Habitable planet found in solar system next door

An artist's impression of the planet Proxima b, orbiting the red dwarf star Proxima Centauri

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An artist’s impression of the planet Proxima b, orbiting the red dwarf star Proxima Centauri (AFP Photo/M. Kornmesser)

Paris (AFP) – Scientists Wednesday announced the discovery of an Earth-sized planet orbiting the star nearest our Sun, opening up the glittering prospect of a habitable world that may one day be explored by robots.

Named Proxima b, the planet is in a “temperate” zone compatible with the presence of liquid water — a key ingredient for life.

The findings, based on data collected over 16 years, were reported in the peer-reviewed journal Nature.

“We have finally succeeded in showing that a small-mass planet, most likely rocky, is orbiting the star closest to our solar system,” said co-author Julien Morin, an astrophysicist at the University of Montpellier in southern France.

“Proxima b would probably be the first exoplanet visited by a probe made by humans,” he told AFP.

An exoplanet is any planet outside our Solar System.

Lead author Guillem Anglada-Escude, an astronomer at Queen Mary University London, described the find as the “experience of a lifetime”.

Working with European Southern Observatory telescopes in the north Chilean desert, his team used the so-called Doppler method to detect Proxima b and describe its properties.

The professional star-gazers spent 60 consecutive days earlier this year looking for signs of gravitational pull on its host star, Proxima Centauri.

Regular shifts in the star’s light spectrum — repeating every 11.2 days — gave a tantalising clue.

They revealed that the star alternately moved towards and away from our Solar System at the pace of a leisurely stroll, about five kilometres (three miles) per hour.

– Goldilocks zone –

After cross-checking an inconclusive 2000-2014 dataset and eliminating other possible causes, the researchers determined that the tug of an orbiting planet was responsible for this tiny to-and-fro.

“Statistically, there is no doubt,” Anglada-Escude told journalists in a briefing.

“We have found a planet around Proxima Centauri.”

Proxima b is a mere four light years from the Solar System, meaning that it is essentially in our back yard on the scale of our galaxy, the Milky Way.

It has a mass around 1.3 times that of Earth, and orbits about seven million kilometres (4.35 million miles) from its star.

A planet so near to our Sun — 21 times closer than Earth — would be an unlivable white-hot ball of fire.

But Proxima Centauri is a so-called red dwarf, meaning a star that burns at a lower temperature.

As a result, the newly discovered planet is in a “Goldilocks” sweet spot: neither so hot that water evaporates, nor so cold that it freezes solid.

But liquid water is not the only essential ingredient for the emergence of life.

An atmosphere is also required, and on that score the researchers are still in the dark.

It all depends, they say, on how Proxima b evolved as a planet.

“You can come up with formation scenarios that end up with and Earth-like atmosphere, a Venus-like atmosphere” — 96 percent carbon dioxide — “or no atmosphere at all,” said co-author Ansgar Reiners, an expert on “cold” stars at the University of Goettingen’s Institute of Astrophysics in Germany.

Computer models suggest the planet’s temperature, with an atmosphere, could be “in the range of minus 30 Celsius (-22 Fahrenheit) on the dark side, and 30C (80F) on the light side,” Reiners told journalists.

Like the Moon in relation to Earth, Proxima b is “tidally locked,” with one face always exposed to its star and the other perpetually in shadow.

Emerging life forms would also have to cope with ultraviolet and X-rays bombarding Proxima b 100 times more intensely than on Earth.

– Search for life –

An atmosphere would help deflect these rays, as would a strong magnetic field.

But even high doses of radiation do not preclude life, especially if we think outside the box, scientists say.

“We have to be very open-minded as to what we call ‘life’,” Jean Schneider, an expert on exoplanets at the Observatoire de Paris, told AFP.

Some 3,500 exoplanets have been discovered since the first confirmed sighting in 1995.

Most of these distant worlds — like our own Jupiter and Neptune — are composed of gas, an inhospitable environment for life.

Even the 10 percent that do have rocky surfaces are mostly too cold or too hot to host water in liquid form.

And — until today — the handful that are in a temperate zone are effectively beyond reach.

Last year, for example, NASA unveiled Kepler 452b, a planet about 60 percent larger than Earth that could have active volcanoes, oceans, sunshine like ours, and a year lasting 385 days.

But at a distance of 1,400 light-years, humankind would have little hope of reaching this Earth-twin any time soon.

By comparison, Proxima b is a stone’s throw away, though still too far away for humans to visit with present-generation chemical rockets.

“This is a dream for astronomers if we think about follow up observations,” said Reiners.

Marlowe Hood

Vector Space Systems aims to launch satellites by the hundreds

Devin Coldewey

8M0I6865 - P-9 in flight

Why wait for the bus when you can hail a cab? That’s the idea behind a new commercial spaceflight startup founded by SpaceX founding team members Jim Cantrell and John Garvey. Vector Space Systems wants to shake up to the commercial space market by providing not tens, but hundreds of launches per year.

Vector Space-logo-black“We’re going to bring real economics to the launch platform,” Cantrell told TechCrunch in an interview. “And we can do that because we bring supply. We’re talking about building hundreds of these things.”

Vector isn’t looking to compete with SpaceX, or even smaller commercial launch platforms like Rocket Lab and Firefly. A launch with these companies might be booked years in advance, with dozens of sub-launches, deliveries, experiments, and what have you packed into a single rocket. It’s like a space bus. Vector wants to be the space taxi.

“I had this experience pounded into my brain with LightSail,” said Cantrell, referring to the Planetary Society’s experimental solar propulsion craft. “We built that thing — I think we finished in 2011 — and it’s still waiting around for launch, because you need a particular orbit and so on. And really nobody has addressed this problem.”

With small rockets carrying single 20-40 kg payloads launching weekly or even every few days, the company can be flexible with both prices and timetables. Such small satellites are a growing business: 175 were launched in 2015 alone, and there’s plenty of room to grow. It’ll still be expensive, of course, and you won’t be able to just buy a Thursday afternoon express ticket to low earth orbit — yet.

Customers will, however, reap other benefits. There are less restrictions on space: no more having to package your satellite or craft into a launch container so it fits into a slot inside a crowded space bus. Less of a wait between build and launch means hardware can be finalized weeks, not years, in advance — and expensive satellites aren’t sitting in warehouses waiting for their turn to go live and get that sweet return on investment.

The last few years have been spent on designing and testing the as-yet-unnamed launch vehicles Vector will be using. The first stage is designed to be reusable — nothing as fancy as SpaceX’s autonomous landings, but rather using a unique aerial recovery system Cantrell seemed excited (though guarded) about.



Dozens of sub-orbital flights have been made, and orbital deployment is the next test. If all goes well, Vector hopes to be making its first real flights in 2017.

Investors are knocking down the front door looking to get in, he said, though he declined to name any. Perhaps they smell profitability: Vector’s business plan has it cash positive after just a few launches. Government money is also in the mix: Cantrell noted humbly that “We’ve been talking with people high up at the Pentagon who want this for obvious reasons.”

A lot depends on successful demonstration of orbital deployment, which should be happening a little later this year. If things go as planned, it could work towards removing one of the most significant restraints currently holding back commercial spaceflight.

Bound for Mars, a robot arrives in Boston for training

Valkyrie, NASA’s humanoid robot prototype that Northeastern researchers will perform advanced research and development on, arrived at UMass Lowell on April 6.
Valkyrie, NASA’s humanoid robot prototype that Northeastern researchers will perform advanced research and development on, arrived at UMass Lowell on April 6.

ASTRONAUTS SPEND YEARS training before they go into space. The same is true for their robot counterparts, two of which recently arrived in Massachusetts to be put through their paces in preparation for a long-off mission to Mars.

Valkyrie is built like a linebacker — 6’2” tall and 275 pounds. Its job is to go to Mars and maintain equipment in anticipation of the arrival of astronauts, potentially years after Valkyrie first touches down on the Red Planet.

“If you don’t start your car for two years, do you expect it will start when you return?” says Taskin Padir, a professor of engineering at Northeastern University who will be leading the university’s work with Valkyrie. “Humanoid robots will be part of the pre-deployment mission to Mars and will maintain equipment prior to the astronauts’ arrival.”

A manned mission to Mars is a high priority for NASA, which hopes to achieve the feat by the 2030s. As conceived, the expedition would require NASA to send equipment like rovers and a human habitat to Mars years before the astronauts launch. This is due to the relative orbits of Earth and Mars, which make it only practical to launch from here to there every two years.

“You need to pre-position assets like a habitat, a power supply. Whatever you need on the surface, all that’s done years before an astronaut gets there,” says William Verdeyen, NASA project manager for Valkyrie.

Valkyrie’s destination may be exotic, but the robot’s tasks will be mundane. The Johnson Space Center in Houston will beam instructions to Mars (the transmission takes about 20 minutes), and the robot will carry them out autonomously. Likely jobs include repairing electronic boards, cutting cords, and changing batteries — all maneuvers that require dexterity, which is complicated to engineer.

“A [good] analogy is replacing batteries in a flashlight,” says Padir. “If we can do that with Valkyrie at the end of two years, that would be a great accomplishment from our perspective.”

Over the next two years, the Northeastern team will work on improving Valkyrie’s performance, especially at these kinds of fine-motor maintenance tasks. A separate team at MIT will be doing similar work with another copy of the robot.

Most of Valkyrie’s movements will take place inside the human habitat — a known environment for the engineers, which makes it relatively easy to navigate. Sometimes, though, the robot will have to venture outside, like to brush dust off of solar panels. There, things get more treacherous. And if Valkyrie falls on the rough, uneven Martian surface, there’s always the risk it will never be able to get back up. Fortunately, though, in all these tasks, time is going to be on Valkyrie’s side.

“This robot will have a lot of free time on Mars,” says Padir. “If your task is to clean a few solar panels in the next week, you don’t have to run.”


NASA invests $67 million into solar electric propulsion for deep space exploration

Emily Calandrelli (@TheSpaceGal)

NASA has selected Aerojet Rocketdyne for a $67 million contract to develop an advanced Solar Electric Propulsion (SEP) system for future deep-space missions.

In a press release, NASA stated that the propulsion system could be used on robotic missions to an asteroid and in other missions related to their Journey to Mars program.

Compared to chemical propulsion (the type of propulsion that rockets use to escape Earth’s gravity well and reach orbit), SEP has lower thrust but is more fuel-efficient and can provide thrust for longer periods of time. For these reasons, SEP works well in the vacuum of space, particularly on spacecraft with long mission lifetimes.

A Hall thruster tested at NASA Glenn Research Center/ Image courtesy of NASA

SEP engines provide thrust by converting solar energy into electricity and using that electricity to accelerate ionized propellant at extremely high speeds. The iconic blue glow from a SEP thruster is created from photons released by the ions as they lose energy upon leaving the engine.

NASA has been working on SEP technology since the 1950s and they’ve used SEP on prior missions like the Dawn spacecraft, which is currently in orbit around the dwarf planet Ceres and is the first spacecraft to orbit around two extraterrestrial bodies.

Illustration of the Dawn spacecraft with its SEP system / Image courtesy of NASA

Under the new contract, NASA hopes to double the thrust capability compared to current electric propulsion systems and increase the fuel efficiency by 10 times the current chemical propulsion.

One challenge with deep-space missions that use SEP is that as you travel deeper into the solar system (farther away from the sun), it becomes more difficult to effectively capture light from the sun to power the spacecraft. Because of this, NASA stated its current SEP research is funded in parallel with work to advance solar array technology.

During the 36-month contract, Aerojet Rocketdyne is responsible for constructing, testing and delivering an SEP product for testing and evaluation. Eventually, the goal is to have Aerojet Rocketdyne deliver four electric propulsion units that will fly in space.

“Through this contract, NASA will be developing advanced electric propulsion elements for initial spaceflight applications, which will pave the way for an advanced solar electric propulsion demonstration mission by the end of the decade.” Steve Jurczyk, associate administrator of NASA’s Space Technology Mission Directorate

In addition to this particular electric propulsion contract, Aerojet Rocketdyne is responsible for the chemical propulsion — the RS-25 engines — for NASA’s Space Launch System, the rocket designed to be used on missions related to NASA’s Journey to Mars initiative.

Illustration of NASA's Asteroid Redirect Mission using SEP / Image courtesy of NASA

Aerojet Rocketdyne’s current contract is part of NASA’s overall push to advance SEP systems. NASA plans to test the largest and most advanced SEP system ever used in space on their Asteroid Redirect Mission, which is designed to capture an asteroid and place it in orbit around the moon. That mission is currently slated for the mid-2020s.


First contact: how we’ll get the news that we found aliens

Image result for alien contact

Cathal O’Connell explains the challenges that will face scientists when they break the biggest news story in history.

However unlikely contact with aliens may be, scientists are thinking about how they would break the news to a nervous planet.CREDIT: AARON FOSTER/GETTY IMAGES

Detecting a signal from an extraterrestrial intelligence would be life changing for everyone on Earth – the biggest news story in history – and could potentially be dangerous, especially if badly handled.

Writing in the journal Acta Astronautica, scientists at the Search for Extra Terrestrial Intelligence (SETI) institute describe a protocol for how to break it to the world that we’re not alone in the Universe – without causing global mayhem.

Rather than a conspiracy of government cover-ups so beloved of sci-fi writes, the study strongly recommends openness as the key to having a “sane global conversation” about the discovery of ET.

Nobody knows how the world would react to the discovery of extraterrestrial intelligence. All we have to go on are the bizarre occurrences where the public thought they were hearing such news.

In 1938 Orson Welles’ radio-play based on HG Wells’s novel The War of the Worlds caused widespread panic in the United States (although the scale of that panic was likely exaggerated). In 1949, a Spanish language version of the same program incited rioting in Ecuador, leading to at least seven deaths, and possibly as many as 20.

Then there’s the risk of the media misreporting or exaggerating the importance of a tentative signal. In October 2015, for example, when a newly discovered extrasolar planet, KIC 8462852, was discovered to show a periodic dip in brightness, the mainstream media latched on to the most speculative, and least likely, explanation – namely that an “alien megastructure” was passing in front of its star. (The periodic dimming is more likely caused by a cloud of comets passing by.)

As a result of these excesses, scientists have been worried about how to break SETI news for decades.

In 1989, the International Academy of Astronautics drew up a set of guidelines for releasing information about a potential alien signal. But that was before the internet and social media transformed the way we consume news stories.

Now, Duncan Forgan and Alexander Scholz, from the University of St Andrew’s in Scotland, have prepared an updated protocol for how scientists should navigate the “unprecedented media onslaught”.

First, Forgan and Scholz advise, all scientists performing a SETI experiment should clearly outline their search methodology as well as define what makes a “discovery”, before the search even begins. This information should be published in a format the media can easily access, such as a blog post.

Then if a signal is detected, the discoverers should not to try to keep it under wraps – the potential fall-out from a leak would be too damaging. Much better to announce a tentative detection, but be clear that it must be assumed to be of natural or manmade origin until proved otherwise.

The scientists should submit their findings to a peer-reviewed journal, while simultaneously uploading all data so it can be pored over by other scientists – and potential known sources ruled out.

The problem is these verifications can take a long time. The best case-study is the so-called “Wow” signal, detected in 1977. That signal was exactly what SETI scientists had been looking for – being at the right frequency to hold an interstellar conversation, and being of unprecedented strength – and is still unexplained almost 39 years later. (Although in early 2016, a study published by the Washington Academy of Sciences suggested that comets could emit such a signal, and identified two comets that were in the right place at the right time in 1977. Future measurements of radio emission by comets should hopefully clear this up.)

In the case where the detection cannot be confirmed, say Forgan and Scholz, the SETI scientists should publish an announcement saying so.

In the case of the detection is confirmed, however, the SETI scientists should become deeply involved in the global conversation by engaging across as many social media platforms as possible – a role they would likely assume for the rest of their lives. They should also be prepared for the downsides of newfound fame – such as cyber attacks.

The latest polls (conducted in Germany, the UK and US last September) show that most people in developed countries believe intelligent aliens exist somewhere in the Universe. But that doesn’t mean we’re ready for a “first contact” event.

However unlikely such a discovery is, a signal from an alien intelligence would be the most momentous discovery the human species is ever likely to make. It’s worth a little thinking ahead.

Cassini spacecraft probes methane-filled sea on Titan

Emilee Speck

Oceanographers may need to study alien worlds sooner than you think.

Observations by NASA‘s Cassini spacecraft indicate Saturn’s moon Titan is more Earth-like with its dense atmosphere, lake-filled surface and possible wetlands.

Other than our home planet Titan is the only known world in the solar system with stable liquid on its surface, according to NASA.

Since 2004, Cassini has found more than 620,000 square miles of Titan’s surface covered in liquid, about two percent of its globe. Planetary scientists have theorized about what elements fill Titan’s liquid bodies, but thanks to Cassini they now have answers

A new study using Cassini’s radar instrument to study Titan’s second largest sea, known as Ligeia Mare, between 2007 and 2015 reveals it’s a filled with methane.

The study published in the Journal of Geophysical Research: Planets confirms what planetary scientists have thought about Titan’s seas for some time.

Using Cassini’s radar instrument to detect echoes from the seafloor of Ligeia Mare scientists used the depth-sounding information to observe temperatures, which helped give clues to their composition, according to the news release.

“Before Cassini, we expected to find that Ligeia Mare would be mostly made up of ethane, which is produced in abundance in the atmosphere when sunlight breaks methane molecules apart. Instead, this sea is predominantly made of pure methane,” said Alice Le Gall, a Cassini radar team member and lead author of the new study.

Ligeia Mare is the about the size of Lake Huron and Lake Michigan together, according to NASA and from Cassini’s flybys scientists were able to determine the sea is 525 feet deep in some areas.

All of Titan’s seas are named for mythical sea creatures. The largest sea, Kraken Mare is about 680 miles long.

Another similarity between our home planet and Titan is they both have nitrogen atmospheres, but Titan is lacking much oxygen. Titan’s atmosphere is mostly methane with trace amounts of ethane and because of the distance from the sun, meaning cold temperatures, the methane and ethane remain in liquid form instead of escaping, according to NASA.

Le Gall offered a few possibilities of how Ligeria Mare became mostly methane filled, instead of ethane as Cassini’s team originally thought.

“Either Ligeia Mare is replenished by fresh methane rainfall, or something is removing ethane from it,” said Le Gall. “It is possible that the ethane ends up in the undersea crust, or that it somehow flows into the adjacent sea, Kraken Mare, but that will require further investigation.”

The study also found Ligeia Mare’s shoreline may warm quicker than in the sea, similar to a beach on Earth.

“It’s a marvelous feat of exploration that we’re doing extraterrestrial oceanography on an alien moon,” said Steve Wall, deputy lead of the Cassini radar team. “Titan just won’t stop surprising us.”



Copyright © 2016, Orlando Sentinel


Astronauts Successfully Attach Inflatable Room to Space Station


Inflatable room attached to space station

A giant addition that one day may be used to support life on Mars has been deployed and is set to undergo a two-year test.It will be expanded to 5 times its size »



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SpaceX delivers world’s 1st inflatable room for astronauts

By MARCIA DUNN | April 10, 2016 | 12:05 PM EDT

In this frame taken from video from NASA TV, the SpaceX Dragon cargo ship is captured by a robot arm from the International Space Station, Sunday April 10, 2016. A SpaceX Dragon cargo ship arrived at the International Space Station on Sunday, two days after launching from Cape Canaveral, Florida. Station astronauts used a big robot arm to capture the Dragon, orbiting 260 miles above Earth. (NASA TV via AP)

CAPE CANAVERAL, Fla. (AP) — SpaceX has made good on a high-priority delivery: the world’s first inflatable room for astronauts.

A SpaceX Dragon cargo ship arrived at the International Space Station on Sunday, two days after launching from Cape Canaveral. Station astronauts used a robot arm to capture the Dragon, orbiting 250 miles above Earth.

The Dragon holds 7,000 pounds of freight, including the soft-sided compartment built by Bigelow Aerospace. The pioneering pod — packed tightly for launch — should swell to the size of a small bedroom once filled with air next month.

It will be attached to the space station this Saturday, but won’t be inflated until the end of May. The technology could change the way astronauts live in space: NASA envisions inflatable habitats in a couple decades at Mars, while Bigelow Aerospace aims to launch a pair of inflatable space stations in just four years for commercial lease.

For now, the Bigelow Expandable Activity Module — BEAM for short — will remain mostly off-limits to the six-man station crew. NASA wants to see how the experimental chamber functions, so the hatch will stay sealed except when astronauts enter a few times a year to collect measurements and swap out sensors.

This is SpaceX’s first delivery for NASA in a year. A launch accident last June put shipments on hold.

SpaceX flight controllers at company headquarters in Hawthorne, California, applauded when the hefty station arm plucked Dragon from orbit. A few hours later, the capsule was bolted securely into place.

“It looks like we caught a Dragon,” announced British astronaut Timothy Peake, who made the grab. “There are smiles all around here,” NASA’s Mission Control replied. “Nice job capturing that Dragon.”

SpaceX is still reveling in the success of Friday’s booster landing at sea.

For the first time, a leftover booster came to a solid vertical touchdown on a floating platform. SpaceX chief executive Elon Musk wants to reuse boosters to save money, a process that he says will open access to space for more people in more places, like Mars. His ambition is to establish a city on Mars.

NASA also has Mars in its sights and looks to send astronauts there in the 2030s. In order to focus on that objective, the space agency has hired U.S. companies like SpaceX to deliver cargo and, as early as next year, astronauts to the space station. U.S. astronauts currently have to hitch rides on Russian rockets.

In a sign of these new commercial space times, a Dragon capsule is sharing the station for the first time with Orbital ATK’s supply ship named Cygnus, already parked there two weeks. This is also the first time in five years that the compound has six docking ports occupied: Dragon, Cygnus, two Russian Progress freighters and two Russian Soyuz crew capsules.

The Dragon will remain at the station for a month before returning to Earth with science samples, many of them from one-year spaceman Scott Kelly. He ended his historic mission last month. Cygnus will stick around a little longer.

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Astronomers spot a never-before-seen type of white dwarf star

Its discovery could change our understanding of star death

By Loren Grush

For the first time ever, researchers have spotted a white dwarf surrounded by an atmosphere of mostly oxygen. A star of this kind, a super-dense dead star with an oxygen atmosphere, had never been seen before, though astronomers had speculated that one might exist. Such a unique finding could change how we think about the evolution of stars and what happens when these stellar objects die.


To find this unique zombie star, an international team of researchers looked through data from the Sloan Digital Sky Survey — a project that measures the colored lines of light coming off of objects throughout the universe. These lines, called spectral lines, can tell astronomers what types of elements make up a star’s atmosphere. Using this data, the researchers found that one particular white dwarf, with the eloquent name ­­SDSS J124043.01+671034.68, didn’t have any hydrogen or helium in its atmosphere; its surrounding air was instead almost pure oxygen.

“It was completely not expected for a star with a low mass like our star,” said study author Kepler Oliveira, an astronomer at the Federal University of Rio Grande do Sul.

An image of SDSS J124043.01+671034.68. (Kepler Oliveira)

The finding is so surprising because it doesn’t quite fit with our current understanding of what stars look like when they die. Typically, when a star like our Sun runs out of fuel, it starts collapsing. As the star becomes more compact, it heats up, causing its outer layers to expand more than 100 times the star’s original size. Eventually those outer layers are lost and only the core of the star remains — the faint white dwarf.

Most of the star’s hydrogen and helium get lost with those outer layers, but a little bit of them are left over in the white dwarf’s atmosphere. The hydrogen and helium float to the top of the star’s surface, because they’re relatively light; the heavier elements, like oxygen and carbon, remain below.

“It’s the same reason that panning for gold works,” said Andrew Vanderburg, an astronomy graduate student at Harvard University, who was not involved in the study. “If you have gold and sediments in water, the gold is heavier so it’ll sink to the bottom, but the sediments are lighter, so they’ll stay at the top.”


The fact that no hydrogen and helium are seen in the atmosphere of the white dwarf in question is puzzling. It means some kind of event has caused the two elements to disappear, making oxygen the lightest element in the star’s atmosphere. But the researchers aren’t sure what kind of event that was, as they’ve never considered it before. “We don’t make models of things we don’t know exist,” Oliveira said. “But now that we know this star exists, we have to calculate the model for it.”

One possible explanation for the lack of helium and hydrogen is that the star experienced a giant thermal pulse when the object was a red giant, and that intense explosion stripped away all the lighter elements. Another possible scenario is that the star was actually part of a binary system. The stars may have merged together, causing an explosion that ejected the hydrogen and helium. These ideas are only loose theories, though. “We don’t have a calculation that shows [a binary merger] happened, but that’s the only explanation that I can think of,” Oliveira said. “It must have come from a binary system.”

The researchers will work to figure out what happened to this star, but in the meantime, the white dwarf’s discovery is a significant find for the astronomy community. “It’s a new class of star,” said Vanderburg. “We don’t understand how it formed, but this is the kind of thing that pushes our field forward, and who knows where it will take us.”



by Evan Gough

Comet Siding Spring (C/2007 Q3) as imaged in the infrared by the WISE space telescope. The image was taken January 10, 2010 when the comet was 2.5AU from the Sun. Credit: NASA/JPL-Caltech/UCLA

In the Autumn of 2014, NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft arrived at Mars and entered into orbit. MAVEN wasn’t the only visitor to arrive at Mars at that time though, as comet Siding Spring (C/2013 A1) also showed up at Mars. Most of MAVEN’s instruments were shut down to protect sensitive electronics from Siding Spring’s magnetic field. But the magnetometer aboard the spacecraft was left on, which gave MAVEN a great view of the interaction between the planet and the comet.

Unlike Earth, which has a powerful magnetosphere created by its rotating metal core, Mars’ magnetosphere is created by plasma in its upper atmosphere, and is not very powerful. (Mars may have had a rotating metal core in the past, and a stronger magnetosphere because of it, but that’s beside the point.) Comet Siding Spring is small, with its nucleus being only about one half a kilometer. But its magnetosphere is situated in its coma, the long ‘tail’ of the comet that stretches out for a million kilometers.

When Siding Spring approached Mars, it came to within 140,000 km (87,000 miles) of the planet. But the comet’s coma nearly touched the surface of the planet, and during that hours-long encounter, the magnetic field from the comet created havoc with Mars’ magnetic field. And MAVEN’s magnetometer captured the event.

MAVEN was in position to capture the close encounter between Mars and comet Siding Spring. Image: NASA/Goddard.

Jared Espley is a member of the MAVEN team at Goddard Space Flight Center. He said of the Mars/Siding Spring event, “We think the encounter blew away part of Mars’ upper atmosphere, much like a strong solar storm would.”

“The main action took place during the comet’s closest approach,” said Espley, “but the planet’s magnetosphere began to feel some effects as soon as it entered the outer edge of the comet’s coma.”

Espley and his colleagues describe the event as a tide that washed over the Martian magnetosphere. Comet Siding Spring’s tail has a magnetosphere due to its interactions with the solar wind. As the comet is heated by the sun, plasma is generated, which interacts in turn with the solar wind, creating a magnetosphere. And like a tide, the effects were subtle at first, and the event played out over several hours as the comet passed by the planet.

Siding Spring’s magnetic tide had only a subtle effect on Mars at first. Normally, Mars’ magnetosphere is situated evenly around the planet, but as the comet got closer, some parts of the planet’s magnetosphere began to realign themselves. Eventually the effect was so powerful that the field was thrown into chaos, like a flag flapping every which way in a powerful wind. It took Mars a while to recover from this encounter as the field took several hours to recover.

MAVEN’s task is to gain a better understanding of the interactions between the Sun’s solar wind and Mars. So being able to witness the effect that Siding Spring had on Mars is an added bonus. Bruce Jakosky, from the University of Colorado’s Laboratory for Atmospheric and Space Physics in Boulder, is one of MAVEN’s principal investigators. “By looking at how the magnetospheres of the comet and of Mars interact with each other,” said Jakosky, “we’re getting a better understanding of the detailed processes that control each one.”