Asteroids Archives

January 10, 2008December 26, 2015 by Nancy Atkinson

Asteroid 2007 WD5 Won’t Hit Mars

Sorry to disappoint those of you hoping for some Martian fireworks the end of this month. NASA’s Near Earth Object (NEO) Program office has effectively ruled out the possibility of Asteroid 2007 WD5 impacting Mars. The probability of such an event has dropped dramatically, to approximately 0.01% or 1 in 10,000 odds of an impact. Observers also say the asteroid has no possibility of impact with either Mars or Earth anytime in the next century.

Recent tracking measurements of the asteroid from several Earth-based observatories have provided a significant reduction in the uncertainties of the asteroid’s position during its close approach to Mars on Jan. 30, 2008. The best estimates now have 2007 WD5 passing about 26,000 km (16,155 miles) from the planet’s center at approximately 12:00 UTC (4:00 am PST) on Jan. 30th. The NEO office at the Jet Propulsion Laboratory has 99.7% confidence that the pass should be no closer than 4000 km (2,485 miles) from Mars’ surface.

The 50 meter (164 feet) wide asteroid was discovered in late November of 2007 by astronomers at the University of Arizona as part of the Catalina Sky Survey. Other telescopes used to track the asteroid are the Kitt Peak telescope in Arizona, the Sloan Digital Sky Survey telescope in New Mexico, New Mexico Tech’s Magdalena Ridge Observatory, the Multi-Mirror Telescope in Arizona, the Mauna Kea telescope in Hawaii and the Calar Alto Observatory in Spain.

An impact on Mars by 2007 WD5 could have created a .8 km (1/2 mile) wide crater on the planet’s surface. Many scientists were excited by the prospect of such an event, one that could possibly be tracked by the many spacecraft orbiting and on the surface of the red planet.

NASA’s Spaceguard Survey continually searches for Near-Earth Asteroids such as 2007 WD5, and their goal is to discover 90% of those larger than 1 km in size. JPL’s NEO office says that goal should be met within the next few years. Each discovered asteroid is continually monitored for the possibility of impact on Earth.

Original News Source: Near Earth Object Program press release

December 28, 2007December 26, 2015 by Ian O'Neill

1-in-75 Chance Of Tunguska-Size Impact On Mars

A 164-foot (50 meter) wide asteroid will be crossing the orbit of Mars at the end of January 2008. Currently, there is a 1-in-75 chance of the “Mars Crosser” hitting the Red Planet, and if it does, the 30,000 mile per hour speeding mass would generate a three megaton explosion (approximately the size of the terrestrial Tunguska impact over Siberia in 1908) and create a crater half-a-mile wide somewhere north of Meridiani Planum. So, the Mars Rover Opportunity will get a ringside seat should this once-in-a-thousand-year event occur…

NASA’s Near-Earth Object Office at the Jet Propulsion Laboratory (JPL) in Pasadena, California reported this month that a known Near Earth Asteroid (NEO) will be crossing the path of Mars on January 30, 2008. This puts asteroid “2007 WD5” in a special group of asteroids: “Mars Crossers“. NASA’s Near Earth Object Observation Program (or “Spaceguard” program) is intended to track asteroids that come close to the orbit of Earth, but also provides data for any asteroids tracked near our planetary neighbors.

Scientists are both excited and concerned by the possibility of an impact on Mars. Whilst this is a once in a lifetime opportunity to observe an impact of this size on Mars (remember the excitement at Shoemaker-Levy hitting Jupiter in 1994?), this event would eject millions of tons of dust into the Mars atmosphere, interfering with the Mars Expedition Rovers, and hindering orbital imaging of the planet. The Phoenix mission (currently en-route) will undoubtedly be affected. Looking far into the future, this event could have serious consequences for manned exploration.

“Right now asteroid 2007 WD5 is about half-way between the Earth and Mars and closing the distance at a speed of about 27,900 miles per hour […] Over the next five weeks, we hope to gather more information from observatories so we can further refine the asteroid’s trajectory,” – Don Yeomans, manager of the NEO Office at JPL.

Although the odds are low, and the asteroid is expected to miss Mars by 30,000 km, asteroid hunters will be keeping a close eye on the progress of 2007 WD5 as it barrels closer and closer to the Red Planet and our robotic explorers.

Source: Near Earth Object Program

December 19, 2007December 26, 2015 by Fraser Cain

Bigger Risks from Smaller Asteroids?

When astronomers first made the connection between asteroid impacts and extinction events on Earth, it was kind of frightening. There are hundreds of thousands of those things out there zipping around! But dedicated asteroid hunters have located many of the largest planet smashers, and new programs are in the works to find the rest. But now it seems that even the smaller asteroids could be more destructive than previously believed.

Almost 100 years ago, something detonated in the atmosphere above Tunguska, Siberia, flatting the forest. Had it struck a populated area, the results would have been disastrous.

But now researchers have simulated the kind of spacerock that caused the Tunguska explosion. And here’s the bad news: it was probably a much smaller object than previously believed.

“The asteroid that caused the extensive damage was much smaller than we had thought,” says Sandia principal investigator Mark Boslough of the impact that occurred June 30, 1908. “That such a small object can do this kind of destruction suggests that smaller asteroids are something to consider. Their smaller size indicates such collisions are not as improbable as we had believed.”

Since smaller asteroids are more likely to hit the Earth than larger objects, we might want to get a little more concerned about the risks.

A new supercomputer simulation recreated the kind of fireball that could have caused the Tunguska explosion. They took into account how winds travel along the topography of the ground, and the health of the forest to see how easily the trees would be blown down.

What was originally believed to be a 10-20 megaton explosion was probably only 3-5 megatons. So it took a much smaller object to create the devastation in Tunguska.

The researchers didn’t actually suggest a new size for the object, estimating that sounds complicated. “It depends on the speed and whether it’s porous or nonpourous, icy or waterless, and other material characteristics.”

Original Source: Sandia News Release

November 13, 2007December 26, 2015 by Fraser Cain

Oops, That Isn’t an Asteroid, it’s Rosetta

Remember when I mentioned that ESA’s Rosetta was inbound to make a flyby of the Earth on November 13th? Well, another group of astronomers were watching this “unknown” object, and thought that it was actually an asteroid that was going to be making a close flyby of our planet. The astronomers realized their mistake, but not after an alert was sent out to the astronomical community. Oops.

The alert was sent out by the Minor Planet Center, a clearinghouse of asteroid information organized by the Smithsonian Astrophysical Observatory for the International Astronomical Union.

Astronomers had been tracking the approaching object, designated 2007 VN84. After many observations from astronomers around the world, they calculated that it would pass us by at a distance of 1.89 radii (from the middle of the Earth).

It would have been huge news, but Denis Denisenko from Moscow’s Space Research Institute (IKI) realized that its flight path perfectly matched the upcoming Rosetta flyby.

Here’s a link to an animation, captured by astronomers in Germany, of Rosetta inbound to the Earth.

And so, just to set the record straight, ESA’s Rosetta spacecraft made its flyby on Tuesday, November 13th at 20:57 GMT, passing just 5,301 km above the Pacific Ocean. This has given it the gravitational boost it needs to meet up with Comet Churyumov-Gerasimenko in 2014.

Original Source: MPEC Alert

October 29, 2007December 26, 2015 by Nicholos Wethington

Tunguska Meteoroid’s Cousins Found?

It’s a cosmic whodunit: a meteorite exploded in the air near a remote part of Russia called Tunguska in 1908, and the meteorite that caused the event all but disappeared. Where did it come from? Was it an asteroid or part of a comet? Astronomers have taken up the case, using mathematical simulations to track down the perpetrator. They even think they might even know a few of its siblings.

Tadeusz J. Jopek and his team at the Astronomical Observatory UAM in Poland â€“ in collaboration with the Observatoire de la CÃ´te d’Azur in France â€“ looked for the possible origins of the Tunguska meteor by essentially running the explosion backwards, and mathematically simulating where the parent object of the event would have been before the impact.

By taking the existing forensic evidence of the impact to estimate the velocity and impact angle of the Tunguska meteorite, the team was able to simulate the possible orbit and speed of the object before it hit the earth. In doing this, they created 3311 virtual “particles” as possible origins of the object.

They then analyzed the orbits of near-earth objects that lie in the most likely region for the past 20,000 years to find possible matches with their simulated particles. It is still unclear exactly where the Tunguska meteor came from, and there are over 130 suspects.

“We believe that TCB originated as the result of a breakup of a single body : a comet or an asteroid. In our study we concluded that it is more probable that it was an asteroid. We cannot point to which one; instead we have found several candidates for the Tunguska parent, and the asteroid 2000 WK63 is an example of it,” Dr. Tadeusz said.

This is a hard case to solve indeed, as there remains little physical evidence of the original object near Tunguska, and the only tools astronomers have to work with are mathematical and statistical simulations. The question still remains whether the parent was a comet or asteroid, and indeed if the near-earth object it came from has been discovered yet.

“Such statistical conclusion gives no absolute sure [sic] that one of the presently known asteroids was indeed the Tunguska cosmic body parent. Therefore it is possible that still, the real Tunguska parent body is undiscovered.” Dr. Tadeusz said.

Source: Earth, Moon, and Planets Journal

October 9, 2007December 26, 2015 by Fraser Cain

Undergrad Team Discovers 1,300 Asteroids

A team of undergrad astronomers at the University of Washington figured out how to turn an annoyance into a major discovery, uncovering 1,300 new asteroids; nearly 1 out of every 250 known objects in the Solar System. How did they pull of this feat? It was actually a side project to their actual research: searching for supernovae. The asteroids were getting in the way.

The undergrad researchers were looking through data gathered as part of the Sloan Digital Sky Survey. This is a collection of detailed images of the sky gathered by an automated 2.5-metre telescope. The researchers were looking for evidence of exploded stars, called supernovae, but asteroids kept getting in the way.

Instead of just working around the asteroids that were blocking their view, they decided to keep track of them, and see if any were unidentified. It turned out that 1,300 were brand new.

Andrew Becker, a UW research assistant professor in astronomy explains the initial frustrations, “I kept asking the students what they had found and they kept saying, ‘More asteroids. No supernovae, but lots of asteroids.'”

The undergrads developed programs that let them search through the Sloan data automatically, identifying asteroids, and helping them classify them. In addition to discovering 1,300 new asteroids, they compiled additional data on 14,000 asteroids that were already known. This allows astronomers to calculate their trajectories with better accuracy, and determine if any are a threat to the Earth in the future.

Original Source: UW News Release

September 27, 2007December 26, 2015 by Fraser Cain

Dawn is Gone

The big day arrived, and nothing could keep that spacecraft on the ground. At 7:34 am EDT NASA’s Dawn spacecraft was lofted into space atop a Boeing Delta 2 rocket, beginning a 3 billion km (1.7 billion mile) journey to meet with two different large asteroids. If all goes well, the spacecraft will make its first encounter with Vesta in October, 2011, and then Ceres in February, 2015.

I know I say this about every mission, but this one, this mission is currently my favourite. In just a few years, a spacecraft is going to orbit an entirely unvisited asteroid, and then just a few years later, it’s going to do it again. It’ll all be so new, I can’t wait. They were once two asteroids, but now Ceres has been reclassified as a dwarf planet, along with Pluto in 2006.

Dawn will serve as a time machine, helping astronomers look back 4.6 billion years to the earliest times in our Solar System’s history. Although they’re both in the asteroid belt, between the orbits of Mars and Jupiter, Ceres and Vesta formed in dramatically different ways. Vesta was closer in, and is dry, without a trace of water – even its interior is probably still hot. Ceres formed further out, and astronomers think it might have a thick layer of ice under its crust, covering a rocky core.

Scientists are especially interested in the large crater on Vesta’s southern pole. It alone is 460 km wide and 13 km deep. Astronomers think this mighty collision could account for 5 percent of all the meteorites found here on Earth.

The key to Dawn’s ability to enter orbit around two different objects is its ion drive. Unlike a heavy chemical rocket, an ion propulsion drive uses solar power to accelerate xenon ions to tremendous speeds. It’s not a strong thrust, but it builds up over long periods helping the spacecraft reach tremendous speeds, with a relatively tiny mass of fuel.

NASA originally canceled Dawn, as part of its science cutbacks to help pay for the human missions to return to the Moon, but then the agency revived the mission in 2006, after they had already invested $449 million to get the mission to this point.

Dawn’s next task will be to report in to NASA, to confirm that it reached its proper trajectory, and is able to communicate. We’ll know later today if the mission hit its target window.

Next stop, Vesta.

Original Source: NASA/JPL News Release

September 26, 2007December 26, 2015 by Fraser Cain

Tether to Keep Asteroid Explorers Grounded

Here on Earth, gravity keeps us firmly on solid ground. But when astronauts set foot on some of the more exotic objects in the Solar System, just walking is going to be a struggle. In the microgravity of an asteroid, every step astronauts take will send him flying up in a long arc, and maybe out into space. It would be almost impossible to get around. Fortunately, MIT researchers have developed a tether system that could keep astronauts firmly anchored to the surface, but still let them walk around.

When humans first set foot on the Moon, they learned right away that the lower gravity was going to cause problems getting around. It took a few missions, but astronauts finally perfected a silly-looking hop that allowed them to skip around in the 1/6th gravity. But on an asteroid which can be only a few kilometres across, the wrong step could put an astronaut into orbit; the gravity’s that low. As long as the asteroid is above 8 km or so, a wrong footed astronaut would eventually return to the surface, but it would make exploration infuriating.

What the MIT researchers have developed is a tether system that astronauts would attach to the surface of the asteroid. The ropes would be strung completely around the asteroid, sort of like putting a rubber band around a ball. Once the lightweight ropes were in place, they would apply pressure downward on the astronauts, giving them a sort of artificial gravity. The idea will be published in an upcoming issue of the journal Acta Astronautica.

Previous researchers have suggested that astronauts could bolt themselves to the surface of the asteroid, but that might not be possible. Researcher Ian Garrick-Bethell describes the flaw in that plan, “it would be like trying to bolt yourself to a pile of gravel or sand.”

The team envisions a rocket that would fly around the asteroid, unraveling a spool of rope. Once the spacecraft completes an orbit of the asteroid, the loop is formed and then tightened.

Nobody still really knows what the surface of an asteroid will be like. Even this might now work, as the rope might cut into the surface of the asteroid and not be usable to hold an astronaut down. But at least they could use it as a handhold to drag themselves along without flying away.

Original Source: MIT News Release

September 25, 2007December 26, 2015 by Astronomy Cast

Podcast: Asteroid Belt

In the last few weeks we’ve had many emails saying that our tour of the solar system would not be complete without a show on the asteroid belt. Your wish is our command! We talked about Mars in episode 52, and now that we’re back on track, our next stop is the asteroids belt.

Click here to download the episode

Asteroid Belt – Show notes and transcript

Or subscribe to: astronomycast.com/podcast.xml with your podcatching software.

September 20, 2007December 26, 2015 by Fraser Cain

Learning How to Stop Dangerous Asteroids

You know the cliche: it’s not a question of if an asteroid will strike the Earth, it’s a question of when. Why wait for the asteroid impact, let’s get out there and learn how to prevent an impact in the first place. Part of this learning process will be to study potential Earth-crossing asteroids in great detail. ESA has just such a mission in the works: Don Quijote.

There are several problems with asteroids. For starters, we don’t even know where they all are. But even when we discover their locations and plot out their orbits, it’s all game of probabilities. Over time, asteroids interact with other objects, and their orbits get changed in ways which are hard to predict. Not only that, but sunlight heats up asteroids in ways that can give them a tiny thrust, so they can change their orbits all on their own.

Astronomers are working hard to catalog all the asteroids out there; automated surveys should find most of the objects larger than 140 metres (460 feet) by about 2020. But plotting out their exact positions, and thus their future trajectories, is the hard part.

So Europe is planning to reach out and tag an asteroid. With a homing beacon, an asteroid will be much easier to track as it moves across the Solar System.

The mission is called Don Quijote, and it will work in two phases. The first phase will consist of an orbiter which will rendezvous with an asteroid and begin circling it. It will monitor the asteroid for several months, studying its size, shape, mass and gravity field.

In the second stage, an impactor spacecraft would slam into the asteroid at a speed of 10 km/s, which the first spacecraft watches – sort of like what happened with Deep Impact. The orbiter could then study the asteroid again, seeing what changed. Ground observers could also make precise measurements on the asteroid’s orbit and determine how its trajectory changed from the impact.

ESA doesn’t have a specific asteroid in mind, but they’re seriously considering a space rock called Apophis, which will come dangerously close to the Earth in the future.

If the mission is approved, it could launch early in the next decade, and take about 25 months to fly to its target. Maybe then we’ll get a much better handle on potentially dangerous asteroids, and learn everything we need to know to prevent them.

Original Source: ESA News Release