Matt Williams, Author at Universe Today

November 18, 2014December 23, 2015 by Matt Williams

How Do Planets Form? Semarkona Meteorite Shows Some Clues

Artist’s impression of a baby star still surrounded by a protoplanetary disc in which planets are forming. Credit: ESO

It may seem all but impossible to determine how the Solar System formed, given that it happened roughly 4.5 billion years ago. Luckily, much of the debris that was left over from the formation process is still available today for study, circling our Solar System in the form of rocks and debris that sometimes make their way to Earth.

Among the most useful pieces of debris are the oldest and least altered type of meteorites, which are known as chondrites. They are built mostly of small stony grains, called chondrules, that are barely a millimeter in diameter.

And now, scientists are being provided with important clues as to how the early Solar System evolved, thanks to new research based on the the most accurate laboratory measurements ever made of the magnetic fields trapped within these tiny grains.

To break it down, chondrite meteorites are pieces of asteroids — broken off by collisions — that have remained relatively unmodified since they formed during the birth of the Solar System. The chondrules they contain were formed when patches of solar nebula – dust clouds that surround young suns – was heated above the melting point of rock for hours or even days.

The dust caught in these “melting events” was melted down into droplets of molten rock, which then cooled and crystallized into chondrules. As chondrules cooled, iron-bearing minerals within them became magnetized by the local magnetic field in the gas cloud. These magnetic fields are preserved in the chondrules right on up to the present day.

*A slice of the NWA 5205 meteorite from the Sahara Desert displays wall-to-wall chondrules. Credit: Bob King*

The chondrule grains whose magnetic fields were mapped in the new study came from a meteorite named Semarkona – named after the town in India where it fell in 1940.

Roger Fu of MIT – working under Benjamin Weiss – was the chief author of the study; with Steve Desch of Arizona State University’s School of Earth and Space Exploration attached as co-author.

According to the study, which was published this week in Science, the measurements they collected point to shock waves traveling through the cloud of dusty gas around the newborn sun as a major factor in solar system formation.

“The measurements made by Fu and Weiss are astounding and unprecedented,” says Steve Desch. “Not only have they measured tiny magnetic fields thousands of times weaker than a compass feels, they have mapped the magnetic fields’ variation recorded by the meteorite, millimeter by millimeter.”

The scientists focused specifically on the embedded magnetic fields captured by “dusty” olivine grains that contain abundant iron-bearing minerals. These had a magnetic field of about 54 microtesla, similar to the magnetic field at Earth’s surface (which ranges from 25 to 65 microtesla).

Coincidentally, many previous measurements of meteorites also implied similar field strengths. But it is now understood that those measurements detected magnetic minerals that were contaminated by the Earth’s own magnetic field, or even from the hand magnets used by the meteorite collectors.

Artist depiction of a protoplanetary disk permeated by magnetic fields. Objects in the foregrounds are millimeter-sized rock pellets known as chondrules. Credit: Hernán Cañellas — *Artist depiction of a protoplanetary disk permeated by magnetic fields. Objects in the foregrounds are millimeter-sized rock pellets known as chondrules.*
*Credit: Hernán Cañellas*

“The new experiments,” Desch says, “probe magnetic minerals in chondrules never measured before. They also show that each chondrule is magnetized like a little bar magnet, but with ‘north’ pointing in random directions.”

This shows, he says, that they became magnetized before they were built into the meteorite, and not while sitting on Earth’s surface. This observation, combined with the presence of shock waves during early solar formation, paints an interesting picture of the early history of our Solar System.

“My modeling for the heating events shows that shock waves passing through the solar nebula is what melted most chondrules,” Desch explains. Depending on the strength and size of the shock wave, the background magnetic field could be amplified by up to 30 times. “Given the measured magnetic field strength of about 54 microtesla,” he added, “this shows the background field in the nebula was probably in the range of 5 to 50 microtesla.”

There are other ideas for how chondrules might have formed, some involving magnetic flares above the solar nebula, or passage through the sun’s magnetic field. But those mechanisms require stronger magnetic fields than what has been measured in the Semarkona samples.

This reinforces the idea that shocks melted the chondrules in the solar nebula at about the location of today’s asteroid belt, which lies some two to four times farther from the sun than the Earth’s orbits.

Desch says, “This is the first really accurate and reliable measurement of the magnetic field in the gas from which our planets formed.”

Macro View Makes Dark Matter Look Even Stranger

New research suggests that Dark Matter may exist in clumps distributed throughout our universe. Credit: Max-Planck Institute for Astrophysics

We know dark matter exists. We know this because without it and dark energy, our Universe would be missing 95.4% of its mass. What’s more, scientists would be hard pressed to explain what accounts for the gravitational effects they routinely see at work in the cosmos.

For decades, scientists have sought to prove its existence by smashing protons together in the Large Hadron Collider. Unfortunately, these efforts have not provided any concrete evidence.

Hence, it might be time to rethink dark matter. And physicists David M. Jacobs, Glenn D. Starkman, and Bryan Lynn of Case Western Reserve University have a theory that does just that, even if it does sound a bit strange.

In their new study, they argue that instead of dark matter consisting of elementary particles that are invisible and do not emit or absorb light and electromagnetic radiation, it takes the form of chunks of matter that vary widely in terms of mass and size.

As it stands, there are many leading candidates for what dark matter could be, which range from Weakly-Interacting Massive Particles (aka WIMPs) to axions. These candidates are attractive, particularly WIMPs, because the existence of such particles might help confirm supersymmetry theory – which in turn could help lead to a working Theory of Everything (ToE).

According to supersymmetry, dark-matter particles known as neutralinos (which are often called WIMPs) annihilate each other, creating a cascade of particles and radiation that includes medium-energy gamma rays. If neutralinos exist, the LAT might see the gamma rays associated with their demise. Credit: Sky & Telescope / Gregg Dinderman. — *According to supersymmetry, dark-matter particles known as neutralinos (aka WIMPs) annihilate each other, creating a cascade of particles and radiation. Credit: Sky & Telescope / Gregg Dinderman.*

But so far, no evidence has been obtained that definitively proves the existence of either. Beyond being necessary in order for General Relativity to work, this invisible mass seems content to remain invisible to detection.

According to Jacobs, Starkman, and Lynn, this could indicate that dark matter exists within the realm of normal matter. In particular, they consider the possibility that dark matter consists of macroscopic objects – which they dub “Macros” – that can be characterized in units of grams and square centimeters respectively.

Macros are not only significantly larger than WIMPS and axions, but could potentially be assembled out of particles in the Standard Model of particle physics – such as quarks and leptons from the early universe – instead of requiring new physics to explain their existence. WIMPS and axions remain possible candidates for dark matter, but Jacobs and Starkman argue that there’s a reason to search elsewhere.

“The possibility that dark matter could be macroscopic and even emerge from the Standard Model is an old but exciting one,” Starkman told Universe Today, via email. “It is the most economical possibility, and in the face of our failure so far to find dark matter candidates in our dark matter detectors, or to make them in our accelerators, it is one that deserves our renewed attention.”

After eliminating most ordinary matter – including failed Jupiters, white dwarfs, neutron stars, stellar black holes, the black holes in centers of galaxies, and neutrinos with a lot of mass – as possible candidates, physicists turned their focus on the exotics.

Particle Collider — *Ongoing experiments at the Large Hadron Collider have so far failed to produce evidence of WIMPs. Credit: CERN/LHC/GridPP*

Nevertheless, matter that was somewhere in between ordinary and exotic – relatives of neutron stars or large nuclei – was left on the table, Starkman said. “We say relatives because they probably have a considerable admixture of strange quarks, which are made in accelerators and ordinarily have extremely short lives,” he said.

Although strange quarks are highly unstable, Starkman points out that neutrons are also highly unstable. But in helium, bound with stable protons, neutrons remain stable.

“That opens the possibility that stable strange nuclear matter was made in the early Universe and dark matter is nothing more than chunks of strange nuclear matter or other bound states of quarks, or of baryons, which are themselves made of quarks,” said Starkman.

Such dark matter would fit the Standard Model.

This is perhaps the most appealing aspect of the Macros theory: the notion that dark matter, which our cosmological model of the Universe depends upon, can be proven without the need for additional particles.

Still, the idea that the universe is filled with a chunky, invisible mass rather than countless invisible particles does make the universe seem a bit stranger, doesn’t it?

Concerns over ESA’s Data Release Policy Amidst Rosetta Comet Landing

Artist's concept of the Rosetta mission's Philae lander on the surface of comet 67P/Churyumov-Gerasimenko. Image Credit: ESA

This week, history was made as the Rosetta mission’s Philae lander touched down on the surface of 67P/Churnyumov-Gerasimenko. Days before this momentous event took place, the science team presented some staggering pictures of the comet at a planetary conference in Tucson, Arizona, where guests were treated to the first color images taken by the spacecraft’s high-resolution camera.

Unfortunately for millions of space enthusiasts around the world, none of these exciting images were released to the public. In addition, much of the images taken of the comet over the past few months as Rosetta closed in on it have similarly not been released. This has led to demands for more openness, which in turn has focused attention on ESA’s image and data release policy.

Allowing scientists to withhold data for some period of time is not uncommon in planetary science. According to Jim Green, the director of NASA’s Planetary Science Division, a 6-month grace period is typical for principal investigator-led spacecraft. However, NASA headquarters can also insist that the principal investigator release data for key media events.

This has certainly been the case where the Curiosity and other Mars rover missions were concerned, not to mention the Cassini-Huygens mission. On many occasions, NASA chose to release images to the public almost immediately after they were obtained.

However, ESA has a different structure than NASA. It relies much more on contributions from member-states, whereas NASA pays for most of its instruments directly. Rosetta’s main mission camera – the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) – was developed by a consortium of institutes led by the Max-Planck-Institute for Solar System Research. As a result, ESA has less control over how information obtained by this specific camera is disseminated.

The surface of comet 67P/Churyumov-Gerasimenko as viewed at a 10-kilometer distance by navigation cameras. Image Credit: ESA/Rosetta/NavCam — *The surface of comet 67P/Churyumov-Gerasimenko as viewed at a 10-kilometer distance by navigation cameras.* *Image Credit: ESA/Rosetta/NavCam*

Journalist Eric Hand recently covered this imagery release dilemma in an article in Science, revealing that even scientists at Darmstadt, Germany this week — the location of ESA’s mission control for Philae’s landing — had not seen the science images that were being shared at the Planetary Science conference. Project scientist Matt Taylor was reduced to learning about the new results by looking at Twitter feeds on his phone.

Hand quoted Taylor as saying the decision when to publicly release images is a “tightrope” walk. And Hand also said some “ESA officials are worried that the principal investigators for the spacecraft’s 11 instruments are not releasing enough information, and many members of the international community feel the same way.”

Back in July, ESA responded to these calls for more information with a press release, in which they claimed that an “open-data” policy is not the norm for either ESA or NASA. Responding to the examples of the Mars rovers and Cassini-Huygens, which have been cited by critics for more openness, ESA countered with the Hubble Space Telescope, the Chandra X-Ray observatory, the MESSENGER mission to Mercury, and even some NASA Mars orbiters.

In these cases, they claimed, the data obtained was subject to a “proprietary period”, which also pertains to data from ESA’s Mars Express, XMM-Newton, and Rosetta missions. This period, they said, is typically 6-12 months, and “gives exclusive access to the scientists who built the instruments or to scientists who made a winning proposal to make certain observations.”

Nevertheless, there is still some criticism by those who think that releasing more images would be a positive gesture and not compromise any ESA scientist’s ability to conduct research.

As space blogger Daniel Fischer said in response to the ESA press release, “Who is writing scientific papers already about the distant nucleus that is just turning into a shape? And on the weekly schedule a sampling of these images is coming out anyway, with a few days delay… Presenting the approach images, say, one per day and with only hours delay would thus not endanger any priorities but instead give the eager public a unique chance to ‘join the ride’, just as they can with Cassini or the Mars rovers.”

The Rosetta Spacecraft's instruments. Image Credit: ESA — *The Rosetta Spacecraft’s instruments. Image Credit: ESA*

In particular, a lot of criticism has been focused on the OSIRIS camera team, led by principal investigator Holger Sierks. Days before the Philae Lander put down on the comet, Stuart Atkinson – an amateur astronomer, space educator and image processor – wrote the following on his space blog Cumbrian Sky:

[The OSIRIS team’s] attitude towards the public, the media, and ESA itself has been one of arrogant contempt, and I have no doubt at all that their selfish behaviour has damaged the mission and the reputation and public image ESA. Their initial arguments that they had to keep images back to allow them to do their research no longer hold up now. They must have taken many hundreds of jaw droppingly detailed images by now, the images everyone has been looking forward to ever since ROSETTA launched a decade ago, so could easily release dozens of images which pose no risk to their work or careers, but they have released only a handful, and those have been the least-detailed, least-remarkable images they could find.

However, in Hand’s Science article, Sierks said that he feels the OSIRIS team has already provided a fair amount of data to the public. Currently, about one image is released a week – a rate that seems to Sierks to be more than adequate given that they are superior to anything before seen in terms of comet research.

Furthermore, Sierks claimed that other researchers, unaffiliated with the Rosetta team, have submitted papers based on these released images, while his team has been consumed with the daily task of planning the mission. After working on OSIRIS since 1997, Sierks feels that his team should get the first shot at using the data.

*Comet 67P/Churyumov-Gerasimenko. Image Credit: ESA*

This echoes ESA’s July press release, which expressed support for their science teams to have first-crack any data obtained by their instruments. “Because no-one has ever been to 67P/C-G before,” it stated, “each new piece of data from Rosetta has the potential for a scientific discovery. It’s only fair that the instrument science teams have the first chance to make and assess those discoveries.”

The same press release also defended ESA’s decision not to release information from the navigation cameras more freely – which they do have control over. Citing overlap, they indicated that they want to “avoid undermining the priority of the OSIRIS team.”

Prior to Rosetta’s launch in 2004, an embargo of 6 months was set for all the instrument teams. ESA scientists have pointed out that mission documents also stipulate that instrument teams provide “adequate support” to ESA management in its communication efforts.

Mark McCaughrean, an ESA senior science adviser at ESTEC, is one official that believes these support requirements are not being met. He was quoted by Eric Hand in Science as saying, “I believe that [the OSIRIS camera team’s support] has by no means been adequate, and they believe it has,” he says. “But they hold the images, and it’s a completely asymmetric relationship.”

Luckily, ESA has released images of the surface of 67P and what it looked like for the Philae Lander and as it made its descent towards the comet. Additionally, stunning imagery from Rosetta’s navigation camera were recently released. In the coming days and weeks, we can certainly hope that plenty of more interesting images and exciting finds will be coming, courtesy of the Rosetta mission and its many contributors.

Further Reading: Science Mag, NASA, ESA

November 13, 2014December 23, 2015 by Matt Williams

Weather Forecasting on Mars Likely to be Trickier Than on Earth

Clouds above the rim of "Endurance Crater" in this image from NASA's Mars Exploration Rover Opportunity. These clouds occur in a region of strong vertical shear. The cloud particles (ice in this martian case) fall out, and get dragged along away from the location where they originally condensed, forming characteristic streamers. Opportunity took this picture with its navigation camera during the rover's 269th martian day (Oct. 26, 2004). Image Credit: NASA/JPL

Predicting the weather here on Earth is never an easy thing, but predicting it on Mars may be ever trickier. Such is the argument presented by a recent study concerning “macroweather” patterns on the Red Planet, a new regime for understanding how planetary environments work.

When it comes to describing the climate of a planet, two important concepts come into play. First, there’s weather, which covers day-to-day changes due to fluctuations in the atmosphere. Second, there’s climate, which is more stable and subject to change over the course of decades. Macroweather, the latest addition to the game, describes the relatively stable periods that exist between short-term weather and long-term climate.

For those of us dwelling here on planet Earth, these are familiar concepts. But researchers say this same three-part pattern applies to atmospheric conditions on Mars. The results of a new paper, published today in Geophysical Research Letters also show that the Sun plays a major role in determining macroweather.

Several dust devils cross a plain in this animation of a series of images acquired by NASA's Mars Rover Spirit in May, 2005. (NASA/JPL-Caltech/Cornell/USGS) — *Several dust devils cross a plain in this animation of a series of images acquired by NASA’s Mars Rover Spirit in May, 2005. (NASA/JPL-Caltech/Cornell/USGS)*

The scientists chose to study Mars because of the wealth of data it has provided in recent decades, which they then used to test their theory that a transitional “macroweather” regime exists on a planet other than Earth. They used information collected from the Viking Mars lander mission from the 1970s and 1980s, and more recent data from the Mars Global Surveyor.

By taking into account how the sun heats Mars, as well as the thickness of the planet’s atmosphere, the scientists predicted that temperatures and wind would fluctuate on Mars similar to how they fluctuate on Earth. However, this transition from weather to macroweather would take place over 1.8 Martian days (about two Earth days), compared with a week to 10 days here on Earth.

“Our analysis of the data from Mars confirmed this prediction quite accurately,” said Shaun Lovejoy, a physics professor at McGill University in Montreal, Canada, and lead author of the paper. “This adds to evidence, from studies of Earth’s atmosphere and oceans, that the sun plays a central role in shaping the transition from short-term weather fluctuations to macroweather.”

Early Spring Dust Storms at the North Pole of Mars. Early spring typically brings dust storms to northern polar Mars. As the north polar cap begins to thaw, the temperature difference between the cold frost region and recently thawed surface results in swirling winds. The choppy dust clouds of several dust storms are visible in this mosaic of images taken by the Mars Global Surveyor spacecraft in 2002. The white polar cap is frozen carbon dioxide. (NASA/JPL/Malin Space Science Systems) — *Early Spring Dust Storms at the North Pole of Mars, taken by the Mars Global Surveyor spacecraft in 2002. Image Credit: NASA/JPL/Malin Space Science Systems*

The findings also indicate that weather on Mars can be predicted with some skill only two days in advance, compared to 10 days on Earth.

“We’re going to have a very hard time predicting the weather on Mars beyond two days given what we have found in weather records there,” said co-author Jan-Peter Muller from the University College London Mullard Space Science Laboratory in the UK, “which could prove tricky for the European lander and rover.”

This research promises to advance scientists’ understanding of the dynamics of Earth’s own atmosphere, and could potentially provide insights into the weather of Venus, Saturn’s moon Titan, and possibly the gas giants Jupiter, Saturn, Uranus, and Neptune.

As always, in learning about other planets and their climates, scientists are finding that the planets of our Solar System may have more in common with Earth than previously thought. Because of this, studying these other worlds will inevitably help us to better understand our own.

Further Reading: AGU, McGill

November 10, 2014June 5, 2022 by Matt Williams

What Did Isaac Newton Discover?

Godfrey Kneller's 1689 portrait of Isaac Newton at age 46. Image credit: Isaac Newton Insitute

Isaac Newton – who lived from December 25th, 1642, to March 20th, 1727 – was an English scientist, mathematician, and “natural philosopher”. In his time, he played a vital role in the Scientific Revolution, helping to advance the fields of physics, astronomy, mathematics and the natural sciences. From this, he established a legacy that would dominate the sciences for the next three centuries.

In fact, the term “Newtonian” came to be used by subsequent generations to describe bodies of knowledge that owed their existence to his theories. And because of his extensive contributions, Sir Isaac Newton is regarded as one of the most influential scholars in the history of science. But what exactly did he discover?

Newton’s Three Laws of Motion:

For starters, his magnum opus – Philosophiæ Naturalis Principia Mathematica (“Mathematical Principles of Natural Philosophy”), which was first published in 1687 – laid the foundations for classical mechanics. In it, he formulated his Three Laws of Motion, which were derived from Johann Kepler’s Laws of Planetary Motion and his own mathematical description of gravity.

William Blake's Newton (1795), depicted as a divine geometer. Image Credit: William Blake Archive/Wikipedia — *William Blake’s* Newton (1795), depicting him as a divine geometer. Image Credit: William Blake Archive/Wikipedia

The first law, known as the “law of inertia”, states that: “An object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force.” The second law states that acceleration is produced when a force acts on a mass – ergo, the greater the mass of the object, the greater the force required to accelerate it. The third and final law states that “for every action, there is an equal but opposite reaction”.

Universal Gravitation:

He also formulated his law of Universal Gravitation in the Principia, which states that every point mass attracts every single other point mass by a force pointing along the line intersecting both point. According to his calculations, this force is proportional to the product of the two masses and inversely proportional to the square of the distance between them. The formula for this theory can be expressed as:

$F = G frac{m_1 m_2}{r^2}$

Newton would go on to use these principles to account for the trajectories of comets, the tides, the precession of the equinoxes, and other astrophysical phenomena. This effectively removed the last doubts about the validity of the heliocentric model of the cosmos which argued that the Sun (not the Earth) was at the center of the planetary system. His work also demonstrated that the motion of objects on Earth and of celestial bodies could be described by the same principles.

*Sapling of the reputed original tree that inspired Sir Isaac Newton to consider gravitation. Credit: Wikipedia Commons/Loodog*

Though Newton’s inspiration for his theories on gravity are often attributed to the “Apple Incident” – i.e. where he watched an apple fall from a tree – the story is considered apocryphal by modern sources who argue that he came to his conclusions over time. However, Newton himself described the incident, and contemporaries of his defend this assertion.

Shape of the Earth:

Additional contributions include his prediction that the Earth was likely shaped as an “oblate spheroid” – i.e. a sphere that experienced flattening at the poles. This theory would later be vindicated by the measurements of Maupertuis, La Condamine, and others. This in turn helped convince most Continental European scientists of the superiority of Newtonian mechanics over the earlier system of Descartes.

In terms of mathematics, he contributed to the study of power series, generalized the binomial theorem to non-integer exponents, developed Newton’s method for approximating the roots of a function, and classified most of the cubic plane curves. He also shares credit with Gottfried Leibniz for the development of calculus.

These discoveries represented a huge leap forward for the fields of math, physics, and astronomy, allowing for calculations that more accurately modeled the behavior of the universe than ever before.

Optics:

In 1666, Newton began contributing to the field of optics, first by observing that color was a property of light by measuring it through a prism. From 1670 to 1672, he lectured at the University of Cambridge on optics and investigated the refraction of light, demonstrating that the multicolored spectrum produced by a prism could be recomposed into white light by a lens and a second prism.

*Sunlight passing through a prism. Image credit: NASA*

As a result of his research, he came to theorize that color is the result of objects interacting with already-colored light rather than objects generating the color themselves, which is known as Newton’s theory of color.

In addition, he concluded that the lens of any refracting telescope would suffer from the dispersion of light into colors (chromatic aberration). As a proof of the concept, he constructed a telescope using a mirror as the objective to bypass that problem. This was the first known functional reflecting telescope in existence, the design of which is now known as a Newtonian telescope.

Other Achievements:

He also formulated an empirical law of cooling, studied the speed of sound, and introduced the notion of a Newtonian fluid. This term is used to describe any fluid where the viscous stresses arising from its flow, at every point, are linearly proportional to the rate of change of its deformation over time.

Beyond his work in mathematics, optics and physics, he also devoted a significant amount of time studying Biblical chronology and alchemy, but most of his work in these areas remained unpublished until long after his death.

So what did Isaac Newton discover? Theories that would dominate the fields of science, astronomy, physics and the natural world for centuries to come. His ideas would go on to influence such luminaries as Joseph-Louis Lagrange and Albert Einstein, the latter of whom is the only scientists believed to have left a comparable legacy.

We have written many interesting articles about Sir Isaac Newton here at Universe Today. Here’s Who was Sir Isaac Newton?, What did Isaac Newton Invent?, Who Discovered Gravity?, What is Absolute Space?, What is the Gravitational Constant?

There are other resources on the internet if you want to learn more about Isaac Newton. This UK site has some great info on his discoveries. You can also check out the PBS website.

You can also check out Astronomy Cast. Episode 44 Einstein’s Theory of Relativity is particularly interesting.

Sources:

November 10, 2014December 23, 2015 by Matt Williams

NASA’s Next Exoplanet Hunter Moves Into Development

A conceptual image of the Transiting Exoplanet Survey Satellite. Image Credit: MIT

NASA’s ongoing hunt for exoplanets has entered a new phase as NASA officially confirmed that the Transiting Exoplanet Survey Satellite (TESS) is moving into the development phase. This marks a significant step for the TESS mission, which will search the entire sky for planets outside our solar system (a.k.a. exoplanets). Designed as the first all-sky survey, TESS will spend two years of an overall three-year mission searching both hemispheres of the sky for nearby exoplanets.

Previous sky surveys with ground-based telescopes have mainly picked out giant exoplanets. In contrast, TESS will examine a large number of small planets around the very brightest stars in the sky. TESS will then record the nearest and brightest main sequence stars hosting transiting exoplanets, which will forever be the most favorable targets for detailed investigations. During the third year of the TESS mission, ground-based astronomical observatories will continue monitoring exoplanets identified by the TESS spacecraft.

“This is an incredibly exciting time for the search of planets outside our solar system,” said Mark Sistilli, the TESS program executive from NASA Headquarters, Washington. “We got the green light to start building what is going to be a spacecraft that could change what we think we know about exoplanets.”

“During its first two years in orbit, the TESS spacecraft will concentrate its gaze on several hundred thousand specially chosen stars, looking for small dips in their light caused by orbiting planets passing between their host star and us,” said TESS Principal Investigator George Ricker of the Massachusetts Institute of Technology..

Artistic representations of the only known planets around other stars (exoplanets) with any possibility to support life as we know it. Credit: Planetary Habitability Laboratory, University of Puerto Rico, Arecibo. — *Artistic representations of known exoplanets with any possibility to support life. Image Credit: Planetary Habitability Laboratory, University of Puerto Rico, Arecibo.*

All in all, TESS is expected to find more than 5,000 exoplanet candidates, including 50 Earth-sized planets. It will also find a wide array of exoplanet types, ranging from small, rocky planets to gas giants. Some of these planets could be the right sizes, and orbit at the correct distances from their stars, to potentially support life.

“The most exciting part of the search for planets outside our solar system is the identification of ‘earthlike’ planets with rocky surfaces and liquid water as well as temperatures and atmospheric constituents that appear hospitable to life,” said TESS Project Manager Jeff Volosin at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Although these planets are small and harder to detect from so far away, this is exactly the type of world that the TESS mission will focus on identifying.”

Now that NASA has confirmed the development of TESS, the next step is the Critical Design Review, which is scheduled to take place in 2015. This would clear the mission to build the necessary flight hardware for its proposed launch in 2017.

“After spending the past year building the team and honing the design, it is incredibly exciting to be approved to move forward toward implementing NASA’s newest exoplanet hunting mission,” Volosin said.

TESS is designed to complement several other critical missions in the search for life on other planets. Once TESS finds nearby exoplanets to study and determines their sizes, ground-based observatories and other NASA missions, like the James Webb Space Telescope, would make follow-up observations on the most promising candidates to determine their density and other key properties.

*The James Webb Space Telescope. Image Credit: NASA/JPL*

By figuring out a planet’s characteristics, like its atmospheric conditions, scientists could determine whether the targeted planet has a habitable environment.

“TESS should discover thousands of new exoplanets within two hundred light years of Earth,” Ricker said. “Most of these will be orbiting bright stars, making them ideal targets for characterization observations with NASA’s James Webb Space Telescope.”

“The Webb telescope and other teams will focus on understanding the atmospheres and surfaces of these distant worlds, and someday, hopefully identify the first signs of life outside of our solar system,” Volosin said.

TESS will use four cameras to study sections of the sky’s north and south hemispheres, looking for exoplanets. The cameras would cover about 90 percent of the sky by the end of the mission.

This makes TESS an ideal follow-up to the Kepler mission, which searches for exoplanets in a fixed area of the sky. Because the TESS mission surveys the entire sky, TESS is expected to find exoplanets much closer to Earth, making them easier for further study.

In addition, Ricker said TESS would provide precision, full-frame images for more than 20 million bright stars and galaxies.

“This unique new data will comprise a treasure trove for astronomers throughout the world for many decades to come,” Ricker said.

Now that TESS is cleared to move into the next development stage, it can continue towards its goal of being a key part of NASA’s search for life beyond Earth.

“I’m still hopeful that in my lifetime, we will discover the existence of life outside of our solar system and I’m excited to be part of a NASA mission that serves as a key stepping stone in that search,” Volosin said.

Further Reading: NASA

November 7, 2014December 23, 2015 by Matt Williams

Canadian Micro-Rover and Lander “Northern Light” Aim for Launch to Mars in 2018

Artist's concept of the Norther Light Lander on the Martian surface. Credit: Mars Rocks

The first Canadian mission to Mars could be blasting off towards the Red Planet in just three years time. At least, that is what Thoth Technology, a Canadian aerospace company from Pembroke, Ontario, hopes to accomplish. And two days ago, they launched an Indiegogo campaign to raise the 1.1 million dollars needed to pay for all the hardware needed to make the mission happen.

If it is successful, it would be first Canadian mission to the surface of Mars.

The project for this Canadian mission would involve sending the Northern Light lander and Beaver rover in space and land them on Mars. Once there, the Beaver rover will be deployed and begin conducting surveys of the Martian surface, alongside the many other robotic rovers and orbiters studying the Martian landscape.

“I think it’s important to do big things,” said Ben Quine, principal investigator for the mission. “Mars is the only other habitable planet in the solar system, and if we want to survive, we need to be a multi-planet species.”

Quine is the technical director and chair of the board at Thoth Technology and a professor of space engineering at York University, which is a partner on the project, houses a lot of the space testing facilities, and will analyze the data from the mission.

*Northern Light Lander and Robotic Arm (concept art). Credit: Mars Rocks/Indiegogo*

The main goal of the mission is to expand upon the efforts being made by NASA’s Curiosity, Spirit, and Opportunity rovers, which have only explored a half dozen sites on Mars. By exploring more areas, they hope to find other signs of life on the harsh landscape, and using knowledge gleaned from studies in the Canadian Arctic no less.

According to Quine, in Antarctica and the Canadian Arctic, photosynthetic microbes can be found in a layer a millimeter or two below the surface of the rock. Here, they are protected from the harshest of the sun’s UV rays, but can still use sunlight to produce energy.

Northern Light will look for similar life on Mars by using the lander’s robotic arm to grind away the surface of rocks. It will then use a device called a photometer to scan for different shades of green that may indicate the presence of photosynthetic organisms. Quine and his colleagues also hope to determine what future technologies will be required to sustain a future human presence.

“If we are serious about living on Mars,” he said, “we need to explore it much more thoroughly. We probably need hundreds of landers to pepper the surface prior to sending people so we know exactly what it is that we’re up against, where we’d find things like minerals and where we’d want to live.”

Intrinsic to the company’s plan is the widespread exploration of Mars using low cost, off-the-shelf technology. For example, the Northern Light lander probe has a mass under 50 kg (including payload) and is made of an advanced composite material that includes thermal shielding and shock absorption. The probe includes solar arrays to generate power for the instrumentation and lander avionics.

*The Beaver Rover prototype. Credit: Thoth Technologies/Indiegogo*

As for the Beaver rover, its small size and low-cost mask the fact that it is like no other rover that has ever gone to Mars. For one thing, it weighs just six kilograms (13 pounds). In comparison, NASA’s Curiosity rover weighs in at a hefty 900 kilograms (1980 pounds, close to an imperial ton), forcing it to rely largely on nuclear power to lug its bulk around.

The NASA rovers, which are controlled from Earth, also move very slowly and cover only a few dozen meters per day because their commands take 15 minutes to reach Mars from Earth. By contrast, the Beaver rover is designed to be quicker, in part by being more independent.

“We’re going to embed intelligence into the rover,” Quine said, “and the rover is going to be tasked to drive around and explore the environment using autonomous algorithms built into the rover to determine things like when it should make a maneuver to avoid falling into a hole or run into a rock.”

Quine said he has already spent 12 years working on the project and his team has spent half a million dollars developing and testing prototypes of the lander and micro-rover. They’ve also performed space tests on some of the instruments by flying them on satellites in low-Earth orbit.

*Northern Light Ground Station at the Algonquin Radio Observatory. Credit: Mars Rocks/Indiegogo*

Thoth Technologies also recently spent $1 million leasing and repairing the Algonquin Radio Observatory from the federal government, which they plan to use as a ground station to communicate with the lander and rover when they are on Mars.

As for the tricky task of getting to Mars, Quine and his colleagues hope to barter their way aboard one of the many missions heading to Mars in 2018. These include the joint Russian-European Space Agency ExoMars rover mission and an Indian Space Research Organization mission that will likely include a lander and rover.

In exchange for hitching a ride on one of these rockets, they will collect and relay other agencies’ data from Mars via the ARO ground station, which can collect them at times of day when places like Russia and India are facing away from Mars.

Those who are interested in supporting their campaign are being incentivized with a chance to help choose the landing site for the mission, and will get rewards ranging from a Frisbee for $20 or the chance to name the lander for $1 million.

The company has also launched a social campaign – featuring Ed Robertson of the “Barenaked Ladies” – urging people to create and upload their own “Mars dance” video to marsrocks.ca.

To find out more, check out their promotional video or click on the link below:

Further Reading: Mars Rocks

November 7, 2014December 23, 2015 by Matt Williams

It’s Complicated: Hubble Survey Finds Unexpected Diversity in Dusty Discs Around Nearby Stars

Images captured by the Hubble Telescope of the vast debris systems surrounding nearby stars. Credit: NASA/ESA/ G. Schneider (University of Arizona), and the HST/GO 12228 Team

Using NASA’s Hubble Space Telescope, astronomers have completed the largest and most sensitive visible-light imaging survey of the debris disks surrounding nearby stars. These dusty disks, likely created by collisions between leftover objects from planet formation, were imaged around stars as young as 10 million years old and as mature as more than 1 billion years old.

The research was conducted by astronomers from NASA’s Goddard Space Center with the help of the University of Arizona’s Steward Observatory. The survey was led by Glenn Schneider, the results of which appeared in the Oct. 1, 2014, issue of The Astronomical Journal.

“We find that the systems are not simply flat with uniform surfaces,” Schneider said. “These are actually pretty complicated three-dimensional debris systems, often with embedded smaller structures. Some of the substructures could be signposts of unseen planets.”

In addition to learning much about the debris fields that surround neighboring stars, the study presented an opportunity to learn more about the formation of our own Solar System.

“It’s like looking back in time to see the kinds of destructive events that once routinely happened in our solar system after the planets formed,” said Schneider.

Once thought to be flat disks, the study revealed an unexpected diversity and complexity of dusty debris structures surrounding the observed stars. This strongly suggest they are being gravitationally affected by unseen planets orbiting the star.

Alternatively, these effects could result from the stars’ passing through interstellar space. In addition, the researchers discovered that no two “disks” of material surrounding stars were alike.

A circumstellar disk of debris around a matured stellar system may indicate that Earth-like planets lie within. Credit: NASA/JPL — *A circumstellar disk of debris around a matured stellar system may indicate that Earth-like planets lie within.* *Credit: NASA/JPL*

The astronomers used Hubble’s Space Telescope Imaging Spectrograph to study 10 previously discovered circumstellar debris systems, plus MP Mus, a mature protoplanetary disk that is comparable in age to the youngest of the debris disks.

Irregularities observed in one ring-like system in particular (around HD 181327) resemble the ejection of a huge spray of debris into the outer part of the system from the recent collision of two bodies.

“This spray of material is fairly distant from its host star — roughly twice the distance that Pluto is from the Sun,” said co-investigator Christopher Stark of NASA’s Goddard Space Flight Center, Greenbelt, Maryland. “Catastrophically destroying an object that massive at such a large distance is difficult to explain, and it should be very rare. If we are in fact seeing the recent aftermath of a massive collision, the unseen planetary system may be quite chaotic.”

Another interpretation for the irregularities is that the disk has been mysteriously warped by the star’s passage through interstellar space, directly interacting with unseen interstellar material. “Either way, the answer is exciting,” Schneider said. “Our team is currently analyzing follow-up observations that will help reveal the true cause of the irregularity.”

Over the past few years astronomers have found an incredible diversity in the architecture of exoplanetary systems. For instance, they have found that planets are arranged in orbits that are markedly different than found in our solar system.

A collision between planets could be the reason for the debris field around HD 181327. Credit: NASA/JPL-Caltech — *A collision between two bodies is one explanation for the ring-like debris system around HD 181327. Credit: NASA/JPL-Caltech*

“We are now seeing a similar diversity in the architecture of accompanying debris systems,” Schneider said. “How are the planets affecting the disks, and how are the disks affecting the planets? There is some sort of interdependence between a planet and the accompanying debris that might affect the evolution of these exoplanetary debris systems.”

From this small sample, the most important message to take away is one of diversity, Schneider said. He added that astronomers really need to understand the internal and external influences on these systems – such as stellar winds and interactions with clouds of interstellar material – and how they are influenced by the mass and age of the parent star, and the abundance of heavier elements needed to build planets.

Though astronomers have found nearly 4,000 exoplanet candidates since 1995, mostly by indirect detection methods, only about two dozen light-scattering, circumstellar debris systems have been imaged over that same time period.

That’s because the disks are typically 100,000 times fainter than (and often very close to) their bright parent stars. The majority have been seen because of Hubble’s ability to perform high-contrast imaging, in which the overwhelming light from the star is blocked to reveal the faint disk that surrounds the star.

The new imaging survey also yields insight into how our solar system formed and evolved 4.6 billion years ago. In particular, the suspected planet collision seen in the disk around HD 181327 may be similar to how the Earth-Moon system formed, as well as the Pluto-Charon system over 4 billion years ago. In those cases, collisions between planet-sized bodies cast debris that then coalesced into a companion moon.

Further Reading: The Hubble Site

November 5, 2014December 23, 2015 by Matt Williams

Where Have All the Pulsars Gone? The Mystery at the Center of Our Galaxy

The galactic core, observed using infrared light and X-ray light. Credit: NASA, ESA, SSC, CXC, and STScI

The galactic center is a happening place, with lots of gas, dust, stars, and surprising binary stars orbiting a supermassive black hole about three million times the size of our sun. With so many stars, astronomers estimate that there should be hundreds of dead ones. But to date, scientists have found only a single young pulsar at the galactic center where there should be as many as 50.

The question thus arises: where are all those rapidly spinning, dense stellar corpses known as pulsars? Joseph Bramante of Notre Dame University and astrophysicist Tim Linden of the University of Chicago have a possible solution to this missing-pulsar problem, which they describe in a paper accepted for publication in the journal Physical Review Letters.

Maybe those pulsars are absent because dark matter, which is plentiful in the galactic center, gloms onto the pulsars, accumulating until the pulsars become so dense they collapse into a black hole. Basically, they disappeared into the fabric of space and time by becoming so massive that they punched a hole right through it.

Dark matter, as you may know, is the theoretical mass that astrophysicists believe fills roughly a quarter of our universe. Alas, it is invisible and undetectable by conventional means, making its presence known only in how its gravitational pull interacts with other stellar objects.

One of the more popular candidates for dark matter is Weakly Interacting Massive Particles, otherwise known as WIMPs. Underground detectors are currently hunting for WIMPs and debate has raged over whether gamma rays streaming from the galactic center come from WIMPs annihilating one another.

In general, any particle and its antimatter partner will annihilate each other in a flurry of energy. But WIMPs don’t have an antimatter counterpart. Instead, they’re thought to be their own antiparticles, meaning that one WIMP can annihilate another.

But over the last few years, physicists have considered another class of dark matter called asymmetric dark matter. Unlike WIMPs, this type of dark matter does have an antimatter counterpart.

Numerical simulation of the density of matter when the universe was one billion years old. Cosmic Infrared Background ExpeRIment (CIBER) Credit: Caltech/Jamie Bock — *Cosmic Infrared Background ExpeRIment (CIBER)* *simulation of the density of matter when the universe was one billion years old, as produced by large-scale structures from dark matter.* *Credit: Caltech/Jamie Bock*

Asymmetric dark matter appeals to physicists because it’s intrinsically linked to the imbalance of matter and antimatter. Basically, there’s a lot more matter in the universe than antimatter – which is good considering anything less than an imbalance would lead to our annihilation. Likewise, according to the theory, there’s much more dark matter than anti-dark-matter.

Physicists think that in the beginning, the Big Bang should’ve created as much matter as antimatter, but something altered this balance. No one’s sure what this mechanism was, but it might have triggered an imbalance in dark matter as well – hence it is “asymmetric”.

Dark matter is concentrated at the galactic center, and if it’s asymmetric, then it could collect at the center of pulsars, pulled in by their extremely strong gravity. Eventually, the pulsar would accumulate so much mass from dark matter that it would collapse into a black hole.

The idea that dark matter can cause pulsars to implode isn’t new. But the new research is the first to apply this possibility to the missing-pulsar problem.

If the hypothesis is correct, then pulsars around the galactic center could only get so old before grabbing so much dark matter that they turn into black holes. Because the density of dark matter drops the farther you go from the center, the researchers predict that the maximum age of pulsars will increase with distance from the center. Observing this distinct pattern would be strong evidence that dark matter is not only causing pulsars to implode, but also that it’s asymmetric.

“The most exciting part about this is just from looking at pulsars, you can perhaps say what dark matter is made of,” Bramante said. Measuring this pattern would also help physicists narrow down the mass of the dark matter particle.

Artist's illustration of a pulsar that was found to be an ultraluminous X-ray source. Credit: NASA, Caltech-JPL — *Artist’s illustration of a pulsar that was found to be an ultraluminous X-ray source.*
*Credit: NASA, Caltech-JPL*

But as Bramante admits, it won’t be easy to detect this signature. Astronomers will need to collect much more data about the galactic center’s pulsars by searching for radio signals, he claims. The hope is that as astronomers explore the galactic center with a wider range of radio frequencies, they will uncover more pulsars.

But of course, the idea that dark matter is behind the missing pulsar problem is still highly speculative, and the likelihood of it is being called into question.

“I think it’s unlikely—or at least it is too early to say anything definitive,” said Zurek, who was one of the first to revive the notion of asymmetric dark matter in 2009. The tricky part is being able to know for sure that any measurable pattern in the pulsar population is due to dark-matter-induced collapse and not something else.

Even if astronomers find this pulsar signature, it’s still far from being definitive evidence for asymmetric dark matter. As Kathryn Zurek of the Lawrence Berkeley National Laboratory explained: “Realistically, when dark matter is detected, we are going to need multiple, complementary probes to begin to be convinced that we have a handle on the theory of dark matter.”

And asymmetric dark matter may not have anything to do with the missing pulsar problem at all. The problem is relatively new, so astronomers may find more plausible, conventional explanations.

“I’d say give them some time and maybe they come up with some competing explanation that’s more fleshed out,” Bramante said.

Nevertheless, the idea is worth pursuing, says Haibo Yu of the University of California, Riverside. If anything, this analysis is a good example of how scientists can understand dark matter by exploring how it may influence astrophysical objects. “This tells us there are ways to explore dark matter that we’ve never thought of before,” he said. “We should have an open mind to see all possible effects that dark matter can have.”

There’s one other way to determine if dark matter can cause pulsars to implode: To catch them in the act. No one knows what a collapsing pulsar might look like. It might even blow up.

“While the idea of an explosion is really fun to think about, what would be even cooler is if it didn’t explode when it collapsed,” Bramante said. A pulsar emits a powerful beam of radiation, and as it spins, it appears to blink like a lighthouse with a frequency as high as several hundred times per second. As it implodes into a black hole, its gravity gets stronger, increasingly warping the surrounding space and time.

Studying this scenario would be a great way to test Einstein’s theory of general relativity, Bramante says. According to theory, the pulse rate would get slower and slower until the time between pulses becomes infinitely long. At that point, the pulses would stop entirely and the pulsar would be no more.

Further Reading: APS Physics, WIRED

November 4, 2014December 23, 2015 by Matt Williams

VLTI Detects Exozodiacal Light Around Exoplanets

Artist's impression of zodiacal light viewed from the surface of an exoplanet. Credit: ESO/L. Calçada

If you’ve ever stood outside after twilight has passed, or a few hours before the sun rises at dawn, then chances are you’ve witnessed the phenomenon known as zodiacal light. This effect, which looks like a faint, diffuse white glow in the night sky, is what happens when sunlight is reflected off of tiny particles and appears to extend up from the vicinity of the Sun. This reflected light is not just observed from Earth but can be observed from everywhere in the Solar System.

Using the full power of the Very Large Telescopic Interferometer (VLTI), an international team of astronomers recently discovered that the exozodiacal light – i.e., zodiacal light around other star systems – close to the habitable zones around nine nearby stars was far more extreme. The presence of such large amounts of dust in the inner regions around some stars may pose an obstacle to the direct imaging of Earth-like planets.

The reason for this is simple: even at low levels, exozodiacal dust causes light to become amplified intensely. For example, the light detected in this survey was roughly 1000 times brighter than the zodiacal light seen around the Sun. While this exozodiacal light had been previously detected, this is the first large systematic study of this phenomenon around nearby stars.

The team used the VLTI visitor instrument PIONIER which is able to interferometrically connect all four Auxiliary Telescopes or all four Unit Telescopes of the VLTI at the Paranal Observatory. This led to not only extremely high resolution of the targets but also allowed for a high observing efficiency.

The Very Large Telescoping Interferometer firing it's adaptive optics laser. Credit: ESO/G. Hüdepohl — *The Very Large Telescoping Interferometer firing its adaptive optics laser.*
*Credit: ESO/G. Hüdepohl*

In total, the team observed exozodiacal light from hot dust close to the habitable zones of 92 nearby stars and combined the new data with their earlier observations.

In contrast to these earlier observations – which were made with the Center for High Angular Resolution Astronomy (CHARA) array at Georgia State University – the team did not observe dust that will later form into planets, but dust created in collisions between small planets of a few kilometers in size – objects called planetesimals that are similar to the asteroids and comets of the Solar System. Dust of this kind is also the origin of the zodiacal light in the Solar System.

As a by-product, these observations have also led to the discovery of new, unexpected stellar companions orbiting around some of the most massive stars in the sample. “These new companions suggest that we should revise our current understanding of how many of this type of star are actually double,” says Lindsay Marion, lead author of an additional paper dedicated to this complementary work using the same data.

“If we want to study the evolution of Earth-like planets close to the habitable zone, we need to observe the zodiacal dust in this region around other stars,” said Steve Ertel, lead author of the paper, from ESO and the University of Grenoble in France. “Detecting and characterizing this kind of dust around other stars is a way to study the architecture and evolution of planetary systems.”

A portrait of the HR8799 planetary system as imaged by the Hale Telescope. Credit: NASA/JPL-Caltech/Palomar Observatory. — *A portrait of the HR8799 planetary system as imaged by the Hale Telescope.*
*Credit: NASA/JPL-Caltech/Palomar Observatory.*

However, the good news is that the number of stars containing zodiacal light at the level of our Solar System is most likely much higher than the numbers found in the survey.

“The high detection rate found at this bright level suggests that there must be a significant number of systems containing fainter dust, undetectable in our survey, but still much brighter than the Solar System’s zodiacal dust,” explains Olivier Absil, co-author of the paper, from the University of Liège. “The presence of such dust in so many systems could therefore become an obstacle for future observations, which aim to make direct images of Earth-like exoplanets.”

Therefore, these observations are only a first step towards more detailed studies of exozodiacal light, and need not dampen our spirits about discovering more Earth-like exoplanets in the near future.

Further Reading: ESO