This graphic portrays the sequence of key events in August 2012 from the time the NASA's Mars Science Laboratory spacecraft, with its rover Curiosity, enters the Martian atmosphere to a moment after it touches down on the surface. Image credit: NASA/JPL-Caltech/Malin Space Science Systems
[/caption]
Now THIS is what I call “must-see TV!” A camera on the next Mars Rover — MSL, also known as Curiosity – will start recording high-definition video about two minutes before the rover lands on Mars, currently scheduled for August 2012. The Mars Descent Imager, or MARDI, will provide all of us Martian-wannabes with the first-ever ride along with the landing — and this will be a very unique landing, with the “Sky –Crane” lowering Curiosity to the planet’s surface. The video won’t be live, however – that’s way too much data for the spacecraft to send back to Earth at such an important event, but we will get to see it later. JPL provided a description of what the video should look like:
This Mars Descent Imager (MARDI) camera will fly on the Curiosity rover of NASA's Mars Science Laboratory mission. Image credit: NASA/JPL-Caltech/Malin Space Science Systems
MARDI will start recording high-resolution video about two minutes before landing in August 2012. Initial frames will glimpse the heat shield falling away from beneath the rover, revealing a swath of Martian terrain below illuminated in afternoon sunlight. The first scenes will cover ground several kilometers (a few miles) across. Successive images will close in and cover a smaller area each second.
The full-color video will likely spin, then shake, as the Mars Science Laboratory mission’s parachute, then its rocket-powered backpack, slow the rover’s descent. The left-front wheel will pop into view when Curiosity extends its mobility and landing gear.
The spacecraft’s own shadow, unnoticeable at first, will grow in size and slide westward across the ground. The shadow and rover will meet at a place that, in the final moments, becomes the only patch of ground visible, about the size of a bath towel and underneath the rover.
Dust kicked up by the rocket engines during landing may swirl as the video ends and Curiosity’s surface mission can begin.
All of this, recorded at about four frames per second and close to 1,600 by 1,200 pixels per frame, will be stored safely into the Mars Descent Imager’s own flash memory during the landing. But the camera’s principal investigator, Michael Malin of Malin Space Science Systems, San Diego, and everyone else will need to be patient. Curiosity will be about 250 million kilometers (about 150 million miles) from Earth at that point. It will send images and other data to Earth via relay by one or two Mars orbiters, so the daily data volume will be limited by the amount of time the orbiters are overhead each day.
“We will get it down in stages,” said Malin. “First we’ll have thumbnails of the descent images, with only a few frames at full scale.”
Subsequent downlinks will deliver additional frames, selected based on what the thumbnail versions show. The early images will begin to fulfill this instrument’s scientific functions. “I am really looking forward to seeing this movie. We have been preparing for it a long time,” Malin said. The lower-resolution version from thumbnail images will be comparable to a YouTube video in image quality. The high-definition version will not be available until the full set of images can be transmitted to Earth, which could take weeks, or even months, sharing priority with data from other instruments.”
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.
June Land Surface Temperature Anomalies in degrees Celsius. Credit: NOAA
[/caption]
Was last month warm where you live? If so, you weren’t alone. According measurements taken by the National Oceanic and Atmospheric Administration (NOAA) June 2010 was the hottest June on record worldwide. But this is not a new trend, at least for this year. March, April, and May 2010 were also the warmest on record. This was also the 304th consecutive month with a global temperature above the 20th century average. The last month with below-average temperature was February 1985.
Here are some of the numbers:
* The combined global land and ocean average surface temperature for June 2010 was the warmest on record at 16.2°C (61.1°F), which is 0.68°C (1.22°F) above the 20th century average of 15.5°C (59.9°F). The previous record for June was set in 2005.
* The June worldwide averaged land surface temperature was 1.07°C (1.93°F) above the 20th century average of 13.3°C (55.9°F)—the warmest on record.
* It was the warmest April–June (three-month period) on record for the global land and ocean temperature and the land-only temperature. The three-month period was the second warmest for the world’s oceans, behind 1998.
* It was the warmest June and April–June on record for the Northern Hemisphere as a whole and all land areas of the Northern Hemisphere.
* It was the warmest January–June on record for the global land and ocean temperature. The worldwide land on average had its second warmest January–June, behind 2007. The worldwide averaged ocean temperature was the second warmest January–June, behind 1998.
* Sea surface temperature (SST) anomalies in the central and eastern equatorial Pacific Ocean continued to decrease during June 2010. According to NOAA’s Climate Prediction Center, La Niña conditions are likely to develop during the Northern Hemisphere summer 2010.
Some regions on the planet, however, had cool temps for a northern hemisphere summer. Spain had its coolest June temperatures since 1997, and Guizhou in southern China had its coolest June since their records began in 1951.
Still, with those cool temperatures, the planet on the whole was warmer.
Arctic sea ice extent for June 2010 was 10.87 million square kilometers (4.20 million square miles). Credit: NSIDC
Other satellite data from the US National Snow and Ice Data Center in Colorado shows that the extent of sea ice in the Arctic was at its lowest for any June since satellite records started in 1979. The ice cover on Arctic Ocean grows each winter and shrinks in summer, reaching its annual low point in September. The monthly average for June 2010 was 10.87 km sq. The ice was declining an average of 88,000 sq km per day in June. This rate of decline is the fastest measured for June.
During June, ice extent was below average everywhere except in the East Greenland Sea, where it was near average.
The VSS Enterprise's first crewed flight on July 15, 2010. Credit: Virgin Galactic.
For the first time, Virgin Galactic’s SpaceShipTwo, named the Enterprise, flew with crew on board. While it stayed attached to the “Eve” mothership for the duration of the July 15 flight, Scaled Composites – the builders of the spacecraft – called the flight a “significant milestone as the team marches towards the first solo flights.” Numerous combined vehicle systems tests were conducted, as two crew members on board VSS Enterprise evaluated all of the spaceship’s systems and functions from end to end in the air, and all objectives were achieved.
[/caption]
This was the third time the Enterprise had flown in its “captive carry” configuration, but the first time with crew on board. It was the 33rd flight for WhiteKnightTwo, also known as Eve. The flight time was 6 hours 12 minutes.
The crew on the Enterprise was Peter Siebold, Michael Alsbury, and on board Eve were Mark Stucky, Peter Kalogiannis, and Brian Maisler.
SpaceShipTwo can fly up to eight people (six passengers and two pilots) on suborbital flights that would provide a weightless experience for 4-6 minutes. Will Whitehorn, president of Virgin Galactic, has stated that the company would “not put a definite timeline on when the commercial flights would begin” but if all goes according to plan they hope to make their first passenger flights in 2011. Tickets are on sale for $200,000 per person.
Concept for a lunar elevator. Credit: Liftport, courtesy Michael Laine
[/caption]
The idea of a space elevator has been around since the late 1800’s, but despite big dreams and years of research, the low-cost, easy access to orbit that a space elevator promises is likely still decades away. The biggest problem rests on the fact that no one has been able to successfully manufacture long ribbons made of ultra-light, ultra-strong carbon nanotubes, the only known material that is strong enough for a space elevator. But entrepreneur Michael Laine believes a lunar elevator – a space elevator from the surface of the Moon – could be created with materials that are available now. With more research and the right amount of capital, Laine says a lunar elevator could be built within a decade.
While Laine said he is still “emotionally very invested” in the concept of a space elevator based on Earth, for now he has shifted his focus to the lunar elevator. “There was a question of where was I going to put my time,” he told Universe Today, “and being able to do this soon – perhaps within 5-7 years and not some mythic 15-25 years in the future is enticing.”
Since the Moon’s gravity is only one sixth that of Earth, it drastically reduces the requirements of the ribbon. A material that is available now, a synthetic polymer material called Zylon (poly(p-phenylene-2,6-benzobisoxazole) which has high strength and excellent thermal stability, could be used.
Additionally, the components to build the elevator that would be sent to the Moon would be relatively lightweight, so a smaller rocket would do the job. “The physical requirements of the system look like you could use a standard Atlas or Delta rocket to launch the components.” Laine said. “That’s a big deal that you don’t need to build something like a Saturn V.”
While Laine said he believes a lunar elevator in 5-7 years is feasible, he didn’t want to go on record as saying it could be built in such a short time frame without adding some major caveats.
The biggest hurdle could be getting access to the 6 cubic meters of the Zylon material. “That actually could be the biggest challenge,” Laine said.
Additionally, there are still an untold amount of unknowns about building such a system. “I used to say for the space elevator that we still didn’t know all the questions, let alone the answers,” Laine said, “and that is even more true for the lunar elevator.”
The other hurdle is money. But a lunar elevator might actually be cheaper to build, initially, than a space elevator from Earth. Artists concept of a space elevator. Credit: Caltech
An Earth-based elevator is essentially a long cable – perhaps 100,000km (62,000 miles) long — that is anchored on Earth at one end with a counterweight at the other end (a large satellite, for example) in (beyond) geosynchronous orbit. Gravity and centripetal acceleration keeps the cable, or ribbon rigid and a small elevator, or “Lifter,” can move up the elevator at a fraction of the energy and financial expenditure of launching an object into orbit. Once the elevator is built, using the elevator to put things in orbit could cost hundreds of dollars per pound, versus the $7,000 per pound it takes to launch satellites with the space shuttle.
A lunar elevator would use a ribbon at least 50,000 kilometers (31,000 miles) long extending through the Earth-Moon L1 LaGrange point from an anchor point near the center of the visible part of Earth’s moon. A smaller Atlas or Delta rocket could send the components the L1 point, and the Zylong ribbon would be spooled from that point towards the Moon and the Earth.
“You would use the Atlas hardware as part of your counter weight,” said Laine. “But that’s a very small counterweight, which means that your cargo that you are taking up and down from the Moon is going to be small. This is not like the Earth elevator where you were going to be putting 100 tons a week into space. This is a very small system, capable of transporting 200-250 kilos.” One concept of a lunar space elevator. Credit: Star Technology and Research, Inc./Jerome Pearson
But to put that in perspective, Laine said, the entire sample return system for the Japanese Hayabusa probe that recently returned from an asteroid was only about 20 kilos.
And that’s what Laine has in mind for the first lunar elevator: a sample return mission. “It would be a lunar sample return mission within the next 5-7 years, for what we think is a pretty reasonable price,” he said.
Once the initial ribbon is up and running, Laine said you could send up more ribbon to strengthen it, using same concepts for the Earth elevator, such as multiple stages of construction and ribbons that are added to it.
Of course, none of this – including the money – is trivial. Although the first string might be less expensive than an Earth elevator, additional construction of the lunar elevator would be fairly expensive, and take more time compared to the Earth elevator. “Once the first string on the Earth elevator is built, you work from the bottom and go up, whereas on the lunar elevator you’ll have to send it from Earth. So that part starts adding up in a hurry,” Laine said. “We don’t have a complete estimate on price yet but an Atlas or Delta, that is a known and reasonable price tag. We’re not talking about billions and billions of dollars here — maybe hundreds of millions — but not billions.”
Still, he has a vision and a plan.
“It is not a flag and footprints vision of going to the Moon,” Laine said, “but it goes to the heart of the new NASA budget and focus of developing technologies and infrastructure so that things can happen. And that’s what we hope we can do by developing this ribbon. And then we jumpstart the process of creating an outpost or a research lab. We’ve played with the idea of using the counterweight at the end and using a habitat, something like a Bigelow (Laine stressed he hasn’t talked with the Bigelow people yet about this) and if we could tie a couple of modules together they would make a great counterweight and that puts you in an interesting position. Some people don’t think going to the Moon is worthwhile if you are going to Mars, but a lot of people think a fuel depot makes sense. We could be a great fuel depot for some of those long duration missions because we want that extra mass. In the Earth elevator, the counterweight is basically dead mass. For the lunar elevator, it becomes a working environment. So some people go to the modules, some people go to the Moon, some people go to Mars using this as a refueling and construction station. Once it is up and running you have safe reliable access to the moon, for the price of a Delta or an Atlas. That’s huge.”
But Laine said he doesn’t want to give anyone the impression that he and others interested in this concept have everything figured out. “We’ve studied this enough to know that it is feasible and interesting and likely to happen sooner rather than later, which is why we’re tackling it.”
So, Laine and a core group of space elevator enthusiasts are starting a series of workshops to discuss this concept and tackle some of the significant questions with anyone who is interested and who might have the brainpower and spirit to understand and undertake such a project.
The first workshop is July 29-August 1 in Seattle Washington. See this link for more information
“I’m a big believer in connecting with community, so if artists and musicians, want to come, that’s great,” Laine said. “Engineers, science guys, rocket guys would be helpful. But politicians and marketing people are equally important to answer the big questions of where we should focus our time and efforts.”
There is also a space elevator conference August 13-15 at the Microsoft Conference Center in Redmond, Washington. Find more details at this link.
Laine started a space elevator company in 2003, LiftPort, which fell to financial problems in 2007. He sees the lunar elevator as a possible rebirth for the company, which once had 14 full-time employees. “This is a renaissance project, a rising again,” he said. “I’m applying a lot of what I learned on the Earth elevator to this new vision. While tackling the Earth elevator, all my money came from real estate, and I had plenty of money for my needs. But this time is different. For us to build this thing we are going to have to earn our way.”
“But I think it could be phenomenally lucrative, too,” Laine continued. “We are going to make discoveries along the way that will lead to products and services that are not related to going to the Moon. We think there is a solid value proposition as part of this.”
Brown dwarf TWA 5B compared to Jupiter and the Sun. Although brown dwarfs are similar in size to Jupiter, they are much more dense and massive - between 13 and 80 Jupiter masses. Credit: chandra.harvard.edu
[/caption]
I feel a certain empathy for brown dwarfs. The first confirmed finding of one was only fifteen years ago and they remain frequently overlooked in most significant astronomical surveys. I mean OK, they can only (stifles laughter) burn deuterium but that’s something, isn’t it?
It has been suggested that a clever way of finding more brown dwarfs is in the radio spectrum. A brown dwarf with a strong magnetic field and a modicum of stellar wind should produce an electron cyclotron maser. Roughly speaking (something you can always depend on from this writer), electrons caught in a magnetic field are spun energetically in a tight circle, stimulating the emission of microwaves in a particular plane from the star’s polar regions. So you get a maser, essentially the microwave version of a laser, that would be visible on Earth – if we are in line of sight of it.
While the maser effect can probably be weakly generated by isolated brown dwarfs, it’s more likely we will detect one in binary association with a lessmass-challenged star that is capable of generating a more vigorous stellar wind to interact with the brown dwarf’s magnetic field.
This maser effect is also proposed to offer a clever way of finding exoplanets. An exoplanet could easily outshine its host star in the radio spectrum if its magnetic field is powerful enough.
So far, searches for confirmed radio emissions from brown dwarfs or orbiting bodies around other stars have been unsuccessful, but this may become achievable in the near future with the steadily growing resolution of the European LOw Frequency ARray (LOFAR), which will be the best such instrument around until the Square Kilometer Array (SKA) is built – which won’t be seeing first light before at least 2017.
Geometrically-challenged aliens struggling to make a crop circle? Nope, it's a component of the LOFAR low frequency radio telescope array. Credit: www.lofar.org
But even if we can’t see brown dwarfs and exoplanets in radio yet, we can start developing profiles of likely candidates. Christensen and others have derived a magnetic scaling relationship for small scale celestial objects, which delivers predictions that fit well with observations of solar system planets and low mass main sequence stars in the K and M spectral classes (remembering the spectral class mantra Old Backyard Astronomers Feel Good Knowing Mnemonics).
Using the Christensen model, it’s thought that brown dwarfs of about 70 Jupiter masses may have magnetic fields in the order of several kilo-Gauss in their first hundred million years of life, as they burn deuterium and spin fast. However, as they age, their magnetic field is likely to weaken as deuterium burning and spin rate declines.
Brown dwarfs with declining deuterium burning (due to age or smaller starting mass) may have magnetic fields similar to giant exoplanets, anywhere from 100 Gauss up to 1 kilo-Gauss. Mind you, that’s just for young exoplanets – the magnetic fields of exoplanets also evolve over time, such that their magnetic field strength may decrease by a factor of ten over 10 billion years.
In any case, Reiners and Christensen estimate that radio light from known exoplanets within 65 light years will emit at wavelengths that can make it through Earth’s ionosphere – so with the right ground-based equipment (i.e. a completed LOFAR or a SKA) we should be able to start spotting brown dwarfs and exoplanets aplenty.
Greetings, fellow SkyWatchers! Are you ready for a rock the night weekend? Then come along as you won’t need a telescope to watch the movement of the planets and the Perseid meteor shower heating up your evenings! If you’d still like a challenge, then why not chase bright asteroid Ceres with binoculars – or look up a challenging globular cluster? If you still need appeal, then there are a couple of great stars that are worth observing… and learning about! Whenever you’re ready, I’ll see you in the backyard….
July 16, 2010 – Today celebrates the 1746 birth of Giuseppe Piazzi. Although we know Piazzi best for his discovery of the asteroid Ceres, did you know he was also the first to notice that 61 Cygni had a large proper motion? Nine days and 38 years later, the man responsible for measuring 61 Cygni, Friedrich Bessel, was born.
This would indeed be a great evening to check out asteroid Ceres for yourself. You’ll find it in Ophiuchus and well placed for either binoculars or a small telescope just above the “sting” of the Scorpion! Here’s a map to help you along the way…
Now let’s take a look at gorgeous 61 Cygni. You’ll easily locate it between Deneb and Zeta on the eastern side. Look for a small trio of just visible stars and choose the westernmost (RA 21 06 54 Dec +38 44 44). Not only is it famous because of Piazzi and Bessel’s work, but it is one of the most noteworthy of double stars for a small telescope. Of the unaided visible stars, 61 is the fourth closest to Earth, with only Alpha Centauri, Sirius, and Epsilon Eridani closer. Just how close is it? Try right around 11 light-years.
Visually, the two components have a slightly orange tint, are less than a magnitude apart in brightness, and have a nice separation of around 30″ to the south-southeast. Back in 1792, Piazzi first noticed its abnormally large proper motion and dubbed it the ‘‘Flying Star.’’ At that time, it was only separated by around 10″, and the B star was to the northeast. It takes nearly seven centuries for the pair to orbit each other, but there is another curiosity here. Orbiting the A star around every 4.8 years is an unseen body that is believed to be about 8 times larger than Jupiter. A star—or a planet? With a mass considerably smaller than any known star, chances are good that when you view 61 Cygni, you’re looking toward a distant world!
July 17, 2010 – This date marks the 1904 passing of Isaac Roberts, an English astronomer who specialized in photographing nebulae. As an ironic twist, this is also the date on which a star was first photographed at Harvard Observatory!
Tonight let’s have a look at a real little powerpunch globular cluster located in northern Lupus—NGC 5824. Although it’s not an easy star hop, you’ll find it about 7 degrees southwest of Theta Librae, and exactly the same distance south of Sigma Librae (RA 15 03 58 Dec –33 04 04). Look for a 5th magnitude star in the finderscope to guide you to its position southeast.
A Class I globular cluster, you won’t find any others that are more concentrated than this. Holding a rough magnitude of 9, this little beauty has a deeply concentrated core region that is simply unresolvable. Discovered by E.E. Barnard in 1884, it enjoys its life in the outer fringes of its galactic halo about 104 thousand light-years away from Earth and contains many recently discovered variable stars.
Oddly enough, this metal-poor globular may have been formed by a merger. Research on NGC 5824’s stellar population leads us to believe that two less dense and differently aged globulars may have approached one another at a low velocity and combined to form this ultra-compact structure. Be sure to mark your observing notes on this one! It also belongs to the Bennett catalog and is part of many globular cluster lists.
July 17, 2010 – Celestial scenery alert! Are you watching the planet dance as Mars heads towards Saturn? You don’t need a telescope to enjoy the early evening trio of bright Venus along the western horizon – or the duet just above it! While you’re out enjoying a relaxing evening, keep your eyes on the skies. The early activity of the annual Perseid meteor shower is really heating up and you can expect to see several “shooting stars” an hour!
Tonight let’s begin with the 1689 birth of Samuel Molyneux. This British astronomer and his assistant were the first to measure the aberration of starlight. What star did they choose? Alpha Draconis, which oscillated with an excursion of 39’’ from its lowest declination in May. Why choose a single star during an early dark evening? Because Alpha Draconis—Thuban—is far from bright.
At magnitude 3.65, Thuban’s ‘‘alpha’’ designation must have come from a time when it, not Polaris, was the northern celestial pole star. If you’re aware that the two outer stars of the ‘‘dipper’’ point to Polaris, then use the two inner stars to point to Thuban (RA 14 04 23 Dec +64 22 33). This 300-light-year distant white giant is no longer main sequence, a rare binary type.
Now head to binary Eta Lupi, a fine double star resolvable with binoculars. You’ll find it by staring at Antares and heading due south two binocular fields to center on bright H and N Scorpii— then one binocular field southwest. Now hop 5 degrees southeast (RA 16 25 18 Dec –40 39 00) to encounter the fine open cluster NGC 6124. Discovered by Lacaille, and known as object I.8, this 5th magnitude open cluster is also Dunlop 514, Melotte 145, and Collinder 301. Situated about 19 light years away, it shows a fine, round, faint spray of stars to binoculars and is resolved into about 100 stellar members to larger telescopes. AlthoughNGC6124 is low for northern observers, it’s worth the wait to try at culmination. Be sure to mark your notes because this delightful galactic cluster is also a Caldwell object and counts for a southern skies binocular award.
Until next week? Keep capturing photons!
This week’s awesome images are (in order of appearance): 61 Cygni, NGC 5824, Alpha Draconis and NGC 6124 are from Palomar Observatory, courtesy of Caltech. Maps are courtesy of “Your Sky”. We thank you so much!
A part of a Herschel/HIFI spectral scan (the white curve) overlaid on a background Spitzer Space Telescope image (ESA/HIFI/HEXOS/E. Bergin).
Love to read science papers? Here’s a batch that will keep you busy for a while. 152 papers were released this morning highlighting the Herschel telescope’s first science results. A few papers describe the observatory and its instruments, and the rest are dedicated to observations of many astronomical targets from bodies in the Solar System to distant galaxies. Herschel is the only space observatory to cover a spectral range from the far infrared to sub-millimeter, so there’s a wide range of objects and topics covered, including star formation, galaxy evolution, and cosmology.
And you thought you’d have nothing to do this weekend!
The July 11, 2010 solar eclipse, as seen on Easter Island. Credit: Jonathan Doochin & Michael Doochin
[/caption]
On July 11, 2010, the new moon passed directly in front of the sun, causing a total solar eclipse. The path of totality stretched across the South Pacific Ocean, and the Moon’s umbral shadow didn’t make landfall except for a few spots; Mangaia (Cook Islands) and Easter Island (Isla de Pascua), southern Chile and Argentina, with a partial eclipse visible from a much larger region covering the South Pacific and southern South America. On hand to witness the event at Easter Island were Jonathan and Michael Doochin, who graciously shared several of the images included here. You can also check out Jonathan’s Twitpic page for more pictures of the eclipse as seen on Easter Island.
A composite image of SOHO and SDO data, plus an image taken by Jay Pasachoff's team from Williams College at Easter Island. Credits: Williams College Eclipse Expedition -- Jay M. Pasachoff, Muzhou Lu, and Craig Malamut; SOHO’s LASCO image courtesy of NASA/ESA; solar disk image from NASA’s SDO; compositing by Steele Hill, NASA's Goddard Space Flight Center.
In this image, the solar eclipse is shown in gray and white from a photo provided by the Williams College Expedition to Easter Island and was embedded with an image of the sun’s outer corona taken by the Large Angle Spectrometric Coronagraph (LASCO) on the SOHO spacecraft and shown in red false color. LASCO uses a disk to blot out the bright sun and the inner corona so that the faint outer corona can be monitored and studied. Further, the dark silhouette of the moon was covered with an image of the sun taken in extreme ultraviolet light at about the same time by the Atmospheric Imaging Assembly on the Solar Dynamics Observatory. The composite brings out the correlation of structures in the inner and outer corona.
29 minutes from totality on Easter Island. Credit: Jonathan Doochin & Michael DoochinScreenshot of a 'diamond ring' effect seen during a webcast from Easter Island.Cheese grater acting as a pin hole camera. Credit: Jonathan Doochin & Michael Doochin
Here you can see multiple eclipses; the team from Williams College used a cheese grater as a pinhole camera to view the eclipse.
The Moon moving off the sun following the eclipse, as seen on Easter Island. Credit: Jonathan Doochin & Michael DoochinRainbow over Easter Island before the eclipse. Credit: Jonathan Doochin & Michael Doochin
What an amazing sight this must have been — a rainbow formed in the skies over Easter Island as people were setting up their cameras for the eclipse event.
Astronomer Jay Pasachoff viewing the eclipse on Easter Island. Credit: Jonathan Doochin & Michael Doochin
Astronomer Jay Pasachoff, who has now witnessed 51 eclipses, was on Easter Island, and Jonathan Doochin captured this image of Pasachoff viewing the eclipse. See our preview article/interview with Pasachoff.
A double-ring basin named Rachmaninoff reveals young volcanism on Mercury. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
[/caption]
Younger volcanoes, stronger magnetic storms and a more intriguing exosphere: three new papers from data gathered during the MESSENGER spacecraft’s third flyby of Mercury in September of last year provide new insights into the planet closest to our Sun. The new findings make the science teams even more anxious for getting the spacecraft into orbit around Mercury. “Every time we’ve encountered Mercury, we’ve discovered new phenomena,” said principal investigator Sean Solomon. “We’re learning that Mercury is an extremely dynamic planet, and it has been so throughout its history. Once MESSENGER has been safely inserted into orbit about Mercury next March, we’ll be in for a terrific show.”
The closest look ever at some of Mercury’s plains suggests the planet’s volcanic activity lasted much longer than previously thought. From new images, researchers identified a 290-kilometer-diameter peak-ring impact basin, among the youngest to be observed on the planet. Named Rachmininoff, the region is characterized by exceptionally smooth, sparsely cratered plains, which formed later than the basin itself, likely from volcanic flow.
“We interpret these plains to be the youngest volcanic deposits yet found on Mercury,” said lead author Louise Prockter, from Johns Hopkins University Applied Physics Laboratory, one of MESSENGER’s deputy project scientists. “Moreover, an irregular depression surrounded by a diffuse halo of bright material northeast of the basin marks a candidate explosive volcanic vent larger than any previously identified on Mercury.
These observations suggest that volcanism on the planet spanned a much greater duration than previously thought, perhaps extending well into the second half of solar system history.”
A depression northeast of the basin is surrounded by a halo of bright mineral deposits, which Prockter and her team propose to be the largest volcanic vent identified on Mercury so far. Both of these findings mean that volcanism continued well into the second half of our Solar System’s history.
A double-ring basin named Rachmaninoff reveals young volcanism on Mercury. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
During the third fly-by, the team was able to take measurements of Mercury’s magnetic field, and this happened to occur during a time when the planet was being hit by a strong solar wind. MESSENGER’s Magnetometer documented for the first time the substorm-like build-up, or “loading,” of magnetic energy in Mercury’s magnetic tail. The tail’s magnetic field increased and decreased by factors ranging from two to 3.5 during very brief periods of just two to three minutes.
“The extreme tail loading and unloading observed at Mercury implies that the relative intensity of substorms must be much larger than at Earth,” said lead author James A. Slavin, a space physicist at NASA’s Goddard Space Flight Center and a member of MESSENGER’s Science Team. “However, what is even more exciting is the correspondence between the duration of tail field enhancements and the Dungey cycle time, which describes plasma circulation through a magnetosphere.”
Substorms on Earth are powered by similar processes—except that the loading of our planet’s magnetosphere is ten times weaker and occurs over the course of a full hour. Therefore, the team said, Mercury’s substorms must release more energy than terrestrial ones.
A third paper analyzed data from specialized instruments on-board the spacecraft to gain a clearer picture of Mercury’s neutral and ionic exospheres. Mercury’s exosphere is a tenuous atmosphere of atoms and ions derived from the planet’s surface and from the solar wind. Notable in the new observations were the differences in altitude of elements like magnesium, calcium, and sodium above the planet’s north and south poles. The team said this indicates that several processes are at work and that a given process may affect each element quite differently
“A striking feature in the near-planet tail ward region is the emission from neutral calcium atoms, which exhibits an equatorial peak in the dawn direction that has been consistent in both location and intensity through all three flybys,” said lead author Ron Vervack, also at the Applied Physics Laboratory. “The exosphere of Mercury is highly variable owing to Mercury’s eccentric orbit and the effects of a constantly changing space environment. That this observed calcium distribution has remained relatively unchanged is a complete surprise.”
