Space and astronomy news
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A clear night, a crescent Moon, Venus, and an ancient castle. What more could you ever want? Our pal Stuart Atkinson captured these gorgeous images taken over the weekend from Kendal, in Cumbria, England. “An absolutely stunning view, seen from Kendal’s historic, ruined castle. Not another soul around as I enjoyed the spectacle,” Stu wrote. See more of his images below, plus you can see loads more at Spaceweather.com’s gallery.
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It’s a space navigator’s dream! The Cassini spacecraft will perform close flybys of two of Saturn’s most enigmatic moons all within less than 48 hours, and with no maneuvers in between. Enceladus and Titan are aligned just right so that Cassini can catch glimpses of these two contrasting moons – one a geyser world and the other an analog to early Earth.
Cassini will make its closest approach to Enceladus late at night on May 17 Pacific time, which is in the early hours of May 18 UTC. The spacecraft will pass within about 435 kilometers (270 miles) of the moon’s surface.
The main scientific goal at Enceladus will be to watch the sun play peekaboo behind the water-rich plume emanating from the moon’s south polar region. Scientists using the ultraviolet imaging spectrograph will be able to use the flickering light to measure whether there is molecular nitrogen in the plume. Ammonia has already been detected in the plume and scientists know heat can decompose ammonia into nitrogen molecules. Determining the amount of molecular nitrogen in the plume will give scientists clues about thermal processing in the moon’s interior.
Then on to Titan: the closest approach will take place in the late evening May 19 Pacific time, which is in the early hours of May 20 UTC. The spacecraft will fly to within 1,400 kilometers (750 miles) of the surface.
Cassini will primarily be doing radio science during this pass to detect the subtle variations in the gravitational tug on the spacecraft by Titan, which is 25 percent larger in volume than the planet Mercury. Analyzing the data will help scientists learn whether Titan has a liquid ocean under its surface and get a better picture of its internal structure. The composite infrared spectrometer will also get its southernmost pass for thermal data to fill out its temperature map of the smoggy moon.
Cassini has made four previous double flybys and one more is planned in the years ahead.
For more information on the Enceladus flyby, dubbed “E10,” see this link.
For more information on the Titan flyby, dubbed “T68,” see this link.
Source: JPL
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For hundreds of years, people have reported seeing ball lighning, a weird phenomenon that resembles glowing, hovering spheres of electricity sometimes witnessed during lightning storms. But scientists have never been able to explain what causes it or even what it really is. Even though some surveys say that 1 in 150 people have seen ball lightening, photographic evidence is basically nonexistent. There are dozens of theories of how ball lightning could form, including the burning of hot silicon particles produced when a lightning strike vaporizes the ground. When people who claim they have seen ball lightining try to explain what they saw, often they are told, “You must be seeing things!”
Perhaps they are.
A pair of physicists from Austria say that the magnetic fields associated with certain types of lightning strikes are powerful enough to create hallucinations of hovering balls of light in nearby observers, and that these visions would be interpreted as ball lightning.
Alexander Kendl and Joseph Peer from the University of Innsbruck analyzed electromagnetic pulses of repetitive lightning discharges and compared them to the magnetic fields used in clinical transcranial magnetic stimulation (TMS), which is a technique used by neuroscientists to explore the workings of the brain; it is also used for psychiatric treatments. Patients are subjected to a rapidly changing magnetic field that is powerful enough to induce currents in neurons in the brain. Patients will sometimes see hallucinations of luminous shapes in their visual field.
Rare but natural long (1-2 seconds) and repetitive lightning strikes produce electromagnetic pulses similar to what happens during TMS. The researchers calculated the time-varying electromagnetic fields of various types of lightning strikes for observers at various distances from the strike, from 20-100 meters away.
Their results suggest the variable magnetic fields produced by lightning are very similar to TMS, in both magnitude and frequency. Those people undergoing TMS have hallucinations, and see balls of light known as cranial phosphenes.
Kendl and Peer postulated that ball lightning could be hallucinations arising from lightning electromagnetic pulses affecting the brains of close observers.
“As a conservative estimate, roughly 1% of (otherwise unharmed) close lightning experiencers are likely to perceive transcranially induced above-threshold cortical stimuli,” said Peer and Kendl in their paper. They add that these observers need not be outside but could be otherwise safely inside buildings or even sitting in aircraft.
The calculations showed that only lightning strikes consisting of multiple return strokes at the same point over a period of seconds could produce a magnetic field long enough to cause cortical phosphenes. This type would account for around 1-5% of lightning strikes, but very few of these would be seen by an observer 20 to 100 meters away, and of those the researchers estimate seeing the light for seconds would occur only in about one percent of unharmed observers. The observer does not need to be outside, but could be inside an aircraft or building. Kendl and Peer also said an observer would be most likely to classify the experience as ball lightning because of preconceptions.
One of the earliest descriptions of ball lighting comes from way back in 1638 at a church in Widecombe-in-the-Moor, Devon, in England. Four people died and approximately 60 were injured when, during a severe storm, an 8-foot (2.4 m) ball of fire was described as striking and entering the church, nearly destroying it. Large stones from the church walls were hurled into the ground and through large wooden beams. The ball of fire allegedly smashed the pews and many windows, and filled the church with a foul sulfurous odor and dark, thick smoke.
That doesn’t sound like a hallucination, but many question whether the reports are accurate or not. Read some more reports of ball lighting at Wikipedia.
Have you seen ball lightning, or know someone who has?
Sources: PhysOrg, Technology Review Blog
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Starting today, the Mars Odyssey orbiter will be listening once again for the Phoenix Mars Lander, lending an ear to hear if Phoenix has come back to life. Until May 21,Odyssey will listen for a signal from Phoenix during 61 flights over the lander’s site on Mars’ northern arctic region. Earlier attempts to detect a transmission from the lander — totaling 150 overflights in January, February and April – were not successful.
NASA decided to add another round of listening sessions that weren’t originally scheduled.
“To be thorough, we decided to conduct this final session around the time of the summer solstice, during the best thermal and power conditions for Phoenix,” said Chad Edwards, chief telecommunications engineer for the Mars Exploration Program at NASA’s Jet Propulsion Laboratory.
Phoenix quit communicating with Earth in November, 2008, and since that time endured a long and fierce Mars winter, where it was likely encased in CO2 ice in temperatures under -150 C. The solar arrays may have cracked and fallen off the vehicle, and the electronics probably became brittle and broke in the severe cold, so the wiring boards probably are nonfunctional.
Phoenix worked superbly for five months before reduced sunlight caused energy to become insufficient to keep the lander functioning. The solar-powered robot was not designed to survive through the dark and cold conditions of a Martian arctic winter.
Northern Mars experienced its maximum-sunshine day, the summer solstice, on May 12 (Eastern Time; May 13, Universal Time), so the sun will be higher in the sky above Phoenix during the fourth listening campaign than during any of the prior ones. Still, expectations of hearing from the lander remain low.
But nobody is ready to give up just yet.
We’ll let you know if Phoenix phones home.
Source: JPL
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Here’s an event we don’t get to see very often. It is a post-launch activity that is not well publicized and of course, with the retirement of the space shuttles fast approaching, we have just a few opportunities to see it again. Early Monday morning, the solid rocket boosters used for space shuttle Atlantis’ launch last week were towed back to Port Canaveral after their recovery from the Atlantic Ocean. Universe Today photographer Alan Walters captured some images of the return, and in the image above, the Liberty Star — one of two unique ships specifically designed and constructed for this task — returns one booster through the locks at the Port. Visible is the “business end” of the booster. A spokesperson at Kennedy Space Center said these two boosters will be refurbished, just in case they are needed in the future.
See more images below.
Here’s a close-up of the nozzle end of the SRB, a little worse for wear after the launch. After the boosters do their job and are jettisoned from the shuttle, they fall back to the ocean. The parachutes provide for a nozzle-first impact, so air is trapped in the empty motor casing, causing the booster to float with the forward end approximately 30 feet (9.1 m) out of the water. Once the boosters are located, divers insert a plug in the nozzle (the metal object in the middle of the nozzle) called the Diver Operated Plug. The divers “dewater” the SRBs by pumping air into and water out of the SRB. This causes the SRB to change from a nose-up floating position to a horizontal attitude more suitable for towing.
The top end of the SRB is visible in this image. The nose cap is jettisoned at an altitude of 2.9 statute miles (2.5 nautical miles/4.6 kilometers) and deploys the pilot parachute.
An SRB fully loaded with propellant weighs about 1.4 million pounds (635,040 kilograms). They stand 149.2 feet (45.5 meters) tall, and have a diameter of 12 feet (3.6 meters). The boosters in use today are the largest solid propellant motors ever developed for space flight and the first to be used on a manned space vehicle. These boosters will propel the orbiter to a speed of 3,512 miles per hour (5,652 kilometers per hour).
Approximately two minutes after the Space Shuttle lifts off from the launch pad, the twin SRBs have expended their fuel, and the boosters separate from the orbiter and its external tank at an altitude of approximately 30.3 statute miles (26.3 nautical miles/48.7 kilometers) above the Earth. After separation, momentum will propel the SRBs for another 70 seconds to an altitude of 44.5 statute miles (38.6 nautical miles/71.6 kilometers) before they begin their long tumble back to Earth.
This is the frustum, which holds the drogue shoot. It is jettisoned from the booster after the drogue shoot stabilizes the SRB in a tail-first attitude, and is separated by a pyrotechnic charge about 243 seconds after SRB separation.
The main parachutes are the first items to be brought on board the recovery ships. Their shroud lines are wound onto each of three of the four reels on the ship’s deck. The drogue parachute, attached to the frustum, is reeled onto the fourth reel until the frustum is approximately 50 feet astern of the ship. The 5,000-pound (2,268-kilogram) frustum is then lifted from the water using the ship’s power block and deck crane.
The ships enter Port Canaveral, where the booster is changed from the stern tow position to a position alongside the ship to allow greater control. The ships then pass through a drawbridge, Canaveral Locks, and transit the Banana River to a hanger. They are lifted from the water with specially made Straddle-Lift cranes and placed on rail cars to begin the disassembly and refurbishment process.
The Liberty Star and the Freedom star each have a crew of ten; a nine-person SRB retrieval team, a retrieval supervisor, a NASA representative, and some observers, with the maximum complement at 24 persons.
While the ships were built especially for NASA for retrieving the SRBs, they’ve also been used for other purposes, including side-scan sonar operations, cable-laying, underwater search and salvage, drone aircraft recovery, platforms for robotic submarine operations and numerous support roles for other government agencies.
The ships have a special water jet system in the stern thruster which allows the ship to move in any direction without the use of propellers. This system was installed to protect the endangered manatee population that inhabits regions of the Banana River where the ships are based. The system also allows divers to work near the ship during operations at a greatly reduced risk.
Thanks to Alan Walters for getting up early this morning to capture these great, unique images.
I’ve now posted the answer in the original post.
The spectacular gravity of neutron stars offers great opportunities for thought experiments. For example, if you dropped an object from a height of 1 meter above a neutron star’s surface, it would hit the surface within a millionth of a second having been accelerated to over 7 million kilometers an hour.
But these days you should first be clear what kind of neutron star you are talking about. With ever more x-ray sensitive equipment scanning the skies, notably the ten year old Chandra space telescope, a surprising diversity of neutron star types are emerging.
The traditional radio pulsar now has a number of diverse cousins, notably magnetars which broadcast huge outbursts of high energy gamma and x-rays. The extraordinary magnetic fields of magnetars invoke a whole new set of thought experiments. If you were within 1000 kilometres of a magnetar, its intense magnetic field would tear you to pieces just from violent perturbation of your water molecules. Even at a safe distance of 200,000 kilometres, it will still wipe all the information off your credit card – which is pretty scary too.
Neutron stars are the compressed remnant of a star left behind after it went supernova. They retain much of that stars angular momentum, but within a highly compressed object only 10 to 20 kilometers in diameter. So, like ice skaters when they pull their arms in – neutron stars spin pretty fast.
Furthermore, compressing a star’s magnetic field into the smaller volume of the neutron star, increases the strength of that magnetic field substantially. However, these strong magnetic fields create drag against the stars’ own stellar wind of charged particles, meaning that all neutron stars are in the process of ‘spinning down’.
This spin down correlates with an increase in luminosity, albeit much of it is in x-ray wavelengths. This is presumably because a fast spin expands the star outwards, while a slower spin lets stellar material compress inwards – so like a bicycle pump it heats up. Hence the name rotation powered pulsar (RPP) for your ‘standard’ neutron stars, where that beam of energy flashing at you once every rotation is a result of the braking action of the magnetic field on the star’s spin.
It’s been suggested that magnetars may just be a higher order of this same RPP effect. Victoria Kaspi has suggested it may be time to consider a ‘grand unified theory’ of neutron stars where all the various species might be explained by their initial conditions, particularly their initial magnetic field strength, as well as their age.
It’s likely that the progenitor star of a magnetar was a particularly big star which left behind a particularly big stellar remnant. Thus, these rarer ‘big’ neutron stars might all begin their lives as a magnetar, radiating huge energies as its powerful magnetic field puts the brakes on its spin. But this dynamic activity means these big stars lose energy quickly, perhaps taking on the appearance of a very x ray luminous, though otherwise unremarkable, RPP later in their life.
Other neutron stars might begin life in less dramatic fashion, as the much more common and just averagely luminous RPPs, which spin down at a more leisurely rate – never achieving the extraordinary luminosities that magnetars are capable of, but managing to remain luminous for longer time periods.
The relatively quiet Central Compact Objects, which don’t seem to even pulse in radio anymore, could represent the end stage in the neutron star life cycle, beyond which the stars hit the dead line, where a highly degraded magnetic field is no longer able to apply the brakes to the stars’ spin. This removes the main cause of their characteristic luminosity and pulsar behaviour – so they just fade quietly away.
For now, this grand unification scheme remains a compelling idea – perhaps awaiting another ten years of Chandra observations to confirm or modify it further.
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Here’s a gallery of images from the last scheduled launch of space shuttle Atlantis, taken by Universe Today photographer Alan Walters (check out his website!), writer Ken Kremer, and a few from NASA. It was a beautiful day and a beautiful launch. But was it really Atlantis’ last? Only time will tell, but for now enjoy these great images.
For larger versions of the NASA images, see the STS-132 gallery on NASA’s Human Spaceflight website. We’ll keep you updated on the status of the mission.
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Earth isn’t the only place we’re seeing volcanic ash these days. New high resolution color images from ESA’s Mars Express of Meridiani Planum on Mars – the Opportunity rover’s neighborhood — shows evidence of volcanic ash in a small impact crater that is about 50 km wide. The wind-blown dark material also provides clues to the prevailing wind direction in this region of Mars. These images are stunning, especially in the large hi-resolution versions, so click on each image to see Mars up close and personal.
Mars is only about one-half the size of Earth, but yet has several volcanoes larger than anything we have on our home planet. The most massive volcanoes are located on huge uplifts or domes in the Tharsis and Elysium regions of Mars. Meridiani Planum lies close to Tharsis, and is a large plain at the northern edge of the southern highlands of Mars.
Poking through the dark covering are small mounds, probably made of harder, more resistant material. The softer material around them has been eroded and blown out of the crater by north-easterly winds and now lies outside the crater, forming dark streaks at the bottom left of the image.
This dark crater is close to Mars’ equator, and early on this area was chosen as a central reference point for Mars’ geographical coordinate system, so the martian prime meridian runs right through here. Hence the name “Meridiani.”
Meridiani Planum extends 127 km by 63 km and covers an area of roughly 8000 sq km
Three craters stretch across Meridiani Planum, as seen in this image. The nearest is an old crater, almost worn away. It is 34 km across. The second is covered in dark material, most likely a substance resembling volcanic ash. It is 50 km wide. The third crater, more distant, is smaller at 15 km wide. Again it possesses a dark floor, perhaps because material from the largest crater has been blown out by the wind and has settled in the smallest one.
The image below gives a broader perspective of the area. The color images were actually taken in 2005 and were just recently released by ESA.
Atlantis launched successfully, and beautifully, on its final scheduled voyage to space Friday at 2:20 pm EDT (1820 GMT). The shuttle and its six astronauts will deliver 3,000 pounds of U.S. supplies, including food and laptop computers to the International Space Station. and — for the first (at last) time — bring a Russian module to the station. The 12-day mission will include 3 spacewalks for that will focus on storing spare components outside the station, including six batteries, a communications antenna and parts for the Canadian Dextre robotic arm.
But will it be the final flight of Atlantis? “We like to call this the first last flight of Atlantis,” said commander Ken Ham in a preflight news conference. Since Atlantis will be ready to go as a rescue ship for the currently schedule final flight of the shuttle program (for the post-Columbia Launch On Need mission), many have said it should be flown.
Continue reading “Atlantis Launches Successfully on Last Scheduled Flight (Video)”