Asteroids | Universe Today

A prototype telescope with an enhanced ability to find moving objects will soon be operational, and its mission will be to detect asteroids and comets that could someday pose a threat to Earth. The system is called Pan-STARRS (for Panoramic Survey Telescope and Rapid Response System) located on Haleakala mountain in Maui,Hawaii, and is the first of four telescopes that will be housed together in one dome. Pan-STARRS will feature the world's largest and most advanced digital camera, providing more than a fivefold improvement in the ability to detect Near Earth Asteroids and comets. "This is a truly giant instrument," said University of Hawaii astronomer John Tonry, who led the team developing the new 1.4-gigapixel camera. "We get an image that is 38,000 by 38,000 pixels in size, or about 200 times larger than you get in a high-end consumer digital camera." The Pan-STARRS camera will cover an area of sky six times the width of the full moon and it can detect stars 10 million times fainter than those visible to the naked eye.
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Ever since our recent encounter with asteroid 2008 TC3 — the first asteroid that was correctly predicted to hit our planet — I've had impact craters on the brain. Earth has about 175 known impact craters, but surely our planet has endured more bashing than that in its history. All the other terrestrial planets and moons in our solar system are covered by impact craters. Just look at our Moon through a telescope or binoculars, or check out the recent images of Mercury sent back by the MESSENGER spacecraft, or pictures of Mars from the armada of spacecraft orbiting the Red Planet, and you'll see that impact craters are the most common landforms in our solar system. But since two-thirds of Earth is covered by water, any asteroid impacts occurring in the oceans are difficult to find. And even though Earth's atmosphere protects us from smaller asteroids, just like in the case of 2008 TC3, which broke up high in the atmosphere, weathering, erosion and the tectonic cycling of Earth's crust have erased much of the evidence of Earth's early bombardment by asteroids and comets. Most of Earth's impact craters have been discovered since the dawn of the space age, from satellite imaging. In fact, a geologist recently discovered an impact crater using Google Earth! Here's my list of Earth's Ten Most Impressive Impact Craters, starting with #1. the largest and oldest known impact crater, Vredefort Crater, shown above, located in South Africa. It is approximately 250 kilometers in diameter and is thought to to be about two billion years old. The Vredefort Dome can be seen in this satellite image as a roughly circular pattern. What an impact that must have been!
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A month after asteroid 2008 TC3 hit the Earth's atmosphere, the first ground-based image of the event has surfaced on the Internet. Admittedly, it's not the fireball everyone has been waiting to see, but it is visual evidence that something hit us above Sudan on October 7th. The image above was taken from a frame of video that was being recorded by Mr. Mohamed Elhassan Abdelatif Mahir in the dawn following the asteroid impact with the atmosphere. The smoky feature is the remnant of the fireball as the 3 meter-wide asteroid blasted through the upper atmosphere, eventually exploding. The long-lasting persistent train is seen hanging in the air, high altitude winds causing it to twist in the morning sunlight.

We may not have a dazzling fireball re-entry video of 2008 TC3, but this striking image provides the first ground-based evidence of the direct hit, and may help refine the search for any meteorites from the disintegrated asteroid…
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Was there a third Martian moon orbiting the planet? Did Phobos and Deimos have a triplet sibling? According to the discovery of two elliptical impact craters, there might just have been another moon, but it ploughed into the Red Planet's surface a long time ago. The moonlet would have been approximately 1.5 km wide (0.9 miles), and it will have succumbed to the Mars gravity, entering the atmosphere at a shallow angle. As it tumbled through the atmosphere it broke in two, hitting the surface and creating two elongated impact craters, near-perfectly aligned.

It is thought that the "third moon" of Mars dropped from orbit a billion years ago and the same will happen with Phobos in a few million years. However, there might be another explanation, with no third moonlet in sight…
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One of the big news items last week was the prediction that an asteroid was on a collision course with Earth. Although it was a small space rock – estimates ranged from 1-5 meters (3-15 feet), scientists were excited because this was the first time an asteroid was discovered with an imminent known impact. Granted, we'd all probably feel a little safer if we knew about this asteroid, named 2008 TC3, days or months ahead of time instead of only 19 hours, but it’s a step in the right direction. Astronomers even predicted correctly the asteroid would come through the atmosphere over Africa. So with this prediction, many were hoping someone with a camera would be watching the skies of Sudan. But the flight path of the object was over a remote area and so far the only ground-based image that has surfaced is the one shown here, taken by a webcam from a beach in Egypt. (The words on the image indicate the objects on the beach — which were illuminated by the fairly distant explosion low on the horizon. try to find the tiny bright spot in the center of the image — that's the asteroid.) But we do have satellites constantly monitoring Earth's atmosphere and a few of them captured images and data about 2008 TC3. However, it's not known if any parts of the meteoroid hit the ground.
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Looking for a little excitement tonight? An asteroid between 1-5 meters (3-15 feet) was discovered just hours ago at an Arizona observatory, and might provide a spectacular light show as it comes through Earth's atmosphere. But don't be alarmed – scientists predict it will be harmless and burn up before it reaches the ground. It is expected to be visible over eastern Africa, at approximately 2:46 a.m. Greenwich Mean Time (10:46 p.m. Eastern time ). There is no danger to people or property since the asteroid will not reach the ground. It will burn up in the upper atmosphere, well above aircraft heights. A brilliant fireball will be visible as a result. "We want to stress that this object is not a threat," said Dr. Timothy Spahr, director of the International Astronomical Union's Minor Planet Center. "We're excited since this is the first time we have issued a prediction that an object will enter Earth's atmosphere," Spahr added. Odds are between 99.8 and 100 percent that the object will encounter Earth, according to calculations provided by Andrea Milani of the University of Pisa.
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Meteorites and asteroids from the inner solar system could be responsible for Earth's store of precious metals such as platinum and iridium, brought to our nascent planet during the period of Late Heavy Bombardment, about 4,000 million years ago. Dr. Gerhard Schmidt from the University of Mainz, Germany, has calculated that about 160 metallic asteroids of about 20 kilometers in diameter would be sufficient to provide the concentrations of these metals, known as Highly Siderophile Elements (HSE), found in the Earth's crust. "A key issue for understanding the origin of planets is the knowledge of the abundances of HSE in the crust and mantle of the Earth, Mars and the Moon. We have found remarkably uniform abundance distributions of HSE in our samples of the Earth's upper crust. A comparison of these HSE values with meteorites strongly suggests that they have a cosmo-chemical source," said Schmidt.
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Well, I've just been accepted into an elite club of people with astronomical objects named after them. And no, my Mom didn't name a star after me. The asteroid hunting team of David Healy and Jeff Medkeff have collectively discovered 487 asteroids, and designated 62 of them. You might already recognize some of asteroid names: Philplait, Paulmyers, Rebeccawatson, and Derekcolanduno.

At the end of August I received an email from David Healy notifying me that I was a new member of the asteroid club.

Asteroid 158092 Frasercain was officially designated on August 21, 2008. You can see the full list of named asteroids here - scroll down to see Frasercain. And you can see its current position in the Solar System here.

Those of you who know Jeff Medkeff will know the sad part of this story. Jeff, aka "The Blue Collar Scientist", passed away on August 3rd from complications with liver cancer - he was 39. I've got to be honest and tell you that I didn't know Jeff. We clearly ran in similar circles, but it wasn't until Phil, Pamela and other people in the space blogging community informed me of his death that I found and read through his blog; I really wish I'd found it earlier.

If you haven't already, please visit the Blue Collar Scientist blog. And you can read a very moving blog entry fulfilling Jeff's last request.

So to Jeff and David, thank you very much for this incredible honour - I promise this won't go to my head… much.

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ESA's Rosetta spacecraft successfully flew by the asteroid 2867 Steins, coming within 800 km (500 miles) and gathering images and data on the irregularly shaped rock in space. "Steins looks like a diamond in the sky," said Uwe Keller, Principal Investigator for the OSIRIS imaging system on board the spacecraft. Watch a movie of the flyby here. Visible in the images are several small craters on the asteroid, and two huge ones. While the wide-angle camera worked perfectly during the flyby, the narrower and higher resolution camera switched itself off and into safe mode a few minutes before closest approach, but switched back on after a few hours. "The software switched off automatically," said Gerhard Schwehm, Rosetta mission manager. "The camera has some software limits and we'll analyze why this happened later."
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A frequent plot device in the old "Mission: Impossible" television show was the special masks the IMF team used so they could impersonate anyone. Viewers were often surprised to find out who ended up being an imposter. Similarly, astronomers and planetary scientists are considering that a fair amount of Near Earth Objects (NEOs) aren't what they appear: they could be comets impersonating asteroids. Paul Abell, from the Planetary Science Institute says between five and ten percent of NEOs could be comets that are being mistaken for asteroids, and Abell is working on ways to make unmasking them a mission that's possible.
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Time critical is approaching for the Rosetta spacecraft and it's flyby of the asteroid 2867 Steins. Closest approach is expected on September 5, at 20:58 CEST, (Central European Summer Time), 2:58 pm EDT (US Eastern Daylight Time). To help the public follow the flyby, the Rosetta team now has a blog available, and a timeline has also been posted. At the time of closest approach, Rosetta is planned to be 800 km from the asteroid, passing by at a speed of 8.6 km/s relative to Steins. Both Rosetta and Steins will be illuminated by the Sun, providing an excellent opportunity for science observations.
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Remember a competition we reported on back in April called "Move An Asteroid"? It was an international technical paper competition looking for unique and innovative concepts for how to deflect an asteroid or comet that might be on a collision course for Earth. The winners have been announced and first prize went to Australian PhD student Mary D'Souza who came up with quite a novel concept: wrap the asteroid with reflective sheeting. Such a coating may increase the asteroid’s reflectivity, enabling deflection by solar radiation pressure.
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ESA’s Rosetta spacecraft will make an historic encounter with asteroid (2867) Steins on September 5, 2008 at 20:58 CEST (Central European Summer Time), 2:58 pm EDT (US Eastern Daylight Time.) A few days ago, Rosetta conducted a successful trajectory correction maneuver using images from the spacecraft's cameras to calculate the asteroid's location, to optimize its trajectory for the fly-by. Rosetta will rendezvous with the asteroid while one its way to its primary mission, to visit comet 67/P Churyumov-Gerasimenko. At its closest approach to the asteroid, the spacecraft will be just 800 km from Steins.
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Astronomers studying ways to deal with incoming near-Earth asteroids (NEA) that might be on a collision course with our planet want to know in detail what these space rocks are made of. The better they "know the enemy" the better they can come up with ways to destroy or change the course of NEAs. Since we've only studied a couple of asteroids up close with spacecraft, the best way to learn more about the composition of asteroids should be fairly easy: just look at meteorites that fall to Earth, which are small chunks of asteroids. But in doing so, researchers discovered quite a huge discrepancy. The vast majority of asteroids that whiz by Earth are of a type that matches only a tiny fraction of the meteorites that most frequently hit our planet. This difference has had astronomer scratching their heads. But a team of researchers has now found what it believes is the answer to the puzzle. The smaller rocks that most often fall to Earth, it seems, come straight in from the main asteroid belt out between Mars and Jupiter, rather than from the near-Earth asteroid population.
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Since waking up in early July from a brief hibernation, the Rosetta space probe has passed yet another milestone on the long journey to its rendezvous with the comet 67/P Churyumov-Gerasimenko in 2014: it has begun tracking the asteroid (2867) Steins. The spacecraft will perform a close flyby of the asteroid on September 5th, 2008, and will spend the next month taking images and science data. Read more…

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The first thing that comes to mind when someone asks: "How do we deflect a near Earth asteroid?" is "Fire some nuclear missiles at it." However, this might not be the best course of action. Akin to opening a walnut with a sledgehammer, there might be a better, less messy option. This is what Apollo astronaut Rusty Schweickart thinks at least. Last year, NASA issued a report suggesting they were seriously considering a nuclear option should an asteroid threaten Earth. However, the ex-lunar module pilot believes this decision was manipulated by political pressure, possibly indicating the asteroid threat was being used to speed up nuclear proliferation in space…
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If you've ever held a real meteorite in your hand, you probably wanted to know, "Where has this rock been in space and where did it come from?" Until now, no one has been able to definitively establish where the majority of meteorites found on Earth came from because of the changes that occur in meteorites after they are ejected from the asteroids they were originally part of. The most common type of meteorite found on Earth, about 75% of those identified, are chondrites, stony bits of space rocks that didn't undergo any melting while out in space. Two astronomers say have determined that most of these meteorites come from the asteroid belt between Mars and Jupiter. Using the GEMINI telescope, they found that asteroids in that region are similar to chondrites found on Earth.
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A rare event has given astronomers a great view of a binary asteroid system. Tonight, asteroid 2008 BT18 passed 1.4 million miles from Earth, shining like a 13th magnitude star. Before July 7th, astronomers believed 2008 BT18 was "just another" near-Earth asteroid, but then the Arecibo radio telescope obtained a "delay-Doppler" image of the asteroid and found it in fact had a binary partner. Although binaries are fairly common in the Solar System, this was a rare opportunity for a ground-based telescope to capture such a clear view…
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Asteroids with moons, called binary asteroids, are fairly common in the solar system. But scientists haven't been able to figure out the dynamics of these asteroids, especially how the moons form. But a group of astronomers studying binary asteroids say the surprising answer is sunlight, which can increase or decrease the spin rate of an asteroid. The researchers also say that since there are a number of "double craters" on Earth – side-by side craters that appear to have formed at about the same time — these binary asteroids may have hit our planet in the past. The image above is of twin circular lakes in Quebec, Canada, formed by the impact of an asteroidal pair which slammed into the planet approximately 290 million years ago. Similar double craters also can be found on other planets, as well.
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About 13,000 years ago, woolly mammoths roamed the North American continent and the first known human society in that region, known as the Clovis civilization, lived there as well. But geologic and archeological evidence shows they both suddenly disappeared, and scientists have long debated the mystery of the mass extinction of both animals and humans about 12,900 years ago. At that time, climatic history suggests the Ice Age should have been drawing to a close, but instead rapid climate change initiated an additional 1,300 years of glacial conditions. But scientists couldn't agree on the cause of the sudden change in climate. However, about two years ago geophysicist Allen West proposed that an asteroid or comet exploded just above the earth’s surface at that time over modern-day Canada, sparking a massive shock wave and heat-generating event that set large parts of the northern hemisphere ablaze, setting the stage for the extinctions. Another scientist set out to prove West wrong, but ended up finding evidence to support the exploding asteroid/comet theory.
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Just yesterday (June 30th) was the 100-year anniversary of the Tunguska event, when a small piece of ice or rock exploded in the air near the Podkammenaya Tungus river in Siberia, flattening trees and scaring the heck out of people in the surrounding area. Thankfully, the blast didn't happen in a populated area and nobody was killed, but there are many more pieces of debris floating around out there in space. If we want to do something about an asteroid headed our way, or keep astronauts safe from space debris, knowing is half the battle. Thanks to a new microsatellite being built by the Canadian Space Agency, we will soon have a better map of the objects surrounding the Earth's orbit. Read more…

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Asteroid 10537 (1991 RY16) is a rarity. It is composed of basaltic rock (i.e. rock that cooled quickly after formation from a molten state) and appears to have evolved independently from the large asteroid Vesta. Vesta suffered a huge impact billions of years ago, and the debris from this collision litters the inner asteroid belt. These "Vestoids" make up the majority of the basaltic asteroids apart from three known isolated bodies including asteroid 1991 RY16. Scientists are therefore very interested to understand the evolution of 1991 RY16, possibly helping us understand the formation of the Solar System and why there aren't more basaltic asteroids out there…
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A British astronomer has discovered a strange spinning object. The fact that it is spinning in itself is not strange, but the speed it is doing so has raised some eyebrows. The near-Earth asteroid 2008 HJ has been spotted spinning at a rate of one rotation every 42.7 seconds, breaking the record for the fastest rotating natural object in the Solar System. It is so fast that it has been designated as a "super-fast rotator". What makes this discovery even more interesting was that it was spotted by an amateur astronomer when using the Australian Faulkes Telescope South observatory, operating it remotely over the Internet, in his Dorset home in the south of the UK…
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What would happen if we spot a Near-Earth Asteroid (NEO) heading straight for us? Assuming we had enough time, we might be able to pull together a group of brave astronauts (or oil drillers) and send them to the asteroid just in the nick of time to destroy it… oh hold on, that sounds like the storyline for a Hollywood blockbuster. Actually, NASA is planning a mission to an NEO, but not because it's aimed at us. An asteroid named 2000SG344 (which threatened the Earth in the year 2000) is being considered as the destination for the first manned asteroid mission. The asteroid astronauts will travel there, chasing the 28,000 mi/hr (45,000 km/hr) speeding body and then carry out experiments, living on it for up to two weeks. Why? To briefly establish a manned outpost, advancing science and technology toward the ultimate goal: Mars.
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There are just so many ways the Universe is out to get us. Astronomers have already considered the threat from our Sun's orbit around the center of the Milky Way. When our Sun rises up out of flat plane of the Milky Way, it appears we might be less protected from intergalactic radiation and cosmic rays. Well, it looks like passing through the middle of the galactic plane might have its own share of risks: an increased number of comets might be hurled towards the Earth because of gravitational interaction with the densest parts of our galaxy.
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