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.
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.
Using images obtained by NASA's Cassini mission, astronomers followed several of what are likely to be dozens of small moons orbiting within the outer edge of Saturn's A ring -- the outermost of the planet's large, dense rings -- from 2005 to 2009.
Scientists for NASA’s Cassini mission noticed some weird-looking propeller-like shapes in the outer edge of Saturn’s A ring. What could be creating these unusual contours? A closer look revealed they were being formed by dozens of moving moonlets. Normally, these kilometer-sized moons would have been almost impossible to see, since they are embedded within the rings. “However, their presence is betrayed by the large tell-tale ‘propeller’ structures they generate in the ring material on either side of them,” said Carolyn Porco, leader of the Cassini imaging team, and co-author on a new paper on these propeller moons. In an email, Porco said similar features had been seen earlier in other locations in Saturn’s rings, but were “much smaller, harder to see, and so numerous that there was no hope of following any one of them. The new propellers, and the moonlets that create them, are some ten times larger and much easier to identify and follow from image to image and year to year.”
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The team said the ability to watch as the embedded moons’ orbits evolve over time could give scientists valuable new clues about how planets form and grow around stars in young solar systems.
“What is outstanding about these new findings is the insight they ultimately will provide into the early stages of solar system formation,” said Porco, “when growing planets become large enough to open gaps in the ring material around them and ultimately truncate their own growth.”
The scientists have tracked eleven of these moons since 2006. Most are between one and several kilometers in diameter, too small to be imaged directly by Cassini’s cameras, but are only distinguishable by the unique double-armed propeller features.
The area in the middle of Saturn’s outermost dense A ring is now known as the “propeller belts,” and the new moonlets have been given appropriate names.
“You may find it amusing that these large propellers have unofficially been named after famous aviators,” Porco said. “Those flight enthusiasts among you will recognize Bleriot, Earhart, Santos-Dumont, and others.”
Cassini caught sight of Blériot (named after a French aviator) more than 100 times, allowing the researchers to map its path in detail. The propeller shape it created is several thousand kilometers long, or half the distance across the continental United States.
“You would expect any object that’s just orbiting Saturn on its own should stay in a constant path,” said lead author Matthew Tiscareno from Cornell University. “What we actually see is that the orbits are changing.”
The most likely explanation, he said, is that the moons are actually interacting with the disk: exchanging angular momentum with the ring particles around them either through gravity or by direct collisions.
Still, other explanations, like resonant interactions with more distant moons, have not been ruled out as causes.
Scientists will be keeping an eye on these wandering little moons in order to figure out if the disk itself is driving the changes, similar to the interactions that occur in young solar systems. If it is, Tiscareno said, this would be the first time such a measurement has been made directly.
Have you been checking out the Solar Dynamics Observatory website and seeing all the amazing, high resolution images of our closest star? If not, you should. Above is a great new video of SDO’s capabilities and latest images. If you want to see what the Sun looks like right now, go to SDO’s homepage. And here’s a link to the SDO image browser where you can see the different images in different wavelengths from the AIA (Atmospheric Imaging Assembly) and HMI (Helioseismic and Magnetic Imager). If you choose the date range option, you can see a “movie” of the Sun’s activity. For example, check out the enormous coronal hole in the northern hemisphere seen last week in AIA 193 (date range 6/28 to 7/3), allow all the images to download and then press “Play.” Completely awesome. The SDO website should be part of your daily internet routine!
An aerial view of space shuttle tank ET-138 -- the last one -- as it rolls out at Michoud Assembly Facility near New Orleans, Louisiana. Credit: NASA
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Almost the end of an era: the last external tank scheduled to fly on a shuttle mission was rolled out of the Michoud Assembly Facility on Thursday. The tank, ET-138, traveled on a wheeled transporter one mile to the Michoud barge dock, accompanied by a brass band and hundreds of the workers who built tanks over the past 37 years. One additional tank will come from Michoud; ET-122, which was at damaged Hurricane Katrina in August 2005, and is being restored to flight configuration and is scheduled for delivery to Kennedy in late September to serve as the “Launch on Need” tank, for the STS-335 rescue ship, if needed. Or, it might get to fly in space – no decision yet if NASA will get one additional mission.
You can see a gallery of images from Thursday’s New Orleans’ style celebration at this NASA Flickr page.
The tank will make a 900-mile sea journey to Kennedy Space Center, (around the oil slicks in the Gulf of Mexico) and then processing will begin to mate it with shuttle Endeavour and solid rocket boosters for the STS-134 mission, scheduled to launch no earlier than mid-November February 2011. The mission will deliver the Express Logistics Carrier 3 and the Alpha Magnetic Spectrometer to the International Space Station. It will be the 36th shuttle mission to the space station and the 134th and final scheduled shuttle flight.
A group of astronomers are now on the mysterious Easter Island, one of the few solid places to stand on Earth where a total solar eclipse will be visible on July 11, 2010. The majority of the eclipse’s path is over the ocean, so this will be one of the least observed eclipses ever. “This is one of the most interesting things that is possible for anyone on Earth to see in one of the most interesting places on the Earth that people can go,” said Jay Pasachoff from Williams College, who is the Chair of the International Astronomical Union’s Working Group on Eclipses. This will be his 51st eclipse.
Williams astronomer Jay Pasachoff during the partial phase of the March 29, 2006 solar eclipse. Photo by Anna Tsykalova.
While the eclipse is thousands of miles long in its is path of totality on Earth, it is just a few hundred miles wide. It will pass through French Polynesia on the Cook Islands, but, Pasachoff said, it doesn’t go through any of the main islands. “It misses Tahiti, but there are some atolls off the side of the path, and some eclipse scientists and ecotourists will be on cruise ships that are going into the path of totality. There will also be a group on an airplane observing the eclipse and we hope to compare all the other observations with the ones we get from Easter Island,” he said.
Easter Island is 4023 km (2,500 miles) west of Chile, and is famous for the Moai, giant statutes that were left by a Polynesian culture that mysteriously disappeared. But while the statues’ constant gaze look outward, all human eyes will be on the skies on July 11.
“The actual four minutes and forty-five seconds of totality that we are scheduled to have at Easter Island will be very exciting, as the last sliver of the sun is covered we can then take off the protective filters we’ve been using,” Pasachoff said, “and look at the next few minutes without any protection because the solar corona is about the same brightness as the full moon and is equally safe to look at. In fact we’ve been having a debate recently about whether we can get a very brief warning on the so-called eclipse glasses that many people use because those glasses are only for when any of the everyday sun is visible. They are so dense that they block the solar corona entirely, and the few people who don’t understand what is going on enough to take those glasses off during totality miss the whole event. There are people who have missed past eclipses by not knowing they had to take their glasses off.”
Pasachoff is joined by Professor Marek Demianski and two students. They will be carrying out high-resolution imaging to look for motions in the corona and to follow the varying magnetic-field configuration in the solar-corona as a function of the solar-activity cycle. Though the sunspot cycle remains in an extreme low, some other indications of solar activity have been increasing and we are eager to see the condition of the low and middle corona. They expect to see motions at least in polar plumes.
Also, they will be using the images to fill in gaps between the observations of the corona on the solar disk taken with NASA’s new Solar Dynamics Observatory and the observations of the outer corona taken with the Naval Research Laboratory’s coronagraph on the Solar and Heliospheric Observatory. Pasachoff and his team have contributed to similar images for the past several eclipses but now will have the improved SDO images as part of their montage. Several of the cameras will be computer controlled using software called Solar Eclipse Maestro written by Xavier Jubier of France.
Universe Today hopes to talk with Pasachoff after the eclipse to hear about his experiences.
The Williams College team is accompanied by a documentary crew filming for National Geographic Channel, and their activities will be covered in a special program entitled Easter Island Eclipse partly pre-recorded and partly expected to have new eclipse footage that will air on the National Geographic Channel on the evening of July 11th, at 11 pm.
Here are some resource Pasachoff provided for the eclipse:
On Sunday, July 11th: total solar eclipse on Easter Island (same time zone as Mountain Time in the US)
Partial eclipse begins 12:40:36 Altitude of Sun: 40°
Totality begins 14:08:30 Altitude of Sun: 40°
Totality ends 14:13:10 Altitude of Sun: 39°
Partial eclipse ends 15:34:16 Altitude of Sun: 32°
Duration of totality: 4 minutes and 40 seconds
Times in UT:
18:40 UT 1st contact
20:08 UT 2nd contact: total eclipse begins
20:13 UT 3rd contact: total eclipse ends
Update: I just received a note from Robin Zimmerman at DISH Network, and for those of you who have the DISH Network, there is a special channel, DishEARTH, Ch. 287, that features live 24/7 views of the earth from space and this Sunday the eclipse be shown. Robin said their network will allow people in the US to see the phenomena, live.
Solar Impulse's Chief Executive Officer and pilot Andre Borschberg flyes in the solar-powered HB-SIA prototype airplane for its first night flight attempt near Payerne airport July 7, 2010. Credit: KEYSTONE/Dominic Favre/POOL/SOLAR IMPULSE
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After flying for over 26 straight hours, pilot André Borschberg landed the solar-powered Solar Impulse HB-SIA airplane to cheers and applause at the Payerne airbase in Switzerland, successfully completing the goal of flying the aircraft through the night. According to Bertrand Piccard, president of Solar Impulse, there was power to spare, with over three hours of energy remaining in the sun-gathering lithium batteries. “This is a highly symbolic moment: flying by night using solely solar power is a stunning manifestation of the potential that clean technologies offer today to reduce the dependency of our society on fossil fuels!” Piccard said. “We are on the verge of the perpetual flight.”
With an official flight time of 26 hours and 9 minutes, the lightweight carbon fiber plane reached a a maximum altitude of 8,700 m (28,543 ft), a top speed of 68 knots (ground speed), an average speed of 23 knots. The HB-SIA flew solely on solar power, gathering and storing it during the daylight hours, and using the energy to fly through the night. Solar Impulse flies towards the night. Credit: KEYSTONE/POOL/Dominic Favre/Solar Impulse
“During the whole of the flight, I just sat there and watched the battery charge level rise and rise! Sitting in a plane producing more energy than it consumes is a fantastic feeling”, said Borschberg, CEO and co-founder of the Solar Impulse project.
The Solar Impulse HB-SIA has 12,000 solar cells built into its 64.3-meter (193-foot) wings, and is a prototype for an aircraft that the Solar Impulse team hope to fly around the world in a continuous flight in 2012.
Solar impulse weights 1,600 kg (3,500 lb), and is powered by four electric motors.
“Nothing can prevent us from another day and night, and the myth of perpetual flight,” a jubilant Piccard said at a press conference following the flight.
Update: Here’s a video from Solar Impulse, as the team waited for the sunrise:
We talk a lot about telescopes here on Astronomy Cast, but you really don’t need any special equipment to appreciate what the night sky has to offer. Just head outside with some sky charts, maybe a planisphere, some friends and hot chocolate, and you’re good to go. Let’s talk about what kinds of things you can see with just your eyes.
And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, let Fraser know if you can be a host, and he’ll schedule you into the calendar.
Finally, if you run a space-related blog, please post a link to the Carnival of Space. Help us get the word out.
Here’s this week’s Where In The Universe Challenge. You know what to do: take a look at this image and see if you can determine where in the universe this image is from; give yourself extra points if you can name the instrument responsible for the image. We’ll provide the image today, but won’t reveal the answer until tomorrow. This gives you a chance to mull over the image and provide your answer/guess in the comment section. Please, no links or extensive explanations of what you think this is — give everyone the chance to guess.
UPDATE: The answer is now posted below.
This image from the Cassini spacecraft shows Saturn’s moon Dione, in the foreground with Tethys behind.
Tethys appears brighter because it has a higher albedo than Dione, meaning Tethys reflects more sunlight. This higher albedo is due to Tethys being closer to the moon Enceladus and the E ring. Bright debris spews from Enceladus, feeding the E ring. This debris then coats Enceladus and Tethys with bright material.
Solar Impulse, which is the first airplane designed to fly day and night without fuel, is attempting to fly for the first time at night. The plane took off at 6:51 this morning, local time from the Payerne airbase in Switzerland, and as of this writing, everything was proceeding as planned, and night was just beginning to fall. “It’s not just a question of flying the plane, but the team working together on the strategy of making the profile of flying through the night,” said Bertrand Piccard, president and founder of the Solar Impulse project, during a webcast update on the flight. “For now, cross fingers, everything is going well. The sky is completely clear, (pilot) Andre (Borscherg) is warm, and so he is looking forward to getting to a higher atmosphere, of 13,000 feet. ”
Piccard said the entire flight is a choreography of timing and execution. They don’t want the plane to reach the desired altitude too quickly, because the batteries need to be fully charged exactly when night falls, and at the top of the airplane’s climb. The lightweight lithium batteries also need to stay within a certain temperature range.
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Borscherg will stay at the highest altitude for awhile, then descend during the night. “We have to manage energy and efficiency,” Piccard said. “If everything works well, Andre will be asked to continue the flight through the night. But if there is any problem before night, we want to bring the plane down to land before 10 pm local time.”
Piccard said this effort is not just about flying an airplane on solar power, but “to show everyone on this planet that we are not so dependent on non-renewable energies as we may think.”
“For 7 years now, the whole team has been passionately working to achieve this first decisive step of the project”, said André Borschberg a few minutes before easing himself into the cockpit for a flight expected to last until Thursday morning.
The plane has a 61 meter wingspan, and the wings are covered with 12,000 state-of-the-art photovoltaic solar cells that power the plane. Using so-called intelligent light materials and new energy storage, the plane will be able to fly both night and day, completely on solar power. Solar impulse weights 1,600 kg and can fly at speeds up to 70 kmh at a maximum altitude of 8,500 m (27,900 ft).
Here is the flight profile for Solar Impulse HB-SIA:
The plane will slowly ascend all day to an altitude of 8,500 meters, while at the same time charging its batteries in preparation for the night flight. When the sun’s rays stop being strong enough to supply the solar cells (about two hours before sunset) with energy, the HB-SIA will start a slow descent, reaching an altitude of around 1,500 meters by 23:00. It should then carry on flying, using the energy stored in its batteries, until the next sunrise. The big question is whether the pilot can make efficient use of the battery energy to fly throughout the night. If this mission is successful, it will be the longest and highest flight ever made by a solar plane.
For more information, see the Solar Impulse website. Here’s an article about the biggest plane in the world.
