Chunks Of Ice Research Articles

EPOXI at Comet Hartley 2

Understanding how comets work--what drives their activity--is crucial to the use of comets in studying the early solar system. EPOXI (Extrasolar Planet Observation and Deep Impact Extended Investigation) flew past comet 103P/Hartley 2, one with an unusually small but very active nucleus, taking both images and spectra. Unlike large, relatively inactive nuclei, this nucleus is outgassing primarily because of CO(2), which drags chunks of ice out of the nucleus. It also shows substantial differences in the relative abundance of volatiles from various parts of the nucleus.

Arctic sea-ice ridges—Safe heavens for sea-ice fauna during periods of extreme ice melt?

Abstract The abundances and distribution of metazoan within-ice meiofauna (13 stations) and under-ice fauna (12 stations) were investigated in level sea ice and sea-ice ridges in the Chukchi/Beaufort Seas and Canada Basin in June/July 2005 using a combination of ice coring and SCUBA diving. Ice meiofauna abundance was estimated based on live counts in the bottom 30 cm of level sea ice based on triplicate ice core sampling at each location, and in individual ice chunks from ridges at four locations. Under-ice amphipods were counted in situ in replicate (N=24–65 per station) 0.25 m2 quadrats using SCUBA to a maximum water depth of 12 m. In level sea ice, the most abundant ice meiofauna groups were Turbellaria (46%), Nematoda (35%), and Harpacticoida (19%), with overall low abundances per station that ranged from 0.0 to 10.9 ind l−1 (median 0.8 ind l−1). In level ice, low ice algal pigment concentrations ( 3 m where abundances were up to 42-fold higher compared with level ice. We propose that the summer ice melt impacted meiofauna and under-ice amphipod abundance and distribution through (a) flushing, and (b) enhanced salinity stress at thinner level sea ice (less than 3 m thickness). We further suggest that pressure ridges, which extend into deeper, high-salinity water, become accumulation regions for ice meiofauna and under-ice amphipods in summer. Pressure ridges thus might be crucial for faunal survival during periods of enhanced summer ice melt. Previous estimates of Arctic sea ice meiofauna and under-ice amphipods on regional and pan-Arctic scales likely underestimate abundances at least in summer because they typically do not include pressure ridges.

Review: Why Care for Nature? In Search of an Ethical Framework for Environmental Responsibility and Education by Dirk Willem Postma

Why Care for Nature? In Search of an Ethical Framework for Environmental Responsibility and Education by Dirk Willem Postma. Netherlands: Springer, 2006. 219 pp. ISBN 978-1-4020-5002-2. On March 26, 2008 an ice chunk about seven times the size of Manhattan collapsed off the Antarctic—an event likely to be the precursor to the collapse of the Wilkins shelf, which is about the size of Connecticut. Although this claim has been contested by a few of their colleagues, the majority of scientists acknowledge that such events, which decrease our planet’s overall ice mass, are caused by global warming. Carbon-based pollutants are released into our atmosphere by the burning of fossil fuels in exchange for the energy necessary for the modern world. According to Al Gore’s movie, An Inconvenient Truth, melting ice produces negative consequences, such as submerging most of the world’s current coastal areas under a rising ocean, resulting in over a hundred million refugees, as well as disturbing nature’s delicate balance in providing water in a timely fashion from mountain snowpack. On the eve of hope in a new administration, Barack Obama promises on his website to decrease the burning of fossil fuels by “ensuring 10 percent of our electricity comes from renewable sources by 2012, and 25 percent by 2025.” 1 However, even the best intentions from the head of government need public “care” for this and other similar statements to become a reality. How do we arouse concern for such events and develop a sense of responsibility for what we have done if we do not suffer immediate consequences? Negative effects might not be witnessed until our generation has passed away. Due to the perceived economic losses associated with decreasing emissions, global warming has become a political issue as much as a scientific one. When fifty thousand copies of An Inconvenient Truth were offered for free to the United States National Science Teachers Association (NSTA), the organization declined the offer and explained in an internal email that accepting them would be an “unnecessary risk upon the [NSTA] capital campaign, especially certain targeted supporters.” 2 Global warming does have some immediate effects, such as increasing the frequency and intensity of devastating storms, as witnessed recently with Hurricane Katrina. Other activities have a much longer time frame for environmental consequences, such as the storage of radioactive waste, which emits rays for up to and over a million years. Two of the most prevalent frameworks discussed in this book which negatively oppose a sense of environmental responsibility are liberalism, which “tends to neglect the structural nature and causes of the environmental crisis” (p. 49), and sustainable development, which “posits an economic-distributive and anthropocentric perspective” (p. 52). Activities that cause the extinction of entire species every day require concern that goes beyond a merely anthropocentric

The Spirit in Me

The Spirit in Me William Hoffman (bio) Cast of Characters Lavinia Ella Betsy Hooper, a deputy sheriff Brother Gormer, a preacher Miss Bozack Darce, a servant Jessica, a rich and beautiful widow Lyle, Jessica’s suitor [End Page 1] Curtain Scene I 1936, the porch of a flaking, white-frame company store among the mountains of a southern West Virginia coal town. The porch holds two unpainted wooden benches, each located on opposite sides of a screen door. Just beneath the tin roof of the store is a sign in black paint: Pope Coal & Coke. At an end of the porch is a battered soft-drink cooler that has a lid on top. A large thermometer advertising Honest Snuff is nailed to a porch post. A limp American flag hangs from a pole over the porch steps. On the porch this hot summer day are three local middle-aged miners’ wives, their names Ella Henry, Lavinia Ackers, and Betsy Terry. They have been shopping at the store. Their clothing is of the 1930s variety, a bit dowdy and out of date, yet with color and attempts at the fashionable—a straw hat, a flower pinned to a bodice, a string of artificial pearls. Lavinia and Ella sit on a bench, their grocery bags beside them are on the floor. A fiddle plays a jolly hillbilly tune before the curtain opens, and tails off as actors begin to speak. Lavinia: (Fans her face with a languid hand) This hot, how we ever going to make it all the way through July? Ella: (Wipes brow) So humid my wash won’t dry on the line. Betsy: (Has just arrived and sets her grocery bag on a bench before sitting) Streams running dry. Lavinia: Leaves shriveling on the trees. Ella: Ground’s cracking open. Betsy: Grass snapping like twigs under your feet. Lavinia: Hot enough to melt rocks. Ella: Coal going to catch itself on fire. Betsy: Food’s so dry it’s like chewing sawdust. Lavinia: Wind’s done forgot how to blow. Ella: Dogs too hot and lazy to bite at they fleas. Lavinia: Hotter than Hell’s kitchen. Betsy: (Rises to cross to soft-drink cooler. She opens the cooler’s lid, lifts a Big Orange from chunks of ice, and uses the bottle opener to lever off the cap.) Need me a swallow to put out [End Page 2] the fire. Helps for a second anyhow. (She drinks, stops at the screen door, and calls out as she holds up the bottle.) Just put it on my ticket, Willie. Giles Hooper, a deputy sheriff, strolls in from stage right, touches his trooper hat in greeting, and lifts a booted foot to a porch step. He wears a brown uniform shirt open at the collar, a badge, a whistle, a holstered Smith & Wesson revolver, a black cartridge belt, whipcord riding britches, and brown leather puttees. He smiles as he pushes back his hat. Hooper: Afternoon, ladies. I know you all been talking it over. Betsy, Ella, Lavinia: What you mean? Roof fall at the mine? Somebody hurt? Hooper: (Holds up a hand as if stopping traffic) Whoa now. Nobody’s hurt. I figured you’d heard about Miss Jessica Tucker. Lavinia: Heard what? Ella: (Excited) She married again? Betsy: Or come home? Hooper: You got it, Miss Betsy. She coming from France sometime this afternoon. Lavinia: How’s she look? Hooper: Ain’t seen her yet. Ella: They opening the big house? Hooper: They been working at it. Betsy: She not been ’round here since they laid Captain Tucker in the grave. Lavinia: (Uses her fingers to count) Been at least three years. Ella: She still pretty? Betsy: Or got herself a man? Hooper: (Amused, he takes off his trooper hat to fan his face.) Yeah, a man from what I hear, though not a husband. Old Darce has been keeping up the house. Betsy: Bet she’s marrying again. She’s mourned the captain...

Monitoring the fall of large atmospheric ice conglomerations: a multianalytical approach to the study of the Mejorada del Campo megacryometeor

Certain local atmospheric anomalies, such as the formation of unusually large ice conglomerations (megacryometeors), have been proposed to be a potential natural hazard for people and aviation, as well as geoindicators for fingerprinting larger-scale atmospheric environmental changes. On March 13th 2007, at approximately 10:15 am, an ice chunk weighing about 10 kg fell from the clear-sky and crashed through the roof (around 15 m) of an industrial storage house in Mejorada del Campo, a town located 20 km east from Madrid. The megacryometeor monitoring follow-up and the original investigation presented here includes, for the first time, both logistic and scientific collaboration between the Laboratory of the Environment, Criminalistic Service (SECRIM, the Spanish "Guardia Civil") and academic and scientific institutions (universities and the Spanish National Research Council). We propose that the management procedure of the incident, along with the detailed scientific research and combination of analytical methodologies in different laboratories, can serve as a protocol model for other similar events.

Lagrange L4/L5 Points and the Origin of Our Moon and Saturn's Moons and Rings

The current standard theory of the origin of the Moon is that the Earth was hit by a giant impactor the size of Mars causing ejection of debris from its mantle that coalesced to form the moon; but where did this Mars-sized impactor come from? Isotopic evidence suggests that it came from 1 AU radius in the solar nebula, and computer simulations are consistent with its approaching Earth on a zero-energy parabolic trajectory. How could such a large object form at 1 AU in a quiescent disk of planetesimals without having already collided with the Earth at an earlier epoch before having the chance to grow large? Belbruno and Gott propose that the giant impactor could have formed in a stable orbit from debris at the Earth's Lagrange point L(5) (or L(4)). It would grow quietly by accretion at L(5) (or L(4)), but eventually gravitational perturbations by other growing planetesimals would kick it out into a horseshoe orbit and finally into a chaotic creeping orbit, which Belbruno and Gott show would, with high probability, hit the Earth on a near zero-energy parabolic trajectory. We can see other examples of this phenomenon occurring in the solar system. Asteroid 2002AA29 is in a horseshoe orbit relative to the Earth that looks exactly like the horseshoe orbits that Belbruno and Gott found for objects that had been perturbed from L(4)/L(5). The regular moons of Saturn are made of ice and have the same albedo as the ring particles (ice chunks, plus some dust). We (J. R. Gott, R. Vanderbei, and E. Belbruno) propose that the regular icy moons of Saturn (out to the orbit of Titan), which are all in nearly circular orbits, formed out of a thin disk of planetesimals (ice chunks) rather like the rings of Saturn today only larger in extent. In such a situation formation of objects at L(4)/L(5) might be expected. Indeed, Saturn's moon Dione is accompanied by moons (Helene and Polydeuces) at both L(4) and L(5) Lagrange points, and Saturn's moon Tethys is also accompanied by moons (Telesto and Calypso) at both L(4) and L(5) Lagrange points. Epimetheus is in a horseshoe orbit relative to Janus that is exactly like the horseshoe orbit expected for an object that has been perturbed from a location at L(4)/L(5). We propose that the rings of Saturn visible today are all that remains of this original disk; they lie inside the Roche limit where tidal forces have simply prevented the formation of large moons by accretion. Further out, the icy particles have accumulated into icy moons. Objects in external solar systems on horseshoe orbits (like those of Epimetheus relative to Janus) could be detected by a slow sinusoidal variation with time of the calculated mass of a planet from radial velocity measurements.

Saturn's rings more placid than thought

Chunks of ice are more like mini moons than wild spinning rings.

Dynamic damage model of crevasse opening and application to glacier calving

Theory and applications of continuum damage mechanics for ice are discussed, and on this basis, an ice damage model, valid at low stresses, is proposed. The model describes the damage itself, the rheology of the damaged ice, and the damage evolution. A local damaging and healing law is considered, and its parameterization is motivated. The model parameters are inferred from published data of laboratory experiments. The model is subsequently implemented in a finite element code and applied to the prediction of a calving process and to the destabilization of an ice chunk from a hanging glacier. Numerical results show good agreement with field measurements.

Two Level Games and the Future of the Climate Regime

The summer of 1988 holds a particularly prominent place in the history of global climate change policy. Heat waves, drought, and forest fires in North America, the first billiondollar hurricane in the Caribbean, and the breakage of a massive chunk of ice off the coast of Antarctica that year were viewed by many as a preview of the impacts of global warming. US presidential candidate George Bush (Sr.) promised that if elected, he would combat the greenhouse effect with “the White House Effect”. Scientists also weighed in, including a famous Senate testimony by NASA climate modeler James Hansen who claimed he was “99% certain” that the anomalous weather in the US was not a chance event, and that it was time to stop “waffling” around scientific uncertainty. Meanwhile the first elements of an international climate treaty began to emerge at the Toronto Conference of the Atmosphere that was hosted by the Canadian government in June 1988. Many key ideas that were introduced at Toronto – the need for industrialized countries to accept historical responsibility and take the first steps at reducing greenhouse emissions, a call for 20% cuts in industrialized country carbon dioxide emissions from 1988 levels by 2005, and the establishment of an international funding mechanism to assist developing countries in enacting any future emissions cuts – have all cast a long shadow on subsequent intergovernmental negotiations. In that same summer of 1988, far removed from the growing policy interest in global warming, Harvard political scientist Robert Putnam published a theoretical essay entitled “Diplomacy and domestic politics: The logic of two-level games” (International Organization, 1988). In this paper Putnam proposed a simple but elegant argument:

Physical and chemical characterization of a spring flood event, Bench Glacier, Alaska, U.S.A.: evidence for water storage

AbstractPrevious studies of alpine glaciers have demonstrated that as water discharge increases through the summer, the predominant mode of subglacial drainage shifts from a distributed system to a more efficient conduit drainage system. We observed an early-melt-season speed-up and flood event lasting roughly 2 days in a small, uncomplicated Alaskan glacier that appears to have resulted from a sudden shift of the subglacial system in response to a significant accumulation of meltwater within the glacier. Calculated melt-water inputs exceeded discharge before the event; the implied change in storage over this 10 day period was equivalent to roughly 0.13 m averaged over the entire glacier bed. The pattern of discharge and suspended-sediment variations and the appearance of large ice chunks in the stream suggest that the speed-up occurred during a period of establishment of new subglacial conduits. A culminating flood and associated suspended-sediment pulse appear to have marked the final establishment of the new section of subglacial conduit. The flood ended the episode of high sliding velocity, but released water with high solute concentrations that reflect relatively long contact time with sediments. Discharge of stored water, inferred from high solute concentrations and lack of diurnal variation in discharge, continued for at least 3 days. While events such as this must recur through the melt season as the conduit system extends up-glacier and the locus of meltwater inputs shifts, their manifestations in the outlet stream will likely be more subdued later in the season.

Physical and chemical characterization of a spring flood event, Bench Glacier, Alaska, U.S.A.: evidence for water storage

AbstractPrevious studies of alpine glaciers have demonstrated that as water discharge increases through the summer, the predominant mode of subglacial drainage shifts from a distributed system to a more efficient conduit drainage system. We observed an early-melt-season speed-up and flood event lasting roughly 2 days in a small, uncomplicated Alaskan glacier that appears to have resulted from a sudden shift of the subglacial system in response to a significant accumulation of meltwater within the glacier. Calculated melt-water inputs exceeded discharge before the event; the implied change in storage over this 10 day period was equivalent to roughly 0.13 m averaged over the entire glacier bed. The pattern of discharge and suspended-sediment variations and the appearance of large ice chunks in the stream suggest that the speed-up occurred during a period of establishment of new subglacial conduits. A culminating flood and associated suspended-sediment pulse appear to have marked the final establishment of the new section of subglacial conduit. The flood ended the episode of high sliding velocity, but released water with high solute concentrations that reflect relatively long contact time with sediments. Discharge of stored water, inferred from high solute concentrations and lack of diurnal variation in discharge, continued for at least 3 days. While events such as this must recur through the melt season as the conduit system extends up-glacier and the locus of meltwater inputs shifts, their manifestations in the outlet stream will likely be more subdued later in the season.

A Self-Consistent Numerical Treatment of Fractal Aggregate Dynamics

A self-consistent numerical treatment for modeling fractal aggregate dynamics is presented. Fractal aggregates play an important role in a number of complex astrophysical regimes, including the early solar nebula and the interstellar medium. Aggregates can be of various forms and sizes, ranging from tiny dust particles to ice chunks in planetary rings and possibly even comets. Many observable properties, such as light scattering and polarization, may depend sensitively on the geometry and motion of such aggregates. Up to now various statistical methods have been used to model the growth and interaction of aggregates. The method presented here is unique in that a full treatment of rigid body dynamics—including rotation—is incorporated, allowing individual particle and cluster trajectories and orientations to be followed explicitly. The method involves solving Euler's equations for rigid body motion and introducing a technique for handling oblique collisions between arbitrarily shaped aggregates. Individual particles may be of any size and can have their own spin. Currently tangential impulses during impacts are assumed negligible, although equations for the treatment of tangential friction are presented. Models for the coagulation and restitution of aggregates are discussed in detail. Some of the key features required for a fragmentation model, not implemented here, are discussed briefly. Torque effects arising from self-gravity, tidal fields, or gas drag are not presently considered. Although the discussion focuses mainly on the theory behind the numerical technique, test simulations are presented to compare with an analytic solution of the coagulation equation and to illustrate the important aspects of the method.

The Antarctic Pack-Ice Ecosystem

t is winter, deep in the heart of the Antarctic sea pack ice at 70? south latitude, 150? west longitude. Under clear blue skies and light winds, 16 researchers, each fattened by 20 pounds of protective bright red clothing to shield against the -16?C temperature, waddle down the port gangway of the research icebreaker, the Nathaniel B. Palmer. They step onto an ice floe a halfmile in diameter, surrounded by open water for an afternoon of data collection. The icebreaker has churned up ice chunks striped with dark brown layers of algae. Antarctic and snow petrels buzz the ship. Six emperor penguins pop up from the water and land on the floe to watch the scientists at work. Just nine years ago, most polar biologists would have scoffed at the idea that so much life could exist in the winter sea pack ice. When people think of Antarctic ice, most envision the great freshwater icebergs that calve from the southernmost con-

The big wham: Thoughts on comets, risks, and a strategic defense initiative for the eco-system

COMMENTARY The Big Wham: Thoughts on Comets, Risks, and a Strategic Defense Initiative for the Eco-System Gregory Benford In mid-July of 1994, Jupiter’s fireworks upstaged the 25th anniversary celebrations of the Apollo moon landing. While aging astronauts exchanged toasts, fragments of Comet Shoemaker-Levy 9 slammed into the giant planet. Only two years ago we did not even know this comet existed. In July, it triggered hotspots as large as the Earth. Those days of ferocious pounding saw the most energetic events ever witnessed by humans. They struck a clear, vibrant chord in the public. Here was disaster, drama, danger. Chunks of ice and dust up to 2.5 miles across vaporized in fiery moments. Acne larger than worlds blotched Jupiter’s face. Scientists, too, got a bonus. Up through the entry tunnels in Jupiter’s ammonia cirrus flowered plumes of fried debris. Surprisingly, there was no immediate evidence for water in the upwelling. Close study may reveal the depths of Jupiter’s atmosphere, telling us much we could never learn on our own. Many drew an even deeper lesson. Worldwide fascination focused beyond the fireworks, to the future. Could that happen to us? Sure; in fact, it has happened to our home world before. Meteoric bombardment has been well known to astronomers for well over a century. Science fiction authors, always game for a bit of catastrophe, started using the idea half a century ago. The notion seems to have reemerged because the striking photos from our planetary survey craft of the 60s and 70s underlined how many bodies in the inner solar system were riddled with impact craters-Mercury, Mars, of course our moon, and the moons of Jupiter as well. Meteor bombardment was once quite common, and even now bits of debris from the early solar system regularly smash into some larger target. Each day about a hundred tons of small particles, mostly ice, fall into our own atmosphere. I became involved with the idea of meteor impact as a threat in the 196Os, spurred by J. E. Enever’s factual article “Giant Meteor Impact” in the March, 1966 AMlog. As far as I know, it was the first detailed study-one not referenced by astronomers. creso~ Bensxd, Department of Physics, University of California, Irvine, CA 92717. Journal of Smiol and EVolutionary Sysfems 17(1):363-370 ISSN: 0161-7361 Copyright @ 1994 by JAI Prea, Inc. All ligbta of reproductiotl in any folm lwuvcd.

Predicting Ice‐Structure Interactive Forces

Structural design of offshore structures in subfreezing temperatures is an engineering challenge. Design loads vary arbitrarily and are difficult to evaluate. One of the design loads is the live load imposed by drifting ice features in the ocean. These ice features vary from small chunks of ice weighing a few hundred pounds to icebergs, which could weigh hundreds of tons. Their drifting speeds depend on the wind speeds and the ocean currents. Usually the structural columns have ice sheets adfrozen around their periphery. Floating ice features come in contact with these adfrozen ice sheets before ever touching the column surface. This makes it difficult to assess the design loads imparted by the floating ice feature to the structure. This article presents a method for estimating these loads and predicting the behavior of the adfrozen ice plate and the invading ice feature.

A behavioral treatment for difficulty in swallowing pills

The present study employed a graded practice procedure to teach a 13-year-old leukemia patient to swallow pills. Progressively larger chunks of ice were used as stimuli in order to keep gagging and choking to a minimum. The criterion was reached after two sessions and generalization to a variety of pills and capsules occured. Treatment effects were maintained at 8 months follow-up.

Planetary rings

The individual ring systems are described with dust/magnetosphere interactions high-lighted somewhat. Jupiter's main ring is tenuous and enveloped by the magnetosphere; it principally contains micron-sized silicate grains. A vertically-extended, radially-localized “halo” of submicron particles lies inward of the main ring while a newly-discovered very faint ring lies outside it. The classical Saturnian system is composed of water ice chunks with sizes principally between cm and meters. Satellite resonances determine some ring structure but most is not understood. The faint exterior rings (E, G, F and one just identified between the A and F rings) are intimately associated with magnetospheric particles and contain mainly small grains, which are also prominent in the “spokes” located in the dense, middle portion of the B ring. Most of the nine narrow Uranian rings are slightly inclined and eccentric, and presumably lie within the putative Uranian magnetosphere. Particles are likely carbonaceous; sizes are thought to be larger than microns.

Lost island found

An abandoned ll‐by‐5‐km kidney‐shaped chunk of freshwater ice, used as a research station for 25 years, was rediscovered after the National Oceanic and Atmospheric Administration (NOAA) lost track of the island for 6 months. The recent find may foreshadow another loss, however: The island is drifting through the Greenland Sea and into the North Atlantic where it should melt within several months and d u m p its cargo of oil drums, equipment, and a wrecked plane into the ocean.Known as Fletcher's Ice Island—after Joseph O. Fletcher, a member of the first team of researchers to inhabit the island and a recently retired NOAA climate researcher—the ice chunk has already melted to a third of its original 49 m thickness. A pilot flying over the area to measure annual pollution buildup in the Arctic located the drifting island 242 km from the North Pole near the International Date Line.