Posted on by Nancy Atkinson

New Trojan Asteroid Discovered Around Neptune

The green arrow shows the asteroid. The other bright objects are stars in the Milky Way. Credit: Scott Sheppard

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Astronomers have found a new object in a region of Neptune’s orbit, tucked away in a very hard-to-find location, and where no previous object was known to exist. The object, 2008 LC18, is a Trojan asteroid, which refers an asteroid that shares an orbit with a larger planet or moon, but does not collide with it because it orbits around one of the two Lagrangian points of stability. Six other Trojan asteroids have been located around Neptune’s L4 region, but this is the first one found in Neptune’s L5 region.

Scott Sheppard from the Carnegie Institution’s Department of Terrestrial Magnetism and colleagues used a new observational technique that used large dark clouds to block background light from the galactic plane in order to discover the new Neptune Trojan. They used the discovery to estimate the asteroid population there and find that it is probably similar to the asteroid population at Neptune’s L4 point.

“We estimate that the new Neptune Trojan has a diameter of about 100 kilometers and that there are about 150 Neptune Trojans of similar size at L5,” said Sheppard “It matches the population estimates for the L4 Neptune stability region. This makes the Neptune Trojans more numerous than those bodies in the main asteroid belt between Mars and Jupiter. There are fewer Neptune Trojans known simply because they are very faint since they are so far from the Earth and Sun.”

Jupiter has the most Trojans, 4,076 (as of February 2010) but there are four known Mars Trojans and now seven known Neptune Trojans. So far, searches have failed to uncover any similar objects in the orbits of any other planets.

The five Lagrangian points of stability are shown at Neptune. Credit: Scott Sheppard

“The L4 and L5 Neptune Trojan stability regions lie about 60 degrees ahead of and behind the planet, respectively,” said Sheppard “Unlike the other three Lagrangian points, these two areas are particularly stable, so dust and other objects tend to collect there. We found 3 of the 6 known Neptune Trojans in the L4 region in the last several years, but L5 is very difficult to observe because the line-of-sight of the region is near the bright center of our galaxy.”

Sheppard and his team, which included Chad Trujillo from the Gemini Observatory, used images from a digitized all-sky survey to identify places in the stability regions where dust clouds in our galaxy blocked out the background starlight from the galaxy’s plane, providing an observational window to the foreground asteroids. They discovered the L5 Neptune Trojan using the 8.2-meter Japanese Subaru telescope in Hawaii and determined its orbit with Carnegie’s 6.5-meter Magellan telescopes at Las Campanas, Chile.

Because Trojans share their planet’s orbit they are sensitive to the planet’s formation and migration, and astronomers say finding these objects provide clues that may help unlock the answers to fundamental questions about planetary formation and migration.

The region of space is also of interest to the teams from the New Horizon spacecraft, as it will pass through this same area after its encounter with Pluto in 2015.

Read the team’s abstract.

Sources: Carnegie Institute, Science Express.

Posted on by Nancy Atkinson

WISE Cryostat is Depleting

An image released in August 2010 from WISE image of the Small Magellanic Cloud. Image credit: NASA/JPL-Caltech/WISE Team

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NASA’s Wide-field Infrared Survey Explorer, or WISE, is losing its cool. The spacecraft is running out of the frozen coolant needed to keep its heat-sensitive instrument chilled, and will only be in operation for 2-3 more months. While the spacecraft was designed to be rather short-lived – 7 to 10 months — it still is sad to see the mission winding down. But WISE has completed its primary mission, a full scan of the entire sky in infrared light, which was accomplished by July 17, 2010. The mission has taken more than 1.5 million snapshots so far, uncovering hundreds of millions of objects, including asteroids, stars and galaxies. It has discovered more than 29,000 new asteroids to date, more than 100 near-Earth objects and 15 comets.

The telescope has two coolant tanks that keep the spacecraft’s normal operating temperature at 12 Kelvin (minus 438 degrees Fahrenheit). The outer, secondary tank is now depleted, causing the temperature to increase. One of WISE’s infrared detectors, the longest-wavelength band most sensitive to heat, stopped producing useful data once the telescope warmed to 31 Kelvin (minus 404 degrees Fahrenheit). The primary tank still has a healthy supply of coolant, and data quality from the remaining infrared detectors remains high.

WISE is continuing a second survey of about one-half the sky as originally planned. It’s possible the remaining coolant will run out before that scan is finished. Scientists say the second scan will help identify new and nearby objects, as well as those that have changed in brightness. It could also help to confirm oddball objects picked up in the first scan.

NASA is hoping to find more Near Earth Objects with WISE’s remaining days of operations.
“WISE’s prime mission was to do an infrared background map,” said Lindley Johnson, program executive for the Near-Earth Objects Observation program at NASA, speaking at a workshop this week to define objectives for exploring asteroids. “But we realized in talking with scientists that it would also make a good asteroid detector by comparing images. It has done a good job of finding a lot of objects for us.”

Source: NASA

Posted on by Nancy Atkinson

Researchers Say Asteroid Has 1 in 1,000 Chance of Hitting Earth in 2182

Doppler data on asteroid 1999 RQ36 from Goldstone. Credit: NASA

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Asteroid trackers from Spain have upgraded the chance that asteroid 1999 RQ36 could hit our planet, saying it now has a one-in-a-thousand chance of impacting the Earth in the year 2182. Previous estimates gave a 1 in 1,400 chance that this asteroid could strike Earth sometime between 2169 and 2199. Currently, however, NASA’s Near Earth Object website gives between a 1 in 3,850 and a 1 in 3,570 chance that 1999 RQ35 could potentially impact Earth on Sept. 24, 2182. To make everyone breathe a little easier, that’s a 99.97200000% chance the asteroid will completely miss the Earth.

1999 RQ36 is an asteroid that has been suggested for a robotic sample return mission, to help us learn more about the makeup of NEOs, especially those that have a potential threat to Earth.

The team from Spain, co-led by María Eugenia Sansaturio from Universidad de Valladolid, said knowing this asteroid poses a potential threat in the twenty-second century “may help design in advance mechanisms aimed at deviating the asteroid’s path.”

“The total impact probability of asteroid ‘(101955) 1999 RQ36’ can be estimated in 0.00092 -approximately one-in-a-thousand chance-, but what is most surprising is that over half of this chance (0.00054) corresponds to 2182,” said Sansaturio.

Sansaturio and team have estimated and monitored the potential impacts for this asteroid through 2200. Asteroid 1999 RQ36 was discovered in 1999, but originally was not considered dangerous. In 2009, researches from Italy said their new calculations and observations revealed a chance of impact sometime during a 30 year span in the mid-to late 2100’s. Read that 2009 paper here.

1999 RQ36 is estimated to be about 560 meters wide, more than twice the size of the more well-known asteroid Apophis, which is projected to have a 1 in 250,000 chance of impact in 2036, reduced from the 1 in 45,000 odds calculated earlier. That asteroid is expected to make a record-setting — but harmless — close approach to Earth on Friday, April 13, 2029, when it comes no closer than 18,300 miles above Earth’s surface.

Artist's concept of the OSIRIS-REx spacecraft collecting a sample from asteroid 1999 RQ36. Credit: NASA

Of course, there is a fair amount of orbital uncertainty, due to the gravitational influences on the asteroid when it passes by the Earth and other objects, plus a minimal amount of influence from the Yarkovsky effect, which is an unbalanced thermal radiation from sunlight hitting one side of the asteroid and not the other that produces a tiny acceleration.

This effect had not been measured for 1999 RQ36 until now. The new research, published in the journal Icarus, predicts what could happen in the upcoming years considering this effect. Up until 2060, the team says the divergence of the impacting orbits is moderate; between 2060 and 2080 it increases 4 orders of magnitude because the asteroid will approach the Earth in those years; then, it increases again on a slight basis until another approach in 2162, it then decreases, and 2182 is the most likely year for the collision.

“The consequence of this complex dynamic is not just the likelihood of a comparatively large impact, but also that a realistic deflection procedure, or path deviation could only be made before the impact in 2080, and more easily, before 2060,” said Sansaturio.

“If this object had been discovered after 2080, the deflection would require a technology that is not currently available,” added Sansaturio. “Therefore, this example suggests that impact monitoring, which up to date does not cover more than 80 or 100 years, may need to encompass more than one century. Thus, the efforts to deviate this type of objects could be conducted with moderate resources, from a technological and financial point of view.”

The research also involved scientists from the University of Pisa (Italy), the Jet Propulsion Laboratory (USA) and INAF-IASF-Rome (Italy).

The proposed robotic mission to this asteroid is called OSIRIS-Rex, the Origins, Spectral Interpretation Resource Identification, and Security, Regolith Explorer, one of three proposals selected by NASA in December 2009 for more study under its New Frontiers program. If chosen the mission would launch in about 2018, and it could provide information about how the solar system was born, and perhaps, shed light on how life began. It also might be one of the first looks at how an asteroid might be deflected. Read more about this proposed mission on the NASA Goddard website.

Sources: Spanish Foundation for Science and Technology via PhysOrg
, NASA’s NEO Program office, New Scientist

Posted on by Nancy Atkinson

Rosetta Meets Asteroid Lutetia

Lutetia at closest approach. Image credit: ESA 2010 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

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Over the weekend, the Rosetta spacecraft flew by asteroid Lutetia, returning the first close up images of this battered, cratered body. By all accounts, the flyby was a spectacular success with Rosetta performing faultlessly. Closest approach took place at 16:10 GMT on July 10, at a distance of 3,162 km (1964 miles). The images show that Lutetia has been on the receiving end of many impacts during its 4.5 billion years of existence. As Rosetta drew close, a giant bowl-shaped depression stretching across much of the asteroid rotated into view. The images confirm that Lutetia is an elongated body, with its longest side around 130 km (80 miles).

“I think this is a very old object. Tonight we have seen a remnant of the Solar System’s creation,” said Holger Sierks, principal investigator for the spacecraft’s OSIRIS instrument, which combines a wide angle and a narrow angle camera. At closest approach, details down to a scale of 60 meters (see below) can be seen over the entire surface of Lutetia.

At a distance of 36,000 kilometers (22,369 miles) the OSIRIS Narrow Angle Camera (NAC) took this image catching the planet Saturn in the background. Image credit: ESA 2010 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

Rosetta raced past the asteroid at 15 km/s completing the flyby in just a minute. But the cameras and other instruments had been working for hours and in some cases days beforehand, and will continue afterwards. Shortly after closest approach, Rosetta began transmitting data to Earth for processing, and the Rosetta team will surely release more details in the coming days and weeks.

In the meantime, enjoy this wonderful poem composed by space poet laureate Stu Atkinson.

Lutetia in the Light

For all these years you were merely
A smear of light through our telescopes
On the clearest, coldest night; a hint
Of a glint, just a few pixels wide
On even your most perfectly-framed portraits.
But now, now we see you!
Swimming out of the dark – a great
Stone shark, your star-tanned skin pitted
And pocked, scarred after aeons of drifting
Silently through the endless ocean of space.
Here on Earth our faces lit up as we saw
You clearly for the first time; eyes wide
With wonder we traced the strangely familiar
Grooves raked across your sides,
Wondering if Rosetta had doubled back to Mars
And raced past Phobos by mistake –

Then you were gone, falling back into the black,
Not to be seen by human eyes again for a thousand
Blue Moons or more. But we know you now,
We know you; you’ll never be just a speck of light again.

—Stuart Atkinson

Zoom in on a possible landslide and boulders at the highest resolution. Image credit: ESA 2010 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

Sources: ESA, JPL, Rosetta Blog

Posted on by Nancy Atkinson

Watch Live Webcast of Rosetta Flyby of Asteroid Lutetia July 10

Rosetta captured this image of asteroid (21) Lutetia on July 9, 2010, at 01:00 UTC, when the spacecraft was still about two million kilometers (and 36 hours) from the asteroid. Credit: ESA 2010 MPS for OSIRIS Team

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On July 10, ESA’s Rosetta spacecraft will fly past 21 Lutetia, the largest asteroid ever visited by a satellite. After weeks of maneuvers and optical observations, Rosetta is perfectly lined up to skim by the asteroid only 3,162 km (2,000 miles) away. ESA is hosting a live webcast at 16:00 GMT on July 10. Below is an embedded feed that will go live once the webcast begins.

For more information and a complete timeline of events, check out this ESA web page.

Watch live streaming video from eurospaceagency at livestream.com

Rosetta is expected to pass Lutetia at a relative speed of 54,000 km/hr. All this takes place 454 million km from Earth. Lutetia is a major scientific target of Rosetta’s mission, so most of the orbiter and lander instruments will be on for flyby, studying the asteroid’s surface, dust environment, exosphere, magnetic field, mass and density.

Rosetta is on its way to a 2014 rendezvous with comet 67P/Churyumov-Gerasimenko.

Posted on by Nancy Atkinson

Hayabusa Sample Return Canister Opened, Contains Material

Hayabusa's sample return canister was opened to reveal a small particle inside. Credit: JAXA

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The sample return canister from the Hayabusa spacecraft has been opened, and does contain a small amount of dust particles, according to the JAXA website. This is very encouraging news! However, it is not yet known if the dust is from the asteroid Itokawa, where Hayabusa briefly touched down, or if it could be from Earth — left in the container from before launch, or it possibly could have made its way in there during the landing/post landing handling. “Material on the planet or asteroid or particulate matter is at this stage is unknown, we will consider in detail,” is the Google translate version of the JAXA press release. According to Emily Lakdawalla at the Planetary Society, the dust grains are extremely small, about 0.01-millimeter in size, and there are about a dozen of them inside the container. This image was taken on June 28, 2010, and below is a magnified view of one of the particles.

Magnified view of a dust particle in the Hayabusa canister. Credit: JAXA

This magnified view was taken on June 29, and shows a magnified view of one very small particle being picked up by a quartz manipulator, which appears as a stripe on the image.
It likely will take several weeks to confirm whether the particles are from the asteroid, but if so, would be the first-ever asteroid sample return.

Below is an image of Earth that Hayabusa took as it approached the home planet.

Earth seen by the returning Hayabusa. Credit: JAXA

Sources: JAXA, The Planetary Society, BBC

Posted on by Nancy Atkinson

Fully Functional Pan-STARRS is now Panning for Stars, Asteroids and Comets

Pan-STARRS PS1 Observatory. Image courtesy of Rob Ratkowski Photography and the Haleakala Amateur Astronomers.

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There’s a new eye on the skies on the lookout for ‘killer’ asteroids and comets. The first Pan-STARRS (Panoramic Survey Telescope & Rapid Response System) telescope, PS1, is fully operational, ready to map large portions of the sky nightly. It will be sleuthing not just for potential incoming space rocks, but also supernovae and other variable objects.

“Pan-STARRS is an all-purpose machine,” said Harvard astronomer Edo Berger. “Having a dedicated telescope repeatedly surveying large areas opens up a lot of new opportunities.”

“PS1 has been taking science-quality data for six months, but now we are doing it dusk-to-dawn every night,” says Dr. Nick Kaiser, the principal investigator of the Pan-STARRS project.

Pan-STARRS PS1 Observatory just before sunrise on Haleakala, Maui. Credit: Harvard-Smithsonian Center for Astrophyiscs

Pan-STARRS will map one-sixth of the sky every month and basically be on the lookout for any objects that move over time. Frequent follow-up observations will allow astronomers to track those objects and calculate their orbits, identifying any potential threats to Earth. PS1 also will spot many small, faint bodies in the outer solar system that hid from previous surveys.

“PS1 will discover an unprecedented variety of Centaurs [minor planets between Jupiter and Neptune], trans-Neptunian objects, and comets. The system has the capability to detect planet-size bodies on the outer fringes of our solar system,” said Smithsonian astronomer Matthew Holman.

Pan-STARRS features the world’s largest digital camera — a 1,400-megapixel (1.4 gigapixel) monster. With it, astronomers can photograph an area of the sky as large as 36 full moons in a single exposure. In comparison, a picture from the Hubble Space Telescope’s WFC3 camera spans an area only one-hundredth the size of the full moon (albeit at very high resolution).

This sensitive digital camera was rated as one of the “20 marvels of modern engineering” by Gizmo Watch in 2008. Inventor Dr. John Tonry (IfA) said, “We played as close to the bleeding edge of technology as you can without getting cut!”

Each image, if printed out as a 300-dpi photograph, would cover half a basketball court, and PS1 takes an image every 30 seconds. The amount of data PS1 produces every night would fill 1,000 DVDs.

Another view of Pan STARRS PS1 Observatory. Image courtesy of Rob Ratkowski Photography and the Haleakala Amateur Astronomers.

“As soon as Pan-STARRS turned on, we felt like we were drinking from a fire hose!” said Berger. He added that they are finding several hundred transient objects a month, which would have taken a couple of years with previous facilities.

Located atop the dormant volcano Haleakala (that’s Holy Haleakala to you, Bad Astronomer) Pan-STARRS exploits the unique combination of superb observing sites and technical and scientific expertise available in Hawaii.

Source: CfA

Posted on by Nancy Atkinson

Hayabusa Sample Return Capsule Retrieved

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

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Scientists from Japan were given the go-ahead to retrieve the sample return capsule from the Hayabusa spacecraft, which is hoped to contain the first piece of asteroid ever brought to Earth, perhaps providing insight into the origins of asteroids – and our universe. The capsule was ejected three hours before reaching Earth, and the sample canister descended through Earth’s atmosphere, preceding the spacecraft which broke up in spectacular fashion (click here to see the video) over the Australian Outback. The capsule lay in the Woomera Prohibited Area until morning when Aboriginal elders deemed it had not landed in any indigenous sacred sites, giving the OK for the scientists to retrieve it.

The insulated and cushioned re-entry capsule, 40 cm in diameter and 25 cm deep has a mass of about 20 kg. The capsule had a convex nose covered with a 3 cm thick ablative heat shield to protect the samples from the high velocity (~13 km/s) re-entry.

Apparently, it landed right on target. The director of the Woomera test range, Doug Gerrie, said the probe had completed a textbook landing in the South Australian desert. “They landed it exactly where they nominated they would.

Hayabusa's heat shield was also recovered from the Australian outback. Credit: JAXA

The capsule will remain sealed until it arrives at the JAXA facility near Tokyo, and may remain unopened for weeks as it undergoes testing.

The mission launched in 2003, and endured a series of technical glitches over its five-billion-kilometer (three-billion-mile) journey to the asteroid Itokawa and back. A large solar flare in late 2003 “injured” the solar panels, providing less power to Hayabusa’s ion engines, delaying the rendezvous with the asteroid. Then, as the spacecraft approached Itokawa, Hayabusa lost the use of its Y-axis reaction wheel. While it flew near the asteroid and sent back data, scientists and engineers aren’t sure if the spacecraft was successful in obtaining samples, as while it appears Hayabusa landed briefly, it is not certain the “bullets” fired to stir up dust for the container to capture. The return to Earth was delayed by three years from more thruster and navigational failures, but the JAXA team nursed and coaxed the spacecraft back home to a spectacular return. There was concern that the parachute batteries may be been depleted due to the extra time it took to get back to Earth, but obviously they worked quite well.

Sources: JAXA, NASA, AFP

Posted on by Nancy Atkinson

Hayabusa Returns!

Japan’s little spacecraft that could returned to Earth, putting on quite a show over the Australian outback, making a fiery reentry. Hayabusa returned around 10 a.m. EDT (1400 GMT) in the Woomera Prohibited Area of South Australia. In the video you’ll see a little speck of light ahead of the falling debris: that’s the sample return canister with, hopefully, some precious goods aboard – samples from asteroid Itokawa. The canister separated about three hours before reaching Earth, and returned to Earth via parachute. The canister has been recovered, and will be taken to Japan where scientists will open it to find out if there is anything inside.

The return was monitored scientists from around the world, including a NASA crew on aboard a DC-8 airplane who took the video footage.
Continue reading “Hayabusa Returns!”

Posted on by Nancy Atkinson

Hayabusa on the Homestretch on Return to Earth

Hayabusa's sample return capsule descends under parachute toward the Woomera desert, Australia. Credit: Corby Waste and Tommy Thompson for NASA / JPL

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After overcoming multiple serious glitches, and a three-year delay in its four billion miles (six billion kilometers) round-trip journey, JAXA’s Hayabusa spacecraft is expected to land in Australia around 14:00 UTC on Sunday, June 13; (midnight local time in Australia, 11 pm in Japan and 11:00 a.m. ET in the US). Scientists and space enthusiasts alike are hoping there is some precious cargo aboard in the sample return capsule: dust from an asteroid.

The latest word from JAXA, as of this writing, is that all systems were doing well on Hayabusa. The teams assessed the trajectory of Hayabusa and confirmed that everything was nominal.

If all goes well, Hayabusa will release a canister that will land in the Woomera Prohibited Area in the outback of South Australia; Hayabusa itself will follow, putting on a show over Australia as it breaks up and incinerates in Earth’s atmosphere.

You can follow the landing in several ways. A NASA team will be attempting to observe the re-entry of Hayabusa in a DC-8 plane, and they hope to have a webcast at this link.

There will be a “Hayabusa Live” website and a Hayabusa blog will be updated frequently, plus this Hayabusa Twitter feed.

Here’s a link to a finder chart and more from Paul Floyd at his website, Night Sky Online.

The Hayabusa spacecraft, formerly known as MUSES-C launched on May 9, 2003 and rendezvoused with the asteroid Itokawa in mid-September 2005. Hayabusa studied the asteroid’s shape, spin, topography, color, composition, density, and history. Then in November 2005, it attempted to land on the asteroid to collect samples but failed to do so. However, it is hoped that some dust swirled into the sampling chamber. You can listen to Universe Today writer Steve Nerlich (from Cheap Astronomy) tell the story of Hayabusa’s trials and tribulations on this 365 Days of Astronomy podcast.

The aim of the $200 million Hayabusa project was to learn more about asteroids and to help in our understanding of the origin and evolution of the solar system.

If Hayabusa is indeed carrying samples from the asteroid, it would be only the fourth sample return of space material in history — including the moon matter collected by the Apollo missions, comet matter by Stardust and solar matter in the Genesis mission.

We’re all hoping for the best for this first sample return from an asteroid, and it should be an interesting time in Australia. Dozens of scientists will be watching and waiting to see the return.

A view of Woomera from the Ghan train. Credit: Col Maybury

Plus, as Col Maybury from radio station 2NUR in Australia tells me, all traffic around the area will be stopped, including the Ghan train, one of the world’s great trains that travels from south to north across the continent of Australia, and it happens to be passing through Woomera right at the time Hayabusa should be returning. Col said he called the train company, and was told that the train engineers are to keep a look out for the entry trail.

“So a mighty train named after Afghan camel drivers may have to halt for a small spacecraft or be hit by a flying object,” Col wrote me in an email. He will have a live report on Radio 2NUR-FM on Tuesday the 15th at 10:20 am in Newcastle, 12:20 GMT, talking with the Woomera officials for a follow-up of the Hayabusa event.

Preliminary analysis of the samples will be carried out by the team in Japan, but after one year scientists around the world can apply for access to bits of the asteroid material for research.