ESA Rosetta Night Time Excursion to reduce orbit to 20Kms

For the last two weeks, ESA's Rosetta has been orbiting comet comet 67P/C-G at a distance of about 30 km on the “Global Mapping Phase” (GMP), and is now set to go even lower.

The aim of the GMP was to gather high-resolution science data to help characterise the potential landing sites for Philae, while also continuing to monitor how the spacecraft responds to the environment of an active comet, before getting closer still.

The Rosetta team discussed whether to fly one complete orbit, the spacecraft conducted two seven-day-long half orbits at about 30 km, in different planes.

That is, on 10 September, the spacecraft was at the terminator plane (the boundary between day and night, which is itself the 06:00/18:00 plane), and performed a thruster burn to insert onto the 30-km circular orbit.

The orbital plane was then 60 degrees away from the Sun’s direction, such that the spacecraft orbited over areas of the comet in their ‘morning’ hours.

Seven days later, when the spacecraft was again on the terminator plane, it conducted another thruster burn to change the orbital plane such that it had the same characteristics as the previous orbit, but instead was flying over ‘afternoon’ areas of the comet.

Thus, from 18 September, the spacecraft was in a 28 km x 29 km orbit around the comet with an orbital period of 13 days 14 hours 59 minutes.

Check out the ESA Rosetta team blog here

NASA’s Mars Spacecraft Maneuvers to Prepare for Close Comet Flyby

This graphic depicts the orbit of comet C/2013 A1 Siding Spring as it swings around the sun in 2014. 

On Oct. 19, the comet will have a very close pass at Mars. 

Its nucleus will miss Mars by about 82,000 miles (132,000 kilometers).

Image Credit: NASA/JPL-Caltech

NASA is taking steps to protect its Mars orbiters, while preserving opportunities to gather valuable scientific data, as Comet C/2013 A1 Siding Spring heads toward a close flyby of Mars on Oct. 19.

The comet’s nucleus will miss Mars by about 82,000 miles (132,000 kilometers), shedding material hurtling at about 35 miles (56 kilometers) per second, relative to Mars and Mars-orbiting spacecraft.

At that velocity, even the smallest particle, estimated to be about one-fiftieth of an inch (half a millimeter) across, could cause significant damage to a spacecraft.

NASA currently operates two Mars orbiters, with a third on its way and expected to arrive in Martian orbit just a month before the comet flyby.

Teams operating the orbiters plan to have all spacecraft positioned on the opposite side of the Red Planet when the comet is most likely to pass by.

"Three expert teams have modeled this comet for NASA and provided forecasts for its flyby of Mars," explained Rich Zurek, chief scientist for the Mars Exploration Program at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.

"The hazard is not an impact of the comet nucleus, but the trail of debris coming from it. Using constraints provided by Earth-based observations, the modeling results indicate that the hazard is not as great as first anticipated."

"Mars will be right at the edge of the debris cloud, so it might encounter some of the particles -- or it might not."

During the day's events, the smallest distance between Siding Spring's nucleus and Mars will be less than one-tenth the distance of any known previous Earthly comet flyby.

The period of greatest risk to orbiting spacecraft will start about 90 minutes later and last about 20 minutes, when Mars will come closest to the center of the widening dust trail from the nucleus.

NASA's Mars Reconnaissance Orbiter (MRO)

NASA's Mars Reconnaissance Orbiter (MRO) made one orbit-adjustment maneuver on July 2 as part of the process of repositioning the spacecraft for the Oct. 19 event. An additional maneuver is planned for Aug. 27.

NASA's Mars Odyssey orbiter

The team operating NASA's Mars Odyssey orbiter is planning a similar maneuver on Aug. 5 to put that spacecraft on track to be in the right place at the right time, as well.

NASA's Mars Atmosphere and Volatile Evolution (MAVEN)

NASA's Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft is on its way to the Red Planet and will enter orbit on Sept. 21.

The MAVEN team is planning to conduct a precautionary maneuver on Oct. 9, prior to the start of the mission's main science phase in early November.

In the days before and after the comet's flyby, NASA will study the comet by taking advantage of how close it comes to Mars.

Researchers plan to use several instruments on the Mars orbiters to study the nucleus, the coma surrounding the nucleus, and the tail of Comet C/2013 A1 Siding Spring, as well as the possible effects on the Martian atmosphere.

This particular comet has never before entered the inner solar system, so it will provide a fresh source of clues to our solar system's earliest days.

MAVEN will study gases coming off the comet's nucleus into its coma as it is warmed by the sun.

MAVEN also will look for effects the comet flyby may have on the planet’s upper atmosphere and observe the comet as it travels through the solar wind.

Odyssey will study thermal and spectral properties of the comet's coma and tail. MRO will monitor Mars’ atmosphere for possible temperature increases and cloud formation, as well as changes in electron density at high altitudes.

The MRO team also plans to study gases in the comet’s coma. Along with other MRO observations, the team anticipates this event will yield detailed views of the comet’s nucleus and potentially reveal its rotation rate and surface features.

NASA Mars MSL Curiosity rover

Mars' atmosphere, though much thinner than Earth's, is thick enough that NASA does not anticipate any hazard to the Opportunity and Curiosity rovers on the planet's surface, even if dust particles from the comet hit the atmosphere and form into meteors.

Rover cameras may be used to observe the comet before the flyby, and to monitor the atmosphere for meteors while the comet's dust trail is closest to the planet.

Observations from Earth-based and space telescopes provided data used for modeling to make predictions about Siding Spring's Mars flyby, which were in turn used for planning protective maneuvers.

The three modeling teams were headed by researchers at the University of Maryland in College Park, the Planetary Science Institute in Tucson, Arizona, and JPL.

'Poisoning' corrosion brings stainless magnesium closer

The aerospace industry is one that could benefit from a breakthrough in reducing the corrosion rate of lightweight metal, magnesium. Credit: iStock 

In a discovery that could have major implications for the aerospace, automotive and electronics industries, scientists have found a way to dramatically reduce the corrosion rate of lightweight wonder metal magnesium: adding arsenic.

Weighing in at two thirds less than aluminium, magnesium is the lightest structural metal.

It has many potential industrial applications, but uptake is severely restricted by its poor resistance to corrosion.

Identification of methods to restrict magnesium corrosion is the first step in engineering such technology into functional alloys.

Nick Birbilis

For the first time, a group of researchers, led by Monash University's Associate Professor Nick Birbilis, have created a magnesium alloy with significantly reduced corrosion rates by adding a cathodic 'poison' - arsenic.

They found that the addition of very low levels of arsenic to magnesium retards the corrosion reaction by effectively 'poisoning' the reaction before it can complete.

Once magnesium is available in a more stainless, or corrosion-resistant, form wider use will lead to significant weight and energy savings in transportation industries.

It has been the subject of significant research efforts concentrating on developing light metals.

Associate Professor Birbilis, of the Monash Department of Materials Engineering, said the discovery would contribute to the birth of more 'stainless' magnesium products by exploiting cathodic poisons.

"This is a very important and timely finding. In an era of light-weighting for energy and emissions reductions, there is a great demand for magnesium alloys in everything from portable electronics to air and land transportation," Associate Professor Birbilis said.

"Magnesium products are rapidly evolving to meet the demands of industry, but presently are hindered by high corrosion rates. The arsenic effect we discovered is now being trialled as a functional additive to existing commercial alloys."

"Our breakthrough will help develop the next generation of magnesium products, which must be more stainless."

The research, conducted with the University of Wales and CSIRO, is published in the journal Electrochemistry Communications.

MESSENGER mission: A close “peak of eternal light” (PEL) near Mercury’s south pole

A close “peak of eternal light” (PEL) near Mercury’s south pole.

Mercury, traveling in its 88-day-long orbit around the Sun with basically zero axial tilt, has many craters at its poles whose insides literally never see the light of day.

These permanently-shadowed locations have been found by the JPL MESSENGER mission to harbour considerable deposits of ice.

This is a seemingly strange discovery on a planet two-and-a-half times closer to the Sun than we are!)

But if there are places on Mercury where the Sun never shines then there may also be places where it always does.

That's what researchers are looking for in illumination maps made from MESSENGER data, and they're getting closer.

The image above shows a region near Mercury's south pole. The yellow arrow points to the closest thing to a true "peak of eternal light" found thus far on Mercury, a point that receives sunlight about 82% of the time i.e. almost constantly illuminated.

Studies of the illumination conditions near the north and south poles of Mercury are of interest because they can be used to determine locations of permanent shadow, extremely cold places where ice deposits lurk.

However, the illumination maps also reveal the locations that receive the maximum duration of sunlight during a Mercury solar day.

A "peak of eternal light" that is illuminated continuously for an entire solar day would be a favourable target for a lander, because solar power would be available all the time.

So far, no such peak of eternal light has been identified at Mercury's south pole.

The spot that get the most illumination (about 82%), is located at 89° S, 50.7° E.

Illumination map of Mercury’s south polar region (Pub. March 2012).

This image was acquired as part of Messenger's MDIS campaign to monitor the south polar region of Mercury.

By imaging the polar region approximately every four MESSENGER orbits as illumination conditions change, features that were in shadow on earlier orbits can be discerned and any permanently shadowed areas can be identified after repeated imaging over one solar day.

The top image above was acquired on Dec. 24, 2011. 

The large crater is Chao Meng-Fu, about 129 km (80 mi.) in diameter. 

Credit: NASA /Johns Hopkins University Applied Physics Laboratory /Carnegie Institution of Washington.

ALMA and VLA Image: Star Formation Close to Milky Way's Supermassive Black Hole

A combined ALMA and ESO's  Very Large Array (VLA) image of the galactic center. 

The supermassive black hole is marked by its traditional symbol Sgr A*. 

The red and blue areas, taken with ALMA, map the presence of silicon monoxide, an indicator of star formation. 

The blue areas have the highest velocities, blasting out at 150-200 kilometers per second. 

The green region, imaged with the VLA, traces hot gas around the black hole and corresponds to an area 3.5 by 4.5 light-years. 

Credit: Yusef-Zadeh et al., ALMA (ESO, NAOJ, NRAO), NRAO/AUI/NSF.

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered signs of star formation perilously close to the supermassive black hole at the center of the Milky Way Galaxy.

If confirmed, this would be the first time that star formation was observed so close to the galactic center.

The center of our galaxy, 27,000 light-years away in the direction of the constellation Sagittarius, is home to a monstrous black hole with a mass of four million suns.

Extending outward from this gravitational behemoth for many light-years is a turbulent region of space that is thought to be wracked by such extreme tidal forces that any star-forming clouds of dust and gas would be stretched thin and shredded long before infant stars could emerge.

Yet against these extreme odds, ALMA spotted telltale jets of material bursting out of what appear to be dense cocoons of gas and dust.

These jets, if they were observed in more placid surroundings, would indicate the formation of a young star. The results were accepted for publication in the Astrophysical Journal Letters.

Farhad Yusef-Zadeh

"People think it is very hard to form stars near a supermassive black hole," said Farhad Yusef-Zadeh of Northwestern University.

"This is because the gravity of the black hole produces extreme tidal forces that would stretch and elongate molecular clouds, preventing them from ever accumulating enough mass to trigger star formation. But what we seem to have found are patches of dust and gas that have become so dense that they are able to overcome their inhospitable surroundings."

Yusef-Zadeh and his colleagues speculate that these molecular clouds have become so massive and dense, possibly by colliding together, that they cross the all-important threshold that allows internal gravity to take over, starting a chain of events that inexorably leads to the birth of a new star.

As this process evolves, material in these clouds clumps together and collapses into an ever denser mass that begins to rotate faster and faster.

This rapid rotation, possibly coupled with the star's magnetic field, accelerates some of the material and shoots it out into space along the nascent star's axis of rotation.

The astronomers were able to detect these characteristic jets of material by tracing the presence of the molecule silicon monoxide (SiO), which is relatively abundant in molecular clouds.

When excited during star formation, SiO emits a very specific set of wavelengths of light in the microwave, or millimeter range. This is precisely the window of light that ALMA was designed to study.

Silicon Monoxide (SiO)

"SiO is an excellent tracer of molecular outflows," said Yusef-Zadeh.

"What we see in these images from ALMA are outflows that appear very much like what we see in star-forming regions elsewhere in galaxy. So the environments may be very different, but once you get the right conditions, collapse takes place and you're able to create what we would observe to be run-of-the-mill massive or intermediate mass stars."

For more than a decade, astronomers have puzzled over the origin of stars seen whipping around the black hole that lurks at the center of our galaxy.

These massive, young stars (less than 10 million years old) are rocketing through an area of space where it was thought they had no business being.

Astronomers believe that they either formed elsewhere under more placid conditions and migrated inward or they somehow overcame their turbulent childhoods to emerge as relatively normal and well-adjusted stellar objects.

"Though this question of stars near the galactic center is still open ended, ALMA will definitely have the power and sensitivity to shed more light on the mystery," said Al Wootten, the North America ALMA Project Scientist with the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia.

"These latest studies do suggest that the conditions necessary for star formation could extend much closer to the galactic center than we previously believed."

Closest Supernova in 25 Years Is a 'Cosmic Classic'

Astronomers have spotted the closest supernova in a generation — and in a week or so, stargazers with a good pair of binoculars might be able to see it, too.

The supernova, or exploded star, flared up Tuesday night (Aug. 23) in the Pinwheel Galaxy, just 21 million light-years from Earth.

It's the closest star explosion of its type observed since 1986, and astronomers around the world are already scrambling to train their instruments on it.

Researchers said they think they caught the supernova, named PTF 11kly, within hours of its explosion. [Photo of the new supernova PTF 11kly]

Smoke from Forest Fires close Moscow Airports

A dense smog shrouded Moscow on Friday, grounding flights at the city's international airports, seeping into homes and offices and stinging the eyes of residents as wildfires raged to the east and south.

Dozens of incoming flights were diverted from the capital's Domodedovo and Vnukovo airport hubs, as smog from blazes around the capital brought runway visibility down to 220 yards, airport officials reported.

All incoming flights to Moscow were being offered alternative airports at which to land, but the decision to divert was up to individual flight crews, Domodedovo spokeswoman Yelena Galanova said.

Moscow's other main airport, situated on the opposite side of the city from most of the blazes, freed up tarmac space to receive some planes. Other flights diverted to St. Petersburg and Kazan, a city 500 miles (800 kilometers) east of Moscow, Irina Ivanova, a Vnukovo Airport spokeswoman, said.

Visibility in parts of the capital was down to a few dozen yards due to the smog caused by the fires, which carries a strong burning smell and causes coughing. Airborne pollutants such as carbon monoxide were four times higher than average readings — the worst seen to date in the Russian capital.

Kremlin spires and church domes disappeared into the dirty mist, which is forecast to hang in the air for days due to the lack of wind.

"It hurts my eyes," student Valeriya Kuleva said on a central Moscow street. "I'm wearing a mask, but nothing helps."

"It's just impossible to work," said Moscow resident Mikhail Borodin, in his late 20s, as he removed a mask to puff on a cigarette. "I don't know what the government is doing, they should just cancel office hours."

More than 500 separate blazes were burning nationwide Friday, mainly across western Russia, according to the Emergencies Ministry. Dozens of forest and peat bog fires around Moscow have ignited amid the country's most intense heat wave in 130 years of record-keeping.

"All high-temperature records have been beaten, never has this country seen anything like this, and we simply have no experience of working in such conditions," Moscow emergency official Yuri Besedin said Friday.

He added that 31 forest fires and 15 peat-bog fires were burning in the Moscow region alone.

At least 52 people have died and 2,000 homes have been destroyed in the blazes. Russian officials have admitted that the 10,000 firefighters battling the blazes aren't enough — an assessment echoed by many villagers, who said the fires swept through their hamlets in minutes.

To minimize further damage, Russian workers have evacuated explosives from military facilities and were sending planes, helicopters and even robots to help control blazes around the country's top nuclear research facility in Sarov, 300 miles east of Moscow.