all mighty saturn

(+) ciclops

all line up

Last week, Mercury, Venus, and the Moon all appeared close together in Earth's sky. This picturesque conjunction was caught on camera behind elements of the Australia Telescope Compact Array (ATCA) near the town of Narrabri in rural New South Wales. The ATCA consists of six radio telescopes in total, each one larger than a house. Together they form one of the highest resolution measurement devices in the world. Impressive planetary conjunctions occur every few years. Involving the brightest objects in the night sky, this alignment was easy to spot just before sunrise. In the picture, taken on the morning of March 6, Mercury is the highest of the three bright celestial beacons.


Credit & Copyright: Graeme L. White & Glen Cozens

sandia's tunguska

The stunning amount of forest devastation at Tunguska a century ago in Siberia may have been caused by an asteroid only a fraction as large as previously published estimates, Sandia National Laboratories supercomputer simulations suggest.

“The asteroid that caused the extensive damage was much smaller than we had thought,” says Sandia principal investigator Mark Boslough of the impact that occurred June 30, 1908. “That such a small object can do this kind of destruction suggests that smaller asteroids are something to consider. Their smaller size indicates such collisions are not as improbable as we had believed.”

Because smaller asteroids approach Earth statistically more frequently than larger ones, he says, “We should be making more efforts at detecting the smaller ones than we have till now.”

The new simulation — which more closely matches the widely known facts of destruction than earlier models — shows that the center of mass of an asteroid exploding above the ground is transported downward at speeds faster than sound. It takes the form of a high-temperature jet of expanding gas called a fireball.

This causes stronger blast waves and thermal radiation pulses at the surface than would be predicted by an explosion limited to the height at which the blast was initiated.

“Our understanding was oversimplified,” says Boslough, “We no longer have to make the same simplifying assumptions, because present-day supercomputers allow us to do things with high resolution in 3-D. Everything gets clearer as you look at things with more refined tools.”

Sandia is a National Nuclear Security Administration laboratory.

The new interpretation also accounts for the fact that winds were amplified above ridgelines where trees tended to be blown down, and that the forest at the time of the explosion, according to foresters, was not healthy. Thus previous scientific estimates had overstated the devastation caused by the asteroid, since topographic and ecologic factors contributing to the result had not been taken into account.

“There’s actually less devastation than previously thought,” says Boslough, “but it was caused by a far smaller asteroid. Unfortunately, it’s not a complete wash in terms of the potential hazard, because there are more smaller asteroids than larger ones.”

Boslough and colleagues achieved fame more than a decade ago by accurately predicting that that the fireball caused by the intersection of the comet Shoemaker-Levy 9 with Jupiter would be observable from Earth.

Simulations show that the material of an incoming asteroid is compressed by the increasing resistance of Earth’s atmosphere. As it penetrates deeper, the more and more resistant atmospheric wall causes it to explode as an airburst that precipitates the downward flow of heated gas.

Because of the additional energy transported toward the surface by the fireball, what scientists had thought to be an explosion between 10 and 20 megatons was more likely only three to five megatons. The physical size of the asteroid, says Boslough, depends upon its speed and whether it is porous or nonporous, icy or waterless, and other material characteristics.

“Any strategy for defense or deflection should take into consideration this revised understanding of the mechanism of explosion,” says Boslough.

One of most prominent papers in estimating frequency of impact was published five years ago in Nature by Sandia researcher Dick Spalding and his colleagues, from satellite data on explosions in atmosphere. “They can count those events and estimate frequencies of arrival through probabilistic arguments,” says Boslough.

The work was presented at the American Geophysical Union meeting in San Francisco on Dec. 11. A paper on the phenomenon, co-authored by Sandia researcher Dave Crawford and entitled “Low–altitude airbursts and the impact threat” has been accepted for publication in the International Journal of Impact Engineering.

The research was paid for by Sandia’s Laboratory-Directed Research and Development office.

(+) Sandia.gov
(+) googlesightseeing.com

eta carinae

Eta Carinae (η Carinae or η Car) is a highly luminous hypergiant double star. Estimates of its mass range from 100–150 times the mass of the Sun, and its luminosity is about four million times that of the Sun.

Very large stars like Eta Carinae use up their fuel very quickly because of their disproportionately high luminosities. Eta Carinae is expected to explode as a supernova or hypernova some time within the next million or so years. As its current age and evolutionary path are uncertain, it could explode within the next several millennia or even in the next few years. LBVs such as Eta Carinae may be a stage in the evolution of the most massive stars; the prevailing theory now holds that they will exhibit extreme mass loss and become Wolf-Rayet Stars before they go supernova, if they are unable to hold their mass to explode as a hypernova.

More recently another possible Eta Carinae analogue was observed; namely SN 2006jc some 77 million light years away in UGC 4904, in the constellation of Lynx. It brightened on 20 October 2004 and was reported by amateur astronomer Koichi Itagaki as supernova. However, it survived and finally exploded two years later as a Mag 13.8 type Ib supernova on 9 October 2006. Its earlier brightening was a supernova impostor event; the initial explosion hurled 0.01 solar masses (~20 Jupiters) of material into space.

Due to the similarity of Eta Carinae and SN 2006jc, Stefan Immler of NASA's Goddard Space Flight Center suggests that Eta Carinae could explode in our lifetime or even in the next few years. However, Stanford Woosley of the University of California in Santa Cruz disagrees with Immler’s suggestion, and he says it is likely that Eta Carinae is at an earlier stage of evolution and that it has several kinds of material left for nuclear fusion.

the young family

The Young Family (2002-3) presents a transgenic creature. The inspiration behind this work is the expectation that we have of growing human organs in other species, especially pigs. Rather than make a didactic image that argues for or against these technologies, I want to address the reality of these possible creatures in a very compassionate way. The question I raise, that I am interested in, relates to the distinction between human and animal characteristics: Not so much her humanity, but the 'animalness' in us. Genetically, we share traits with her, but also we share the fundamental trait of looking after offspring. I am interested in the kinds of ways that we look at the many ethical issues that surround medical technologies.
There are two kinds of people who are thinking about these issues; those who are objective observers, and those that are actually affected by the issues, such as somebody who has a family member who is affected by a disease. These two viewpoints are often very different. It is impossible to be objective about these issues when you are emotionally involved, but I don't think that is a bad thing. These are not simple issues with easy answers: It is one thing to talk about an idea and another to be confronted by the emotional reality of a creature, and yet another to be in need of what that creature might provide.

Title: The Young Family 2002-3
Author: Patricia Piccinini (+)

more info (+)

sky raptor

An F-22 Raptor, the world's first stealth air-to-air fighter, demonstrates combat maneuvers while participating in the 2007 Naval Air Station Oceana Air Show. The three-day air show featured demonstrations from the Blue Angels, British Red Devils and Blac

cocoon

The Cocoon Nebula, cataloged as IC 5146, is a strikingly beautiful nebula located about 4,000 light years away toward the constellation of the Swan (Cygnus). Inside the Cocoon Nebula is a newly developing open cluster of stars. Like other stellar nurseries, the Cocoon Nebula holds, at the same time, a bright red emission nebula, blue reflection nebulas, and dark absorption nebulas. Given different mixtures, these three processes create a host of colors in this image taken recently by the Canada-France-Hawaii Telescope (CFHT) in Hawaii, USA.
Speculation based on recent measurements holds that the massive star towards the left of the picture opened a hole in an existing molecular cloud through which much of the glowing material flows. The same star, which formed about 100,000 years ago, now provides the energy source for much of the emitted and reflected light from this nebula.

european monster

JET, the Joint European Torus, is the largest nuclear fusion experimental reactor yet built.

The reactor is situated on an old Navy airfield near Culham, Oxfordshire, in the UK: the construction of the buildings which house the project was undertaken by Tarmac Construction, starting in 1978 with the first experiments beginning in 1983.

JET is equipped with remote handling facilities to cope with the radioactivity produced by Deuterium-Tritium (D-T) fuel, which is the fuel proposed for the first generation of fusion power plants. Pending construction of ITER, JET remains the only large fusion reactor with facilities dedicated to handling the radioactivity released from D-T fusion. The power production record breaking runs from JET and TFTR used 50-50 D-T fuel mixes.

During a full D-T experimental campaign in 1997 JET achieved a world record peak fusion power of 16 MW which equates to a measured Q of approximately 0.7. Q is the ratio of fusion alpha heating power to input heating power, a self-sustaining nuclear fusion reaction would have an infinite Q value (requiring no external heating). In order to achieve a burning plasma, a Q value greater than 1 is required. This figure does not include other power requirements for operation, most notably confinement. A commercial fusion reactor would probably need a QJT-60 tokamak, however this was not achieved under real D-T conditions but estimated from experiments performed with a pure Deuterium (D-D) plasma. Similar extrapolations have not been made for JET, however it is likely that increases in Q over the 1997 measurements could now be achieved if permission to run another full D-T campaign was granted.

In December 1999 JET's international contract ended and the United Kingdom Atomic Energy Authority (UKAEA) then took over managing the safety and operation of the JET facilities on behalf of its European partners. From that time (2000), JET's experimental programme was then co-ordinated by the European Fusion Development Agreement (EFDA) Close Support Unit.

JET operated throughout 2003 culminating in experiments using small amounts of tritium. For most of 2004 it was shut down for a series of major upgrades increasing total available heating power to over 40 MW, enabling further studies relevant to the development of ITER to be undertaken. In the future it is possible that JET-EP (Enhanced Performance) will further increase the record for fusion power.

In late September 2006, experimental campaign C16 was started. Its objective is to study ITER-like operation scenarios.

Image: EFDA-JET (+)

ancient eye

When 17th-century astronomers first turned their telescopes to Jupiter, they noted a conspicuous reddish spot on the giant planet. This Great Red Spot is still present in Jupiter's atmosphere, more than 300 years later. It is now known that it is a vast storm, spinning like a cyclone. Unlike a low-pressure hurricane in the Caribbean Sea, however, the Red Spot rotates in a counterclockwise direction in the southern hemisphere, showing that it is a high-pressure system. Winds inside this Jovian storm reach speeds of about 270 mph. The Red Spot is the largest known storm in the Solar System. With a diameter of 15,400 miles, it is almost twice the size of the entire Earth and one-sixth the diameter of Jupiter itself.
The long lifetime of the Red Spot may be due to the fact that Jupiter is mainly a gaseous planet. It possibly has liquid layers, but lacks a solid surface, which would dissipate the storm's energy, much as happens when a hurricane makes landfall on the Earth. However, the Red Spot does change its shape, size, and color. Such changes are demonstrated in high-resolution Wide Field and Planetary Cameras 1 & 2 images of Jupiter obtained by NASA's Hubble Space Telescope, and presented here by the Hubble Heritage Project team.
The Hubble images were originally collected by Amy Simon (Cornell U.), Reta Beebe (NMSU), Heidi Hammel (Space Science Institute, MIT), and their collaborators, and have been prepared for presentation by the Hubble Heritage Team.

jupiter variation

Why does Jupiter have rings? Jupiter's rings were discovered in 1979 by the passing Voyager 1 spacecraft, but their origin was a mystery. Data from the Galileo spacecraft that orbited Jupiter from 1995 to 2003 later confirmed that these rings were created by meteoroid impacts on small nearby moons. As a small meteoroid strikes tiny Adrastea, for example, it will bore into the moon, vaporize, and explode dirt and dust off into a Jovian orbit.

Pictured above is an eclipse of the Sun by Jupiter, as viewed from Galileo. Small dust particles high in Jupiter's atmosphere, as well as the dust particles that compose the rings, can be seen by reflected sunlight.

we're sustained by the corpse of a fallen constellation

Messier 74 (also known as NGC 628) is a face-on spiral galaxy in the constellation Pisces. The galaxy contains two clearly-defined spiral arms and is therefore used as an archetypal example of a Grand Design Spiral Galaxy. The galaxy's low surface brightness makes it the most difficult Messier object for amateur astronomers to observe. However, the relatively large angular size of the galaxy and the galaxy's face-on orientation make it an ideal object for professional astronomers who want to study spiral arm structure and spiral density waves.

mother's belly

1st Lt. Jason Edwards checks the bomb load of a B-1B Lancer Dec. 29 as he and the rest of the aircrew preflight check the bomber prior to a mission. Lieutenant Edwards is with the 9th Expeditionary Bomb Squadron at an air base in Southwest Asia.

U. S. Air Force photo/Staff Sgt. Douglas Olsen