June 21st is an important day this year. Not only is it the summer solstice (that is to say, the longest day of the year in the northern hemisphere), but it is also one of the longest days ever in the history of the Earth. Not only is it one of the longest days ever, but it’s Father’s day!
My dad inspired me to become a scientist and astronomer. He is one of the most curious people I know; in fact, I guarantee that he will be one of the first people to read this article. Back when I lived in a suburb of Seattle filled with light pollution, he would enthusiastically break out his refracting telescope. From the end of our driveway, pointing away from that damn streetlight that would never turn off, we’d gaze upon Saturn and Jupiter. Continue reading “This Father’s Day is One of the Longest Days in the History of the Earth – Here’s Why”
In the outer Solar System, there are many worlds that are so large and impressive to behold that they will probably take your breath away. Not only are these gas/ice giants magnificent to look at, they are also staggering in size, have their own system a rings, and many, many moons. Typically, when one speaks of gas (and/or ice) giants and their moons, one tends to think about Jupiter (which has the most, at 67 and counting!).
But have you ever wondered how many moons Uranus has? Like all of the giant planets, it’s got rather a lot! In fact, astronomers can now account for 27 moons that are described as “Uranian”. Just like the other gas and ice giants, these moons are motley bunch that tell us much about the history of the Solar System. And, just like Jupiter and Saturn, the process of discovering these moons has been long and involved on multiple astronomers.
Oberon, as imaged by the Voyager 2 probe during its flyby on Jan. 24, 1986. Credit: NASA
In 1610, Galileo’s observed four satellites orbiting the distant gas giant of Jupiter. This discovery would ignite a revolution in astronomy, and encouraged further examinations of the outer Solar System to see what other mysteries it held. In the centuries that followed, astronomers not only discovered that other gas giants had similar systems of moons, but that these systems were rather extensive.
For example, Uranus has a system of 27 confirmed satellites. Of these, Oberon is the outermost satellite, as well as the second largest and second most-massive. Named in honor of a mythical king of fairies, it is also the ninth most massive moon in the Solar System.
Discovery and Naming:
Discovered in 1787 by Sir William Herschel, Oberon was one of two major satellites discovered in a single day (the other being Uranus’ moon of Titania). At the time, he reported observing four other moons; however, the Royal Astronomical Society would later determine that these were spurious. It would be almost five decades after the moons were discovered that an astronomer other than Herschel observed them.
Initially, Oberon was referred to as “the second satellite of Uranus”, and in 1848, was given the designation Uranus II by William Lassell. In 1851, Lassell discovered Uranus’ other two moons – later named Ariel and Miranda – and began numbering them based on their distance from the planet . Oberon was thus given the designation of Uranus IV.
Size comparison between the Earth, the Moon, and Uranus’ moon of Oberon. Credit: Tom.Reding/Public Domain
By 1852, Herschel’s son John suggested naming the moon’s his father observed Oberon and Titania, at the request of Lassell himself. All of these names were taken from the works of William Shakespeare and Alexander Pope, with the name Oberon being derived from the King of the Fairies in A Midsummer Night’s Dream.
Size, Mass and Orbit:
With a diameter of approx. 1,523 kilometers, a surface area of 7,285,000 km², and a mass of 3.014 ± 0.075 x 10²¹ kilograms, Oberon is the second largest, and second most massive of Uranus’ moons. It is also the ninth most massive moon in the solar system.
At a distance of 584,000 km from Uranus, it is the farthest of the five major moons from Uranus. However, this distance is subject to change, as Oberon has a small orbital eccentricity and inclination relative to Uranus’ equator. It has an orbital period of about 13.5 days, coincident with its rotational period. This means that Oberon is a tidally-locked, synchronous satellite with one face always pointing toward the planet.
Since (like all of Uranus’ moons) Oberon orbits the planet around its equatorial plane, and Uranus orbits the Sun almost on its side, the moon experiences a rather extreme seasonal cycle. Essentially, both the northern and southern poles spend a period of 42 years in complete darkness or complete sunlight – with the sun rising close to the zenith over one of the poles at each solstice.
Voyager 2:
So far, the only close-up images of Oberon have been provided by the Voyager 2 probe, which photographed the moon during its flyby of Uranus in January 1986. The images cover about 40% of the surface, but only 25% of the surface was imaged with a resolution that allows geological mapping.
In addition, the time of the flyby coincided with the southern hemisphere’s summer solstice, when nearly the entire northern hemisphere was in darkness. This prevented the northern hemisphere from being studied in any detail. No other spacecraft has visited the Uranian system before or since, and no missions to the planet are currently being planned.
Composition:
Oberon’s density is higher than the typical density of Uranus’ satellites, at 1.63 g/cm³. This would indicate that the moon consists of roughly equal proportions of water ice and a dense non-ice component. The latter could be made of rock and carbonaceous material including heavy organic compounds.
Spectroscopic observations have confirmed the presence of crystalline water ice in the surface of the moon. It is believed that Oberon, much like the other Uranian moons, consists of an icy mantle surrounding a rocky core. If this is true, then the radius of the core (480 km) would be equal to approx. 63% of the radius of the moon, and its mass would be around 54% of the moon’s mass.
False-color image of Oberon, showing the Hamlet and Othello craters (right of center and lower left) and the Mommur Chasma (upper left). Credit: USGS Astrogeology Research Program
Currently, the full composition of the icy mantle is unknown. However, it it were to contain enough ammonia or other antifreeze compounds, the moon may possess a liquid ocean layer at the core–mantle boundary. The thickness of this ocean, if it exists, would be up to 40 km and its temperature would be around 180 K.
It is unlikely that at these temperatures, such an ocean could support life. But assuming that hydrothermal vents exist in the interior, it is possible life could exist in small patches near the core. However, the internal structure of Oberon depends heavily on its thermal history, which is poorly known at present.
Interesting Facts:
Oberon is the second-darkest large moon of Uranus (after Umbriel), with a surface that appears to be generally red in color – except where fresh impact deposits have left neutral or slightly blue colors. In fact, Oberon is the reddest moon amongst its peers, with a trailing hemisphere that is significantly redder than its leading hemisphere.
The reddening of the surfaces is often a result of space weathering caused by bombardment of the surface by charged particles and micrometeorites over many millions of years. However, the color asymmetry of Oberon is more likely caused by accretion of a reddish material spiraling in from outer parts of the Uranian system.
Oberon’s surface is the most heavily cratered of all the Uranian moons, which would indicate that Oberon has the most ancient surface among them. Consistent with the planet’s name, these surface features are named after characters in Shakespearean plays. The largest known crater, Hamlet, measures 206 kilometers in diameter, while the Macbeth, Romeo, and Othello craters measure 203, 159, and 114 km respectively.
Uranus and its five major moons. Credit: space.com
Other prominent surface features are what is known as chasmata – steep-sided depressions that are comparable to rift valleys or escarpments here on Earth. The largest known chasmata on Oberon is the Mommur Chasma, which measures 537 km in diameter and takes its name from the enchanted forest in French folklore that was ruled by Oberon.
As you can plainly see, there is much that remains unknown about this satellite. Much like its peers, how they came to be, and what secrets may lurk beneath their surfaces, is still open to speculation. One can only hope that future generations will choose to mount another Voyager-like expedition to the Outer Solar System for the sake of studying the Uranian satellites.
An artist's conception of an Iridium-NEXT satellite in low Earth orbit. Credit: Iridium Communications Inc.
The skies, they are uh changin’… I remember reading in Astronomy magazine waaaay back in the late 1990s (in those days, news was disseminated in actual paper magazines) about a hot new constellation of satellites that were said to flare in a predictable fashion.
This is the Iridium satellite constellation, a series of 66 active satellites and six in-orbit and nine ground spares. The ‘Iridium’ name comes from the element with atomic number 77 of the same name (the original project envisioned 77 satellites in low Earth orbit), and the satellites serve users with global satellite phone coverage.
A ‘double Iridium flare’ capture! Image credit: Mary Spicer
Over the years, Iridium satellite flares have become a common sight in the night sky… but that may change soon.
Known as Iridium-NEXT, the first launch is set for October of this year from Dombarovsky air base Russia atop a converted ICBM Dnepr rocket. The Dnepr can carry two satellites on each launch, and SpaceX has also recently agreed to deploy 70 satellites over the span of seven missions launching from Vandenberg Air Force Base in California later this year.
Both the initial Iridium satellites and Iridium NEXT are operated by Iridium Communications Incorporated. The original satellites were built by Motorola and Lockheed Martin, and the prime contract for Iridium NEXT construction went to Thales Alenia Space.
There are also several fascinating issues surrounding the history of the Iridium constellation, both past and present.
Originally fielded by Motorola in the 1990s, satellite phones were to be “the next big thing” until mobile phones took over. Conceived in the late 1980s, the concept of satellite phones was practically obsolete before the first Iridium satellite got off the ground. The high cost of satellite phone services assured they could never manage to compete with the explosive growth of the mobile phone industry, and satellite phones at best only found niche applications for remote operations worldwide. Iridium Communications declared bankruptcy in 1999, and the $6 billion US dollar project was bought by a group of private investors for only $35 million dollars.
Airmen using an Iridium satellite phone in Antarctica. Image credit: Robert Tingle/USAF
The original Iridium constellation employed a unique system of Inter-Satellite Links, enabling them to directly route signals from satellite to satellite. Iridium NEXT will use an innovative L-band phased array antenna, allowing for larger bandwidth and faster data transmission. The Iridium NEXT constellation is planned to eventually contain 81 satellites including spares, and the system will be much more robust and reliable.
The Iridium NEXT constellation will also face some stiff competition, as Google, SpaceX and OneWeb are also looking to get into the business of satellite Internet and communications. This will also place hundreds of new satellites—not to mention the growing flock of CubeSats—into an already very crowded region of low Earth orbit. The Iridium 33 satellite collision with the defunct Kosmos 2251 satellite in 2009 highlighted the ongoing issues surrounding space debris.
The company applied for a plan to deorbit the original Iridium constellation starting in 2017 as soon as the new Iridium NEXT satellites are in place.
Now, I know what the question of the hour is, as it’s one that we get frequently from other satellite spotters and lovers of artificial things that flash in the sky:
Will the Iridium NEXT satellites flare in manner similar to their predecessors?
Unfortunately, the prospects aren’t good. Missing on Iridium NEXT are the three large refrigerator-sized antennae which are the source of those brilliant -8 magnitude flares. And sure, while these flares weren’t Iridium’s sole mission purpose, they were sure fun to watch!
An ‘Iridium classic…’ note the trio of reflective antennae on the lower bus. Image credit: Iridium Communications inc.
David Cubbage, Associate Director of NEXT Spacecraft Development and Satellite Production recently told Universe Today:
“It was very exciting when we first discovered that the Iridium Block 1 satellite vehicles (SVs) reflected the sunlight into a concentrated “flare” that could be viewed in the night sky. The unique design of the Block 1 SV, with three highly reflective Main Mission Antennas (MMA) deployed at an angle from the SV body, is what caused that to happen. For the Iridium NEXT constellation, the SVs will be built under a different design with a single MMA that faces the Earth — a design that requires fewer parts that do not need to be as reflective. As a result, it will not likely produce the spectacular flares of the Block 1 design.”
But don’t despair. Though the two decade ‘Age of the Iridium flare’ may be coming to an end, lots of other satellites, including the Hubble Space Telescope, MetOp-A and B, and the COSMO-SkyMed series of satellites can ‘slow flare’ on occasion. We recently saw something similar during a pass of the U.S. Air Force’s super-secret ATV-4 space plane currently carrying out its OTV-4 mission, suggesting that a large reflective solar panel may be currently deployed.
An Iridium flare passing through the constellations Orion and Lepus. Image credit: David Dickinson
And though the path to commercial viability for satellite internet and communications is a tough one, we hope it does indeed take off soon… we personally love the idea of being able to stay connected from anywhere worldwide.
Be sure to catch those Iridium flares while you can… we’ll soon be telling future generations of amateur astronomers that we remember “back when…”
-Check out the chances for the next Iridium flare coming to a sky near you on Heavens-Above.
Comet C/2013 US10 Catalina imaged on June 22nd, 2013. Image credit and copyright: Efrain Morales
Live in (or planning on visiting) the southern hemisphere soon? A first time visitor to the inner solar system is ready to put on the first of a two part act starting this month, as Comet C/2013 US10 Catalina breaks +10th magnitude and crosses southern hemisphere skies.
Discovered by the Catalina Sky Survey on Halloween 2013, the comet received its unusual ‘US10’ designation as it was initially thought to be an asteroid early on in a periodic six year orbit, until a longer observation arc was completed. This is not an unusual situation, as new objects are often lost in the Sun’s glare before their orbit can be refined.
Recent images of US10 Catalina from May 18th, 2015. Image credit and copyright: Joseph Brimacombe
We now know that US10 Catalina is on a million year long journey from the distant Oort Cloud. Most likely, it was disturbed by an unrecorded close stellar passage long ago. We say that such comets are dynamically new, and this passage will eject US10 Catalina from the solar system. The comet also has a highly inclined orbit tilted almost 149 degrees relative to the ecliptic, and was at +19th magnitude and 7.7 AU from the Earth when it was discovered, suggesting an intrinsically bright comet.
Prospects for US10 Catalina currently favor latitude 35 degrees north southward in late June, though that’ll change radically as the comet makes the plunge south this summer. As of this writing, US10 Catalina was at +11 magnitude ‘with a bullet’ and currently sits in the constellation Sculptor at a declination -30 degrees in the southern sky.
The orbit of Comet US10 Catalina. Image credit: NASA/JPL
Binoculars are our favorite tools for observing comets, as they’ve easy to sweep the skies with on our cometary quest. As with nebulae and deep sky objects, keep in mind that quoted magnitude for a comet is spread out over its apparent surface area, causing them to appear fainter than a star of the same magnitude.
Here’s a blow-by-blow for Act I for Comet C/2013 US10 Catalina over the next few months:
(Unless otherwise noted, we documented stellar passages below that are within 2 degrees of stars brighter than +5th magnitude, and fine NGC deep sky objects brighter than +8th magnitude)
July 1st: May break binocular visibility, at +10th magnitude.
July 6th: Crosses into the constellation of Phoenix.
July 23rd: Crosses into the constellation Grus.
July 25th: Crosses into the constellation Tucana.
July 26th: Passes the +4th magnitude star Gamma Tucanae.
The path of Comet US10 Catalina as seen from 30 degrees south. Image credit: Created using Starry Night Education software
August 1st: Reaches opposition.
August 2nd: Passes the +4.5th magnitude star Delta Tucanae.
August 4th: Crosses into the constellation Indus.
August 6th: Photo op: Passes 12 degrees from 47 Tucanae and the Small Magellanic Cloud.
August 8th: Crosses into the constellation Pavo.
August 12th: Passes the +4th magnitude star Epsilon Pavonis.
August 14th: Reaches its greatest declination south at almost -74 degrees.
August 15th: Sits at 1.1 AU from the Earth.
August 17th: Crosses into the constellation Apus.
August 19th: Passes 5 degrees from the +7.7 magnitude globular cluster NGC 6362.
August 22nd: Crosses into the constellation Triangulum Australe and passes the +1.9 magnitude star Atria.
August 28th: Passes the +2.8 magnitude star Beta Trianguli Australis.
August 29th: Passes 3 degrees from the +5th magnitude open cluster NGC 6025.
September 1st: Crosses into the constellation Circinus
The passage of Comet US10 Catalina through the southern sky from mid-June through September 1st. Image credit: Starry Night Education software
From there, Comet US10 Catalina heads towards perihelion 0.8229 astronomical units from the Sun on November 15th, before vaulting up into the northern hemisphere sky in the early dawn. Like Comet Q2 Lovejoy last winter, US10 Catalina should top out at around +4th magnitude or so as it glides across the constellation Ursa Major just after New Years.
And like many comets, the discriminating factor between a ‘great’ and ‘binocular comet’ this time around is simply a matter of orbital geometry. Had C/2013 US10 Catalina arrived at perihelion in the May time frame, it would’ve passed less than 0.2 AU (30 million kilometres) from the Earth!
The projected light curve for Comet US10 Catalina. The black dots denote actual observations, and the purple vertical line marks the perihelion passage for the comet. Image credit: Seiichi Yoshida’s Weekly Information about Bright Comets
But that’s cosmic irony for you. Keep in mind, with Comet US10 Catalina being a dynamically new first time visitor to the inner solar system, it may well up brighten ahead of expectations.
And there’s more to come… watch for Act II as we follow the continuing adventures of Comet C/2013 US10 Catalina this coming September!
The Mir space station hangs above the Earth in 1995 (photo by Atlantis STS-71, NASA)
The Mir Space Station was Russia’s greatest space station, and the first modular space station to be assembled in orbit. Commissioned in 1986, the name can be translated from Russian as “peace”, “world”, and even “village” – alluding to the spirit of international cooperation that led to its creation. Owned and operated by the Soviet Union, it became the property of the Russian Federal Space Agency (Roscosmos) after 1991.
The space station was intended to advocate world peace and hosted international scientists and NASA astronauts. In this respect, Mir was very much the curtain-raiser for the International Space Station, which succeeded it as the largest satellite in Earth’s orbit after 2001.
Origin:
During the 1960s and 70s, when the United States was largely focused on Apollo and the Space Shuttle program, Russia began to focus on developing expertise in long-duration spaceflight, and felt that a larger space station would allow for more research in that area. Authorized in February 1976 by a government decree, the station was originally intended to be an improved model of the Salyut space stations.
The original plan called for a core module that would be equipped with a total of four docking ports, but eventual grew to include several ports for crewed Soyuz spacecraft and Progress cargo spaceships. By August 1978, the plan had grown to the final configuration of one aft port and five ports in a spherical compartment at the forward end of the station.
The Mir Space Station and Earth limb observed from the Orbiter Endeavour during NASA’s STS-89 mission in 1998. Credit: NASA
Two would be located at either end of the station (as with the Salyut stations) with an additional two on either side of a docking sphere at the front of the station to enable further modules to expand the station’s capabilities. These docking ports would each accommodate 20-tonne space station modules based on the TKS spacecraft – a previous generation of space craft used to bring cosmonauts and supplies to the Salyut space stations.
Work began on the station in 1979, and drawings were released in 1982 and 83. By early 1984, work had ground to a halt as virtually all of Russia’s space resources were being put into the Buran program – a Soviet and later Russian reusable spacecraft project. Funding resumed in early 1984 when the Central Committee became determined to orbit Mir by early 1986, just in time for the 27th Communist Party Congress.
Deployment:
On February 19th, 1986, the assembly process began with the launching of Mir’s core module on a Proton-K rocket into orbit. Between 1987 and 1996, four of the six modules were launched and added to the station – Kvant-2 in 1989, Kristall in 1990, Spektr in 1995 and Priroda in 1996. In these cases, the modules were sent into orbit aboard a Proton-K, chased the station automatically, and then used their robot Lyappa arms to mate with the core.
Soviet/Russian space station Mir, after completion in 1996. The date shown for each module is its year of launch. Credit: Encyclopedia Britannica
Kvant-1, having no engines of its own, was delivered by a TKS spacecraft in 1987, while the docking module was brought to the station aboard Space Shuttle Atlantis (STS-74) in 1995. Various other external components, including three truss structures, several experiments and other unpressurized elements, were also mounted to the exterior of the station over the course of its history.
The station’s assembly marked the beginning of the third generation of space station design, being the first to consist of more than one primary spacecraft. First generation stations such as Salyut 1 and Skylab had monolithic designs, consisting of one module with no resupply capability, while second generation stations (Salyut 6 and Salyut 7) comprised a monolithic station with two ports to allow resupply cargo spacecraft (like Progress).
The capability of Mir to be expanded with add-on modules meant that each could be designed with a specific purpose in mind, thus eliminating the need to install all the station’s equipment in one module. After construction was finished, Mir had a collection of facilities. At 13.1 meters (43 feet) long, the “core” module of the station was the main area where the cosmonauts and astronauts did their work. It also housed the main computer and vital space station parts, such as communications.
In addition to solar arrays and a docking port, the station had several facilities for orbital science. These included, but were not limited to, the two Kvant modules (where astronomy and other scientific research was conducted), the Kristall module (which had a facility for microgravity manufacturing) and Spektr (focused on Earth work).
A view of the Russian space station Mir on 3 July 1993 as seen from Soyuz TM-17. Credit: spacefacts.de
Missions:
During its 15-year spaceflight, Mir was visited by a total of 28 long-duration, or “principal”, crews. Expeditions varied in length, but generally lasted around six months. Principal expedition crews consisted of two to three crew members, who often launched as part of one expedition but returned with another.
As part of the Soviet Union’s manned spaceflight program effort to maintain a long-term research outpost in space, operated by the new Russian Federal Space Agency after 1991, the vast majority of the station’s crew were Russian. However, through international collaborations, the station was made accessible to astronauts from North America, several European nations and Japan.
Collaborative programs included the Intercosmos, Euromir and Shuttle-Mir programs. Intercosmos, which ran from 1978-1988, involved astronauts from other Warsaw Pact Nations, other socialist nations – like Afghanistan, Cuba, Mongolia, and Vietnam – and pro-Soviet non-aligned nations such as India, Syria, and even France.
Euromir, which began in the 1990s, was a collaborative effort between the Russian Federal Space Agency and the European Space Agency (ESA) to bring European astronauts to the space station. With help provided by the NASA Space Shuttle program, the goal was to recruit and train European astronauts for the then-planned International Space Station.
Meanwhile, the Shuttle–Mir Program was a collaborative space program between Russia and the United States, and involved American Space Shuttles visiting the space station, Russian cosmonauts flying on the shuttle, and an American astronaut flying aboard a Soyuz spacecraft to engage in long-duration expeditions aboard Mir.
A view of the US Space Shuttle Atlantis and the Russian Space Station Mir during STS-71 as seen by the crew of Mir EO-19 in Soyuz TM-21. Credit: NASA
By the time of the station’s deorbit, it had been visited by 104 different people from twelve different nations, making it the most visited spacecraft in history (a record later surpassed by the International Space Station).
Decommissioning:
When it was launched in 1986, Mir was only supposed to have a life span of about five years, but it proved to have a greater longevity than anyone expected. Unfortunately, a series of technical and structural problems eventually caught up with the station; and in November 2000, the Russian government announced that it would decommission the space station.
This began on Jan. 24th, 2001, when a Russian Progress cargo ship rendezvoused with the station carrying twice its normal amount of fuel. The extra fuel was intended to fire the Progress’ thrusters once it had docked with Mir and push the station into a controlled descent through the Earth’s atmosphere.
The Russian government purchased insurance just in case the space station hit any populated area when it crashed to Earth. Luckily, the station ended up crashing into the South Pacific Ocean, landing about 2,897 kilometers from New Zealand. In 2001, former RKA General Director Yuri Koptev estimated that the cost of the Mir program to be $4.2 billion (including development, assembly and orbital operation).
Legacy:
The Mir Space Station endured for 15 years in orbit, three times its planned lifetime. It hosted scores of crew members and international visitors, raised the first crop of wheat to be grown from seed to seed in outer space, and served as a symbol of Russia’s past glories and it’s potential as a future leader in space exploration.
Jerry Linenger dons a mask during his mission on Mir in 1997. Credit: NASA
In addition, the station was a source of controversy over the years, due to the many accidents and hazards it endured. The most famous of these took place on February 24, 1997 during mission STS-81. On this occasion, which saw the Space Shuttle Atlantis delivering crew, supplies, and conducting a series of tests, the worst fire aboard an orbiting spacecraft broke out.
This caused failures in various on-board systems, a near collision with a Progress resupply cargo ship during a long-distance manual docking system test, and a total loss of station electrical power. The power failure also caused a loss of attitude control, which led to an uncontrolled “tumble” through space. Luckily, the crew managed to suppress the fire and regain control before long.
Another major incident took place on June 25th, when a Progress resupply ship collided with solar arrays on the Spektr module, creating a hole which caused the station to lose pressure. This was the first orbital depressurization in the history of spaceflight to take place. Luckily, no astronauts were lost while serving aboard the station.
Mir is also famous for hosting long-duration missions during its early years in space. Topping the list was Russian cosmonaut Valeri Polyakov, who spent nearly 438 days aboard Mir and landed on March 22, 1995. The station itself orbited the Earth more than 86,000 times during its lifespan, and was also the largest orbiting object in the Solar System.
But most importantly of all, Mir served as the stage for the first large-scale, technical partnership between Russia and the United States after a half-century of mutual antagonism. Without it, there would be no ISS today, and numerous joint-research efforts between NASA, the ESA, Russia, and other federal space agencies, would not have been possible.
A rayed crater on Ceres with a great deal of fresh material (ice?) exposed by impact. Credit: NASA
Those bright mystery spots aren’t the only ones on Ceres. Recent photos posted on JPL’s Photojournal sitefeature a spectacular rayed crater resembling the familiar lunar craters Kepler and Copernicus.
Unique view of the lunar crater Proclus showing an extension system of bright rays taken from Apollo 15. Credit: NASABright dots and patches of material are seen in this photo taken by Dawn on May 22, 2015 from 3,200 miles (5,100 km) away. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDATaken back on May 4 from 8,400 miles (13,600 km), this photo shows the rayed crater (bottom) and another bright spot above center. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Lunar rays are bright because they contrast with their older surroundings which have been darkened by exposure to solar and cosmic radiation. Impacts expose fresh material from below the surface that settles into a spider web of rays around the newly excavated crater. Huge boulders lofted above the Moon’s surface during the impact slam back into the crust to create secondary craters also crowned with bright dust and rock.
Based on Ceres’ density, it contains a large fraction of low density materials including clays, water ice, salts and organic compounds. This schematic gives a general idea of the dwarf planet’s makeup. Credit: NASA/ESA/STScI
Most models of Ceres depict a rocky crust, mantle of ice and a rocky inner core. This makes us wonder if the bright material unearthed might be ice. If so, it would gradually vaporize on the virtually air-free dwarf planet.
Dawn will spend through early 2016 at Ceres during its primary mission and then remain in orbit there perpetually. We should be able to cipher the composition of the white material during that time with the spacecraft’s Gamma Ray and Neutron Detector and Visible and Infrared Mapping Spectrometer, but a lengthy stay might allow us to see changes in the extent of any ice exposures as they gradually vaporize away.
Uncropped, untoned view of the rayed crater seen in the earlier image. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
One thing we know for certain about Ceres are its dimensions. Dawn observations have revised the size to be about 599 miles (963 km) across at the equator with a polar diameter of 554 miles (891 km). Like Earth and other planets, Ceres is a slightly flattened sphere wider at the equator than from pole to pole. The temperature there ranges from about -100°F (-73°C) during the day and dips to -225°F (-143°C) at night. That makes its daytime high about 28° warmer than coldest temperature ever recorded on Earth.
The Milky Way glitters above the ALMA array in this image taken from a time lapse sequence during the ESO Ultra HD Expedition.
This article is a guest post by Anna Ho, who is currently doing research on stars in the Milky Way through a one-year Fulbright Scholarship at the Max Planck Institute for Astronomy (MPIA) in Heidelberg, Germany.
In the Milky Way, an average of seven new stars are born every year. In the distant galaxy GN20, an astonishing average of 1,850 new stars are born every year. “How,” you might ask, indignant on behalf of our galactic home, “does GN20 manage 1,850 new stars in the time it takes the Milky Way to pull off one?”
To answer this, we would ideally take a detailed look at the stellar nurseries in GN20, and a detailed look at the stellar nurseries in the Milky Way, and see what makes the former so much more productive than the latter.
But GN20 is simply too far away for a detailed look.
This galaxy is so distant that its light took twelve billion years to reach our telescopes. For reference, Earth itself is only 4.5 billion years old and the universe itself is thought to be about 14 billion years old. Since light takes time to travel, looking out across space means looking back across time, so GN20 is not only a distant, but also a very ancient, galaxy. And, until recently, astronomers’ vision of these distant, ancient galaxies has been blurry.
Consider what happens when you try to load a video with a slow Internet connection, or when you download a low-resolution picture and then stretch it. The image is pixelated. What was once a person’s face becomes a few squares: a couple of brown squares for hair, a couple of pink squares for the face. The low-definition picture makes it impossible to see details: the eyes, the nose, the facial expression.
A face has many details and a galaxy has many varied stellar nurseries. But poor resolution, a result simply of the fact that ancient galaxies like GN20 are separated from our telescopes by vast cosmic distances, has forced astronomers to blur together all of this rich information into a single point.
The situation is completely different here at home in the Milky Way. Astronomers have been able to peer deep into stellar nurseries and witness stellar birth in stunning detail. In 2006, the Hubble Space Telescope took this unprecedentedly detailed action shot of stellar birth at the heart of the Orion Nebula, one of the Milky Way’s most famous stellar nurseries:
A detailed close-up of stellar birth. Credit: NASA,ESA, M. Robberto (Space Telescope Science Institute/ESA) and the Hubble Space Telescope Orion Treasury Project Team
There are over 3,000 stars in this image: The glowing dots are newborn stars that have recently emerged from their cocoons. Stellar cocoons are made of gas: thousands of these gas cocoons sit nestled in immense cosmic nurseries, which are rich with gas and dust. The central region of that Hubble image, encased by what looks like a bubble, is so clear and bright because the massive stars within have blown away the dust and gas they were forged from. Majestic stellar nurseries are scattered all over the Milky Way, and astronomers have been very successful at uncloaking them in order to understand how stars are made.
Observing nurseries both here at home and in relatively nearby galaxies has enabled astronomers to make great leaps in understanding stellar birth in general: and, in particular, what makes one nursery, or one star formation region, “better” at building stars than another. The answer seems to be: how much gas there is in a particular region. More gas, faster rate of star birth. This relationship between the density of gas and the rate of stellar birth is called the Kennicutt-Schmidt Law. In 1959, the Dutch astronomer Maarten Schmidt raised the question of how exactly increasing gas density influences star birth, and forty years later, in an illustration of how scientific dialogues can span decades, his American colleague Robert Kennicutt used data from 97 galaxies to answer him.
Understanding the Kennicutt-Schmidt Law is crucial for determining how stars form and even how galaxies evolve. One fundamental question is whether there is one rule that governs all galaxies, or whether one rule governs our galactic neighborhood, but a different rule governs distant galaxies. In particular, a family of distant galaxies known as “starburst galaxies” seems to contain particularly productive nurseries. Dissecting these distant, highly efficient stellar factories would mean probing galaxies as they used to be, back near the beginning of the universe.
Enter GN20. GN20 is one of the brightest, most productive of these starburst galaxies. Previously a pixelated dot in astronomers’ images, GN20 has become an example of a transformation in technological capability.
In December 2014, an international team of astronomers led by Dr. Jacqueline Hodge of the National Radio Astronomy Observatory in the USA, and comprising astronomers from Germany, the United Kingdom, France, and Austria, were able to construct an unprecedentedly detailed picture of the stellar nurseries in GN20. Their results were published earlier this year.
The key is a technique called interferometry: observing one object with many telescopes, and combining the information from all the telescopes to construct one detailed image. Dr. Hodge’s team used some of the most sophisticated interferometers in the world: the Karl G. Jansky Very Large Array (VLA) in the New Mexico desert, and the Plateau de Bure Interferometer (PdBI) at 2550 meters (8370 feet) above sea level in the French Alps.
With data from these interferometers as well as the Hubble Space Telescope, they turned what used to be one dot into the following composite image:
GN20 in unprecedented detail (false color image). The 10 kpc (10,000 parsec) scale corresponds to 32,600 light-years. Image credit: Jacqueline Hodge et al. 2015
This is a false color image, and each color stands for a different component of the galaxy. Blue is ultraviolet light, captured by the Hubble Space Telescope. Green is cold molecular gas, imaged by the VLA. And red is warm dust, heated by the star formation it is shrouding, detected by the PdBI.
Unbundling one pixel into many enabled the team to determine that the nurseries in a starburst galaxy like GN20 are fundamentally different from those in a “normal” galaxy like the Milky Way. Given the same amount of gas, GN20 can churn out orders of magnitude more stars than the Milky Way can. It doesn’t simply have more raw material: it is more efficient at fashioning stars out of it.
Some of the 66 radio antennas of ALMA, which can be linked to act like a much larger telescope. Image credit: ALMA (ESO/NAOJ/NRAO)/B. Tafreshi (twanight.org)
This kind of study is currently unique to the extreme case of GN20. However, it will be more common with the new generation of interferometers, such as the Atacama Large Millimeter/submillimeter Array (ALMA).
Located 5000 meters (16000 feet) high up in the Chilean Andes, ALMA is poised to transform astronomers’ understanding of stellar birth. State-of-the-art telescopes are enabling astronomers to do the kind of detailed science with distant galaxies – ancient galaxies from the early universe – that was once thought to be possible only for our local neighborhood. This is crucial in the scientific quest for universal physical laws, as astronomers are able to test their theories beyond our neighborhood, out across space and back through time.
Philae may have woken up even earlier, but yesterday afternoon the lander contacted Earth for the first time since November. Credit: ESA
Fantastic news! Philae’s alive and kicking. The lander “spoke” with its team on ground via Rosetta for 85 seconds — its first contact since going into hibernation in November.
Signals were received at ESA’s European Space Operations Center in Darmstadt at 4:28 p.m. EDT yesterday June 13. The lander sent more than 300 data packets reporting on its condition as well as information about the comet.
“Philae is doing very well. It has an operating temperature of -35ºC (-31°F) and has 24 watts available,” said DLR Philae Project Manager Dr. Stephan Ulamec. “The lander is ready for operations.”
Philae spent two hours drifting above Comet 67P/C-G after its harpoons failed to anchor it to the surface. Credit: ESA
If coming out of hibernation isn’t surprising enough, it appears Philae has been awake for a while because it included historical data along with its current status in those packets. There are still more than 8000 data packets in Philae’s mass memory which will give the mission scientists information on what happened to the lander in the past few days on Comet 67P/C-G.
Philae went into hibernation on November 15, 2014 after running out of battery power. Credit: ESA
Philae shut down on November 15 after about 60 hours of operation on the comet after landing at the base of a steep cliff in a shaded area that prevented the solar panels from charging its batteries. Since March 12, the Rosetta lander has been “listening” for a signal from the lost lander.
First image taken by Philae after landing on Comet 67P/Churyumov-Gerasimenko on November 12, 2014 showing a steep cliff and one of the lander’s legs. Credit: ESA/ROSETTA/PHILAE/CIVA
Throughout, mission scientists remained hopeful that the comet’s changing orientation and increase in the intensity of sunlight as it approached perihelion would eventually power up the little lander. Incredible that it really happened.
Yesterday, we looked at the many attempts to find Philae. A day later it’s found us!
Both amateurs and professional astronomers across the world are in constant contact sharing observations of Comet 67P/C-G and news from the Rosetta mission. Klim Churyumov, co-discoverer of the comet, had this to say upon hearing the news of Philae’s awakening:
“Hurrah! Hurrah! Hurrah! Landing probe Philae awake! Everybody, please accept my sincere congratulations! It happened on 13 June 2015 in the day of birthday of my mother – Antonina Mikhailovna (108 years have passed since the day of her birth). And I’m starting from 13 November 2014 to this day, every morning pronounced a short prayer: “Lord, please wake Philae and support Rosetta”. God and the Professional Navigators woke Philae! It is fantastic! All the best! – Klim Churyumov.
How poignant Philae awoke on Klim’s mother’s birthday!
Padma Yanamandra-Fisher (left), Senior Research Scientist at the Space Science Institute, who runs the PACA site, and comet co-discoverer Klim Churyumov. Courtesy Padma Yanamandra-Fisher
Churyumov made his statement on the Pro-Am Collaborative Astronomy (PACA) site devoted to pro-amateur collaboration during comet observing campaigns. I encourage you to check out the group and participate by submitting your own observations of Comet 67P as it brightens this summer and early fall.
* UPDATE: In the coming days, the mission teams will reestablish contact with Philae and increase the amount of time it can “talk” with the lander. Once regular contact is established, science observations can begin again. Slowly. One instrument at a time.
The first instruments activated, those measuring temperature, magnetic fields and electrical conductivity on the comet, make small demands on Philae’s power. Slightly more power-hungry operations like picture taking and radio ranging will follow. Using the images and new data, scientists should be able to pinpoint the lander’s location.
After these steps, mission engineers will attempt to recharge the probe’s drained batteries to fire up its ovens (used to heat samples to determine their composition) and run the drill to collect fresh material.
Astronaut, engineer, author, and actor, Edwin “Buzz” Aldrin is what you might call a living legend. As the Lunar Module Pilot aboard the Apollo 11 mission, and second man to walk on the Moon, he is exceeded only by Neil Armstrong when it comes to the most famous astronauts that have ever lived.
And much like all astronauts who left an indelible mark on history, the path that brought Aldrin to the Moon began early in his life. And since achieving the dream of countless generations, he has gone on to inspire others to make similar leaps, advocating space exploration, and a mission to Mars.
Early Life: Born Edwin Eugene Aldrin on January 20th, 1930, in Montclair, New Jersey to a military family, Aldrin picked up his famous nickname from the younger of his two elder sisters. Unable to pronounce brother, he let her call him “buzzer”, which was eventually shortened to “Buzz”. During his childhood, Aldrin was also a boy scout, earning the rank of Tenderfoot Scout.
After graduating from high school, Aldrin wanted to follow in his father’s footsteps. As such, he turned down a scholarship to the Massachusetts Institute of Technology (MIT) and instead enrolled in the United States Military Academy at West Point, New York. He would later enroll at MIT to complete his studies, but not before going off to war.
Military Career:
Upon graduating in 1951 from West Point with a Bachelors of Science in Mechanical Engineering, Aldrin was commissioned as a 2nd Lieutenant in the United States Air Force. During the Korean War, he served as a jet fighter pilot, flying 66 combat missions in F-86 Sabres and shooting down two MiG-15 aircraft.
After the war, he was assigned as an aerial gunnery instructor at Nellis Air Force Base in Nevada before becoming a flight commander at Bitburg Air Base in West Germany, where he flew F-100 Super Sabres with the 22nd Fighter Squadron.
Buzz Aldrin in the cockpit of an F-86 Sabre while serving as part of the 16th FS, 51st FW, in Korea, 1953. Credit: openroadmedia.kinja.com
After completing his military service, Aldrin returned to MIT to receive his Doctor of Science degree in Aeronautics. In 1963, he was assigned to the Gemini Target Office of the Air Force Space Systems Division in Los Angeles, and began to pursue a career in space exploration. Initially, his application was rejected since he had never been a test pilot. However, that prerequisite was lifted when Aldrin re-applied, and he was accepted into the third group of astronauts in October of 1963.
Gemini Program:
Aldrin was initially selected to participate in the Gemini program, and after the deaths of the original Gemini 9 prime crew (Elliot See and Charles Bassett) Aldrin and Jim Lovell were promoted to backup crew for the mission. The main objective of the revised mission (Gemini 9A) was to rendezvous and dock with a target vehicle.
When this failed, Aldrin improvised an effective exercise for the craft to rendezvous with a co-ordinate in space. On his next mission – Gemini 12, which took place in 1966 – Aldrin served as the pilot and set a record for extra-vehicular activity (EVA), demonstrating that astronauts could work outside spacecraft.
Photograph of Major Edwin E. Aldrins helmet taken during the Gemini XII mission during orbit no. 14 on November 12,1966. Credit: NASA
Apollo 11:
As the Lunar Module Pilot of the Apollo 11 mission, Aldrin became the second astronaut to walk on the Moon on July 21st, 1969. Aldrin’s first words on the Moon were “Beautiful view. Magnificent desolation.” As a Presbyterian, Aldrin decided to hold a religious ceremony on the Moon, and became the first man to do so.
Using a home communion kit given to him, he reciting words used by his pastor at Webster Presbyterian Church (Rev. Dean Woodruff). The ceremony was not communicated back to Earth and was a private affair. However, after landing on the Moon, Aldrin radioed Earth and said:
I’d like to take this opportunity to ask every person listening in, whoever and wherever they may be, to pause for a moment and contemplate the events of the past few hours, and to give thanks in his or her own way.
In later years, Aldrin expressed some regret, thinking that a Christian service may not have been in keeping with the spirit of going to the Moon for all of humanity. However, for him personally, it was a significant event and in keeping with his personal faith.
According to different NASA accounts, it had originally been proposed that Aldrin be the first to step onto the Moon’s surface. But due to the physical positioning of the astronauts inside the compact lunar landing module, it was easier for the commander, Neil Armstrong, to be the first to exit the spacecraft.
The iconic photo of Buzz Aldrin walking on surface the Moon as part of the Apollo 11 mission. Credit: NASA
Retirement:
After leaving NASA in 1971, Aldrin was assigned as the Commandant of the U.S. Air Force Test Pilot School at Edwards Air Force Base, California. In March 1972, Aldrin retired from active duty after 21 years of service, due to personal issues stemming from clinical depression and alcoholism. Afterward, he sought treatment for these problems, and his life improved considerably.
Following his retirement, Aldrin remained active in promoting space. He created a nonprofit organization named ShareSpace which supports space education, has written several books, and even released a CD with Snoop Dogg and other rappers in order to promote space. He has been very vocal regarding his belief that NASA should be moving ahead with a manned mission to Mars.
Since retiring from NASA, he has also had an impressive career in television and film, appearing on multiple episodes of hit TV shows, TV movies, documentaries, and as a contestant on Dancing with the Stars. He has also done extensive voice-over work for animated shows, movies, and the video game Mass Effect 3.
Like Neil Armstrong, Buzz Aldrin has received numerous medals and awards for his service – including the Presidential Medal of Freedom, the Air Force Distinguished Service Medal, three Air Medals, the NASA Distinguished Service Medal, the NASA Exceptional Service Medal, two NASA Space Flight Medals, and the Harmon International Trophy. He has also received honorary degrees from six colleges and universities.
Aldrin has been married three times and has three children and one grandson.
