Could Comet ISON Still Become the 'Comet of the Century?

The future of a potential "comet of the century" is still uncertain, with just under two months to go before the icy wanderer makes its closest approach to the sun.

With just two months to go before Comet ISON skims within about three-quarters of a million miles (1 million kilometers) above the sun's surface, it's still uncertain whether the comet will evolve into a stunningly bright object that will put on a memorable show in December, or turn out to be nothing more than a dim fuzz ball.

The comet was masked by the glare of the sun for much of the summer and began to emerge into darker skies in mid-August.

Because the comet's brightening had seemed to stall during the first half of this year, there was hope that once it reappeared, it would look significantly brighter. It was, indeed, brighter, yet not as bright as many had hoped. In fact, the comet was running about two magnitudes — or six times fainter — than forecasts had originally suggested.

Sizzle or fizzle?

This new information has spawned two camps anticipating ISON's future performance: those who think ISON will be a major disappointment and those who are still holding on to the hope that ISON will become a bright naked-eye spectacle.

Astronomer Bruce Gary was the first to photograph ISON after it emerged from the glare of the rising sun on Aug. 12, and belongs to the first camp. According to Gary's calculations, the comet might not get much brighter than fifth or sixth magnitude, which is near the threshold of naked-eye visibility.

"I've begun to lose interest in this comet, which may never become visible to the unaided eye," Gary said. "I wonder why someone ever suggested that it could become the 'comet of the century.'"

On the other hand, astronomer Karl Battams of the Naval Research Lab in Washington, D.C. has issued a more sanguine outlook.

"Certainly, we would love it to be a couple of magnitudes brighter right now, but it's doing just fine," Battams said. "I'd say it's still on course to become a very eye-catching object." 

Slowly brightening

Earlier in September, based on a consensus of visual observations made by reputable observers, Comet ISON appeared as bright as 13th magnitude — still more than 600 times fainter than the dimmest star that can be perceived with the naked eye.

Through large telescopes, the comet's head (called a coma) appeared about 1/30 the apparent size of the moon. 

Over the last few weeks, the comet has nearly doubled in brightness to about magnitude 12. 

Denis Buczynski, secretary of the British Astronomical Association's comet section, photographed ISON in a somewhat hazy sky on the morning of Sept. 26.

"ISON seems to show some evidence of gas tail/streamers in my images north of the head," Buczynski wrote in a description. "The comet is beginning to look quite active now."

The view from Mars

More time and more observations will be needed to get a better handle on exactly how bright Comet ISON will get. Some of those observations will truly be out of this world: Scientists will observe the comet from Earth, and rovers on Mars and spacecraft orbiting the Red Planet will have a great view of the celestial showcase.

On Tuesday, (Oct. 1), the comet will pass just 6.5 million miles (10.5 million km) above the Martian surface.

Researchers aren't sure whether Mars rover Curiosity will be able to capture images of the comet from the surface of Mars — that will depend on how bright ISON is as it makes its closest pass to the Red Planet.

According to astronomer Carey Lisse of the Johns Hopkins University Applied Physics Lab in Maryland, the best bet for observation will be NASA's Mars Reconnaissance Orbiter (MRO). The MRO satellite is equipped with a powerful half-meter (1.5 feet) telescope named HiRISE that is capable of detecting ISON's fuzzy coma and tail. HiRISE will be turned toward the comet on Oct 1 and 2.

In addition, an unprecedented 16 other NASA spacecraft observe the comet as it heads sunward. The astronauts on board the International Space Station will be watching, too.

Finally revving up?

Buczynski's observations may also suggest that ISON is in the process of crossing the so-called "frost line," where heat from the sun starts to vaporize the frozen water of the comet.

Up to 90 percent of the volatile material in a typical comet are water ice. Carbon dioxide and other gases are likely behind the relatively little brightening of Comet ISON. But if ISON crosses the frost line in the coming days, "the whole comet could erupt in geysers of gas," Lisse said.

Moment of truth

The moment of truth will come on the U.S.' Thanksgiving Day (Nov. 28), when the comet will graze the sun's surface.

Don't forget: ISON is, after all, a chunk of material that has spent thousands of years in the depths of deep space, where temperatures barely hover above absolute zero (minus 459.7 degrees Fahrenheit or minus 273.2 degrees Celsius). For eons, the comet has been "soaking up the cold," so to speak. 

But on Nov. 28, ISON will be moving through the sun's outer atmosphere, where it will be subjected to temperatures in excess of 1 million degrees F (555,538 degrees C). This extreme heat could cause the comet's 3-mile-wide (4.8 km) nucleus to break apart into several pieces — much like what could happen when you pour hot tea into a cold cup.

All hope for the comet is not lost, however. The fracturing process could release a fresh stream of dust into space that could translate into a spectacularly long and bright tail in early December. It could also cause the comet's brightness to suddenly spike.

But it is still possible that the comet could disintegrate.

Comet Lovejoy did just that in December 2011, but only after it passed the sun. Lovejoy eventually evolved into a celestial showpiece, and disappeared a few weeks later. ISON could also disintegrate before it reaches the sun, but at least one expert does not think that will happen.

Astronomer John Bortle, a highly reputable comet observer, thinks "ISON appears likely to survive the in-bound leg of its journey all the way to the sun."

"It will probably brighten more slowly than all the early hype led the public to believe," Bortle said. "Nevertheless, Comet ISON should very briefly become exceptionally bright, at least rivaling the planet Venus in the hours preceding its closest approach to the sun."

Source of Article: Space.com

Incredible Technology: How to Clean Up Dangerous Space Junk

The vast amount of manmade debris in orbit around Earth is untenable, but emerging and currently available technologies could be used to get these objects under control.

Humanity is generating space junk more quickly than the debris can fall back toward Earth naturally, putting satellites and spacecraft at risk of colliding with s

peeding pieces of debris. Unless something is done, the problem could get worse, said Donald Kessler, retired head of NASA's Orbital Debris Program Office.

"In the long term, everything will eventually break up due to collisions," Kessler told SPACE.com. "Even if you don't add anything else to the environment, the collision frequency due to random collisions will create more debris than will re-enter naturally." 

At the moment, NASA officials estimate that about 500,000 pieces of debris larger than a marble orbit the planet. There are 22,000 bits of junk as big as a softball, and there could be more than 100 million tiny fragments at least 1 millimeter across racing around Earth.

But how can mission controllers on the ground remove those troublesome pieces of space junk  — including defunct satellites, spent rocket stages and other pieces of manmade debris — from their dangerous orbits?

The "old-fashioned" method

Technology readily available today could mitigate the space junk threat, Kessler said. By taking only five satellites out of orbit each year for the next 100 years, while adhering to an international understanding called the 25-year rule, space agencies could stabilize the orbital environment, according to a NASA study. The 25-year rule stipulates that nations should not launch objects whose lifetime in space will exceed 25 years after the completion of their missions.

Space agencies could also rely on a somewhat basic method to remove the debris, Kessler said. Engineers would need to develop some kind of technology to grapple the target piece of debris and pull it into a part of space where it could quickly to burn up in Earth's atmosphere.

"Technologically speaking, the easiest way to do it is what I've been referring to as the old-fashioned way," Kessler said. "You just design a spacecraft to go up and get it, attach a rocket to it and send it on its way or wherever you want to put it."

On the horizon

There are other, more high-tech options on the horizon for space cleanup as well.

The Defense Advanced Research Projects Agency's (DARPA)  Phoenix spacecraft project would use old, but functioning pieces of defunct satellites to create new space-based systems — instead of adding completely new satellites. Officials working with the program would launch a "tender" vehicle that would make use of small "satlets" launched without an expensive antenna needed to make satellites function.

Once in space, the tender would move a relatively inexpensive satlet to a defunct geosynchronous satellite. There, the old satellite's antenna could be recycled and incorporated into the tiny satellite, effectively creating a new communications system without necessarily producing more space junk.

Scientists could also use lasers to mitigate the risks posed by orbital debris.

"There are two ways that a laser works" to get rid of a piece of space debris, Kessler said. "One is using what they call photon power — just letting light waves slow it down until it re-enters [Earth's atmosphere], but that works really well on small stuff.

"To get a big force out of it, you need to vaporize part of the surface and essentially form a jet … but when you're doing that, you don't know what might happen, so there's some uncertainty there," Kessler added. "You would hate to cause it to blow up for example." 

Space junk-targeting lasers probably won't be built anytime soon, however, because the national security implications of such a tool could make it a non-starter, Kessler said. That is, the possibility of weaponizing a powerful space or ground-based laser could make building such a device politically difficult.

Another mission — expected to launch to space in 2015 or 2016 — will aim to rendezvous with and grapple obsolete satellites. CleanSpace One, a project of the Swiss Space Center, is designed to be the first satellite capable of grappling a piece of space junk in orbit and plunging with it into Earth's atmosphere, disintegrating both spacecraft.

Source of Article: Space.com

NASA Finds Ingredient for Plastic on Saturn's Moon Titan

For the first time, a chemical essential for the creation of plastic on Earth has been found in a far-off part of the solar system: Saturn's largest Titan.

The discovery, made by NASA's Cassini spacecraft currently orbiting Saturn, found that the atmosphere of Titan contains propylene, a key ingredient of plastic containers, car bumpers and other everyday items on Earth. NASA scientists announced the discovery  with a video describing the propylene find on Titan.

"This chemical is all around us in everyday life, strung together in long chains to form a plastic called polypropylene," Conor Nixon, a NASA planetary scientist and lead author of a paper detailing the new research in today's (Sept. 30) issue of the Astrophysical Journal Letters said in a statement. "That plastic container at the grocery store with the recycling code 5 on the bottom — that's polypropylene." 

Scientists used Cassini's composite infrared spectrometer (CIRS) instrument, which measures infrared light given off by Saturn and its moon, made the discovery.

The new study helps piece together a long-standing mystery about Titan's atmosphere. When Voyager 1 conducted the first close flyby of the moon in 1980, it recognized gasses in the moon's brown atmosphere as hydrocarbons.

Scientists have found that hydrocarbons — which make up fossil fuels on Earth — form on Titan after sunlight breaks apart methane and the chemicals reform into chains of two or more carbons. Voyager found evidence of the heaviest three-carbon hydrocarbon, propane, and the spacecraft also discovered propyne — one of the lightest in the family.

The middle-weight chemicals like propylene, however, were missing from the Voyager data.

"This measurement was very difficult to make because propylene's weak signature is crowded by related chemicals with much stronger signals," Michael Flasar, Goddard scientist and principal investigator for the CIRS instrument, said in a statement. "This success boosts our confidence that we will find still more chemicals long hidden in Titan's atmosphere."

Titan is about half the size of Earth and is the second-largest moon in the solar system — only Jupiter's Ganymede beats it out in size. The moon is also the only one in the solar system that harbors clouds and a planet-like atmosphere, which is mostly composed of nitrogen and methane.

Cassini launched to space in 1997, arriving in orbit around Saturn in July 2004. The mission — centered on understanding Saturn and its many moons — is expected to continue until 2017 when the spacecraft will be crashed into Saturn's atmosphere.

Source of Article: Space.com

Did Earth Life Come from Space? Tough Algae Suggests Panspermia Possibility

Scientists have long debated the possibility of that the microbial seeds of life did not originate on Earth, but were perhaps delivered here from an alien source, encased in comets or meteorites from Mars.

But to get here, simple life forms would have had to endure a litany of harsh cosmic conditions, including ejection into space, freezing temperatures, fiery re-entry and impact.

Now, a team of researchers found new evidence that a terrestrial algae just might be able to survive the physical strains of space travel, a discovery that may support the possibility that panspermia, the concept that microbial life is everywhere in the universe and can spread between planets, could potentially occur.

The scientists, who presented their findings at the European Planetary Science Congress in London on Sept. 12, focused on a type of single-celled ocean-dwelling algae called Nannochloropsis oculata.

Using a two-stage light gas gun, the researchers shot frozen pellets of the algae into water at extremely high speeds and then analyzed their sample to see if any of the organisms came out alive.

"As you might expect, increasing the speed of impact does increase the proportion of algae that die, but even at 6.93 kilometers per second (4.31 miles per second), a small proportion survived," study researcher Dina Pasini, of the University of Kent explained in a statement. "This sort of impact velocity would be what you would expect if a meteorite hit a planet similar to the Earth."

The researchers say their findings suggest that alien life and panspermia may not be impossible, though the theory still remains unproven. Pasini and colleagues noted that space travel might not be so bad for a tiny life-form. Enclosed in a natural spaceship of rock and ice, alien organisms might be protected from radiation and extreme heat.

"Our research raises several questions," Pasini said in the statement. "If we find life on another planet, will it be truly alien or will it be related to us? And if so, did it spawn us or did we spawn it? We cannot answer these questions just now, but the questions are not as farfetched as one might assume."

Pasini's research is not affiliated with another study announced Thursday (Sept. 19) that claims to have found evidence of alien life in Earth's upper atmosphere.

That separate study is based on findings by British scientists who deployed a research balloon over England. The balloon returned a sample containing the cell wall of a diatom, a type of microscopic algae.

The British researchers, led by astrobiology researcher Milton Wainwright, of the University of Sheffield in the United Kingdom, took the discovery as proof that life is continually arriving to Earth from space and perhaps didn't originate on our planet, but the claims have been met with wide skepticism.

Source of Article: Space.com

Exoplanet-Hunting Telescope to Seek Strange, New Worlds from Giant Balloon

The scientists behind the project call it EchoBeach: a plan to send a giant helium balloon into the skies to study planets in other solar systems. And indeed, it could well be a beachhead for Echo - another ambitious space mission currently under consideration.

Led by physicist Enzo Pascale of Cardiff University in the U.K., the EchoBeach experiment would allow researchers to identify what the atmospheres of distant alien worlds are made of – and do so much cheaper than other space missions.

“It will be a 1.5m telescope hanging from a balloon at very high altitude - 40 kilometers (or nearly 25 miles) – in the stratosphere,” Pascale said. “There’s science to be done, very compelling science.”

Lately, there has been no shortage of exoplanets: new ones are discovered regularly, and today’s count is nearly a thousand.

The now retired space observatory Kepler has found thousands of potential exoplanets in recent years; Hubble has also spotted a few, as have several big ground-based telescopes.

But so far, scientists have only been able to characterize the atmosphere of eight of them. 

That’s because exoplanets are too far away, faint and close to their parent stars to be imaged directly.

Echo’s precursor

EchoBeach could be launched as early as 2017. It would be a pathfinder for a space mission dubbed Echo, which, if it gets the go-ahead, will also be studying the chemical composition of the atmosphere of exoplanets ‑ but on a much wider scale.

Echo is one of five proposed space missions under consideration at the European Space Agency. The verdict on which mission gets the go-ahead should come in February 2014.

While Echo will be able to study hundreds of exoplanets, including those in what is called the “habitable zone” where water could be found in liquid form, EchoBeach will only be sensitive enough to look at the hottest and largest of them, the Jupiter-like gas giants.

“Echo will be much, much better. It will be in space, which means the Earth’s atmosphere won’t pollute the observation, and therefore it will be of orders of magnitude more sensitive that anything we have used so far, including EchoBeach,” Pascale said.

But Echo would only be launched in 2022 at the earliest, and the balloon-borne precursor would get there first. “While we are waiting for Echo, which will give us the ultimate view of all these alien worlds, EchoBeach could be a forerunner, an aide for Echo, it can help us to design the best possible space mission,” Pascale said.

Both projects will be using a method called transiting spectroscopy. The transit method of spotting an exoplanet is indirect, and it is the one that was used by the Kepler telescope. The instruments measure tiny dips in the brightness of stars when a planet passes through the line of sight.

Once a planet is confirmed, the next step is to determine its key parameters such as mass and radius. Other instruments then measure whether there is an atmosphere, and if yes, what it is made of. This instrument is called a spectrometer, and that’s what both EchoBeach and later Echo could be tasked with.

A spectrometer disperses the light into its different colors, like a prism. EchoBeach and Echo will be working in the infrared part of the spectrum, invisible to the naked eye.

Balloon-borne missions

There have been a number of balloon-borne astronomy experiments, launched by NASA, 

France, Sweden and Canada. ESA, though, has so far launched none.

The EchoBeach concept has had forerunners. A balloon called BLAST carried an instrument tasked with studying star formation, and preceded a similar instrument on the ESA Herschel telescope, three years before Herschel went into orbit.

Another balloon program, Boomerang, was a precursor for an instrument on the ESA-led Planck mission, which peers deep into the early cosmos, studying the Big Bang’s fossil light – the cosmic microwave background radiation.

Cosmologist Mark Devlin of the University of Pennsylvania, who is not involved in EchoBeach but has launched 10 balloon-borne astronomy projects, says that such missions can have a significant advantage over space programs.

A balloon can carry a telescope above 99.5 percent of the atmosphere and provide a near-space environment. “For many observations, this is perfectly fine,” he said.

And they can be conceived, built and executed on a very short time scale compared to a satellite – and at much less cost. This way, a space agency can test new technologies quickly and cheaply, which “significantly mitigates the technology risks for full-blown satellite missions,” Devlin said.

NASA, for instance, has also been considering a possible balloon-borne spectroscopy experiment, with several ideas proposed by researchers. So far, none have been funded, but Devlin said that NASA “considers planet finding to be a very high priority and are keen to get [such a] mission going.”

The EchoBeach team is currently in talks with U.S. researchers, to possibly launch a balloon-borne mission together.

“I’m sure that one of those experiments will go ahead soon,” Pascale said. “Regarding EchoBeach, I think we will know for sure next spring whether it’ll happen or not. I hope it will.”

Source of Article: Space.com

The Moon Is 100 Million Years Younger Than Thought

The moon is quite a bit younger than scientists had previously believed, new research suggests.

The leading theory of how the moon formed holds that it was created when a mysterious planet — one the size of Mars or larger — slammed into Earth about 4.56 billion years ago, just after the solar system came together. But new analyses of lunar rocks suggest that the moon, which likely coalesced from the debris blasted into space by this monster impact, is actually between 4.4 billion and 4.45 billion years old.

The finding, which would make the moon 100 million years younger than previously thought, could reshape scientists' understanding of the early Earth as well as its natural satellite, researchers said.

"There are several important implications of this late moon formation that have not yet been worked out," Richard Carlson, of the Carnegie Institution for Science in Washington, D.C., said in a statement.

"For example, if the Earth was already differentiated prior to the giant impact, would the impact have blown off the primordial atmosphere that formed from this earlier epoch of Earth history?" added Carlson, who is presenting the new results Monday (Sept. 23) in London at a meeting organized by the Royal Society called "Origin of the Moon."

Scientists know the solar system's age (4.568 billion years) quite well. And they can pin down the formation times of relatively small bodies such as asteroids precisely, too, by noting when these objects underwent extensive melting — a consequence, in part, of the heat generated by the collision and fusion of these objects' building-block "planetesimals."

For example, analysis of meteorites that came from the asteroid Vesta and eventually rained down on Earth reveals that the 330-mile-wide (530 kilometers) space rock is 4.565 billion years old. Vesta cooled relatively quickly and is too small to have retained enough internal heat to drive further melting or volcanism, Carlson explained.

But it's tougher to nail down the age of larger solar-system bodies, he said.

"Ask the same question of the Earth or moon, and you don't get a very precise answer," Carlson said. "Earth likely took longer to grow to full size compared to a small asteroid like Vesta, and every step in its growth tends to erase, or at least cloud, the memory of earlier events."

Scientists keep getting better and better estimates, however, as they refine their techniques and technology improves. And those estimates are pushing the moon's formation date farther forward in time.

The moon is thought to have harbored a global ocean of molten rock shortly after its dramatic formation. Currently, the most precisely determined age for the lunar rocks that arose from that ocean is 4.360 billion years, the researchers said.

And here on Earth, scientists have found signs in several locations of a major melting event that occurred around 4.45 billion years ago. So, evidence is building that the catastrophic collision that formed the moon and reshaped Earth occurred around that time, rather than 100 million years or so before, the researchers said.

Source of Article: Space.com

Organic Molecules Found in Sutter's Mill Meteorite, Not Previously Found in Any Meteorites

An important discovery has been made concerning the possible inventory of molecules available to the early Earth. Scientists led by Sandra Pizzarello, a research professor in ASU's Department of Chemistry and Biochemistry, found that the Sutter's Mill meteorite, which exploded in a blazing fireball over California last year, contains organic molecules not previously found in any meteorites. These findings suggest a far greater availability of extraterrestrial organic molecules than previously thought possible, an inventory that could indeed have been important in molecular evolution and life itself.

The work is being published in this week's Proceedings of the National Academy of Sciences. The paper is titled "Processing of meteoritic organic materials as a possible analog of early molecular evolution in planetary environments," and is co-authored by Pizzarello, geologist Lynda Williams, NMR specialist Gregory Holland and graduate student Stephen Davidowski, all from ASU.

Coincidentally, Sutter's Mill is also the gold discovery site that led to the 1849 California Gold Rush. Detection of the falling meteor by Doppler weather radar allowed for rapid recovery so that scientists could study for the first time a primitive meteorite with little exposure to the elements, providing the most pristine look yet at the surface of primitive asteroids.

"The analyses of meteorites never cease to surprise you ... and make you wonder," explains Pizzarello. "This is a meteorite whose organics had been found altered by heat and of little appeal for bio- or prebiotic chemistry, yet the very Solar System processes that lead to its alteration seem also to have brought about novel and complex molecules of definite prebiotic interest such as polyethers."

Pizzarello and her team hydrothermally treated fragments of the meteorite and then detected the compounds released by gas chromatography-mass spectrometry. The hydrothermal conditions of the experiments, which also mimic early Earth settings (a proximity to volcanic activity and impact craters), released a complex mixture of oxygen-rich compounds, the probable result of oxidative processes that occurred in the parent body. They include a variety of long chain linear and branched polyethers, whose number is quite bewildering.

This addition to the inventory of organic compounds produced in extraterrestrial environments furthers the discourse of whether their delivery to the early Earth by comets and meteorites might have aided the molecular evolution that preceded the origins of life.

Source of Article: ScienceDaily.com