. With more research and the right amount of capital, Laine says a lunar elevator could be built within a decade.

Hayabusa's sample return capsule descends under parachute toward the Woomera desert, Australia. Credit: Corby Waste and Tommy Thompson for NASA / JPL

16. Hayabusa Returns To Earth with Samples of Asteroid

Japan’s little spacecraft that could returned to Earth this summer, making a fiery reentry in the Australian outback, overcoming several problems and obstacles. Later, scientists opened the sample return container revealing small particles which are likely from asteroid Itokawa.


17. More Mysteries of Titan Revealed

2010 was the year we learned more about Titan, as the Cassini spacecraft continues to send back more incredible images and data of Saturn’s largest Moon. Scientists were able to discern more about the weather on Titan, and they also saw clouds in the Moon’s atmosphere, plus one researcher found that Titan’s atmosphere could produce the building blocks of life, while another group found evidence of cryovolcanoes on Titan.

Posted on by Jason Rhian

Numerous Companies Propose Possible ‘Space Taxis’

Orbital Sciences is one of many space companies that are vying to produce a 'space taxi.' Image Credit: Orbital Sciences Corporation

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Once, the field had only had few entries, but now there are several companies vying to send American astronauts into orbit. With NASA’s Commercial Crew Development program, or CCDev 2, and the encouragement of commercial space firms to produce their own vehicles, the number of potential ‘space-taxis’ has swelled, with virtually every established and up-and-coming aerospace company either producing – or proposing one.

SpaceX has successfully demonstrated the capabilities of its Dragon spacecraft. Image Credit: SpaceX

One of the first firms to unveil a potential means of transportation to the International Space Station (ISS) was Space Exploration Technologies (SpaceX). SpaceX launched the first of its Dragon spacecraft on Dec. 8, and shortly thereafter became the first private company to safely recover a spacecraft after it returned from orbit.

Boeing was once of the first companies to unveil its proposal. Image Credit: Boeing

Not to be out done by the ‘new kid on the block’ Boeing unveiled its version of a space taxi this past September. Boeing’s Crew Space Transportation-100 (CST-100) spacecraft which it described could be used for missions to the space station or other ‘LEO platforms.’ One potentially exciting prospect about this endeavor is that any excess seating capacity will be available for purchase through Space Adventures.

Orbital Sciences has proposed using a space plane to ferry astronauts to orbit: Image Credit: Orbital

A step away from what most of these companies are doing, Orbital Sciences has proposed producing a ‘mini-shuttle’ to ferry passengers to and from orbit. Most aerospace companies that have submitted designs and ideas have stepped away from the space plane concept as it is now viewed as too complicated and expensive. However, the U.S. Air Force recently successfully demonstrated the viability of its unmanned X-37B space plane. It was perhaps with this in mind that emboldened Orbital to go a step further and produce a man-rated mini space plane. Orbital images show their spacecraft proposal being lifted to orbit atop a Delta IV Heavy.

Just this month Virgin Galactic also announced its plans to produce a space plane (the company uses a space plane in its sub-orbital commercial efforts – this new space plane appears to be an extension of that).

Sierra Nevada also has proposed using a space plane as an orbital transport vehicle. Image Credit: Sierra Nevada Space

Lastly Sierra Nevada Corp also has thrown its name into the ring proposing a winged spacecraft. Their ‘Dream Chaser’ spacecraft is similar to Orbital’s proposal, a winged spacecraft that would be launched to orbit atop an expendable launch vehicle.

These companies are all vying for the $200 million that NASA has placed into a program to promote ease of access to orbit. While the Orion spacecraft, produced by Lockheed Martin, is part of a NASA program – these other organizations are hoping that by demonstrating the viability of their technology – that they can also secure a strong position in the emerging commercial space market.

Posted on by Jon Voisey

Magnetic Fields on O-Class Stars

Star classifications. Image credit: Kieff

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The primary method by which astronomers can measure magnetic field strength on stars is the Zeeman effect. This effect is the splitting of spectral lines into two due to the magnetic field’s effect on the quantum structure of the orbitals. For massive O-class stars, their spectra are largely featureless in the visual portion of the spectra due to an insufficient number of atoms with electrons in the necessary orbitals to undergo transitions which can produce visual spectral lines. Thus, determining whether or not these stars have magnetic fields has been a unique challenge. A new paper from researchers at the University of Amsterdam, led by Roald Schnerr, looks for evidence of these fields in the form of synchrotron radiation.

Synchrotron radiation is a form of light produced when relativistic, charged particles move through a magnetic field. The light emitted can be generated in any portion of the spectra from radio to gamma rays, depending on the strength of the field. Astronomically, this was first detected in 1956 by Geoffrey Burbidge in the jets of M87 and has since been used to explain emission in planetary magnetospheres, supernovae, near black holes, and around pulsars.

This form of energy distinguishes itself from other forms of light in two main fashions. The first is that it is highly polarized. This property is generated by the electric and magnetic components always being in the same planes and can be studied with filters that only allow light with its fields in appropriate planes to pass. The second is that the radiation created is “non-thermal”. In other words, it doesn’t match the distribution of wavelengths generated by a blackbody.

Models of massive, O-class stars suggest they should contain magnetic fields. Some evidence has seemed to confirm this. Previous studies have also shown that the stellar winds from some of these stars varies with timescales similar to the rotation rates of the stars which could be interpreted as winds being slowed on some faces by the magnetic field as it swept by.

Schnerr’s team attempted to bolster the evidence for magnetic fields by detecting the non-thermal radiation from these stars. The team selected 5 stars which have been shown to have strongly variable winds, some with cyclic variations and used the Westerbork Synthesis Radio Telescope, in the Netherlands to search for non-blackbody signals. The radio range was selected due to the predicted magnetic field strength.

Ultimately, only three of the five selected targets could be observed with the chosen telescope and only one of those, ξ Persei, showed evidence of a non-thermal spectrum. But while this strengthens the case for magnetic fields on the star, it raises another question: From where do the relativistic particles originate? Although O-class stars have strong stellar winds, their speeds are well studied and well below the necessary velocity.

One clue could come from the fact that ξ Persei is a “runaway star”. These stars have velocities and plunge through the interstellar medium at 30-200 km/sec. The team suggests that a bow shock created by this motion could result in sufficiently high velocities. Whether or not ξ Per has such a bow shock is something that could be determined with additional observations.

While this research provides some interesting clues to the nature of these magnetic fields on these stars, it still relies on a small sample. This technique can certainly be expanded to a larger number of stars in the future and may help astronomers better constrain their models of stellar workings.

Posted on by Steve Nerlich

Astronomy Without A Telescope – The Edge of Greatness

The foamy cosmic web – at this scale we run out of superlatives to describe the large scale structure of the universe.

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The so-called End of Greatness is where you give up trying to find more superlatives to describe large scale objects in the universe. Currently the Sloan Great Wall – a roughly organised collection of galactic superclusters partitioning one great void from another great void – is about where most cosmologists draw the line.

Beyond the End of Greatness, it’s best just to consider the universe as a holistic entity – and at this scale we consider it isotropic and homogenous, which we need to do to make our current cosmology math work. But at the very edge of greatness, we find the cosmic web.

The cosmic web is not a thing we can directly observe since its 3d structure is derived from red shift data to indicate the relative distance of galaxies, as well as their apparent position in the sky. When you pull all this together, the resulting 3d structure seems like a complex web of galactic cluster filaments interconnecting at supercluster nodes and interspersed by huge voids. These voids are bubble-like – so that we talk about structures like the Sloan Great Wall, as being the outer surface of such a bubble. And we also talk about the whole cosmic web being ‘foamy’.

It is speculated that the great voids or bubbles, around which the cosmic web seems to be organised, formed out of tiny dips in the primordial energy density (which can be seen in the cosmic microwave background), although a convincing correlation remains to be demonstrated.

The two degree field (2df) galaxy redshift survey – which used an instrument with a field of view of two degrees, although the survey covered 1500 square degrees of sky in two directions. The wedge shape results from the 3d nature of the data - where there are more galaxies the farther out you look, within one region of the sky. The foamy bubbles of the cosmic web are visible. Credit: The Australian Astronomical Observatory.

As is well recorded, the Andromeda Galaxy is probably on a collision course with the Milky Way and they may collide in about 4.5 billion years. So, not every galaxy in the universe is rushing away from every other galaxy in the universe – it’s just a general tendency. Each galaxy has its own proper motion in space-time, which it is likely to continue to follow despite the underlying expansion of the universe.

It may be that much of the growing separation between galaxies is a result of expansion of the void bubbles, rather than equal expansion everywhere. It’s as though once gravity loses its grip between distant structures – expansion (or dark energy, if you like) takes over and that gap begins to expand unchecked – while elsewhere, clusters and superclusters of galaxies still manage to hold together. This scenario remains consistent with Edwin Hubble’s finding that the large majority of galaxies are rushing away from us, even if they are not all equally rushing away from each other.

van de Weygaert et al are investigating the cosmic web from the perspective of topology – a branch of geometry which looks at spatial properties which are preserved in objects undergoing deformation. This approach seems ideal to model the evolving large scale structure of an expanding universe.

The paper below represents an early step in this work, but shows that a cosmic web structure can be loosely modelled by assuming that all data points (i.e. galaxies) move outwards from the central point of the void they lie most proximal to. This rule creates alpha shapes, which are generalised surfaces that can be built over data points – and the outcome is a mathematically modelled foamy-looking cosmic web.

Further reading: van de Weygaert et al. Alpha Shape Topology of the Cosmic Web.

Posted on by Jon Voisey

M33’s “Object-X”

Often times, objects that are unremarkable in one portion of the spectra, can often be vivid in others. In M33, the Triangulum Galaxy, a star that’s barely visible in the optical, stands out as the second brightest source (and single brightest single star) in the mid-infrared. This unusual star has been the target of a recent study, led by Rubab Khan at the Ohio State University and may help astronomers to understand an unusual supernova from 2008.

The supernova 2008S occurred February first in NGC 6946, the Fireworks Galaxy. Since it happened in a galaxy that is relatively nearby, astronomers seized the opportunity to explore the progenitor star in archival images. Yet images from the Large Binocular Telescope and other optical observatories could not find a star that could be identified as a parent. Instead, the detection of the star responsible came from Spitzer, an infrared observatory. Observations from this instrument indicated that the star responsible may have been unexpectedly low mass for such a powerful explosion leading other astronomers to question whether or not SN 2008S was a true supernova, or merely an impostor in the form of an eruption of a Luminous Blue Variable (LBV), which tend to be more massive stars and would be in stark contradiction to the Spitzer findings.

Yet, regardless of the nature of the nature of SN 2008S, teams all seemed to agree that the progenitor had only been detected in the infrared because it was veiled by a thick curtain of dust. So to help better understand this class of dusty stars, astronomers have been working to uncover more of them, against which they can test their hypotheses.

To find these objects, astronomers have been searching the infrared portion of the spectrum for objects that are exceptionally bright yet lack optical counterparts. The brightest of the stellar sources in M33 features faint star in the red portion of the optical spectrum from the Local Group Galaxies Survey published in 2007, but no star at all in archival records with similar limiting magnitudes from 1949 and 1991. The authors of the new study have dubbed this odd source, Object-X.

The team rules out the possibility that the object could be a young stellar object (YSO), blocked by a thick dust disc along the line of sight, noting that models of even the thickest dust discs still predict more light to be scattered back along the line of sight. Instead, the team concludes that Object-X must be a self-obscured star that has undergone relatively recent mass loss which has cooled to form either graphite or silicate dust. Depending on which type of dust is predominant, the team was able to fit the data to two wildly different temperatures for the star: either 5000 K for graphite, or 20,000 K for the silicate. In all cases, the predicted mass for the central star was always greater than 30 solar masses.

In general, there are two mechanisms by which a star can eject material to form such a curtain. The first is through stellar winds, which increase as the star enters the red giant phase, swelling up and lowering the force of gravity near the surface. The second is “impulsive mass ejections” in which stars shudder and throw mass off that way. A classical example of this is Eta Carinae. The team predicts from the features they found, that Object-X is most likely a cool hypergiant. The fact that the star was completely obscured until very recently hints that the mass loss is not constant (as stellar wind), but patchy, coming from frequent eruptions. As the shell of dust expands, the star should reemerge in the optical, becoming visible again in the next few decades.

Posted on by Nancy Atkinson

Tearing Apart Apollo 11 Inaccuracies

The movie trailer for Transformers 3 came out over a week ago, and seeing it is a facepalm moment for any true human spaceflight follower, fan, aficionado, or historian. I mean really, — and yes, I know this is a movie — but how could they portray what they call “a generation’s greatest achievement” so inaccurately? I originally decided I wasn’t going to post it, because it basically re-writes history and I can only imagine how the conspiracy theorists will run with this. Plus getting this kind of thing into the public mindset, I fear, will be another “Capricorn 1” moment where people construe the movie as proof that NASA is hiding things. But Robert Pearlman over at collectSPACE posted an article today, basically tearing apart the trailer, discussing every inaccuracy in detail. So watch the trailer, above, and then go check out Robert’s article — its great.

And then, while you’re at it, go read Robert Krulwich’s article on NPR’s website, where he gets a unusually lengthy response from Neil Armstrong about what really happened on the Apollo 11 moon walk, and why it was so short.

Posted on by Matt Williams

Convex Lens

Convex Lens

As every child is sure to find out at some point in their life, lenses can be an endless source of fun. They can be used for everything from examining small objects and type to focusing the sun’s rays. In the latter case, hopefully they choose to be humanitarian and burn things like paper and grass rather than ants! But the fact remains, a Convex Lens is the source of this scientific marvel. Typically made of glass or transparent plastic, a convex lens has at least one surface that curves outward like the exterior of a sphere. Of all lenses, it is the most common given its many uses.

A convex lens is also known as a converging lens. A converging lens is a lens that converges rays of light that are traveling parallel to its principal axis. They can be identified by their shape which is relatively thick across the middle and thin at the upper and lower edges. The edges are curved outward rather than inward. As light approaches the lens, the rays are parallel. As each ray reaches the glass surface, it refracts according to the effective angle of incidence at that point of the lens. Since the surface is curved, different rays of light will refract to different degrees; the outermost rays will refract the most. This runs contrary to what occurs when a divergent lens (otherwise known as concave, biconcave or plano-concave) is employed. In this case, light is refracted away from the axis and outward.

Lenses are classified by the curvature of the two optical surfaces. If the lens is biconvex or plano-convex, the lens is called positive or converging. Most convex lenses fall into this category. A lens is biconvex (or double convex, or just convex) if both surfaces are convex. These types of lenses are used in the manufacture of magnifying glasses. If both surfaces have the same radius of curvature, the lens is known as an equiconvex biconvex. If one of the surfaces is flat, the lens is plano-convex (or plano-concave depending on the curvature of the other surface). A lens with one convex and one concave side is convex-concave or meniscus. These lenses are used in the manufacture of corrective lenses.

For an illustrated example of how images are formed with a convex lens, click here.

We have written many articles about lenses for Universe Today. Here’s an article about the concave lens, and here’s an article about telescope lens.

If you’d like more info on convex lens, check out these articles from The Physics Classroom and Wikipedia.

We’ve also recorded an episode of Astronomy Cast all about the Telescope. Listen here, Episode 33: Choosing and Using a Telescope.

Sources:
http://en.wikipedia.org/wiki/Lens_(optics)
http://homepage.mac.com/cbakken/obookshelf/cvreal.html
http://www.play-hookey.com/optics/lens_convex.html
http://www.answers.com/topic/convex-lens-1
http://www.physicsclassroom.com/class/refrn/u14l5a.cfm
http://www.tutorvista.com/content/science/science-ii/refraction-light/formation-convex.php

Posted on by Matt Williams

Conservation of Mass

Conservation of Mass
Conservation of Mass. Image Credit: www.efm.leeds.ac.uk

[/caption]While it may offend anyone currently trying to lose that holiday weight, it is a classic physical law that in a closed system, mass can neither be created nor destroyed. Feeling discouraged yet? Well, don’t! Strictly speaking, this law does NOT mean you can’t drop pounds, just that within an isolated system (which your body is not) mass cannot be created/destroyed, although it may be rearranged in space, and changed into different types of particles. This law is known as the Conversation of Mass, otherwise known as the principal of mass/matter conservation. More specifically, the law states that the mass of an isolated system cannot be changed as a result of processes acting inside the system. This implies that for any chemical process in a closed system, the mass of the reactants must equal the mass of the products. The law is considered “classical” in that it does not take into consideration more recent physical laws, such as special relativity or quantum mechanics, but still applies in many contexts.

This law is rooted in classical Greek philosophy, which states that “nothing can come from nothing”, often stated in its Latin form: ex nihlionihlio fit. The basic premise here, first espoused by Empedocles (ca. 490–430 BCE), is that no new matter can come into existence where none was present before. It was further elaborated on by Epicurus, Parmenedes, and a number of Indian and Arab philosophers. However, it was not until the 18th century with Antoine Lavoisier that it graduated from the field of cosmology and became a scientific law. Lavoisier was the first to clearly outlined it in his seminal work TraitéÉlémentaire de Chimie (Elementary Treatise on Chemistry) in 1789.

Historically, the conservation of mass and weight was obscure for millennia because of the buoyant effect of the Earth’s atmosphere on the weight of gases. In addition, when a substance burns, mass appears to be lost since ashes weight less than the original substance. These effects were not understood until careful experiments in which chemical reactions such as rusting were performed in sealed glass ampules, whereby it was found that the chemical reaction did not change the weight of the sealed container. Once understood, the conservation of mass was of great importance in changing alchemy to modern chemistry. When chemists realized that substances never disappeared from measurement with the scales (once buoyancy effects were held constant, or had otherwise been accounted for), they could for the first time embark on quantitative studies of the transformations of substances.

The historical concept of both matter and mass conservation is widely used in many fields such as chemistry, mechanics, and fluid dynamics. In relativity, the mass-energy equivalence theorem states that mass conservation is equivalent to energy conservation, which is the first law of thermodynamics.

We have written many articles about the conservation of mass for Universe Today. Here’s an article about nuclear fusion, and here’s an article about the atom.

If you’d like more info on the law of conservation of mass, check out these articles from NASA Glenn Research Center and Engineering Toolbox.

We’ve also recorded an entire episode of Astronomy Cast all about the Atom. Listen here, Episode 164: Inside the Atom.

Sources:
http://en.wikipedia.org/wiki/Conservation_of_mass
http://www.grc.nasa.gov/WWW/K-12/airplane/mass.html
http://en.wikipedia.org/wiki/Nothing_comes_from_nothing
http://en.wikipedia.org/wiki/Antoine_Lavoisier
http://en.wikipedia.org/wiki/Jain_philosophy

Posted on by Ken Kremer

Powerful Mars Orbiter Directs Opportunity to Clays and Hydrated Minerals

This map indicates geological units in the region of Mars around a smaller area where Opportunity has driven from early 2004 through late 2010. The blue-coded unit encompassing most of the southern half of the mapped region is ancient cratered terrain. In the northern region, it is overlain by younger sediments of the Meridiani Plains, punctuated by the even younger Bopulu impact. At Endeavour Crater, in the upper right near the gold line of Opportunity's traverse, ancient cratered terrain is exposed around the crater rim. Locations where orbital observations have detected clay minerals are indicated at the western edge of Endeavour and at two locations in the southern portion of the map. The mineral mapping was done by Sandra Wiseman and Ray Arvidson of Washington Universty in St. Louis based on observations by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on NASA's Mars Reconnaissance Orbiter.

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NASA is using its powerful science surveyor orbiting more than 241 kilometers above Mars to target the surface explorations of the long lived Opportunity rover to compelling science targets on the ground. Opportunity is currently on a long term trek to the giant crater named Endeavour, some 22 kilometers in diameter, which shows significant signatures of clays and water bearing sulfate minerals which formed in the presence of flowing liquid water billions of years ago.

An armada of orbiters and rovers from Earth are carrying out a coordinated attack plan to unlock the mysteries of the red planet, foremost being to determine whether life ever arose on Mars.

On Dec. 15 (Sol 2450), Opportunity arrived at Santa Maria crater which is just 6 km distant from the western rim of Endeavour. Over the past 2 years, the rover has traversed more than two thirds of the 19 km distance from Victoria crater -her last big target – to Endeavour.

High resolution spectral and imaging mappers aboard NASA’s Mars Reconnaissance Orbiter (MRO) are enabling researchers on the rover team to prioritize targets and strategically guide Opportunity to the most fruitful locations for scientific investigations.

The on board CRISM mapping spectrometer has detected clay minerals, or phyllosilicates, at multiple locations around Endeavour crater including the western rim closest to Opportunity. CRISM is the acronym for Compact Reconnaissance Imaging Spectrometer for Mars. Images from MRO’s HiRISE camera are utilized to scout out the safest and most efficient route. See maps above and below.

“This is the first time mineral detections from orbit are being used in tactical decisions about where to drive on Mars,” said Ray Arvidson of Washington University in St. Louis. Arvidson is the deputy principal investigator for the Spirit and Opportunity rovers and a co-investigator for CRISM.

Clay minerals are a very exciting scientific find because they can form in more neutral and much less acidic aqueous environments which are more conducive to the possibility for the formation of life. They have never before been studied up close by science instruments on a landed mission.

Opportunity may soon get a quick taste of water bearing sulfate minerals at Santa Maria because spectral data from CRISM suggest the presence of sulfate deposits at the southeast rim of the crater. Opportunity has previously investigated these sulfate minerals at other locations along her circuitous traverse route – but which she discovered without the help of orbital assets.

“We’ve just pulled up to the rim of Santa Maria, and the workload is very high,” Steve Squyres informed me. Squyres, of Cornell University, is the Principal Scientific Investigator for NASA’s Spirit and Opportunity Mars rovers.

Opportunity drove to within about 5 meters of the crater rim on Dec. 16 (Sol 2451). JPL Mars rover driver Scott Maxwell tweeted this message ; “Today’s NAVCAM mosaic of Santa Maria Crater. Woo-hoo! Glorious and beautiful!” and this twitpic

Orbital Observations at Santa Maria Crater.
Opportunity just arrived at the western side of Santa Maria Crater, some 90 meters wide, on 15 December 2010. Researchers are using data collected by a powerful mineral mapping spectrometer (CRISM) aboard NASA’s Mars Reconnaissance Orbiter (MRO) to direct the route which Opportunity is traversing on Mars during the long term journey to Endeavour crater. Spectral observations recorded by CRISM indicates the presence of water-bearing sulfate minerals at the location shown by the red dot on the southeast rim crater whereas the crater floor at the blue dot does not. This image was taken by the the High Resolution Imaging Science Experiment (HiRISE) camera also on MRO. Credit: NASA/JPL-Caltech/Univ. of Arizona

The rover will conduct an extensive science campaign at Santa Maria by driving to different spots over the next several weeks and gathering data to compare observations on the ground to those from CRISM in orbit.

Opportunity Navcam camera view of Santa Maria Crater just 5 m from the rim on Sol 2451, Dec. 16, 2010. Click to enlarge

Santa Maria crater appears to be relatively fresh and steep walled and was likely created by a meteor strike only a few million years ago. Endeavour is an ancient crater with a discontinuous rim that is heavily eroded at many points. By exploring craters, scientists can look back in time and decipher earlier geologic periods in Mars history.

Scientists believe that the clay minerals stem from an earlier time period in Martian history and that the sulfate deposits formed later. Mars has experiences many episodes of wet environments at diverse locations in the past and climate-change cycles persist into the present era.

After the upcoming Solar Conjunction in February 2011, Opportunity will depart eastwards for the last leg of the long march to Endeavour. She heads for a rim fragment dubbed Cape York which spectral data show is surrounded by exposures of water bearing minerals. Cape York is not yet visible in the long distance images because it lies to low. See maps below.

Thereafter, Opportunity alters direction and turns south towards her next goal –
Cape Tribulation – which is even more enticing to researchers because CRISM has detected exposures of the clay minerals formed in the milder environments more favorable to life. Cape Tribulation has been clearly visible in rover images already taken months ago in early 2010.

Opportunity could reach Endeavour sometime in 2011 if she can continue to survive the harsh environment of Mars and drive at her current accelerated pace. Opportunity arrived at Mars in January 2004 for a planned 90 day mission. The rover has far surpassed all expectations and will soon celebrate 7 earth years of continuous operations on the red planet. Virtually all the data from Spirit and Opportunity are relayed back to Earth via NASA’s Mars Odyssey orbiter.


Opportunity used its panoramic camera in a super-resolution technique to record this view of the horizon on Sol 2298 (July 11, 2010) which shows the western rim of Endeavour Crater, including the highest ridge informally named “Cape Tribulation”. CRISM data revealed exposures of clay minerals at Cape Tribulation.

Opportunity’s Path on Mars Through Sol 2436
The red line shows where Opportunity has driven from the place where it landed in January 2004 — inside Eagle Crater, at the upper left end of the track — to where it reached on the 2,436th Martian day, or sol, of its work on Mars (Nov. 30, 2010). The map covers an area about 15 kilometers (9 miles) wide. North is at the top. Subsequent drives brought Opportunity to Santa Maria Crater, which is about 90 meters (295 feet) in diameter. After investigating Santa Maria the rover heads for Endeavour Crater. The western edge of 22-kilometer-wide (14-mile-wide) Endeavour is in the lower right corner of this map. Some sections of the discontinuous raised rim and nearby features are indicated with informal names on the map: rim segments “Cape York” and “Solander Point”; a low area between them called “Botany Bay”; “Antares” crater, which formed on sedimentary rocks where the rim was eroded down; and rim fragment “Cape Tribulation,” where orbital observations have detected clay minerals. The base map is a mosaic of images from the Context Camera on NASA’s Mars Reconnaissance Orbiter.

Posted on by Nancy Atkinson

Astronomy Cast Ep. 209: Exotic Life

Is this arsenic based life?

We don’t like to cover news on Astronomy Cast, but sometimes there’s a news story that’s interesting, complicated, and rapidly unfolding – and it happens to cover an area that we haven’t talked much about. So today we thought we’d talk about the discovery of arsenic-based life, and exotic forms of life in general. Maybe we need to redefine our definition of life. Or maybe we just got introduced to some distant cousins.

Click here to download Episode 209: Exotic Life
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Episode 209 Show notes and transcript