Asteroids are much in the news these days, with Japanese and European missions returning outstanding photos and information about them. While we await testing on what may be fragments of the asteroid Itokawa from the Hayabusa team, we now prepare for another asteroid flyby on the part of the European Space Agency's Rosetta spacecraft, which carries DLR's Philae lander, a craft destined for eventual touchdown on the comet 67P/Churyumov-Gerasimenko. But that's not until 2014, when the most detailed study of a comet ever attempted reaches its destination. Along the way, Rosetta has delivered interesting asteroid results, including a 2008 flyby of the 'diamond in the sky' asteroid called Steins. We can now look forward to a flyby of the main belt asteroid 21 Lutetia, which will occur on July 10. Three instruments on the lander -- a magnetometer and plasma monitor (ROMAP), and two gas analyzers -- will be switched on during the flyby. More in this DLR news release, which notes that...

These days we think of Giovanni Cassini in relation to Saturn, for obvious reasons, but the Italian astronomer (1625-1712) did a lot more than discovering the division in the rings of Saturn that would later bear his name. In addition to his studies of the Saturnian moons, Cassini shares credit for the discovery of Jupiter's Great Red Spot, and in conjunction with Jean Richer, made parallax observations of Mars that allowed its distance to be determined in 1672. But back to Jupiter, for in 1686 Cassini reported seeing a dark spot on the planet, one that from his description was roughly the size of the largest impact made by the Comet P/Shoemaker-Levy comet fragments in 1994. We're dealing with crude telescopes and lack of corroborating information with Cassini's observation, but Shoemaker-Levy left us with Hubble imagery when it struck the giant planet after breaking apart into more than twenty pieces enroute. I mention Cassini's early sighting because it's possible he was also...

Why mount a mission to an asteroid? For one thing, some of them cross the Earth's orbit, and that makes gathering knowledge about their composition essential to any future trajectory-altering operation. For another, the science return could be immense. These are unprepossessing objects, no more than chunks of rock and dust, but they can tell us much about the early Solar System. Moreover, getting to an asteroid, as NASA GSFC is now proposing to do with a mission called OSIRIS-REx, would allow us to examine samples in situ, something mission proponent Bill Cutlip finds more valuable than studying chunks of asteroids that fall to Earth in the form of meteorites: "[Meteorites] are toasted on their way through Earth's atmosphere. Once they land, they then soak up the microbes and chemicals from the environment around them." No, pristine is better, for we're trying to learn about the earliest days of our system, the period of planetary formation and the origins of the organic compounds...

I'm looking at the National Research Council's final report on the detection of near-Earth objects, the culmination of the study that produced the NRC's interim report last year. Let's recall the context: It was in 2005 that Congress mandated that NASA find 90 percent of NEOs with a diameter of 140 meters or greater, such discovery to be concluded by 2020. The interim report, discussed in an earlier Centauri Dreams story, concluded that NASA couldn't meet this goal because funds for the survey had never been appropriated. Now we have a final report with suggestions on what NASA could do to finish the survey as soon as possible after the original 2020 deadline. Two possibilities emerge: A space-based telescope working in tandem with a ground-based telescope could finish the job the fastest. But if cost-cutting is necessary, the space option will have to be abandoned in favor of ground-based equipment. Gratifyingly, the NRC stands up strongly to defend Arecibo, whose role in asteroid...

Sankar Chatterjee (Texas Tech) and a team of researchers have been looking at something known as the Shiva basin, that area west of India that is heavily laden with oil and gas resources. Chatterjee believes the Shiva basin is in fact a huge, multi-ringed impact crater, one caused by a bolide perhaps as much as 40 kilometers in diameter, big enough, as the scientist says, to create its own tectonics. The supposed dinosaur killer impactor in the Yucatan, by contrast, is thought to have been between eight and ten kilometers wide. Is Shiva basin the crater left by the actual extinction event? Mostly submerged, Shiva's outer rim forms a 500-kilometer ring with a central peak extending some three miles from the ocean floor. One result of such a strike, if the team's theories hold up, is that the volcanic eruptions at the nearby Deccan Traps may well have been enhanced, not to mention the ensuing formation of the Seychelles Islands, which would have broken off the Indian tectonic plate....

New observations of asteroid Apophis, reported at the Division for Planetary Sciences meeting in Puerto Rico, indicate that the chances of its striking the Earth in 2036 must be recalculated, diminishing from roughly 1 in 45,000 to 1 in 250,000. There goes one disaster scenario, but enter another: An impact possibility exists for the year 2068. Says David Tholen (University of Hawaii): "Our new orbit solution shows that Apophis will miss Earth's surface in 2036 by a scant 20,270 miles, give or take 125 miles. That's slightly closer to Earth than most of our communications and weather satellites." Too close for comfort, but a miss is a miss. Apophis reappears from behind the Sun in 2010 and is sure to be the object of even more intense scrutiny in years to come. But bear in mind that, just as we were able to refine our figures for the 2029 and 2036 encounters, we will probably be able to reduce the 1 in 333,000 chance now calculated for Apophis to actually strike in 2068. Image:...

Some things to keep in mind with regard to near-Earth objects: NASA is working with a Congressional mandate from 2005 that it discover ninety percent of all NEOs that are 140 meters in diameter or greater. The deadline for this task is 2020, and the interim report Near-Earth Object Surveys and Hazard Mitigation Strategies (written by a committee appointed by the National Research Council) says the surveys currently in progress are not capable of meeting this goal. The final report is to appear in December. Now switch to Arecibo. The radio telescope there, run by Cornell University and the National Science Foundation, has run into serious funding questions. NSF must decide whether the current cooperative relationship between Cornell and NSF should continue, and whether the observatory itself should be funded. You may recall that an NSF panel recommended in late 2006 that Arecibo's operating budget be reduced in a series of steps, ultimately taking it from $10.5 million to $4 million...

A recent report from the National Academy of Sciences points out that NASA has been tasked to locate 90 percent of the most deadly objects that could conceivably strike our planet. Yet only about a third of this assignment has been completed, and the money has yet to be found to complete the job. The agency calculates it needs about $800 million between now and 2020 to make the needed inventory, while $300 million would allow it to find most objects larger than 300 meters across. The problem is that even the smaller sum is not available, and this AP story quotes space policy expert John Logsdon (George Washington University) as saying the money may never come through, calling the program "a bit of a lame duck." In other words, there is not yet enough pressure on Congress to produce the needed funds. Meanwhile, asteroid detection remains a low priority for other governments as well, making this a problem we're choosing to ignore in the absence of recent reminders of its potential....

A note the other day from astrodynamics wizard Edward Belbruno (Princeton University) has put me in mind of the ongoing study of the L4 and L5 points being conducted by the STEREO mission. STEREO is a two-spacecraft observatory designed to study solar activity, but in September and October the craft will be making their closest approach to the two gravitational wells at L4 and L5, and it's possible we'll discover a resident population of asteroids in the process. If so, we may be looking at material from the birthplace of a long-gone planet. Call this hypothetical world, as Belbruno does, Theia. We looked at this secondary mission for STEREO last February, but as Belbruno passed along a link to the 2005 paper on the subject of Theia for which he was lead author, it's time to revisit it. The paper is a lively piece of work, noting that current thinking is that our Moon was the result of a giant impactor, a planetary-sized object that hit the Earth and produced debris that eventually...

Once again we're asked to reconsider our views about the outer Solar System. In this case, the area in question is the Oort Cloud, which begins at roughly 1000 AU and continues, by some estimates, as far as three light years from the Sun. It's a spherical cloud of comets, probably numbering in the billions of objects, most of which will never be observed because of their distance and faint signature. Getting comets into the inner Solar System is necessary for closer observation, but it's also risky for living beings. At least, that's been the prevailing belief, given that comet collisions with Earth could theoretically produce extinction events. New research, however, has begun to challenge this view. Nathan Kaib (University of Washington) and doctoral adviser Thomas Quinn have developed computer models to study how comet clouds behave. The simulations trace the evolution of comets over a 1.2 billion year period and allow the team to estimate the highest number of comets possible in...

It's a lively Solar System indeed. In yet another confirmation of the value of amateur astronomy, Australia's Anthony Wesley tipped off scientists on July 19 that a new object had struck Jupiter and observatories around the world zeroed in on the event. It comes exactly fifteen years after the 'string of pearls' comet Shoemaker-Levy 9 struck the giant planet. Infrared images show a likely impact point near the south polar region, visible in the image below. Image: A large impact shown on the bottom left on Jupiter's south polar region captured on July 20, 2009, by NASA's Infrared Telescope Facility in Mauna Kea, Hawaii. Image credit: NASA/JPL/Infrared Telescope Facility. Unlike Shoemaker-Levy 9, this event may have been caused by a single object. UC Berkeley and SETI Institute astronomer Franck Marchis explains: "The analysis of the shape and brightness of the feature will help in determining the energy and the origin of the impactor. We don't see other bright features along the same...

The driver who took me from Aosta to Milan yesterday evening spoke no English, but he was an affable young man who had a love for fast cars. As we drove along a fine Alpine highway, a low red sports car moved fast us so quickly that I almost didn't see it. But suddenly the driver, who had said next to nothing thus far, erupted with "Italian car! Beautiful!" He stretched out the last word as if savoring the idea, then looked over at me making a thumbs up. Well, it was beautiful, and it was followed by two more similar cars making speeds I could only guess at. I wondered what it felt like to drive such a car, and how quickly it would get to Milan. One of the best things about wrapping up the Aosta conference, which we did with a farewell party yesterday afternoon, is that I head back to the States with a satchel full of papers. I've only been able to mention a few of them thus far, but next week I should have the chance to talk about them at more leisure. Here in Milan I have a few...

By Larry Klaes Apropos of yesterday's story on the possible cometary origin of the Tunguska Event in 1908, Tau Zero journalist Larry Klaes looks at the NExT (New Exploration of Tempel) mission, which gives us a second crack at observing comet Tempel 1. Ancient artifacts of the early Solar System, comets can tell us much about its earliest days, but as Larry points out, getting data out of the Deep Impact mission proved to be unexpectedly complicated. NExT is a useful re-purposing of an earlier mission that may unlock further cometary secrets when it returns to Tempel 1 in 2011. If a comet did cause Tunguska, here's hoping such events continue to be rare, but in the meantime, garnering all the information we can about how comets are made is as important for planetary security as it is for the study of Solar System origins. An Impact to Remember Late on the Fourth of July in 2005, while fireworks brightened the sky across the United States, another group of American citizens were...

Back in my flying days, I found myself becoming absorbed with meteorology, enough to wind up teaching the subject in various flight school settings. I was no expert, but looking for clues on flying conditions in the next few hours by studying cloud formation and movement was fascinating. In all that time, the one cloud phenomenon I always wanted to see but never did was the noctilucent cloud, an unusual, lovely formation made up of ice particles that occurs at extremely high altitudes. 'Noctilucent' means 'night-shining,' and that's just what these clouds do when they're illuminated by sunlight from below the horizon. Space Shuttle launches have been found to generate them as the vehicle pumps about 300 metric tons of water vapor into the thermosphere, the layer of atmosphere beginning at about ninety kilometers above the surface, just above the mesosphere. Photographs of such clouds show a unique beauty, though it's one that might also seem eerie, at least in certain settings. For...

Meteorites are in the news in two starkly different ways this week, but I'll lead with a story that has implications for how planetary systems like ours are born. Philipp Heck (University of Chicago) and colleagues have been analyzing interstellar grains from the Murchison meteorite, a large object that fell near the town of Murchison, Victoria in Australia in 1969. The Murchison grains are thought to have been blown into space by dying stars long before the formation of Earth. We'd like to know more about such grains because they became incorporated into the earliest solids forming in the Solar System, and hence offer a window into that era. Moreover, their composition helps us understand a bit more about their history. "The concentration of neon," says Heck, "produced during cosmic-ray irradiation, allows us to determine the time a grain has spent in interstellar space." Image: A fragment of the Murchison meteorite. Copyright New England Meteoritical Services, 2001. The...

None of us would have wanted to be around during the Late Heavy Bombardment, that frenetic bashing of our planet as the young Solar System worked out its debris problems between 4.1 and 3.8 billion years ago. The Hadean period was a time when enormous asteroids pummeled our world over a span lasting as long as 200 million years, an ongoing series of events one would have assumed lethal for whatever organisms may have evolved by then. But was the Late Heavy Bombardment really the deadly rain we've always assumed? A new paper in Nature questions the idea, basing its results on computer modeling of the Earth's heating during the bombardment. Oleg Abramov and Stephen J. Mojzsis (University of Colorado) argue that our planet's surface would likely have been sterilized during this period, but microbial life below the surface or in underwater conditions would almost certainly have survived. "Our new results point to the possibility life could have emerged about the same time that evidence...

Some scientific hypotheses seem too perfect to be anything but true. Long before we understood the processes behind plate tectonics, the natural fit between the coasts of Africa and South America made the notion of their original linkage seem obvious. Although dismissed in many quarters as mere coincidence, the piecing together of earlier continents would follow. The hypothesis of continental movement, whatever the cause, was almost too obvious not to be true. But does science really work so neatly? Writing about his work on the evident 'dinosaur killer' event at the Cretaceous/Tertiary boundary, Walter Alvarez once said: "Much of the work we do as scientists involves filling in the details about matters that are basically understood already, or applying standard techniques to new specific cases. But occasionally there is a question that offers an opportunity for a really major discovery." And the K/T impact seemed, like the continental coastlines, to be an obvious fit, a...

Diverting incoming asteroids is a high priority item, and so is a mission to a nearby asteroid for a close-up study of its composition and a shakeout of operating technologies. Think about the movie Deep Impact. Nukes are used to break up an incoming object, in this case a comet, but the resultant deadly chunks are still headed toward Earth. The planet suffers one disastrous collision, but it turns out to be survivable due to quick thinking and the willingness of a spacecraft crew to sacrifice themselves by blowing up the remaining impactor. Get past the Hollywood cliffhanger elements and Deep Impact had its moments (in any case, I'll sign off on any movie with Robert Duvall in it). The use of nuclear weapons in the movie does raise a legitimate question -- do we know enough about what might hit us to predict what would happen if we did try to destroy it this way? That's one reason we need early missions to study Earth-crossing asteroids, and it's also a reminder that keeping our...

Asteroid 2008 TC3 is surely a sign of progress. The eighty ton asteroid, which made a spectacle of itself upon entry into Earth's atmosphere on the morning of October 7, 2008, was the first space rock to have been observed before it collided with our planet. What we're hoping, of course, is that any future objects headed our way will be spotted early enough that, if their size warrants, they can be diverted or destroyed. It was thought that 2008 TC3 did a good job of destroying itself when it exploded some 37 kilometers above the Nubian desert, but two researchers recently traveled to the Sudan and, with help from students at the University of Khartoum, collected 280 pieces of asteroid over a 29-kilometer field. Peter Jenniskens (SETI Institute) calls the event "...an extraordinary opportunity, for the first time, to bring into the lab actual pieces of an asteroid we had seen in space." Jenniskens is lead author on the paper that now appears as the cover on the latest Nature. I...

I love it when we find uses for instruments that they were never intended for. In deep space terms, we can go back to Voyager 2, which carried a plasma wave instrument that was designed to measure the charged particles inside the magnetic fields of the gas giant planets it would pass. Voyager 2 was able to tell us much about dust impacts on a fast-moving spacecraft when it was realized that the plasma wave instrument would be able to sense the plasma created by vaporized particles. In other words, the instrument became a de facto dust detection device. Now I see that the two STEREO spacecraft may be pressed into service to study what's lurking in the L4 and L5 Lagrangian points, each 150 million kilometers from Earth, with L4 60 degrees in front of our planet and L5 60 degrees behind. Balancing the gravitational field of the Sun with that of Earth, the Lagrange points are interesting places, possibly a junkyard of debris from the early Solar System. It's known that such points appear...