Deep Space Radar Unveils Rotating Asteroid 2010 JL33

A radar image of asteroid 2010 JL33, generated from data taken by NASA's Goldstone Solar System Radar on Dec. 11 and 12, 2010. Image credit: NASA/JPL-Caltech

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Intriguing details about the physical properties and characteristics of a recently discovered asteroid have just been unveiled in amazing images obtained using a large radar dish in California. The radar dish serves as a key component of NASA’s Deep Space Network (DSN). The Near Earth asteroid, dubbed 2010 JL33, was imaged by radar on Dec. 11 and 12, 2010 at NASA’s Goldstone Solar System Radar in California’s Mojave Desert when a close approach to Earth offered an outstanding opportunity for high quality science.

Asteroids studies have taken on significantly increased importance at NASA ever since President Obama decided to cancel the Constellation ‘Return to the Moon’ program and redirect NASA’s next human spaceflight goal to journeying to an Asteroid by around 2025.

Update: Orbital diagram added below
A sequence of 36 amazingly detailed images has been assembled into a short movie (see below) by the science team at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif. The movie shows about 90 percent of one rotation.

The data gathered by radar revealed that the asteroid measures roughly 1.8 kilometers (1.1 miles) in diameter and rotates once every nine hours.

Orbital diagram of Asteroid 2010 JL33 shows location as of Jan 14, 2011. Credit: NASA
click to enlage all images

“Asteroid 2010 JL33 approached within 17 Earth-Moon distances [some 7 million km] in December 2010 and offered an outstanding opportunity to study it with radar,” said Lance Benner, a scientist at JPL who studies asteroids.

“To get detailed radar images, an asteroid must be close to Earth,” Benner told me, for Universe Today.

The object was only discovered on May 6 by the Mount Lemmon Survey in Arizona. The radar observations were led by a team headed by JPL scientist Marina Brozovic.

Video Caption: While safely passing Earth, NASA’s Goldstone Solar System Radar captured the rotation of asteroid 2010 JL33 — an irregular, elongated object roughly 1.8 kilometers (1.1) miles wide. The video consists of 36 frames.

“The radar images we got enabled us to estimate the asteroid’s size, rotation period, and to see features on its surface, most notably, the large concavity that appears as a dark region in the collage,” Benner elaborated.

“It was discovered so recently that little else is known about it.”

The object was revealed to be elongated and irregularly shaped.

70-meter diameter NASA Deep Space Network (DSN) antenna at Goldstone, California.

The 70-meter (230-foot) diameter antenna is the largest, and therefore most sensitive, DSN antenna, and is capable of tracking a spacecraft travelling more than 16 billion kilometers (10 billion miles) from Earth.
The surface of the 70-meter reflector must remain accurate within a fraction of the signal wavelength, meaning that the precision across the 3,850-square-meter (41,400 sq. ft.) surface is maintained within one centimeter (0.4 in.). Credit: NASA


The large concavity is clearly visible in the images and may be an impact crater. It took about 56 seconds for the radio signals from the 70-meter (230-foot) diameter Goldstone radar dish to make the roundtrip from Earth to the asteroid and back to Earth again.

“When we get deeper into our analysis of the data, we will use the images to estimate the three-dimensional shape of the asteroid as well,” Benner added.

Benner belongs to a team that is part of a long-term NASA program to study asteroid physical properties and to improve asteroid orbits using radar telescopes at Goldstone and also at the Arecibo Observatory in Puerto Rico. The 1,000-foot-diameter (305 meters) Arecibo radar dish antenna is operated by the National Science Foundation.

“Each close approach by an asteroid provides an important opportunity to study it, so we try to exploit as many such opportunities as possible to investigate the physical properties of many asteroids. In the bigger picture, this helps us understand how the asteroids formed,” Benner told me.

“Asteroid 2010 JL33 is in an elongated orbit about the Sun. On average, it’s about 2.7 times farther from the Sun than the Earth is, but its distance from the Sun varies from 0.7 to 4.6 times that of the Earth.” That takes the asteroid nearly out to Jupiter at Aphelion. It takes about 4.3 years to complete one orbit around the sun.

But, there’s no need to fret about disaster scenarios. “The probability of impact with Earth is effectively zero for the foreseeable future,” Benner explained.

“On rare occasions it approaches closely to Vesta,” he said. Vesta is the second most massive asteroid and will be visited for the first time by NASA’s Dawn spacecraft later this year.

In addition to the ground based radar imaging, the tiny space rock was investigated by an Earth orbiting telescope.

“This asteroid was also studied by NASA’s Wide-field Infrared Survey Explorer (WISE) spacecraft,” according to Benner. “Our observations will help WISE scientists calibrate their results because we provided an independent means to estimate the size of this object.”

More at this JPL press release. The NASA-JPL Near-Earth Object Program website has an interactive map that allows you to see the asteroid’s position at any time you desire. Go to here

To see the trajectory of any other near-Earth asteroid, go to here

For more information about asteroid radar research, go to here

Information about the Deep Space Network is here

Did GD61 Eat a Planetessimal?

Dusty debris around an old white dwarf star (NASA)

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The primary method by which astronomers hope to study exoplanet atmospheres is by detecting their absorption spectra as they transit their parent stars. However, another way would be to detect the signal of the atmospheric components in the atmosphere of a star that recently cannibalized a planet or other large body. White dwarfs offer an excellent class of stars on which to use this method since convection will pull heavy elements down more rapidly, leaving surfaces with near pristine hydrogen and helium photospheres. The presence of other elements would indicate recent accretion. This method has been used on several white dwarfs previously, but a new study reexamines data from a 2008 paper, adding their own data on the white dwarf GD61 to propose that the star isn’t just eating dust and small bodies, but a sizable one, likely containing water.

Data for the project were taken in 2009 using the SPITZER telescope. One of the first clues to the presence of a recent case of cannibalism was the presence of warm dust within the Roche limit of the star. This disc did not extend more than 26 stellar radii from the star, leading the team to suspect that this was not simply a large scale disc feeding the star with rocky materials, but an object that had fallen inwards to be tidally torn apart.

To support this, the new team used the Keck I telescope on Mauna Kea with the HIRES spectograph to analyze the spectrum. The findings from this confirmed the previous study that, in order of decreasing abundance, the star contained helium, hydrogen, oxygen, silicon, and iron. Based on the amount of material present in the spectrum and estimated convection rates for such stars, the team concluded that, if the disc were created by a single body, it would have been an asteroid at least 100 km in diameter. So why should the team expect that it was a single body as opposed to many smaller ones?

The key lies in the relative amount of detected elements. For GD61, oxygen was the most abundant element not typically present in white dwarf atmospheres. In fact, its presence far outweighed the other elements such that, even if all of it had been previously bound to the silicon, iron, carbon, and other trace elements, there would still be an inexplicable excess. This oxygen would necessarily have been combined into some molecule or have dissipated during the red giant phase. The only way the team could account for its presence would be to have it wrapped up in water (H2O) which, after disassociation, would allow the hydrogen to blend in the the expected hydrogen already present. Since water readily sublimates without sufficient pressures, the team notes that a large number of small bodies would be unable to bury the water deep enough to keep it from escaping previously, that the best explanation would be a large body which could shield water inside it during the previous red giant phase.

The evidence of water rich asteroids speaks to the formation of our own solar system because it provides a delivery mechanism for water to our planet beyond direct accretion. Water rich asteroids and comets would likely have supplemented our supply. Indeed, Ceres, the largest known asteroid in our solar system, is suspected to harbor as much as 25% of its mass in water.

Asteroid Scheila Sprouts a Tail and Coma

(596) Scheila, the asteroid with a tail. Image credit: Peter Lake

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When is an asteroid not an asteroid? When it turns out to be a comet, of course. Has this ever happened before? Why, yes it has. In fact it was just announced December 12, 2010 that the asteroid (596) Scheila has sprouted a tail and coma! This is likely a comet that has been masquerading as an asteroid.

Taken from New Mexico Skies between 8h15m and 11h45m UT. The image is a stack of 10 x 600 sec exposures using a 20 inch RCOS and STL11K camera. Scale is 0.91 asec/px.. Image courtesy of Joseph Brimacombe

See an animation by Joseph Brimacombe at this link.

Steve Larson of the Lunar and Planetary Laboratory (LPL), University of Arizona first reported that images of the minor planet (596) Scheila taken on December 11th showed the object to be in outburst, with a comet-like appearance and an increase in brightness from magnitude 14.5 to 13.4. The cometary appearance of the object was confirmed by several other observers within hours.

A quick check of archived Catalina images of Scheila from October 18, November 2 and November 11 showed Scheila to look star-like, which is what asteroids look like from Earth. They just happen to be moving across the field of view in contrast to the fixed background stars. The image taken by Catalina on December 3rd shows some slight diffuseness and an increase in overall brightness. So, it appears this event began on or around December 3rd.

Upon hearing the news, there was some speculation that this might be evidence of an impact event. Had something crashed into asteroid Scheila? It seems unlikely, and this is a story we have heard before.

The asteroid discovered in 1979 and named 1979 OW7 was lost to astronomers for years and then recovered in 1996. It was subsequently renamed 1996 N2. That same year it was discovered to have a comet-like appearance, and many believed this was the signature of an impact between two asteroids. After years of inactivity 1996 N2 sprouted a tail again in 2002. One collision between two asteroids was unlikely enough. The odds of it happening again to the same object were essentially zero. What we had was a comet masquerading as an asteroid. This object is now known by its cometary name 133P/Elst-Pizarro, named after the two astronomers who discovered its initial cometary outburst.

The 2002 outburst and the discovery of more active asteroids showing mass-loss led to a paper (Hsieh and Jewitt 2006, Science, 312, 561-563) introducing an entirely new class of solar system objects, Main Belt Comets (MBC). MBCs look like comets because they show comae and have tails but they have orbits inside Jupiter’s orbit like main belt asteroids.

The most likely cause of the mass loss activity in MBCs is sublimation of water ice as the surface of the MBC is heated by the Sun. This is suggested most strongly by the behavior of the best-studied example, namely 133P/Elst-Pizarro. Its activity is recurrent, and it is strongest near and after perihelion, the point in its orbit nearest the Sun, like other comets.

MBCs are interesting to astronomers because they appear to be a third reservoir of comets in our solar system, distinct from the Oort cloud and Kuiper belt. Since we know of no way for these other reservoirs to have deposited comets in the inner solar system, the ice in MBCs probably has a different history than the ice in the outer comets. This allows researchers to study the differences in the Sun’s proto-planetary disk at three separate locations. This might lead to information on the Earth’s oceans, one of the continuing lines of investigation by solar system scientists.

Now it seems we have another MBC to add to the sample. And Scheila will probably be getting a new name soon. Asteroid (596) Scheila was discovered Feb. 21, 1906, by A. Kopff at Heidelberg. The 113Km in diameter ‘asteroid’ was named after an acquaintance, an English student at Heidelberg. In the future it will be called XXXP/Lawson or something similar, and Kopff’s Scheila will become just another footnote in the history of astronomical nomenclature.

Venus Has a Moon?

Venusian quasi-satellite 2002 VE68. Illustration: NASA/JPL/Caltech

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Astronomers have been busy trying to determine the spin period and composition of Venus’ moon. December 8, 2010, results were announced by JPL/Caltech scientists, led by Michael Hicks.

“Wait a minute; back up”, I hear you ask. “Venus has a Moon?”
Of course it does. Well, kind of…
Let me explain.

It has the rather unfortunate name of 2002 VE68. That is because it was discovered on November 11, 2002 by LONEOS, the Lowell Observatory Near Earth Object Search. 2002 VE68 is an earth orbit-crossing asteroid that has been designated a Potential Hazardous Asteroid by the Minor Planet Center. For obvious reasons, this makes it a very interesting subject of study for JPL scientists.

2002 VE68 used to be a run of the mill, potential impact threat, Near Earth Object. But approximately 7000 years ago it had a close encounter with Earth that kicked it into a new orbit. It now occupies a place in orbit around the Sun where at its closest it wanders inside the orbit of Mercury and at its furthest it reaches just outside the orbit of the Earth. It is now in a 1:1 orbital resonance with Venus.

An orbital resonance is when two orbiting bodies exert a regular, periodic gravitational influence on each other due to their orbital periods being related by a ratio of two small numbers. For example, Pluto and Neptune are in an orbital resonance of 2:3, which simply means for every two times Pluto goes around the Sun, Neptune makes three trips around.

In the case of Venus and 2002 VE68, they both take the same time to orbit the Sun once. They are in a 1:1 orbital resonance. So by definition, 2002 VE68 is considered a quasi-satellite of Venus. If you watch the Orbital Viewer applet at the JPL small body page you can watch this celestial dance as the two bodies orbit the Sun and each other as 2002 VE68 dodges Earth and Mercury in the process.

Often these resonances result in an unstable interaction, in which the bodies exchange momentum and shift orbits until the resonance no longer exists. In this case, scientists believe 2002 VE68 will only remain a Venusian quasi-satellite for another 500 years or so.

So getting back to the story, Hicks and his team used the recent close apparition of 2002 VE68 to do photometric measurements over the course of three nights in November using the JPL Table Mountain 0.6m telescope near Wrightwood, California. From the color data they obtained they determined that 2002 VE68 is an X type asteroid. This is a group of asteroids with very similar spectra that could potentially have a variety of compositions. They are further broken down into Tholen classification types as either E, M or P types. Unfortunately Hicks’ team was not able to resolve the sub-classification with their equipment.

They were able to determine the approximate size of the asteroid to be 200 meters in diameter, based on its absolute magnitude, and they determined a spin rate of 13.5 hours. The amplitude of the fluctuation on the light curve of 2002 VE68 could imply hat it is actually a contact binary, two clumps of asteroidal material orbiting a center of mass in contact with each other.

For more information on some of the strange and curious beasts in the asteroidal zoo, visit the NASA Near Earth Object Program website.

Confirmed: Hayabusa Nabbed Asteroid Particles

An electron micrograph image of the edge of a special Teflon spatula that scraped the interior surfaces of Hayabusa's sample return capsule. Credit: JAXA

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The Japan Aerospace Exploration Agency (JAXA) has confirmed that the tiny particles inside the Hayabusa spacecraft’s sample return container are in fact from the asteroid Itokawa. Scientists examined the particles to determine if the probe successfully captured and brought back anything from the asteroid, and in a press release said “about 1,500 grains were identified as rocky particles, and most were determined to be of extraterrestrial origin, and definitely from Asteroid Itokawa.”

These are the first samples from an asteroid ever returned to Earth; the only other extraterrestrial samples brought back to Earth came from the Apollo missions to the Moon. See correction, below.

Previously, JAXA said that although particles were inside the container, it wasn’t clear if they were from the asteroid or if they could be of terrestrial origin (dust from Earth that could have been inside the container).

The particles samples were collected from the chamber by a specially shaped Teflon spatula and examined with a scanning electron microscope. There were two chambers inside the container, and from the press release (in Japanese) it appears all the particles were found in one chamber, Chamber A.

Most of the particles are extremely small, about 10 microns in size and require special handling and equipment. Unfortunately they aren’t the “peanut-sized” chunks of rock that the mission originally hoped to capture. This will make analyzing the particles difficult, but not impossible.

Hayabusa's sample return cannister and parachute on the ground in the Australian outback. Credit: JAXA

During the seven-year round trip journey, Hayabusa arrived at Itokawa in November, 2005. The mechanism that was intended to capture the samples apparently failed, but scientists were hopeful that at least some dust had made its way into the return canister. After a circuitous and troubled-filled return trip home, the sample return capsule was ejected and landed in Australia in June of this year.

Here are the other successful sample return missions:
Apollo Moon missions (1969-1972)
Soviet Union’s Luna 16 (1970) returned 101 grams of lunar soil
Luna 20 (1974) returned 30 grams
Luna 24 (1976) returned 170.1 grams.
The Orbital Debris Collection (ODC) experiment, deployed on the Mir space station for 18 months during 1996–1997, used aerogel to capture interplanetary dust particles in orbit.
Genesis (2001-2004) captured and returned molecules collected from the solar wind. It crashed in the Utah desert, but samples were able to be retreived.
Stardust (1999-2006) collected particles from the tail of a comet, as well as a few interstellar dust grains.

Source: JAXA

Calculate the Effect of an Asteroid Impact on Earth

Impact Earth website

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A 20-km asteroid has just been predicted to hit Earth and you want to know if a. You should run for it, b. You should call Bruce Willis, or c. You can rest easy because your part of the world won’t be affected. All you have to do is input the parameters of the asteroid on the recently updated “Impact Earth” website, and you’ll find out everything about what an impactor will do to Earth, including an estimate of the size of the crater, how far away you’ll need to be in order to avoid being affected by the impact (and if that is possible), tsunami wave height, and other details of the subsequent disaster. The fun part is, you can simulate the destruction of Earth multiple times, without hurting anyone.

The original Impact Earth website was created in 2002 for use by NASA and homeland security. The new version, built in a collaboration between Purdue University and Imperial College London, is more user-friendly for the general public, as well as providing more visual details of an impact. Besides being rather fun to play around with, the website is highly educational about what a various sized impacts would do Earth, depending on if it hit ground or water.

Go play around with it.

Mitigating Asteroid Threats Will Take Global Action

Computer generated simulation of an asteroid strike on the Earth. Credit: Don Davis/AFP/Getty Images

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During the past 24 hours, the Earth has been hit by about a million small meteoroids – most of which burned up in the atmosphere as shooting stars. This happens every day. And occasionally – once every 10,000 years or so — a really big asteroid (1 km in diameter or larger) comes along and smacks Earth with an extinction-level impact. That idea might cause some of us to lose some sleep. But in between are other asteroid hits that occur every 200-300 years where a medium-sized chunk of space rock intersects with Earth’s orbit, producing a Tunguska-like event, or worse.

“Those are the objects we are concerned with,” said former Apollo astronaut Rusty Schweickart, speaking at a 3-day workshop in Darmstadt, Germany which focused on plans and recommendations for global coordination and response to an asteroid threat. “We need to take action now to bring the world together and recognize this as a global threat so that we can make a cooperative international decision to act to extend the survival of life on Earth.”

There are likely about one million Near Earth Objects out there that could do substantial damage if one hit the Earth. This isn’t anything new – Earth has been in this same environment for billions years.

“What’s new is that we have now opened our eyes via telescopes and are seeing something flying by our heads, so to speak,” said Schweickart during a media event at the workshop. “When you see something flying by your head, you duck. It turns out we have the capability of ducking and causing these objects to miss us. Because we now know about this threat and because we can in fact prevent an impact, we then have a moral obligation to do so.”

Former astronaut Tom Jones, who also attended the workshop, told Universe Today that NASA hopes to find all the 500 meter objects within a few decades, “and thus through action be able to prevent an impact from that large an object, removing it from the overall asteroid hazard. Smaller objects are much more numerous (the approximately million NEOs mentioned above) and can cause city-size damage. We’ll have to search diligently for those in the coming decade and it’ll be several decades before we find those hundreds of thousands of 30-meter sized -subTunguskas.”

Schweickart discussed in a recent Universe Today article that we do possess the technology to move asteroids or change their orbits, and that this technology does need to be tested, and tested soon. But since an impact event could affect the entire world, the decisions on policies and international agreements about asteroid mitigation could actually pose a bigger challenge in dealing with an asteroid threat than putting the technology together.

“Bureaucracy is the most likely reason we will be hit with an asteroid in the future, not the technology,” said Schweickart. “That is an audacious statement to make, but if we can get past that and do our jobs right we should never be hit in the future by an asteroid that could threaten life on Earth. And it’s going to be a heck of a challenge.”

The Mission Planning and Operations Group (MPOG) workshop included astronauts and space scientists and was the latest in a series of workshop designed to offer suggestions to the UN Committee on the Peaceful Uses of Outer Space. Included were representatives from NASA, ESA, the Secure World Foundation and the Association of Space Explorers. They are working on defining future planning tasks and studies for the Group that will later be merged with findings of other experts to create a final report to the UN committee. This report will recommend how to react to an impact threat.

But there are issues such as, how changing an asteroid’s orbit could make it miss one area on Earth and instead hit another area.

“The issue of NEOs is an issue that the United nations has been considering for 10 years or so,” said Sergio Camacho, representing the UN Committee. “The reason it has to go through the UN is that when we make a decision, whatever action is taken might affect others and put them at risk where they are not at risk at the beginning. That can’t be a unilateral decision, and we need to pool the resources of space agencies in order to address the problem. It will be within the framework of the UN that we will be able to master this cooperation.”

Schweickart and the Association of Space Explorers, have been working on this issue for over 9 years and are just now beginning to see a little headway in the bureaucratic process. Everyone at the workshop agreed that political decisions and political awareness is something that has to be taken seriously.

“Two weeks ago a small object passed in between the Earth and the Moon,” said Schweickart,“ and on Halloween an object half a kilometer in diameter Is going to pass within five lunar distances of Earth — in terms of astronomical distances, that is very close. These things are happening, but I hope we areable to act soon and act responsibly without having to have a reminder” – meaning the wake-up call of an actual impact and not being prepared for it.

For more information:

The MPOG workshop (where you can watch the press conference)

Association of Space Explorers,

Graphic Shows Biggest and Closest Near Earth Objects (and it’s not scary)

Near Earth Objects graphic, created by Zachary Vabolis. Used by permission.

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Just for fun, graphic design student Zachary Vabolis created this fantastic graphic showing the closest and biggest Near Earth Objects. However, Vabolis wants to make clear that the information represented here is not meant to portray that the end of the world is nigh. His image has appeared on several websites recently, and some of the headlines have included words such as “doomsday,” etc. But, that’s not what he intended.

“I’m not sure if anyone who has seen my graphic is reading more into it than I intended,” Vabolis told Universe Today, “but I wanted to state that I did not create this graphic to scare people. In fact if you look at the information it contains, Earth has almost no chance of being hit by any of the asteroids listed and NASA even mentions that as well on their website.”

Vabolis said he created the graphic because he really enjoys creating projects outside of his curriculum to help hone his skills, plus it is just a fun pastime for him. “I’ve always been fascinated by outer space so I wanted to do a graphic within that subject,” Vabolis said in an email. “I came up with the Near Earth Objects topic because it’s a fairly current subject and after doing a little research I found that no one else had created such a graphic yet.”

The graphic was created using the information on NASA’s Near Earth Object Fact Sheet website, which states, “There are no known NEO’s on a collision course with the Earth. There is a possibility that an as yet undiscovered large NEO may hit the Earth, but the probability of this happening over the next 100 years is extremely small.”

So breathe easy and enjoy learning more about NEO’s from Vabolis’ graphic. You can see more of his work at his page on Behance.

How to Deflect an Asteroid with Today’s Technology

Artist concept of a space tug. Credit: NASA

Apollo 9 astronaut Rusty Schweickart is among an international group of people championing the need for the human race to prepare for what will certainly happen one day: an asteroid threat to Earth. In an article on Universe Today published yesterday, Schweickart said the technology is available today to send a mission to an asteroid in an attempt to move it, or change its orbit so that an asteroid that threatens to hit Earth will pass by harmlessly. What would such a mission entail?

In a phone interview, Schweickart described two types of “deflection campaigns” for a threatening asteroid: a kinetic impact would roughly “push” the asteroid into a different orbit, and a gravity tractor would “tug slowly” on the asteroid to precisely “trim” the resultant change course by using nothing more than the gravitational attraction between the two bodies. Together these two methods comprise a deflection campaign.

Artist Impression of Deep Impact - Credit: NASA

“In a way, the kinetic impact was demonstrated by the Deep Impact mission back in 2005,” said Schweickart. “But that was a very big target and a small impactor that had relatively no effect on the comet. So, we haven’t really demonstrated the capability to have the guidance necessary to deflect a moderately sized asteroid.”

Most important, the gravity tractor spacecraft would arrive prior to the kinetic impactor, precisely determine the asteroid’s orbit and observe the kinetic impact to determine its effectiveness. Following the kinetic impact it would then determine whether or not any adjustment trim were required.

“You want to know what happens when you do a kinetic impact, so you want an ‘observer’ spacecraft up there as well,” Schweickart explained. “You don’t do a kinetic impact without an observation, because the impactor destroys itself in the process and without the observer you wouldn’t know what happened except by tracking the object over time, which is not the best way to find out whether you got the job done.”

So, 10-15 years ahead of an impact threat — or 50 years if you have that much time — an observer spacecraft is sent up. “This, in fact, would also be a gravity tractor,” Schweickart said. “It doesn’t have to be real big, but bigger gets the job done a little faster. The feature you are interested in the outset is not the gravity tractor but the transponder that flies in formation with the asteroid and you track the NEO, and back on Earth we can know exactly where it is.”

Schweickart said even from ground tracking, we couldn’t get as precise an orbit determination of an NEO as we could by sending a spacecraft to the object. Additionally, generally speaking, we may not know when we send an observer spacecraft what action will be required; whether an impact will be required or if we could rely on the gravity tractor. “You may launch at the latest possible time, but at that time the probability of impact may be 1 in 5 or 1 or 2,” Schweickart said. “So the first thing you are going to do with the observer spacecraft is make a precise orbit determination and now you’re going to know if it really will impact Earth and even perhaps where it will impact.”

Artist concept of an impactor heading towards an asteroid. Credit: ESA

After the precise orbit is known, the required action would be determined. “So now, if needed you launch a kinetic impactor and now you know what job has to be done,” Schweickart said. “As the impactor is getting ready to impact the asteroid, the observer spacecraft pulls back and images what is going on so you can confirm the impact was solid, –not a glancing blow — and then after impact is done, the observer spacecraft goes back in and makes another precision orbit determination so that you can confirm that you changed its velocity so that it no longer will hit the Earth.”

The second issue is, even if the NEO’s orbit has been changed so that it won’t hit Earth this time around, there’s the possibility that during its near miss it might go through what is called a “keyhole,” whereby Earth’s gravity would affect it just enough that it would make an impact during a subsequent encounter with Earth. This is a concern with the asteroid Apophis, which is projected to miss Earth in 2029, but depending on several factors, could pass through a keyhole causing it to return to hit Earth in 2036.

“So if it does go through that keyhole,” said Schweickart, “now you can use the gravity tractor capability of the spacecraft to make a small adjustment so that it goes between keyholes on that close approach. And now you have a complete verified deflection campaign.”

Schweickart said a Delta-sized rocket would be able to get a spacecraft to meet up with an asteroid. “A Delta rocket would work,” he said, “but if there is a more challenging orbit we might have to use something bigger, or we may have to use a gravity assist and do mission planning for type of thing which hasn’t been done yet. So we can get there, we can do it – but ultimately we will probably need a heavy lift vehicle.”
As for the spacecraft, we can use a design similar to vehicles that have already been sent into space.

“A gravity tractor could be like Deep Space 1 that launched in 1998,” Schweickart said. “ You can make any spacecraft into a gravity tractor fairly easily.”

Rusty Schweickart

But it hasn’t been demonstrated and Schweickart says we need to do so.

“We need to demonstrate it because we – NASA, the technical community, the international community — need to learn what you find out when you do something for the first time,” he said. “Playing a concerto in front of an audience is quite different from playing it alone in your house.”

Video: Asteroid 2010 TD54 Whizzes Close to Earth

A 'movie' put together from images of the October 12, 2010 approach of asteroid 2010 TD54.Image credit: Patrick Wiggins, NASA/JPL Solar System Ambassador to Utah

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Amateur astronomer Patrick Wiggins from Utah (and fellow Solar System Ambassador) was able to capture images this morning of the newly found asteroid 2010 TD54 that whizzed by Earth — harmlessly — coming within about 46,000 km (less than 30,000 miles) of our planet. The small asteroid was only detected this past Saturday, and NASA’s Near Earth Object Office predicted there was only 1 in a million chance it would hit Earth, and was small enough that it wouldn’t survive a fiery trip through the atmosphere even if it was going to make crash head-on into Earth. Patrick put together a couple of “movies” from the images he captured. They show the asteroid whispering silently through the sky, although moving along fairly quickly at 17.37 km/s. Estimates are the asteroid is about 7.3 m wide, and contained the energy of about 22 kilotons if it would have come crashing through Earth’s atmosphere. For this animation, the mount was set to allow the target to pass through the field of view, and includes 16 five-second exposures shot between 08:51:51 and 08:54:04 UTC.

There’s an additional image below.

In this animation, asteroid 2010 TD54 appears stationary as the stars move. Image credit: Patrick Wiggins, NASA/JPL Solar System Ambassador to Utah

For this set of images, Patrick set the mount set to nearly follow the target. The animation includes 23 five- second exposures shot between 09:01:27 and 09:04:39 UTC.

Patrick uses a Paramount ME, Celestron C-14 operating at f/5.5, SBIG ST-10 binned 3×3 with clear filter. The field of view in this image is about 18×26 arc minutes.

“The target was rotating quickly during both sequences which is “reflected” (pun intended) by its rapidly changing brightness,” Patrick wrote on a news group webpage for asteroid and comet researchers.

Great work! And Universe Today thanks Patrick for allowing us to post his images/animations.

While most people are breathing a sigh of relief that this asteroid didn’t hit Earth, others are of the opinion this near miss was a missed opportunity. “The message here should be: It was a pity that TD54 *missed* Earth because it would have made a nice fireball and meteorite shower!” said astronomer and writer Daniel Fischer, who writes the Cosmos4U blog.

Other astronomers and meteorite buffs said this asteroid could have ended up like the famous 2008 TC3, the first asteroid to have been spotted before hitting Earth, which crashed in northern Sudan, providing a treasure trove of information about asteroids and the early solar system in a very handy “sample return.”