Universe Today

May 30, 2013October 16, 2016 by Fraser Cain

How Old Is The Earth?

This article comes from the Universe Today archive, but was updated with this spiffy video.

How old is the Earth? Scientists think that the Earth is 4.54 billion years old. Coincidentally, this is the same age as the rest of the planets in the Solar System, as well as the Sun. Of course, it’s not a coincidence; the Sun and the planets all formed together from a diffuse cloud of hydrogen billions of years ago.

In the early Solar System, all of the planets formed in the solar nebula; the remnants left over from the formation of the Sun. Small particles of dust collected together into larger and larger objects – pebbles, rocks, boulders, etc – until there were many planetoids in the Solar System. These planetoids collided together and eventually enough came together to become Earth-sized.

At some point in the early history of Earth, a planetoid the size of Mars crashed into our planet. The resulting collision sent debris into orbit that eventually became the Moon.

How do scientists know Earth is 4.54 billion years old? It’s actually difficult to tell from the surface of the planet alone, since plate tectonics constantly reshape its surface. Older parts of the surface slide under newer plates to be recycled in the Earth’s core. The oldest rocks ever found on Earth are 4.0 – 4.2 billion years old.

Scientists assume that all the material in the Solar System formed at the same time. Various chemicals, and specifically radioactive isotopes were formed together. Since they decay in a very known rate, these isotopes can be measured to determine how long the elements have existed. And by studying different meteorites from different locations in the Solar System, scientists know that the different planets all formed at the same time.

Failed Methods for Calculating the Age of the Earth
Our current, accurate method of measuring the age of the Earth comes at the end of a long series of estimates made through history. Clever scientists discovered features about the Earth and the Sun that change over time, and then calculated how old the planet Earth is from that. Unfortunately, they were all flawed for various reasons.

Declining Sea Levels – Benoit de Maillet, a French anthropologist who lived from 1656-1738 and guessed (incorrectly) that fossils at high elevations meant Earth was once covered by a large ocean. This ocean had taken 2 billion years to evaporate to current sea levels. Scientists abandoned this when they realized that sea levels naturally rise and fall.
Cooling of the Earth – William Thompson, later known as Lord Kelvin, assumed that the Earth was once a molten ball of rock with the same temperature of the Sun, and then has been cooling ever since. Based on these assumptions, Thompson calculated that the Earth took somewhere between 20 and 400 million years to cool to its current temperature. Of course, Thompson made several inaccurate assumptions, about the temperature of the Sun (it’s really 15 million degrees Kelvin at its core), the temperature of the Earth (with its molten core) and how the Sun is made of hydrogen and the Earth is made of rock and metal.
Cooling of the Sun – In 1856, the German physicist Hermann Ludwig Ferdinand von Helmholtz attempted to calculate the age of the Earth by the cooling of the Sun. He calculated that the Sun would have taken 22 million years to condense down to its current diameter and temperature from a diffuse cloud of gas and dust. Although this was inaccurate, Helmholtz correctly identified that the source of the Sun’s heat was driven by gravitational contraction.
Rock Erosion – In his book, The Origin of Species by Means of Natural Selection, Charles Darwin proposed that the erosion of chalk deposits might allow for a calculation of the minimum age of the planet. Darwin estimated that a chalk formation in the Weald region of England might have taken 300 million years to weather to its current form.

Orbit of the Moon – George Darwin, the son of Charles Darwin, guessed that the Moon might have been formed out of the Earth, and drifted out to its current location. The fission theory proposed that the Earth’s rapid rotation caused a chunk of the planet to spin off into space. Darwin calculated that it had taken the Moon at least 56 million years to reach its current distance from Earth. We now know the Moon was probably formed when a Mars-sized object smashed into the Earth billions of years ago.
Salinity of the Ocean – In 1715, the famous astronomer Edmund Halley proposed that the salinity of the oceans could be used to estimate the age of the planet. Halley observed that oceans and lakes fed by streams were constantly receiving more salt, which then stuck around as the water evaporated. Over time, the water would be come saltier and saltier, allowing an estimate of how long this process has been going on. Various geologists used this method to guess that the Earth was between 80 and 150 million years old. This method was flawed because scientists didn’t realize that geologic processes are extracting salt out of the water as well.

Radiometric Dating Provides an Accurate Method to Know the Age of the Earth
In 1896, the French chemist A. Henri Becquerel discovered radioactivity, the process where materials decay into other materials, releasing energy. Geologists realized that the interior of the Earth contained a large amount of radioactive material, and this would be throwing off their calculations for the age of the Earth. Although this discovery revealed flaws in the previous methods of calculating the age of the Earth, it provided a new method: radiometric dating.

Geologists discovered that radioactive materials decay into other elements at a very predictable rate. Some materials decay quickly, while others can take millions or even billions of years to fully decay. Ernest Rutherford and Frederick Soddy, working at McGill University, determined that half of any isotope of a radioactive element decays into another isotope at a set rate. For example, if you have a set amount of Thorium-232, half of it will decay over a billion years, and then half of that amount will decay in another billion years. This is the source of the term “half life”.

By measuring the half lives of radioactive isotopes, geologists were able to build a measurement ladder that let them accurately calculate the age of geologic formations, including the Earth. They used the decay of uranium into various isotopes of lead. By measuring the amount of three different isotopes of lead (Pb-206, Pb-207, and Pb-208 or Pb-204), geologists can calculate how much Uranium was originally in a sample of material.

If the Solar System formed from a common pool of matter, with uniformly distributed Pb isotopes, then all objects from that pool of matter should show similar amounts of the isotopes. Also, over time, the amounts of Pb-206 and Pb-207 will change because as these isotopes are end-products of uranium decay. This makes the amount of lead and uranium change. The higher the uranium-to-lead ratio of a rock, the more the Pb-206/Pb-204 and Pb-207/Pb-204 values will change with time. Now, supposing that the source of the Solar system was also uniformly distributed with uranium isotopes, then you can draw a data line showing a lead-to-uranium plot and, from the slope of the line, the amount of time which has passed since the pool of matter became separated into individual objects can be computed.

Bertram Boltwood applied this method of dating to 26 different samples of rocks, and discovered that they had been formed between 92 and 570 million years old, and further refinements to the technique gave ages between 250 million to 1.3 billion years.

Geologists set about exploring the Earth, seeking the oldest rock formations on the planet. The oldest surface rock is found in Canada, Australia and Africa, with ages ranging from 2.5 to 3.8 billion years. The very oldest rock was discovered in Canada in 1999, and estimated to be just over 4 billion years old.

This set a minimum age for the Earth, but thanks to geologic processes like weathering and plate tectonics, it could still be older.

Meteorites as the Final Answer to the Age of the Earth
The problem with measuring the age of rocks on Earth is that the planet is under constant geological change. Plate tectonics constantly recycle portions of the Earth, blending it up and forever hiding the oldest regions of the planet. But assuming that everything in the Solar System formed at the same time, meteorites in space have been unaffected by weathering and plate tectonics here on Earth.

Geologists used these pristine objects, such as the Canyon Diablo meteorite (the fragments of the asteroid that impacted at Barringer Crater) as a way to get at the true age of the Solar System, and therefore the Earth. By using the radiometric dating system on these meteorites, geologists have been able to determine that the Earth is 4.54 billion years old within a margin of error of about 1%.

Sources:
Understanding Science – Lord Kelvin
USGS Age of the Earth
Lord Kelvin’s Failed Scientific Clock
The Role of Radioactive Decay
Astronomy Cast Episode 51: Earth
Oldest Rock Formations Found

May 30, 2013December 23, 2015 by Tammy Plotner

Black Hole Secrets: Revealing The S-Star

Sgr A Chandra Image Courtesy of NASA/CXC/MIT/F. Baganoff, R. Shcherbakov et al.

Deep in the heart of the Milky Way resides a black hole. However, that is not the mysterious object which scientists Fabio Antonini, of the Canadian Institute for Theoretical Astrophysics, and David Merritt, of the Rochester Institute of Technology, have been endeavoring to explain. The objects of their attention are the orbits of massive young stars which attend it. They are called “S-stars”.

No. That’s not a stutter. S-Stars are a legitimate phenomenon which enable researchers to even more closely examine black hole activity. Their very presence causes astronomers to question what they know. For example, how is it possible for these massive young stars to orbit so close to a region where it would be highly unlikely for them to form there? The sheer force of the strong gravity near a black hole means these stars had to have once been further away from their observed position. However, when theoreticians created models to depict how S-stars might have traveled to their current orbital positions, the numbers simply didn’t match up. How could their orbits be so radically removed from predictions?

Today, Dr. Antonini offered his best explanation of this enigma at the annual meeting of the Canadian Astronomical Society (CASCA). In “The Origin of the S-star Cluster at the Galactic Center,” he gave a unified theory for the origin and dynamics of the S-stars. It hasn’t been an easy task, but Antonini has been able to produce a very viable theory of how these stars were able to get in close proximity to a supermassive black hole in only tens of millions of years since their formation.

“Theories exist for how migration from larger distances has occurred, but have up until now been unable to convincingly explain why the S-stars orbit the galactic center the way they do,” Antonini said. “As main-sequence stars, the S-stars cannot be older than about 100 million years, yet their orbital distribution appears to be ‘relaxed’, contrary to the predictions of models for their origin.”

3-dimensional visualization of the stellar orbits in the Galactic center based on data obtained by the W. M. Keck Telescopes between 1995 and 2012. Stars with the best determined orbits are shown with full ellipses and trails behind each star span ~15-20 years. These stars are color-coded to represent their spectral type: Early-type (young) stars are shown in teal green, late-type (old) stars are shown in orange, and those with unknown spectral type are shown in magenta. Stars without ellipses are from a statistical sample and follow the observed radial distributions for the early (white) or late (yellow/orange) type stars. These stars are embedded in a model representation of the inner Milky Way provided by NCSA/AVL to provide context for the visualization.

According to Antonini and Merritt’s model, S-stars began much further away from the galactic center. Normal? Yep. Normal mode. Then these seemingly normal orbiting stars encountered the black hole’s gravity and began their spiral inward. As they made the inexorable trek, they then encountered the gravity of other stars in the vicinity which then changed the S-stars orbital pattern. It’s a simple insight, and one that verifies how the galactic center evolves from the conjoined influence of a supermassive black holes relativistic effects and the handiwork of gravitational interactions.

“Theoretical modeling of S-star orbits is a means to constrain their origin, to probe the dynamical mechanisms of the region near the galactic center and,” says Merritt, “indirectly to learn about the density and number of unseen objects in this region.”

Although the presence of supermassive black holes at the center of nearly all massive galaxies isn’t a new concept, further research into how they take shape and evolve leads to a better understanding of what we see around them. These regions are deeply connected to the very formation of the galaxy where they exist. With the center of our own galaxy – Sagittarius A – so near to home, it has become the perfect laboratory to observe manifestations such as S-stars. Tracking their orbits over an extended period of time has validated the presence of a supermassive black hole and enlightened our thinking of our own galaxy’s many peculiarities.

Original Story Source: Canadian Astronomical Society Press Release

May 30, 2013December 23, 2015 by Nancy Atkinson

Beautiful Timelapse of a Triple Planetary Conjunction

A sequence of 6 consecutive Jupiter-Venus-Mercury conjunction photos taken on May 23 - 28, 2013. Credit and copyright: Joe Shuster.

We’ve shared oodles of great images from the recent planetary conjunction of Jupiter, Mercury and Venus, visible in the evening skies last week. But this video from astrophotographer César Cantú is just plain beautiful. On the evening of May 25, the conjunction of the three planets formed a triangle that moved through the sky, as seen from Big Bear Park in California, USA. César said via Twitter that the “star” effect was create by processing the video or with 4,6 or 8 point star filters.

And we’ve got one more conjunction image to share — actually six.

Joe Shuster from Salem, Missouri had six great evenings of photographing the planetary conjunction, and put them together into one collage. He used a Canon T1i and Nikkon 105mm lens. Lucky guy!

May 30, 2013December 23, 2015 by Elizabeth Howell

Black Holes Can Get Really Big, And We Have No Idea Why

Artist’s rendering of the environment around the supermassive black hole at the center of Mrk 231. The broad outflow seen in the Gemini data is shown as the fan-shaped wedge at the top of the accretion disk around the black hole, in side view. A similar outflow is probably present under the disk as well. The total amount of material entrained in the broad flow is at least 400 times the mass of the sun per year. Credit: Gemini Observatory/AURA, artwork by Lynette Cook

Right now, as you read this article, it’s quite possible that the ultra-huge black hole at the center of our galaxy is feasting on asteroids or supercooked gas.

We’ve seen these supermassive black holes in other spots in the universe, too: merging together, for example. They’re huge heavyweights, typically ranging between hundreds of thousands to billions of times the mass of the Sun. But we also know, paradoxically, that mini supermassive black holes exist.

So while we’ve observed the gravitational effects of these monsters, a University of Alberta researcher today (May 30) is going to outline the big question: how the heck some of them got so massive. For now, no one knows for sure, but scientists are naturally taking a stab at trying to figure this out.

Maybe they were your ordinary stellar black holes, just three to 100 times the mass of the sun, that underwent a growth spurt. There’s a sticking point with that theory, though: “To do this, the black holes would have to gorge excessively, at rates that require new physics,” stated the Canadian Astronomical Society.

Illustration of Cygnus X-1, another stellar-mass black hole located 6070 ly away. (NASA/CXC/M.Weiss) — Illustration of Cygnus X-1, a stellar-mass black hole located 6070 ly away. (NASA/CXC/M.Weiss)

“We might also expect to see some black holes that are intermediate in mass between stellar-mass and supermassive black holes in our nearby universe,” the society added, “like a band that is consistently releasing albums, but never making it truly big.”

Anyway, Jeanette Gladstone (a postdoctoral researcher) will make a presentation at CASCA’s annual meeting in Vancouver today outlining some ideas. Gladstone, by the way, focuses on X-rays (from black holes) in her work. Here’s what she said on her research page:

HLX-1 in the periphery of the edge-on spiral galaxy ESO 243-49. Credit: Heidi Sagerud.

“I am currently trying to understand a strange group of curiously bright X-ray binaries. These ultraluminous X-ray sources emit too much X-ray radiation to be explained by standard accretion [of] only a regular stellar mass black hole,” she wrote.

“So I use various parts of the electromagnetic spectrum to try and understand what makes them appear so bright. More recently I have started looking at the very brightest of these sources, a group of objects that have recently become a class in their own right. These are the hyperluminous X-ray sources.”

For context, here’s more info on a hyperluminous X-ray source (and its black hole) in spiral galaxy ESO 234-9, as studied by the Hubble Space Telescope and the Swift X-Ray Telescope.

Astronomers were pretty excited with this 2012 work: “For the first time, we have evidence on the environment, and thus the origin, of this middle-weight black hole,” said Mathieu Servillat, a member of the Harvard-Smithsonian Center for Astrophysics research team, at the time.

Credit: CASCA

May 30, 2013December 23, 2015 by Nancy Atkinson

Surprise! Earth Passing Asteroid 1998 QE2 Has a Moon

Radar images from May 30, 2012 of Asteroid 1998 QE2, showing its binary companion. Credit: NASA.

Late yesterday, NASA turned the 230-foot (70-meter) Deep Space Network antenna at Goldstone, California towards Asteroid 1998 QE2 as it was heading towards its closest approach to Earth, and they got a big surprise: the asteroid is a binary system. 1998 QE2 itself is 1.7 miles (2.7 kilometers) in diameter, and the newly found orbiting moon is about 600 meters in diameter.

The radar images were taken were taken on May 29, 2013, when the asteroid was about 3.75 million miles (6 million kilometers) from Earth.

“Radar really helps to pin down the orbit of an asteroid as well as the size of it,” said Paul Chodas of NASA’s Near-Earth Object Program office, speaking during a JPL webcast about this asteroid on May 30. “We now know our size estimates were pretty good, but finding it was a binary was surprising.”

NASA said that about 16 percent of asteroids are binary or even triple systems.

Each of the images above are snippets of about 5 minutes of radar data. You can watch a movie of the data, below:

Other surprises were several radar-dark features, which may be cavities or impact craters, said Marina Brozovic, a scientist at JPL. The asteroid is also rotating more slowly than originally thought.

Near Earth Asteroid (NEA) 285263 (1998 QE2) will pass 5.86 million km from the Earth on Friday, May 31st at 20:59 Universal Time (UT) or 4:59PM EDT. This is the closest approach of 1998 QE2 for this century, and it poses no threat – and there’s not any threat in the future – as it is passing over 15 times as distant as the Earth’s Moon. But the rather large size of this space rock makes it an object of interest for astronomers.

Chodas added that they will continue to take radar data of this asteroid while they can to improve its orbital parameters, and that the presence of the moonlet means they can get an even more precise mass estimate of the asteroid.

Want to try and see this asteroid for yourself? Our very own David Dickinson has written a great “how-to” for this object, but you are going to need a fairly large backyard telescope, since it will be about 100 times fainter than what can be seen with the naked eye, even at closest approach.

The Slooh online telescope will have views of online tomorrow, which you can watch at their website. The webcast will start at 20:30 UTC (4:30 p.m. EDT) on Friday, May 31.

Also, starting at 20:00 UTC (4:00 p.m. EDT), astrophysicist Gianluca Masi will have a webcast from the Virtual Telescope Project in Italy.

Additionally, if you want to have a Bruce Willis-type view of this asteroid, check out NASA’s Eyes on the Solar System. They have a special feature on this asteroid, and you can “ride along with it for the next few days,” said Doug Ellison, Visualization Producer at JPL, speaking during the webcast.

This amazing tool creates realistic simulated views based on real data, and allows you to travel to any planet, moon or spacecraft across time and space, in 3D and in real time — or speed up to see the future.

Just go to the Eyes on the Solar System website, and when the window opens, click on “Tours and Features” in the upper right hand corner, then click on “1998 QE2” in the dropdown box, and away you go. If you click on the “Live” button the left, you’ll see the current location; click on “Ride Along” and find yourself sitting on the asteroid heading towards Earth.

At the bottom control panel “dock” (click on the bottom box on the lower right side if the panel isn’t showing), you can speed up time and see how far from Earth this asteroid will get and where it will go in the future.

Ellison added that right now the imagery on Eyes on the Solar System doesn’t have the moonlet orbiting 1998 QE2, but they will be adding it soon to make the visualization as realistic as possible.

NASA’s @AsteroidWatch Twitter account shared the news about the moon:

That’s no moon. Wait. Yes it is! New radar data reveal #asteroidQE2 has a previously undiscovered moon. youtu.be/VnMyDYrgFws

— Asteroid Watch (@AsteroidWatch) May 30, 2013

Also, if you want more asteroids, on Friday May 31, the White House is hosting an asteroid-themed “We the Geeks” Google+ Hangout starting at 2 p.m. EDT.

The live video conference will feature Bill Nye the Science Guy, former astronaut Ed Lu, NASA Deputy Administrator Lori Garver, and Peter Diamandis, co-founder of asteroid mining company Planetary Resources. They will discuss identification, resource potential and threat of asteroids. Here’s the link the White House’s Google+ page.

May 30, 2013December 23, 2015 by Nancy Atkinson

New Images of Comet ISON Hurtling Towards the Sun

Images of Comet ISON obtained using the Gemini Multi-Object Spectrograph at Gemini North on February 4, March 4, April 3, and May 4, 2013 (left to right, respectively; Comet ISON at center in all images). Color composite produced by Travis Rector, University of Alaska Anchorage. Credit: Gemini Observatory/AURA

As Comet C/2012 S1 (ISON) heads closer to Earth, we’re getting a better view of what has been billed by some as the “Comet of the Century.” Astronomers say these new photos from the Gemini North telescope on Mauna Kea, Hawai‘i provide hints of how well this comet might survive one of the closest comet encounters with the Sun ever recorded, on November 28, 2013.

With astronomy enthusiasts hopeful and optimistic about having a spectacular comet visible in our skies, it’s anyone’s guess if the comet will actually survive its extremely close pass of the Sun to become early morning eye-candy in early December 2013.
The time-sequence images, spanning early February through May 2013, show that the comet is quite active, despite how distant it is from the Sun.

When Gemini obtained these images, the comet ranged between roughly 455-360 million miles (730-580 million kilometers; or 4.9-3.9 astronomical units) from the Sun, or just inside the orbital distance of Jupiter. Each image in the series, taken with the Gemini Multi-Object Spectrograph at the Gemini North telescope on Mauna Kea, Hawai‘i, shows the comet in the far red part of the optical spectrum, which emphasizes the comet’s dusty material already escaping from the nucleus. The final image in the sequence, obtained in early May, consists of three images, including data from other parts of the optical spectrum, to produce a color composite image.

Gemini astronomers say the images show the comet sporting a well-defined parabolic hood in the sunward direction that tapers into a short and stubby tail pointing away from the Sun. These features form when dust and gas escape from the comet’s icy nucleus and surround that main body to form a relatively extensive atmosphere called a coma. Solar wind and radiation pressure push the coma’s material away from the Sun to form the comet’s tail, which we see here at a slight angle (thus its stubby appearance).

“Early analysis of our models shows that ISON’s brightness through April can be reproduced by outgassing from either carbon monoxide or carbon dioxide,” said Karen Meech, at the University of Hawaii’s Institute for Astronomy (IfA) in Honolulu. “The current decrease may be because this comet is coming close to the Sun for the first time, and a “volatile frosting” of ice may be coming off revealing a less active layer beneath. It is just now getting close enough to the Sun where water will erupt from the nucleus revealing ISON’s inner secret.”

Comet ISON will come within 800,000 miles (1.3 million km) of the Sun’s surface on November 28. Shortly before that critical passage, the comet may appear bright enough for expert observers using proper care to see it close to the Sun in daylight.

“Comets may not be completely uniform in their makeup and there may be outbursts of activity as fresh material is uncovered,” added IfA astronomer Jacqueline Keane. “Our team, as well as astronomers from around the world, will be anxiously observing the development of this comet into next year, especially if it gets torn asunder, and reveals its icy interior during its exceptionally close passage to the Sun in late November.”

NASA’s Hubble Space Telescope provides a close-up look of Comet ISON (C/2012 S1), as photographed on April 10, when the comet was slightly closer than Jupiter’s orbit at a distance of 386 million miles from the sun. Credit:NASA, ESA, J.-Y. Li (Planetary Science Institute), and the Hubble Comet ISON Imaging Science Team.

NASA’s Swift satellite and the Hubble Space Telescope (HST) have also imaged Comet ISON recently in this region of space. Swift’s ultraviolet observations determined that the comet’s main body was spewing some 850 tons of dust per second at the beginning of the year, leading astronomers to estimate the comet’s nucleus diameter is some 3-4 miles (5-6 kilometers). HST scientists concurred with that size estimate, adding that the comet’s coma measures about 3100 miles (5000 km) across.

The comet gets brighter as the outgassing increases and pushes more dust from the surface of the comet. Scientists are using the comet’s brightness, along with information about the size of the nucleus and measurements of the production of gas and dust, to understand the composition of the ices that control the activity. Most comets brighten significantly and develop a noticeable tail at about the distance of the asteroid belt (about 3 times the Earth-Sun distance –– between the orbits of Mars and Jupiter) because this is when the warming rays of the Sun can convert the water ice inside the comet into a gas. This comet was bright and active outside the orbit of Jupiter — when it was twice as far from the Sun. This meant that some gas other than water was controlling the activity.

Meech said that Comet ISON “…could still become spectacularly bright as it gets very close to the Sun” but also added caution. “I’d be remiss, if I didn’t add that it’s still too early to predict what’s going to happen with ISON since comets are notoriously unpredictable,” she said.

Source: Gemini Observatory

May 30, 2013December 23, 2015 by Jason Major

NASA’s Particle-Hunting ISS-CREAM Will Be Anything But Vanilla

The CREAM instrument prior to launch aboard a long-duration balloon. (NASA)

Balloon-based research on cosmic particles that began over a century ago will get a big boost next year — all the way up to low-Earth orbit, when NASA’s Cosmic Ray Energetics and Mass (CREAM) will be sent to the Space Station thus becoming (are you ready for this?) ISS-CREAM, specifically designed to detect super-high-energy cosmic rays and help scientists determine what their mysterious source(s) may be.

“The answer is one the world’s been waiting on for 100 years,” said program scientist Vernon Jones.

Read more about this “cool” experiment below:

Cosmic Ray Energetics and Mass (CREAM) will be the first cosmic ray instrument designed to detect at such higher energy ranges, and over such an extended duration in space. Scientists hope to discover whether cosmic rays are accelerated by a single cause, which is believed to be supernovae. The new research also could determine why there are fewer cosmic rays detected at very high energies than are theorized to exist.

“Cosmic rays are energetic particles from outer space,” said Eun-Suk Seo, principal investigator for the CREAM study. “They provide a direct sample of matter from outside the solar system. Measurements have shown that these particles can have energies as high as 100,000 trillion electron volts. This is an enormous energy, far beyond and above any energy that can be generated with manmade accelerators, even the Large Hadron Collider at CERN.”

Researchers also plan to study the decline in cosmic ray detection, called the spectral “knee” that occurs at about a thousand trillion electron-volts (eV), which is about 2 billion times more powerful than the emissions in a medical nuclear imaging scan. Whatever causes cosmic rays, or filters them as they move through the galaxy, takes a bite out of the population from 1,000 trillion electron-volts upwards. Further, the spectrum for cosmic rays extends much farther beyond what supernovas are believed to be able to produce.

A long-duration balloon carrying CREAM prepares to launch from a location near McMurdo Station (NASA)

To tackle these questions, NASA plans to place CREAM aboard the space station, becoming ISS-CREAM. The instrument has flown six times for a total of 161 days on long-duration balloons circling the South Pole, where Earth’s magnetic field lines are essentially vertical.

The idea of energetic particles coming from space was unknown in 1911 when Victor Hess, the 1936 Nobel laureate in physics credited for the discovery of cosmic rays, took to the air to tackle the mystery of why materials became more electrified with altitude, an effect called ionization. The expectation was that the ionization would weaken as one got farther from Earth. Hess developed sensitive instruments and took them as high as 3.3 miles (5.3 kilometers) and he established that ionization increased up to fourfold with altitude, day or night.

A better understanding of cosmic rays will help scientists finish the work started when Hess unexpectedly turned an earthly question into a stellar riddle. Answering that riddle will help us understand a hidden, fundamental facet of how our galaxy, and perhaps the universe, is built and works.

The phenomenon soon gained a popular but confusing name, cosmic rays, from a mistaken theory that they were X-rays or gamma rays, which are electromagnetic radiation, like light. Instead, cosmic rays are high-speed, high-energy particles of matter.

As particles, cosmic rays cannot be focused like light in a telescope. Instead, researchers detect cosmic rays by the light and electrical charges produced when the particles slam into matter. The scientists then use detective work to identify the original particle by direct measurement of its electric charge and its energy determination from the avalanche of debris particles creating their own overlapping trails.

CREAM does this trace work using an ionization calorimeter designed to make cosmic rays shed their energies. Layers of carbon, tungsten and other materials present well-known nuclear “cross sections” within the stack. Electrical and optical detectors measure the intensity of events as cosmic particles, from hydrogen to iron, crash through the instrument.

Even though CREAM balloon flights reached high altitudes, enough atmosphere remained above to interfere with measurements. The plan to mount the instrument to the exterior of the space station will place it above the obscuring effects of the atmosphere, at an altitude of 250 miles (400 kilometers).

“On what can we now place our hopes of solving the many riddles which still exist as to the origin and composition of cosmic rays?”

– Victor F. Hess, Nobel Lecture, Dec. 1936

Source: NASA

May 30, 2013December 23, 2015 by Elizabeth Howell

This Machine Could Help Robots Stick The Landing On Other Worlds

The system the European Space Agency is using to aim for pinpoint landings on nearby moons and planets. Credit: ESA

Mission planners really hate it when space robots land off course. We’re certainly improving the odds of success these days (remember Mars Curiosity’s seven minutes of terror?), but one space agency has a fancy simulator up its sleeve that could make landings even more precise.

Shown above, this software and hardware (tested at the European Space Agency) so impressed French aerospace center ONERA that officials recently gave the lead researcher an award for the work.

“If I’m a tourist in Paris, I might look for directions to famous landmarks such as the Eiffel Tower, the Arc de Triomphe or Notre Dame cathedral to help find my position on a map,” stated Jeff Delaune, the Ph.D. student performing the research.

“If the same process is repeated from space with enough surface landmarks seen by a camera, the eye of the spacecraft, it can then pretty accurately identify where it is by automatically comparing the visual information to maps we have onboard in the computer.”

ESA's SMART-1 mission took this collection of lunar pictures around the south pole, a possible landing target for future missions. Credit: ESA — ESA’s SMART-1 mission took this collection of lunar pictures around the south pole, a possible landing target for future missions. Credit: ESA

Because landmarks close-up can look really different from far away, this system has a method to try and get around that problem.

The so-called ‘Landing with Inertial and Optical Navigation’ (LION) system takes the real-time images generated by the spacecraft’s camera and compares it to maps from previous missions, as well as 3-D digital models of the surface.

LION can take into account the relative size of every point it sees, whether it’s a huge crater or a tiny boulder.

At ESA’s control hardware laboratory in Noordwijk, the Netherlands, officials tested the system with a high-res map of the moon.

Though this is just a test and there is still a ways to go before this system is space-ready, ESA said simulated positional accuracy was better than 164 feet at 1.86 miles in altitude (or 50 meters at three kilometers in altitude.)

Oh, and while it’s only been tested with simulated moon terrain so far, it’s possible the same system could help a robot land on an asteroid, or Mars, ESA adds.

No word on when the system will first hitch an interplanetary ride, but Delaune is working to apply the research to terrestrial matters such as unmanned aerial vehicles.

Check out more details on the testing on ESA’s website.

Source: ESA

May 29, 2013December 23, 2015 by Nancy Atkinson

Saturn’s Moon Dione May Have Been Active Like Enceladus

Saturn's moon Dione, as seen by the Cassini spacecraft. Credit: NASA/JPL-Caltech/Space Science Institute

From a JPL press release:

From a distance, most of the Saturnian moon Dione resembles a bland cueball. Thanks to close-up images of a 500-mile-long (800-kilometer-long) mountain on the moon from NASA’s Cassini spacecraft, scientists have found more evidence for the idea that Dione was likely active in the past. It could still be active now.

“A picture is emerging that suggests Dione could be a fossil of the wondrous activity Cassini discovered spraying from Saturn’s geyser moon Enceladus or perhaps a weaker copycat Enceladus,” said Bonnie Buratti of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who leads the Cassini science team that studies icy satellites. “There may turn out to be many more active worlds with water out there than we previously thought.”

Janiculum Dorsa, a mountain that appears as the long, raised scar in the middle of this Cassini image, is providing new evidence that the Saturnian moon Dione was recently active. Credit: NASA/JPL-Caltech/Space Science Institute.

Other bodies in the solar system thought to have a subsurface ocean – including Saturn’s moons Enceladus and Titan and Jupiter’s moon Europa – are among the most geologically active worlds in our solar system. They have been intriguing targets for geologists and scientists looking for the building blocks of life elsewhere in the solar system. The presence of a subsurface ocean at Dione would boost the astrobiological potential of this once-boring iceball.

Hints of Dione’s activity have recently come from Cassini, which has been exploring the Saturn system since 2004. The spacecraft’s magnetometer has detected a faint particle stream coming from the moon, and images showed evidence for a possible liquid or slushy layer under its rock-hard ice crust. Other Cassini images have also revealed ancient, inactive fractures at Dione similar to those seen at Enceladus that currently spray water ice and organic particles.

The mountain examined in the latest paper — published in March in the journal Icarus — is called Janiculum Dorsa and ranges in height from about 0.6 to 1.2 miles (1 to 2 kilometers). The moon’s crust appears to pucker under this mountain as much as about 0.3 mile (0.5 kilometer).

The topography of a mountain known as Janiculum Dorsa on the Saturnian moon Dione. Color denotes elevation, with red as the highest area and blue as the lowest. Credit: NASA/JPL-Caltech/Space Science Institute.

“The bending of the crust under Janiculum Dorsa suggests the icy crust was warm, and the best way to get that heat is if Dione had a subsurface ocean when the ridge formed,” said Noah Hammond, the paper’s lead author, who is based at Brown University, Providence, R.I.

Dione gets heated up by being stretched and squeezed as it gets closer to and farther from Saturn in its orbit. With an icy crust that can slide around independently of the moon’s core, the gravitational pulls of Saturn get exaggerated and create 10 times more heat, Hammond explained. Other possible explanations, such as a local hotspot or a wild orbit, seemed unlikely.

Scientists are still trying to figure out why Enceladus became so active while Dione just seems to have sputtered along. Perhaps the tidal forces were stronger on Enceladus, or maybe the larger fraction of rock in the core of Enceladus provided more radioactive heating from heavy elements. In any case, liquid subsurface oceans seem to be common on these once-boring icy satellites, fueling the hope that other icy worlds soon to be explored – like the dwarf planets Ceres and Pluto – could have oceans underneath their crusts. NASA’s Dawn and New Horizons missions reach those dwarf planets in 2015.

May 29, 2013April 26, 2016 by Elizabeth Howell

Why Are Dying Stars in 47 Tucanae Cooling Off So Slowly?

The Hubble Space Telescope is going to be used to settle an argument. It’s a conflict between computer models and what astronomers are seeing in a group of stars in 47 Tucanae.

White dwarfs — the dying embers of stars who have burnt off all their fuel — are cooling off slower than expected in this southern globular cluster, according to previous observations with the telescope’s Wide Field Camera and Advanced Camera for Surveys.

Puzzled astronomers are now going to widen that search in 47 Tucanae (which initially focused on a few hundred objects) to 5,000 white dwarfs. They do have some theories as to what might be happening, though.

White dwarfs, stated lead astronomer Ryan Goldsbury from the University of British Columbia, have several factors that chip in to the cooling rate:

The Hubble Space Telescope. Image credit: NASA, tweaked by D. Majaess.

– High-energy particle production from the white dwarfs;

– What their cores are made up of;

– What their atmospheres are made up of;

– Processes that bring energy from the core to the surface.

Somewhere, somehow, perhaps one of those factors is off.

This kind of thing is common in science, as astronomers create these programs according to the best educated guesses they can make with respect to the data in front of them. When the two sides don’t jive, they do more observations to refine the model.

“The cause of this difference is not yet understood, but it is clear that there is a discrepancy between the data and the models,” stated the Canadian Astronomical Society (CASCA) and the University of British Columbia in a press release.

Since the white dwarfs are in a cluster that presumably formed from the same cloud of gas, it allows astronomers to look at a group of stars at a similar distance and to determine the distribution of masses of stars within the cluster.

“Because all of the white dwarfs in their study come from a single well-studied star cluster, both of these bits of information can be independently determined,” the release added.

You can read the entire article on the previous Hubble research on 47 Tucanae at the Astrophysical Journal.

Today’s announcement took place during the annual meeting of CASCA, which is held this year in Vancouver.

Source: CASCA/UBC