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Monday, March 15, 2010

Lava likely made river-like channel on Mars

Flowing lava can carve or build paths very much like the riverbeds and canyons etched by water, and this probably explains at least one of the meandering channels on the surface of Mars. These results were presented on March 4, 2010 at the 41st Lunar and Planetary Science Conference by Jacob Bleacher at NASA’s Goddard Space Flight Center, Greenbelt, Md. Whether channels on Mars were formed by water or by lava has been debated for years, and the outcome is thought to influence the likelihood of finding life there.

"To understand if life, as we know it, ever existed on Mars, we need to understand where water is or was," says Bleacher. Geologists think that the water currently on the surface of Mars is either held in the soil or takes the form of ice at the planet's north and south poles. But some researchers contend that water flowed or pooled on the surface sometime in the past; water in this form is thought to increase the chance of some form of past or present life.

One of the lines of support for the idea that water once flowed on Mars comes from images that reveal details resembling the erosion of soil by water: terracing of channel walls, formation of small islands in a channel, hanging channels that dead-end and braided channels that branch off and then reconnect to the main branch. "These are thought to be clear evidence of fluvial [water-based] erosion on Mars," Bleacher says.
Lava is generally not thought to be able to create such finely crafted features. Instead, "the common image is of the big, open channels in Hawaii," he explains.

Bleacher and his colleagues carried out a careful study of a single channel on the southwest flank of Mars' Ascraeus Mons volcano, one of the three clustered volcanoes collectively called the Tharsis Montes. To piece together images covering more than 270 kilometers (~168 miles) of this channel, the team relied on high-resolution pictures from three cameras—the Thermal Emission Imaging System (THEMIS), the Context Imager (CTX) and the High/Super Resolution Stereo Color (HRSC) imager—as well as earlier data from the Mars Orbiter Laser Altimeter (MOLA). These data gave a much more detailed view of the surface than previously available.

Because the fluid that formed this and other Ascraeus Mons channels is long-gone, its identity has been hard to deduce, but the visual clues at the source of the channel seem to point to water. These clues include small islands, secondary channels that branch off and rejoin the main one and eroded bars on the insides of the curves of the channels.

But at the channel's other end, an area not clearly seen before, Bleacher and colleagues found a ridge that appears to have lava flows coming out of it. In some areas, "the channel is actually roofed over, as if it were a lava tube, and lined up along this, we see several rootless vents," or openings where lava is forced out of the tube and creates small structures, he explains. These types of features don't form in water-carved channels, he notes. Bleacher argues that having one end of the channel formed by water and the other end by lava is an "exotic" combination. More likely, he thinks, the entire channel was formed by lava.

To find out what kinds of features lava can produce, Bleacher, along with W. Brent Garry and Jim Zimbelman at the Smithsonian Institution in Washington, examined the 51-kilometer (~32 mile) lava flow from the 1859 eruption of Mauna Loa on the Big Island of Hawaii. Their main focus was an island nearly a kilometer long in the middle of the channel; Bleacher says this is much larger than islands typically identified within lava flows. To survey the island, the team used differential GPS, which provides location information to within about 3 to 5 centimeters (1.1 to 1.9 inches), rather than the roughly 3 to 5 meters (9.8 to 16.4 feet) that a car's GPS can offer.

"We found terraced walls on the insides of these channels, channels that go out and just disappear, channels that cut back into the main one, and vertical walls 9 meters (~29 feet) high," Bleacher says. "So, right here, in something that we know was formed only by flowing lava, we found most of the features that were considered to be diagnostic of water-carved channels on Mars."

The new results make "a strong case that fluid lava can produce channels that look very much like water-generated features," says Zimbelman. "So, we should not jump to a water-related conclusion when we see such channels on other planets, particularly in volcanic terrain such as that around the Tharsis Montes volcanoes."

Further evidence that such features could be created by lava flows came from the examination of a detailed image of channels from the Mare Imbrium, a dark patch on the moon that is actually a large crater filled with ancient lava rock. In this image, too, the researchers found channels with terraced walls and branching secondary channels.

The conclusion that lava probably made the channel on Mars "not only has implications for the geological evolution of the Ascraeus Mons but also the whole Tharsis Bulge [volcanic region]," says Andy de Wet, a co-author at Franklin & Marshall College, Lancaster, Penn. "It may also have some implications for the supposed widespread involvement of water in the geological evolution of Mars."

Bleacher notes that the team's conclusions do not rule out the possibility of flowing water on Mars, nor of the existence of other channels carved by water. "But one thing I've learned is not to underestimate the way that liquid rock will flow," he says. "It really can produce a lot of things that we might not think it would."

Philip Christensen of Arizona State University is the principal investigator for the THEMIS instrument on the Mars Odyssey orbiter, and Mike Malin of Malin Space Science Systems is the principal investigator for the CTX instrument aboard the Mars Reconnaissance Orbiter. Both missions are managed by NASA’s Jet Propulsion Laboratory (JPL), Pasadena, Calif. MOLA was aboard the Mars Global Surveyor, built by JPL. HRSC is aboard the European Space Agency's Mars Express spacecraft.

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Tuesday, December 23, 2008

How a Firework Rocket Works

Background: Developed in the second-century BCE, by the ancient Chinese, fireworks are the oldest form of rockets and the most simplistic model of a rocket. Originally fireworks had religious purposes in ceremonies but were later adapted for military use during the middle ages in the form of "flaming arrows." During the tenth and thirteenth centuries the Mongols and the Arabs brought the major component of these early rockets to the West: gunpowder. Although the cannon, and gun became the major developments from the eastern introduction of gunpowder, a tickling of rockets also resulted. These rockets were essentially enlarged fireworks which propelled, further than the long bow or cannon, packages of explosive gunpowder. During the late eighteenth century imperialistic wars, Colonel Congreve, developed his famed rockets, which trave range distances of four miles. The "rockets' red glare" (American Anthem) records the usage of rocket warfare, in its early form of military strategy, during the inspirational battle of Fort McHenry.

Function: Gunpowder, a mixture composing of: 75% Potassium Nitrate (KNO3), 15% Charcoal (Carbon), and 10% Sulfur, provides the thrust of most fireworks. This fuel is tightly packed into the casing, a thick cardboard or paper rolled up tube (figure 1.2), forming the propellant-core of the rocket (figure 1.5) in a typical length to width or diameter ratio of 7:1.

A fuse (cotton twine coated with gunpowder) is lit by a match or by a "punk" (a wooden stick with a coal-like red-glowing tip). This fuse burns rapidly into the core of the rocket where it ignites the gunpowder walls of the interior core. One might think that the fuse would burn out once inside of the core, due to the lack of surrounding air but the chemistry of gunpowder solves this point. As mentioned before one of the chemicals in gunpowder is potassium nitrate, the most important ingredient. The molecular structure of this chemical, KNO3, contains three atoms of oxygen (O3), one atom of nitrogen (N), and one atom of potassium (K). The three oxygen atoms locked into this molecule provide the "air" that the fuse and the rocket use to burn the other two ingredients, carbon and sulfur. Thus potassium nitrate oxidizes the chemical reaction by easily releasing it oxygen. This reaction is not spontaneous though, and must be initiated by heat such as the match or "punk."

Thrust is produced once the burning fuse enters the core. The core is quickly filled with flames and thus, the necessary heat to ignite, continue, and spread the reaction. After the initial surface of the core has been exhausted a layer of gunpowder is exposed continuing, for the few seconds the rocket will burn, to produce thrust. The action reaction (propulsion ) effect explains the thrust as produced when the hot expanding gases (produced in the reaction burning of gunpowder)escape the rocket via the nozzle (figure 1.3). Constructed of clay, the nozzle can withstand the intense heat of the flames that pass through.

The original sky rocket used a long wooden or bamboo stick (figure 1.8) to provide a low center of balance (by distributing the mass of the rocket over a greater linear distance) and thus stability to the rocket through its flight. Fins usually three set at 120 degree angles of one another or four set at 90 degree angles of one another, had their developmental roots in arrow feather guides. The principles that governed the flight of an arrow were the same for early fireworks. But fins could be omitted altogether since a simple stick seemed to grant sufficient stability. Only when firework-type rockets became more developed did the fin rocket gain popularity. With fins properly set (in creating a suitable center of balance) the extra mass of the drag (air resistance) creating guide-stick could be removed, increasing rocket performance. Also, as rockets become larger and more powerful the exhaust from the engine would consume the guide-stick, destroying the rockets mode of guidance.

Fireworks have remained popular in today's age due to the spectacle of colors and sounds they are so renown for. The component of a rocket that produces these stars, reports ("bangs"), and colors is typically located just below the nosecone (figure 1.7) section of a rocket. After the rocket engine has consumed all of its fuel an internal fuse is lit that delays the release of the stars, or other effect. This delay allows for coasting time where the rocket continues its ascent. As gravity will eventually pull the firework back to earth, it slows and eventually reaches an apex (highest point: where velocity of the rocket is zero) and begins its descent. The delay usually lasts just before this apex, at an optimum velocity, where a small explosion shoots the firework's stars in desired directions and thus producing a brilliant effect. The colors, reports, flashes, and, stars are analogous to flavor one adds with spices (chemicals with special pyrotechnic properties) to a soup of otherwise bland gunpowder.

Advantages/Disadvantages: Gunpowder's relatively low specific impulse (amount of thrust per unit propellant) limits its capacity of thrust production on larger scales. Fireworks are the simplest of solid rockets and the weakest. Evolution from fireworks brought about more complex solid fueled rockets, which use more exotic and powerful fuels. The low-explosive properties of gunpowder, relative to the high-explosive properties of more advanced solid fuels testify to the "survival of the fittest," as the use of firework-type engines (for purposes other than entertainment or education) has virtually ceased since the late ninteenth century. Yet with all these drawbacks fireworks will continue to maintain their use as a traditional pastime with an on-going history of nearly 5,000 years.


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Wednesday, November 12, 2008

STS-126 Mission Information

Veteran space flier Navy Capt. Christopher J. Ferguson will command the STS-126 mission aboard Endeavour to deliver equipment to the International Space Station that will enable larger crews to reside aboard the complex. Air Force Lt. Col. Eric A. Boe will serve as the pilot. The mission specialists are Navy Capt. Stephen G. Bowen, Army Lt. Col. Robert S. Kimbrough, Navy Capt. Heidemarie M. Stefanyshyn-Piper and NASA astronauts Donald R. Pettit and Sandra H. Magnus.

Magnus will remain on the station, replacing Expedition 17/18 Flight Engineer Gregory E. Chamitoff, who returns to Earth with the STS-126 crew. Magnus will serve as a flight engineer and NASA science officer for Expedition 18. Magnus will return to Earth on shuttle mission STS-119.

Endeavour will carry a reusable logistics module that will hold supplies and equipment, including additional crew quarters, additional exercise equipment, equipment for the regenerative life support system and spare hardware.


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Thursday, October 16, 2008

Collecting 50 Years of NASA Space History

At a celebration of NASA’s 50th anniversary held outside Washington, DC late last month, a champagne toast was offered in recognition of the five decades of exploration that the agency had accomplished. NASA had put men on the Moon, sent probes to the planets, and improved our understanding of life here at home.

As invited guests raised their glasses, many noticed that on the side of the flute was imprinted the logo for NASA's 50 Years. As the toast ended and the glasses were emptied, many held onto to the stemware as a souvenir of the event and NASA’s anniversary.

These glasses were just the latest example of five decades of commemorative mementos collected in the wake of NASA's crowning space achievements.

The public, enamored by space exploration, have long desired to own a piece of NASA's adventures. In some instances, the space agency met this longing by sharing memorabilia that had been carried to orbit on some of its flights. More often, companies looking to celebrate the United States’ space achievements produced collectibles inspired by NASA’s missions and milestones.

Even the astronauts got into the game. While America’s first astronaut, Alan Shepard had only enough room to fly a U.S. flag on his sub-orbital Mercury flight, Virgil “Gus” Grissom, who followed Shepard to space, packed his spacesuit pockets with miniature Mercury capsules and rolls of Roosevelt dimes. Originally intended for friends and family members, these early space-flown trinkets have been passed down and traded to become very popular NASA collectibles.

In the years that followed, astronauts extended the tradition, flying mementos for those close to them, but also carrying medallions for themselves. They designed mission patches, small embroidered and silk-screened emblems that uniquely represented their flight. Replicas of these insignia were produced for the public and the hobby of space patch collecting was born. Today, hundreds of individual designs offer a colorful timeline to space history and allow everyone the chance to own a tangible connection with their favorite space explorers and missions.

Astronaut autographs were also immensely popular. No sooner had NASA announced its first seven astronauts in 1959, were requests for the newly named American heroes’ signatures received. NASA did its best to fulfill every request but the demand was so great, that had the astronauts answered every mailed-in appeal, they would have barely been left the time to train and fly. To balance this, NASA sometimes employed a machine – an “autopen” – that traced a pattern based on the astronauts’ signatures onto photographs, books and other items sent in by the public. To this day, children (of all ages) from around the world write NASA for astronauts’ autographs and continue to receive authentic and autopenned responses.

That’s not to say that all NASA space collectibles are focused on the crewed missions. Mementos from the agency’s unmanned efforts to explore the solar system and beyond have also been sought. Model and toy versions of planetary probes, such as the Mars rovers, flew off store shelves. Postage stamps celebrating the magnificent imagery captured by the Hubble Space Telescope were saved by more than just stamp collectors, but by those who desired a souvenir of the orbiting observatory.

When NASA was established in October 1958, so was the hobby of collecting NASA memorabilia. For 50 years, the public has celebrated the space agency through the commemorative items it has inspired. And as NASA looks forward to its next 50 years exploring space, so will the public seek to own a part of those achievements.

For a year-by-year tour of the first 50 years of space collectibles, click through to collectSPACE.com, a Houston-based website for space history enthusiasts.

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Tuesday, October 7, 2008

Birth of a Planet

This artist's conception shows binary-star system HD 113766, where astronomers suspect a rocky Earth-like planet is forming around one of the stars. At approximately 10-16 million years old, astronomers suspect this star is at just the right age for forming rocky planets.

The brown ring of material circling closest to the central star depicts a huge belt of dusty material, more than 100 times as much as in our asteroid belt, or enough to build a Mars-size planet or larger. The rocky material in the belt represents the early stages of planet formation, when dust grains clump together to form rocks, and rocks collide to form even more massive rocky bodies called planetesimals. The belt is located in the middle of the system's terrestrial habitable zone, or the region around a star where liquid water could exist on any rocky planets that might form. Earth is located in the middle of our sun's terrestrial habitable zone.

The white outer ring shows a concentration of icy dust also detected in the system. This material is at the equivalent position of the asteroid belt in our solar system, but only contains about one-sixth as much material as the inner ring. Astronomers say it is not clear from the Spitzer observations if anything is occurring in the icy belt, but they believe it could be a source of water for the planet that grows from the inner warm ring.


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Tuesday, September 23, 2008


Rockets will help you learn the basic math and physics that govern the design and flight of rockets. We'll look at many different kinds of rockets, from stomp rockets, which are a special kind of artillery shell, to bottle rockets, to model rockets, to full scale boosters. We'll look at the similarities and the differences in these rockets and include some instructions for making and flying your own rockets.

At this Web site you can study how rockets operate at your own pace and to your own level of interest. There is a lot of mathematics at this web site, so we provide background pages on many mathematical topics. The flight of the rocket involves the interaction of forces, so we include background pages on the fundamentals of forces. Aerodynamics plays a major role in the flight of toy rockets and in the generation of thrust for full scale rockets, so there are background pages devoted to basic aerodynamics . There are also background pages on thermodynamics and gas dynamics because of the role they play in rocket propulsion. Since we will be sending rockets to the Moon and Mars , we provide some background information on these planets in addition to our home planet.

The majority of the information at this web site is presented at a high school or early college level, although much of the information can also be used by middle school students and the general public. Information is provided for both students and teachers. The site includes materials that were developed over a ten year span by several different authors, so the pages do not all look the same. We have added navigation buttons to ease movement across and within the work of a given author. Most of the pages are presented in the following format: a graphic at the top which the user can capture and incorporate into their own presentations or class notes; a text explaining the topic presented in the graphic and including many hyperlinks to related topics; navigation links at the bottom to related educational activities, closely related web pages, and an index of all the pages.

Using the Index of Web Pages, you are never more than two clicks away from any other Web page at this site. Just click on the word "Index" at the bottom of any page, and then click to a new page from the index. We have intentionally organized this site to mirror the unstructured nature of the world wide web. However, if you prefer a more structured approach, you can also take one of our Guided Tours through the site. Each tour provides a sequence of pages dealing with some type or aspect of rockets. Web pages that include Interactive Java applets are noted in the index. RocketModeler II, RocketThrust Simulator, and the AtmosModeler Simulator are provided to encourage students to explore science and math. The programs allow students to design and fly rockets on their personal computer and can be downloaded to operate off-line. Additional Classroom Activities are also available at this site.

This site was prepared at the NASA Glenn Research Center in support of the Educational Programs Office and was funded by the Exploration Systems Mission Directorate. Many of the pages at this site were prepared to support videoconferencing for teachers and students as provided by the Digital Learning Network. Much of the information available in the Rockets Educator's Guide publication is available on-line at this site.


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Wednesday, September 10, 2008

How to Find Faraway Moons

Special to SPACE.com. Excerpt: While the number of confirmed extrasolar planets is now approaching 300, the tally of extrasolar moons so far identified is still a rather disappointing zero. ...But the search is not impossible, says Darren Williams, associate professor of physics and astronomy at Penn State Erie, the Behrend College. Williams believes a moon in orbit around a known extrasolar planet will also be detectable if we look hard enough with the right techniques.

... Finding moons is more than just an academic quest to count them up. Planetary satellites can be highly interesting in their own right. It's possible, for example, that life could exist on extrasolar moons, researchers say. And it has been suggested that the ocean tides induced by Earth's moon may have been necessary to create the conditions for life on our planet to begin. At the least, the evolution of life has been affected by our moon's constant tugging.

...It will be easier to see moons that happen to transit the face of a star, such as what the space telescope Kepler will attempt to do starting next year," Williams explained. The space-based Kepler observatory will note dips in starlight caused by planets crossing in front of stars. If the planets are aligned in such a favourable manner, then thinking goes, moons ought to transit the stars too. ...A similar conclusion is reached by Szabó, Szatmáry, Diveki and Simon in a paper published in Astronomy and Astrophysics in 2005. They conclude that the Kepler mission should identify a few extrasolar moons using this method of detection.


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