ESA BepiColombo Mercury Planetary Orbiter (MPO) Integration Testing Completed

ProtoFlight Models (PFM) of the BepiColombo Mercury Planetary Orbiter (MPO) [foreground] and the Mercury Transfer Module (MTM) [background], during the press event at Thales Alenia Space Turin, 4 July 2014.

Integration and functional testing activities for the protoflight models of the BepiColombo Mercury Planetary Orbiter, Mercury Transfer Module, and Magnetospheric Orbiter Sunshield and Interface Structure have now been completed at the Thales Alenia Space facility in Turin, Italy.

All the mission components have been, or will soon be, delivered to ESA's European Space Research and Technology Centre in Noordwijk, the Netherlands, where additional integration tasks and an environmental testing campaign will be performed.

On 4 July 2014, a press event was held at the Turin facility of Thales Alenia Space (TAS-I) to mark the completion of a shipment readiness review held before the ProtoFlight Models (PFMs) of the BepiColombo Mercury Planetary Orbiter (MPO), Mercury Transfer Module (MTM), and Magnetospheric Orbiter Sunshield and Interface Structure (MOSIF) were prepared for transport to ESA's European Space Research and Technology Centre (ESTEC) in Noordwijk, the Netherlands.

At ESTEC, final integration tasks and then environmental testing will be performed.

The MTM and MOSIF left Turin on the evening of 7 July and arrived at ESTEC during the night of 10/11 July. The MPO is scheduled to leave on 4 August and arrive on 7/8 August.

Mercury Transfer Module (MTM)

Mercury Transfer Module
The MTM was delivered to TAS-I by Astrium UK (now EADS Airbus Defence and Space).

As supplied, it consisted of the mechanical spacecraft bus and the chemical propulsion system.

The MTM radiator panels were removed from the central structure and the module has been equipped with the rest of its subsystems while in Turin.

However, for the electrical propulsion subsystem, the relevant high voltage harness and electronic units are still representative dummy models, used to confirm the routing of the harness.

While the spacecraft is at ESTEC, these will be replaced with the flight units and the four electric thrusters will be installed on the thruster pointing mechanisms already integrated on the MTM thruster floor.

Once this has been completed, the thermal blankets will be fitted, prior to a Thermal Balance/Thermal Vacuum (TB/TV) test in ESTEC's Large Space Simulator (LSS) during the first half of 2015.

Magnetospheric Orbiter Sunshield and Interface Structure

Magnetospheric Orbiter Sunshield And Interface Structure
Integration of the MOSIF structure and harness has been completed in Turin.

The thermal protection will be integrated while it is at ESTEC, in readiness for testing as part of the complete spacecraft stack.

Mercury Planetary Orbiter (MPO)

Mercury Planetary Orbiter
Last year, the MPO was transported to TAS-I from ESTEC, where it had been baked out to remove potential contaminants after having been assembled by Astrium UK.

As delivered, it consisted of the spacecraft mechanical bus with the heat pipes and chemical propulsion system installed.

Nearly all of its other subsystems and payload components have been integrated and tested while it has been in Turin.

Once it arrives back at ESTEC next month, some final integration tasks will be completed and installation of the thermal blankets will be finalised. Later this year, it will undergo TB/TV testing in the LSS.

Russian Foton-M satellite Bio-Satellite Communications restored

The satellite with geckos, fruit flies, silkworm eggs, mushrooms and seeds of higher plants was launched on July 19 from the Baikonur Cosmodrome in Kazakhstan. 

Experiments on board Russia's Foton-M bio satellite will continue despite the spacecraft's failure to reach the designated orbit, the head of the spacecraft's manufacturer TsSKB-Progress said Monday.

"We are not going to start the spacecraft's thruster, and will work in the low-earth orbit."

"This won't affect the experiments, we are successfully carrying out 18 out of 24 scheduled [experiments]," TsSKB-Progress Director General Alexander Kirilin said.

Communication with the Foton-M satellite was lost on July 19 and restored on July 26. Since Saturday, scientists have been receiving stable telemetric data from the spacecraft.

A source in Roscosmos, Russia's Federal Space Agency, told RIA Novosti a total of 17 communications sessions have been conducted since July 28. The spacecraft operation is under the control of the Mission Control Center.

The agency earlier specified that the design and onboard control systems of the Foton-M enable self-sufficient operation.

The satellite with geckos, fruit flies, silkworm eggs, mushrooms and seeds of higher plants was launched on July 19 from the Baikonur Cosmodrome in Kazakhstan.

The biological mission of the Foton-M satellite includes eight experiments. The experiments involving five geckos are to monitor their reproductive activity in space.

The mission is to study the effect of weightlessness on plants and insects, and to conduct experiments on the growth of semiconductor crystals.

NASA Curiosity Rover: Long-lived rover sets off-world driving record

This natural colour view from NASA's Mars Exploration Rover Opportunity shows "Lunokhod Crater," which lies south of Solander Point on the west rim of Endeavour Crater. 

Credit: NASA/JPL-Caltech /Cornell /Arizona State Univ.

NASA's Opportunity Mars rover, which landed on the Red Planet in 2004, now holds the off-Earth roving distance record after accruing 25 miles (40 kilometers) of driving.

The previous record was held by the Soviet Union's Lunokhod 2 rover.

"Opportunity has driven farther than any other wheeled vehicle on another world," said Mars Exploration Rover Project Manager John Callas, of NASA's Jet Propulsion Laboratory in Pasadena, California.

"This is so remarkable considering Opportunity was intended to drive about one kilometer and was never designed for distance but what is really important is not how many miles the rover has racked up, but how much exploration and discovery we have accomplished over that distance."

A drive of 157 feet (48 meters) on July 27 put Opportunity's total odometry at 25.01 miles (40.25 kilometers).

This month's driving brought the rover southward along the western rim of Endeavour Crater.

The rover had driven more than 20 miles (32 kilometers) before arriving at Endeavour Crater in 2011, where it has examined outcrops on the crater's rim containing clay and sulfate-bearing minerals.

The sites are yielding evidence of ancient environments with less acidic water than those examined at Opportunity's landing site.

If the rover can continue to operate the distance of a marathon, 26.2 miles (about 42.2 kilometers), it will approach the next major investigation site mission scientists have dubbed "Marathon Valley."

Observations from spacecraft orbiting Mars suggest several clay minerals are exposed close together at this valley site, surrounded by steep slopes where the relationships among different layers may be evident.

The Russian Lunokhod 2 rover, a successor to the first Lunokhod mission in 1970, landed on Earth's moon on Jan. 15, 1973, where it drove about 24.2 miles (39 kilometers) in less than five months, according to calculations recently made using images from NASA's Lunar Reconnaissance Orbiter (LRO) cameras that reveal Lunokhod 2's tracks.

Irina Karachevtseva at Moscow State University of Geodesy and Cartography's Extraterrestrial Laboratory in Russia, Brad Jolliff of Washington University in St. Louis, Tim Parker of JPL, and others collaborated to verify the map-based methods for computing distances are comparable for Lunokhod-2 and Opportunity.

This chart illustrates comparisons among the distances driven by various wheeled vehicles on the surface of Earth's moon and Mars. 

Of the vehicles shown, the NASA Mars rovers Opportunity and Curiosity are still active and the totals for those two are distances driven as of May 15, 2013.

Credit: NASA/JPL-Caltech

"The Lunokhod missions still stand as two signature accomplishments of what I think of as the first golden age of planetary exploration, the 1960s and '70s," said Steve Squyres of Cornell University in Ithaca, New York, and principal investigator for NASA's twin Mars rovers, Opportunity and Spirit.

"We're in a second golden age now, and what we've tried to do on Mars with Spirit and Opportunity has been very much inspired by the accomplishments of the Lunokhod team on the moon so many years ago. It has been a real honour to follow in their historical wheel tracks."

As Opportunity neared the mileage record earlier this year, the rover team chose the name Lunokhod 2 for a crater about 20 feet (6 meters) in diameter on the outer slope of Endeavour's rim on Mars.

Silicon-capped hydrocarbons: Mysterious molecules in space

This graph shows absorption wavelength as a function of the number of carbon atoms in the silicon-terminated carbon chains SiC_(2n+1)H, for the extremely strong pi-pi electronic transitions. 

When the chain contains 13 or more carbon atoms, not significantly longer than carbon chains already known to exist in space, these strong transitions overlap with the spectral region occupied by the elusive diffuse interstellar bands. 

Credit: D. Kokkin, ASU

Over the vast, empty reaches of interstellar space, countless small molecules tumble quietly though the cold vacuum.

Forged in the fusion furnaces of ancient stars and ejected into space when those stars exploded, these lonely molecules account for a significant amount of all the carbon, hydrogen, silicon and other atoms in the universe.

In fact, some 20 percent of all the carbon in the universe is thought to exist as some form of interstellar molecule.

Many astronomers hypothesize that these interstellar molecules are also responsible for an observed phenomenon on Earth known as the "diffuse interstellar bands," spectrographic proof that something out there in the universe is absorbing certain distinct colours of light from stars before it reaches the Earth.

But since we don't know the exact chemical composition and atomic arrangements of these mysterious molecules, it remains unproven whether they are, in fact, responsible for the diffuse interstellar bands.

Now in a paper appearing this week in The Journal of Chemical Physics, from AIP Publishing, a group of scientists led by researchers at the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass. has offered a tantalising new possibility: these mysterious molecules may be silicon-capped hydrocarbons like SiC3H, SiC4H and SiC5H, and they present data and theoretical arguments to back that hypothesis.

At the same time, the group cautions that history has shown that while many possibilities have been proposed as the source of diffuse interstellar bands, none has been proven definitively.

"There have been a number of explanations over the years, and they cover the gamut," said Michael McCarthy a senior physicist at the Harvard-Smithsonian Center for Astrophysics (CfA) who led the study.

Molecules in Space and How We Know They're There
Astronomers have long known that interstellar molecules containing carbon atoms exist and that by their nature they will absorb light shining on them from stars and other luminous bodies.

Because of this, a number of scientists have previously proposed that some type of interstellar molecules are the source of diffuse interstellar bands, the hundreds of dark absorption lines seen in color spectrograms taken from Earth.

In showing nothing, these dark bands reveal everything. The missing colours correspond to photons of given wavelengths that were absorbed as they travelled through the vast reaches of space before reaching us.

More than that, if these photons were filtered by falling on space-based molecules, the wavelengths reveal the exact energies it took to excite the electronic structures of those absorbing molecules in a defined way.

Armed with that information, scientists here on Earth should be able to use spectroscopy to identify those interstellar molecules, by demonstrating which molecules in the laboratory have the same absorptive "fingerprints."

But despite decades of effort, the identity of the molecules that account for the diffuse interstellar bands remains a mystery.

Nobody has been able to reproduce the exact same absorption spectra in laboratories here on Earth.

"Not a single one has been definitively assigned to a specific molecule," said Neil Reilly, a former postdoctoral fellow at Harvard-Smithsonian Center for Astrophysics (CfA) and a co-author of the new paper.

Now Reilly, McCarthy and their colleagues are pointing to an unusual set of molecules, silicon-terminated carbon chain radicals, as a possible source of these mysterious bands.

As they report in their new paper, the team first created silicon-containing carbon chains SiC3H, SiC4H and SiC5H in the laboratory using a jet-cooled silane-acetylene discharge.

They then analysed their spectra and carried out theoretical calculations to predict that longer chains in this family might account for some portion of the diffuse interstellar bands.

However, McCarthy cautioned that the work has not yet revealed the smoking gun source of the diffuse interstellar bands.

To prove that these larger silicon capped hydrocarbon molecules are such a source, more work needs to be done in the laboratory to define the exact types of transitions these molecules undergo, and these would have to be directly related to astronomical observations.

But the study provides a tantalising possibility for finding the elusive source of some of the mystery absorption bands, and it reveals more of the rich molecular diversity of space.

"The interstellar medium is a fascinating environment," McCarthy said. "Many of the things that are quite abundant there are really unknown on Earth."

More information: The Journal of Chemical Physics, July 29, 2014. DOI: 10.1063/1.4883521

ESA Gaia Telescope: After early troubles, all go for Milky Way telescope

ESA's Gaia Milky Way Telescope.

Credit: ESA

A billion-dollar telescope designed to provide the most detailed map yet of the Milky Way is ready to start work after teething problems, the European Space Agency (ESA) said on Tuesday.

"Following extensive in-orbit commissioning and several unexpected challenges... Gaia is now ready to begin its science mission," the agency said.

Launched on December 19, the 740-million-euro ($990-million) device is the most advanced space telescope ever built by Europe.

It seeks to compile an "astronomical census" of around a billion stars, repeatedly observing them from the so-called Lagrange point L2, a position 1.5 million kilometres (937,000 miles) from Earth.

Data on the distance, speed, direction and motion of these stars will help astronomers build an unprecedented 3-D map of our section of the galaxy, ESA hopes.

Timo Prusti, ESA's Gaia scientist with Gaia in the background.

Credit: ESA

Gaia's commissioning phase was supposed to last only four months, but engineers ran into problems as they prepared the gadget for its five-year mission.

One was water that may have been trapped in the telescope before launch and which froze on some parts of the optics, affecting visibility. This has been fixed by heating the optics to remove the ice.

Another problem is of "stray light" from the Sun that finds its way past Gaia's sunshield, a hitch that will affect Gaia's ability to detect very faint stars but not its ability to spot brighter ones, ESA said.

"The commissioning phase has been challenging... (but) all in all Gaia is in good shape to fulfil its promise, all of the core scientific goals are still achievable, as hoped," Gaia scientist Timo Prusti said.

An intermediate library of data will be released to scientists and the public in mid-2016, somewhat later than expected, he said.

"However, if rapidly-changing objects such as supernovas are detected, open alerts will be made as soon as possible, a service we hope to have up and running before the end of this year."

NASA-funded X-ray instrument settles interstellar debate

Colours indicate the density of interstellar helium near Earth and its enhancement in a downstream cone as neutral atoms respond to the sun's gravity (blue is low density, red is high). 

Also shown are the observing angles for DXL and ROSAT. 

Credit: NASA's Goddard Space Flight Center

New findings from a NASA-funded instrument have resolved a decades-old puzzle about a fog of low-energy X-rays observed over the entire sky.

Local hot bubble (LHB)

Thanks to refurbished detectors first flown on a NASA sounding rocket in the 1970s, astronomers have now confirmed the long-held suspicion that much of this glow stems from a region of million-degree interstellar plasma known as the local hot bubble (LHB).

At the same time, the study also establishes upper limits on the amount of low-energy, or soft, X-rays produced within our planetary system by the solar wind, a gusty outflow of charged particles emanating from the sun.

"Interactions between the solar wind and neutral atoms in comets, the outer atmospheres of planets, and even interstellar gas produce soft X-rays," explained team member Steve Snowden, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

Steve Snowden

"We need to account for these processes because the X-rays they produce complicate our observations of the wider universe."

Decades of mapping the sky in X-rays with energies around 250 electron volts, about 100 times the energy of visible light, revealed strong emission precisely where it shouldn't be.

This glow, known as the soft X-ray diffuse background, is surprisingly bright in the gas-rich central plane of our galaxy, where it should be strongly absorbed.

This suggested the background was a local phenomenon, arising from a bubble of hot gas extending out a few hundred light-years from the solar system in all directions.

Improved measurements also made it increasingly clear that the sun resides in a region where interstellar gas is unusually sparse.

Taken together, the evidence suggests our solar system is moving through a region that may have been blasted clear by one or more supernova explosions during the past 20 million years.

In the 1990s, a six-month all-sky survey by the German X-ray observatory ROSAT provided improved maps of the diffuse background, but it also revealed that comets were an unexpected source of soft X-rays.

As scientists began to understand this process, called solar wind charge exchange, they realized it could occur anywhere neutral atoms interacted with solar wind ions.

Within the last decade, some scientists have been challenging the LHB interpretation, suggesting that much of the soft X-ray diffuse background is a result of charge exchange," said F. Scott Porter, a Goddard astrophysicist also participating in the study.

"The only way to check is to design an instrument and make measurements."


This animation illustrates solar wind charge exchange in action. An atom of interstellar helium (blue) collides with a solar wind ion (red), losing one of its electrons (yellow) to the other particle. As it settles into a lower-energy state, the electron emits a soft X-ray. 

Credit: NASA's Goddard Space Flight Center 

While hydrogen atoms quickly ionize and respond to numerous forces, the helium atoms travel paths largely governed by the sun's gravity.

This creates a "helium focusing cone" downstream from the sun that crosses Earth's orbit and is located high in the sky near midnight in early December.

"This helium focusing creates a region with a much greater density of neutral atoms and a correspondingly enhanced charge exchange rate," Snowden said.

The solar wind is accelerated in the sun's corona, the hottest part of its atmosphere, so its atoms have been ionized, stripped of many of their electrons.

When a neutral atom collides with a solar wind ion, one of its electrons often jumps to the charged particle.

Once captured by the ion, the electron briefly remains in an excited state, then emits a soft X-ray and settles down at a lower energy. This is solar wind charge exchange in action.

To establish a baseline for the soft X-ray background, the researchers used data captured by the ROSAT mission in September 1990 in a direction looking along, rather than into, the helium focusing cone.

The results, published online in the journal Nature on July 27, indicate that only about 40 percent of the soft X-ray background originates within the solar system.

"We now know that the emission comes from both sources but is dominated by the local hot bubble," said Galeazzi. "This is a significant discovery.

Specifically, the existence or nonexistence of the local bubble affects our understanding of the area of the galaxy close to the sun, and can, therefore, be used as a foundation for future models of the galaxy structure."

Galeazzi and his collaborators are already planning the next flight of DXL, which will include additional instruments to better characterize the emission. The launch is currently planned for December 2015.

"The DXL team is an extraordinary example of cross-disciplinary science, bringing together astrophysicists, planetary scientists, and heliophysicists," added Porter.

"It's unusual but very rewarding when scientists with such diverse interests come together to produce such groundbreaking results." Explore further: The source of the sky's X-ray glow

More information: "The origin of the local 1/4-keV X-ray flux in both charge exchange and a hot bubble." M. Galeazzi, et al. Nature (2014) DOI: 10.1038/nature13525. 

"Pressure Equilibrium between the Local Interstellar Clouds and the Local Hot Bubble." S. L. Snowden et al. 2014 ApJ 791 L14 DOI: 10.1088/2041-8205/791/1/L14

NASA Cassini: The geyser basin of Saturn's moon Enceladus

This view looks across the geyser basin of Saturn's moon Enceladus, along fractures spewing water vapour and ice particles into space. 

Cassini scientists have pinpointed the source locations of about 100 geysers and gained new insights into what powers them. 

Credit: NASA/JPL-Caltech/SSI

Scientists using mission data from NASA's Cassini spacecraft have identified 101 distinct geysers erupting on Saturn's icy moon Enceladus.

Their analysis suggests it is possible for liquid water to reach from the moon's underground sea all the way to its surface.

These findings, and clues to what powers the geyser eruptions, are presented in two articles published in the current online edition of the Astronomical Journal.

Over a period of almost seven years, Cassini's cameras surveyed the south polar terrain of the small moon, a unique geological basin renowned for its four prominent "tiger stripe" fractures and the geysers of tiny icy particles and water vapour first sighted there nearly 10 years ago.

The result of the survey is a map of 101 geysers, each erupting from one of the tiger stripe fractures, and the discovery that individual geysers are coincident with small hot spots.

These relationships pointed the way to the geysers' origin.

After the first sighting of the geysers in 2005, scientists suspected that repeated flexing of Enceladus by Saturn's tides as the moon orbits the planet had something to do with their behaviour.

One suggestion included the back-and-forth rubbing of opposing walls of the fractures generating frictional heat that turned ice into geyser-forming vapour and liquid.

Alternate views held that the opening and closing of the fractures allowed water vapor from below to reach the surface.

This artist's rendering shows a cross-section of the ice shell immediately beneath one of Enceladus' geyser-active fractures, illustrating the physical and thermal structure and the processes ongoing below and at the surface.

Image Credit: NASA/JPL-Caltech/Space Science Institute

Before this new study, it was not clear which process was the dominating influence.

Nor was it certain whether excess heat emitted by Enceladus was everywhere correlated with geyser activity.

To determine the surface locations of the geysers, researchers employed the same process of triangulation used historically to survey geological features on Earth, such as mountains.

When the researchers compared the geysers' locations with low-resolution maps of thermal emission, it became apparent the greatest geyser activity coincided with the greatest thermal radiation.

Comparisons between the geysers and tidal stresses revealed similar connections. However, these correlations alone were insufficient to answer the question, "What produces what?"

The answer to this mystery came from comparison of the survey results with high-resolution data collected in 2010 by Cassini's heat-sensing instruments.

Individual geysers were found to coincide with small-scale hot spots, only a few dozen feet (or tens of meters) across, which were too small to be produced by frictional heating, but the right size to be the result of condensation of vapor on the near-surface walls of the fractures.

This immediately implicated the hot spots as the signature of the geysering process.

"Once we had these results in hand, we knew right away heat was not causing the geysers, but vice versa," said Carolyn Porco, leader of the Cassini imaging team from the Space Science Institute in Boulder, Colorado, and lead author of the first paper.

"It also told us the geysers are not a near-surface phenomenon, but have much deeper roots."

Thanks to recent analysis of Cassini gravity data, the researchers concluded the only plausible source of the material forming the geysers is the sea now known to exist beneath the ice shell.

They also found that narrow pathways through the ice shell can remain open from the sea all the way to the surface, if filled with liquid water.

In the companion paper, the authors report the brightness of the plume formed by all the geysers, as seen with Cassini's high-resolution cameras, changes periodically as Enceladus orbits Saturn.

Armed with the conclusion that the opening and closing of the fractures modulates the venting, the authors compared the observations with the expected venting schedule due to tides.

They found the simplest model of tidal flexing provides a good match for the brightness variations Cassini observes, but it does not predict the time when the plume begins to brighten.

Some other important effect is present and the authors considered several in the course of their work.

More information: "Tidally Modulated Eruptions on Enceladus: Cassini ISS Observations and Models." Francis Nimmo et al. 2014, Astronomical Journal 148 46. DOI: 10.1088/0004-6256/148/3/46