Matt Williams, Author at Universe Today

August 1, 2017August 1, 2017 by Matt Williams

Impending Asteroid Flyby Will be a Chance to Test NASA’s Planetary Defense Network!

Artist's concept of a large asteroid passing by the Earth-Moon system. Credit: A combination of ESO/NASA images courtesy of Jason Major/Lights in the Dark.

This coming October, an asteroid will fly by Earth. Known as 2012 TC4, this small rock is believed to measure between 10 and 30 meters (30 and 100 feet) in size. As with most asteroids, this one is expected to sail safely past Earth without incident. This will take place on October 12th, when the asteroid will pass us at a closest estimated distance of 6,800 kilometers (4,200 miles) from Earth’s surface.

That’s certainly good news. But beyond the fact that it does not pose a threat to Earth, NASA is also planning on using the occasion to test their new detection and tracking network. As part of their Planetary Defense Coordination Office (PDCO), this network is responsible for detecting and tracking asteroids that periodically pass close to Earth, which are known as Potentially Hazardous Objects (PHOs)

In addition to relying on data provided by NASA’s Near-Earth Object (NEO) Observations Program. the PDCO also coordinates NEO observations conducted by National Science Foundation (NSF)-sponsored ground-based observatories, as well as space situational awareness facilities run by the US Air Force. Aside from finding and tracking PHOs, the PDCO is also responsible for coming up with ways of deflecting and redirecting them.

*On Oct. 12, 2017, asteroid 2012 TC4 will safely fly past Earth at an estimated distance of 6,800 km (4,200 mi). Credits: NASA/JPL-Caltech*

The PDCO was officially created in response to the NASA Office of Inspector General’s 2014 report, titled “NASA’s Efforts to Identify Near-Earth Objects and Mitigate Hazards.” Citing such events as the Chelyabinsk meteor, and how such events are relatively common, the report indicated that coordination, early warning and mitigation strategies were needed for the future:

“[I]n February 2013 an 18-meter (59 foot) meteor exploded 14.5 miles above the city of Chelyabinsk, Russia, with the force of 30 atomic bombs, blowing out windows, destroying buildings, injuring more than 1,000 people, and raining down fragments along its trajectory… Recent research suggests that Chelyabinsk-type events occur every 30 to 40 years, with a greater likelihood of impact in the ocean than over populated areas, while impacts from objects greater than a mile in diameter are predicted only once every several hundred thousand years.”

The PDCO was established in 2016, which makes this upcoming flyby the first chance they will have to test their network of observatories and scientists dedicated to planetary defense. Michael Kelley is the program scientist and the NASA Headquarters lead for the TC4 observation campaign, which has been monitoring 2012 TC4 for years. As he said in a recent NASA press statement:

“Scientists have always appreciated knowing when an asteroid will make a close approach to and safely pass the Earth because they can make preparations to collect data to characterize and learn as much as possible about it. This time we are adding in another layer of effort, using this asteroid flyby to test the worldwide asteroid detection and tracking network, assessing our capability to work together in response to finding a potential real asteroid threat.”

*Diagram showing the data gathered from 1994-2013, indicating daytime (orange) and nighttime (blue) impacts of small meteorites. Credit: NASA*

In addition, the flyby will be an opportunity to reacquire 2012 TC4, which astronomers lost track of in 2012 when it moved beyond the range of their telescopes. For this reason, people like Professor Vishnu Reddy of the University of Arizona are also excited. A member of the Lunar and Planetary Laboratory, Reddy also leads the campaign to reacquire the asteroid. As he indicated, this flyby will be a chance for collaborative observation.

“This is a team effort that involves more than a dozen observatories, universities and labs across the globe so we can collectively learn the strengths and limitations of our near-Earth object observation capabilities,” he said. “This effort will exercise the entire system, to include the initial and follow-up observations, precise orbit determination, and international communications.”

2012 TC4 was originally discovered on Oct. 5th, 2012, by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) at the Haleakala Observatory in Hawaii. After it sped past Earth in that same year, it has not been directly observed since. And while it is slightly larger than the meteor that exploded in Earth’s atmosphere near Chelyabinsk, Russia, in 2013, scientists are certain that it will pass us by at a safe distance.

This is based on tracking data that was collected by scientists from NASA’s Center for Near-Earth Object Studies (CNEOS). After monitoring 2012 TC4 for a period of seven days after it was discovered in 2012, they determined that at its closest approach, the asteroid will pass no closer than 6,800 km (4,200 mi) to Earth. However, it is more likely that it will pass us at distance of about 270,000 km (170,000 mi).

*The Pan-Starrs telescope at dawn. The mountain in the distance is Mauna Kea, about 130 kilometers southeast. Credit: pan-starrs.ifa.hawaii.edu*

This would place it at a distance that is about two-thirds the distance between the Earth and the Moon. The last time this asteroid passed Earth, it did so at a distance that was one-quarter the distance between the Earth and the Moon. Therefore, the odds of it passing by without incident are even greater this time around. So rather than representing a threat, the passage of this asteroid represents a good chance for research.

As Paul Chodas, the manager of the CNEOS at NASA’s Jet Propulsion Laboratory, stated:

“This is the perfect target for such an exercise because while we know the orbit of 2012 TC4 well enough to be absolutely certain it will not impact Earth, we haven’t established its exact path just yet. It will be incumbent upon the observatories to get a fix on the asteroid as it approaches, and work together to obtain follow-up observations than make more refined asteroid orbit determinations possible.”

By monitoring 2012 TC4 as it flies by, astronomers will be able to refine their knowledge about the asteroid’s orbit, which will help them to predict and calculate future flybys with even greater precision. This will further mitigate the risk posed by PHOs down the road, and help the PDCO to develop and test strategies to address possible future impacts.

In short, remain calm! This flyby is a good thing!

Further Reading: NASA

July 31, 2017July 31, 2017 by Matt Williams

NASA Detects More Chemicals on Titan that are Essential to Life

Titan's atmosphere makes Saturn's largest moon look like a fuzzy orange ball in this natural-color view from the Cassini spacecraft. Cassini captured this image in 2012. Image Credit: NASA/JPL-Caltech/Space Science Institute — According to a study from UCLA, Titan experiences severe methane rainstorms, leading to a the alluvial fans found found in both hemispheres. Credit: NASA/JPL-Caltech/Space Science Institute

Saturn’s largest moon Titan may be the most fascinating piece of real-estate in the Solar System right now. Not surprising, given the fact that the moon’s dense atmosphere, rich organic environment and prebiotic chemistry are thought to be similar to Earth’s primordial atmosphere. As such, scientists believe that the moon could act as a sort of laboratory for studying the processes whereby chemical elements become the building blocks for life.

These studies have already led to a wealth of information, which included the recent discovery of “carbon chain anions” – which are thought to be building blocks for more complex molecules. And now, thanks to data from the the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, a team of NASA researchers have detected the presence of acrylonitrile, another chemical elements that could be the basis for life on that moon.

The study that details their findings – titled “ALMA detection and astrobiological potential of vinyl cyanide on Titan” – was published in the July 28th issue of the journal Science Advances. In it, the team explains how data from the ALMA array indicated that large quantities of acrylonitrile (C₂H₃CN) exist on Titan – most likely within the moon’s stratosphere.

As Maureen Palmer, a researcher with the Goddard Center for Astrobiology and the lead author on the paper, indicated in a NASA press release: “We found convincing evidence that acrylonitrile is present in Titan’s atmosphere, and we think a significant supply of this raw material reaches the surface.”

Also known as vinyl cyanide, acrylonitrile is used here on Earth in the manufacture of plastics. In the past, it has been speculated that this compound could be present in Titan’s atmosphere. However, it was only recently that scientists became aware of the possibility that it be the basis for living creatures within Titan’s rich organic environment – with its steady supply of carbon, hydrogen, and nitrogen.

This is based on a study that was conducted in 2015, where a team of Cornell scientists sought to determine if organic cells could form in Titan’s harsh environment. Given that the moon experiences average surface temperatures of -179 °C (-290 °F) and the atmosphere is predominantly nitrogen and hydrocarbons, lipid bilayer membranes (which are the foundation of life on Earth) could not survive there.

However, after conducting molecular simulations, the team determined that small organic nitrogen compounds would be capable of forming a sheet of material similar to a cell membrane. They also determined that these sheets could form hollow, microscopic spheres that they dubbed “azotosomes”, and that the best chemical candidate for this sheets would be acrylonitrile.

*Artist concept of Methane-Ethane lakes on Titan (Credit: Copyright 2008 Karl Kofoed). Click for larger version.*

Such a material would be capable of surviving in liquid methane and at extremely cold temperatures, and would therefore be the most likely basis for organic life on Titan. As Michael Mumma, the director of the Goddard Center for Astrobiology, explained:

“The ability to form a stable membrane to separate the internal environment from the external one is important because it provides a means to contain chemicals long enough to allow them to interact. If membrane-like structures could be formed by vinyl cyanide, it would be an important step on the pathway to life on Saturn’s moon Titan.”

For the sake of their study, the Goddard team combined 11 high-resolution data sets from ALMA, which they retrieved from an archive of observations that were used to calibrate the array. From the data, Palmer and her team determined that acrylonitrile is relatively abundant in Titan’s atmosphere, reaching concentrations of up to 2.8 parts per billion. They also determined that it would be most common in Titan’s upper atmosphere.

It is here that carbon, hydrogen and nitrogen could chemically bond from exposure to sunlight and energetic particles from Saturn’s magnetic field. Eventually, the acrylonitrile would make its way down through the cold atmosphere and condense to form rain droplets that would fall to the surface. The team also estimated how much of this material would accumulate in Ligeia Mare – Titan’s second-largest methane lake – over time.

Finally, they calculated that within every cubic centimeter (cm³) of its volume, Ligeia Mare could form as many as 10,000,000 azotosomes. That roughly ten times the amount of bacteria that exists in the waters along Earth’s coastal regions. As Martin Cordiner, one of the senior authors on the paper, indicated, these findings are certainly encouraging when it comes to the search for extra-terrestrial life in our Solar System.

“The detection of this elusive, astrobiologically relevant chemical is exciting for scientists who are eager to determine if life could develop on icy worlds such as Titan,” he said. “This finding adds an important piece to our understanding of the chemical complexity of the solar system.”

Granted, the study and the basis for its conclusions are quite speculative. But they do show that within certain established parameters, life could exist within our Solar System well-beyond the limits of our Sun’s “habitable zone”. This study could also have implications in the hunt for life in extrasolar systems. If scientists can say definitively that life does not need warmer temperatures and liquid water to exist, it opens up immense possibilities.

In the coming decades, several missions are expected to go to Titan, ranging from submarines that will explore its methane lakes to drones and aerial platforms that will study its atmosphere and surface. Already, it is expected that they will obtain valuable information about the formation of the Saturn system. But to also discover entirely new forms of life? That would truly be Earth-shattering!

Further Reading: NASA, Science Advances

July 28, 2017July 28, 2017 by Matt Williams

What Is the Name Of Our Galaxy?

The band of light (the Milky Way) that is visible in the night sky, showing the stellar disk of our galaxy. Credit: Bob King

Since prehistoric times, human beings have looked up at at the night sky and pondered the mystery of the band of light that stretches across the heavens. And while theories have been advanced since the days of Ancient Greece as to what it could be, it was only with the birth of modern astronomy that scholars have come come to know precisely what it is – i.e. countless stars at considerable distances from Earth.

The term “Milky Way”, a term which emerged in Classical Antiquity to describe the band of light in the night sky, has since gone on to become the name for our galaxy. Like many others in the known Universe, the Milky Way is a barred, spiral galaxy that is part of the Local Group – a collection of 54 galaxies. Measuring 100,000 – 180,000 light-years in diameter, the Milky Way consists of between 100 and 400 billion stars.

Structure:

The Milky Way consists of a Galactic Center that is shaped like a bar and a Galactic Disk made up of spiral arms, all of which is surrounded by the Halo – which is made up of old stars and globular clusters. The Center, also known as “the bulge”, is a dense concentration of mostly old stars that measures about 10,000 light years in radius. This region is also the rotational center of the Milky Way.

*Illustration of the supermassive black hole at the center of the Milky Way. Credit: NRAO/AUI/NSF*

The Galactic Center is also home to an intense radio source named Sagittarius A*, which is believed to have a supermassive black hole (SMBH) at its center. The presence of this black hole has been discerned due to the apparent gravitational influence it has on surrounding stars. Astronomers estimate that it has a mass of between 4.1. and 4.5 million Solar masses.

Outside the barred bulge at the Galactic Center is the Galactic Disk of the Milky Way. This consists of stars, gas and dust which is organized into four spiral arms. These arms typically contain a higher density of interstellar gas and dust than the Galactic average, as well as a greater concentration of star formation. While there is no consensus on the exact structure or extent of these spiral arms, they are commonly grouped into two or four different arms.

In the case of four arms, this is based on the traced paths of gas and younger stars in our galaxy, which corresponds to the Perseus Arm, the Norma and Outer Arm, the Scutum-Centaurum Arm, and the Carina-Sagittarius Arm. There are also at least two smaller arms, which include the Cygnus Arm and the Orion Arm. Meanwhile, surveys based on the presence of older stars show only two major spirals arms – the Perseus arm and the Scutum–Centaurus arm.

Beyond the Galactic Disk is the Halo, which is made up of old stars and globular clusters – 90% of which lie within 100,000 light-years (30,000 parsecs) from the Galactic Center. Recent evidence provided by X-ray observatories indicates that in addition to this stellar halo, the Milky way also has a halo of hot gas that extends for hundreds of thousands of light years.

*Artist’s conception of the spiral structure of the Milky Way with two major stellar arms and a bar. Credit: NASA/JPL-Caltech/ESO/R. Hurt*

Size and Mass:

The Galactic Disk of the Milky Way Galaxy is approximately 100,000 light years in diameter and about 1,000 light years thick. It is estimated to contain between 100 and 400 billion stars, though the exact figure depends on the number of very low-mass M-type (aka. red dwarf) stars. This is difficult to determine because these stars also have low-luminosity compared to other class.

The distance from the Sun to the Galactic Center is estimated to be between 25,000 to 28,000 light years (7,600 to 8,700 parsecs). The Galactic Center’s bar (aka. its “bulge”) is thought to be about 27,000 light-years in length and is composed primarily of red stars, all of which are thought to be ancient. The bar is surrounded by the ‘5-kpc ring’, a region that contains much of the galaxy’s molecular hydrogen and where star-formation is most intense.

The Galactic Disk has a diameter of between 70,000 and 100,000 light-years. It does not have a sharp edge, a radius beyond which there are no stars. However, the number of stars drops slowly with distance from the center. Beyond a radius of roughly 40,000 light years, the number of stars drops much faster the farther you get from the center.

Location of the Solar System:

The Solar System is located near the inner rim of the Orion Arm, a minor spiral arm located between the Carina–Sagittarius Arm and the Perseus Arm. This arm measures some 3,500 light-years (1,100 parsecs) across, approximately 10,000 light-years (3,100 parsecs) in length, and is at a distance of about 25,400 to 27,400 light years (7.78 to 8.4 thousand parsecs) from the Galactic Center.

History of Observation:

Our galaxy was named because of the way the haze it casts in the night sky resembled spilled milk. This name is also quite ancient. It is translation from the Latin “Via Lactea“, which in turn was translated from the Greek for Galaxias, referring to the pale band of light formed by stars in the galactic plane as seen from Earth.

Persian astronomer Nasir al-Din al-Tusi (1201–1274) even spelled it out in his book Tadhkira: “The Milky Way, i.e. the Galaxy, is made up of a very large number of small, tightly clustered stars, which, on account of their concentration and smallness, seem to be cloudy patches. Because of this, it was likened to milk in color.”

Astronomers had long suspected the Milky Way was made up of stars, but it wasn’t proven until 1610, when Galileo Galilei turned his rudimentary telescope towards the heavens and resolved individual stars in the band across the sky. With the help of telescopes, astronomers realized that there were many, many more stars in the sky, and that all of the ones that we can see are a part of the Milky Way.

In 1755, Immanuel Kant proposed that the Milky Way was a large collection of stars held together by mutual gravity. Just like the Solar System, this collection would be rotating and flattened out as a disk, with the Solar System embedded within it. Astronomer William Herschel (discoverer of Uranus) tried to map its shape in 1785, but he didn’t realize that large portions of the galaxy are obscured by gas and dust, which hide its true shape.

It wasn’t until the 1920s, when Edwin Hubble provided conclusive evidence that the spiral nebulae in the sky were actually whole other galaxies, that the true shape of our galaxy was known. Thenceforth, astronomers came to understand that the Milky Way is a barred, spiral galaxy, and also came to appreciate how big the Universe truly is.

The Milky Way is appropriately named, being the vast and cloudy mass of stars, dust and gas it is. Like all galaxies, ours is believed to have formed from many smaller galaxies colliding and combining in the past. And in 3 to 4 billion years, it will collide with the Andromeda Galaxy to form an even larger mass of stars, gas and dust. Assuming humanity still exists by then (and survives the process) it should make for some interesting viewing!

We have written many interesting articles about the Milky Way here at Universe Today. Here’s 10 Interesting Facts About the Milky Way, How Big is the Milky Way?, Why is our Galaxy Called the Milky Way?, What is the Closest Galaxy to the Milky Way?, Where is the Earth in the Milky Way?, The Milky Way has Only Two Spiral Arms, and It’s Inevitable: Milky Way, Andromeda Galaxy Heading for Collision.

If you’d like more info on galaxies, check out Hubblesite’s News Releases on Galaxies, and here’s NASA’s Science Page on Galaxies.

We’ve also recorded an episode of Astronomy Cast about the Milky Way. Listen here, Episode 99: The Milky Way.

Sources:

July 27, 2017 by Matt Williams

Cassini Finds that Titan is Building the Chemicals that Might Have Led to Life on Earth

Image of Titan's atmosphere, snapped by the Cassini spacecraft. Credit: NASA/JPL/Space Science Institute

Titan, Saturn’s largest moon, has been a source of mystery ever since scientists began studying it over a century ago. These mysteries have only deepened with the arrival of the Cassini-Huygens mission in the system back in 2004. In addition to finding evidence of a methane cycle, prebiotic conditions and organic chemistry, the Cassini-Huygens mission has also discovered that Titan may have the ingredient that help give rise to life.

Such is the argument made in a recent study by an international team of scientists. After examining data obtained by the Cassini space probe, they identified a negatively charged species of molecule in Titan’s atmosphere. Known as “carbon chain anions”, these molecules are thought to be building blocks for more complex molecules, which could played a key role in the emergence of life of Earth.

The study, titled “Carbon Chain Anions and the Growth of Complex Organic Molecules in Titan’s Ionosphere“, recently appeared in The Astrophysical Journal Letters. The team included researchers from University College in London, the University of Grenoble, Uppsalla University, UCL/Birkbeck, the University of Colorado, the Swedish Institute of Space Physics, the Southwest Research Institute (SwRI), and NASA’s Goddard Space Flight Center.

*Diagram of the internal structure of Titan according to the fully differentiated dense-ocean model. Credit: Wikipedia Commons/Kelvinsong*

As they indicate in their study, these molecules were detected by the Cassini P lasma Spectrometer (CAPS) as the probe flew through Titan’s upper atmosphere at an distance of 950 – 1300 km (590 – 808 mi) from the surface. They also show how the presence of these molecules was rather unexpected, and represent a considerable challenge to current theories about how Titan’s atmosphere works.

For some time, scientists have understood that within Titan’s ionosphere, nitrogen, carbon and hydrogen are subjected to sunlight and energetic particles from Saturn’s magnetosphere. This exposure drives a process where these elements are transformed into more complex prebiotic compounds, which then drift down towards the lower atmosphere and form a thick haze of organic aerosols that are thought to eventually reach the surface.

This has been the subject of much interest, since the process through which simple molecules form complex organic ones has remained something of a mystery to scientists. This could be coming to an end thanks to the detection of carbon chain anions, though their discovery was altogether unexpected. Since these molecules are highly reactive, they are not expected to last long in Titan’s atmosphere before combining with other materials.

However, the data showed that the carbon chains became depleted closer to the moon, while precursors to larger aerosol molecules underwent rapid growth. This suggests that there is a close relationship between the two, with the chains ‘seeding’ the larger molecules. Already, scientists have held that these molecules were an important part of the process that allowed for life to form on Earth, billions of years ago.

*A halo of light surrounds Saturn’s moon Titan in this backlit picture, showing its atmosphere. Credit: NASA/JPL/Space Science Institute*

However, their discovery on Titan could be an indication of how life begins to emerge throughout the Universe. As Dr. Ravi Desai, University College London and the lead author of the study, explained in an ESA press release:

“We have made the first unambiguous identification of carbon chain anions in a planet-like atmosphere, which we believe are a vital stepping-stone in the production line of growing bigger, and more complex organic molecules, such as the moon’s large haze particles. This is a known process in the interstellar medium, but now we’ve seen it in a completely different environment, meaning it could represent a universal process for producing complex organic molecules.”

Because of its dense nitrogen and methane atmosphere and the presence of some of the most complex chemistry in the Solar System, Titan is thought by many to be similar to Earth’s early atmosphere. Billions of years ago, before the emergence of microorganisms that allowed for subsequent build-up of oxygen, it is likely that Earth had a thick atmosphere composed of nitrogen, carbon dioxide and inert gases.

Therefore, Titan is often viewed as a sort planetary laboratory, where the chemical reactions that may have led to life on Earth could be studied. However, the prospect of finding a universal pathway towards the ingredients for life has implications that go far beyond Earth. In fact, astronomers could start looking for these same molecules on exoplanets, in an attempt to determine which could give rise to life.

*This illustration shows Cassini above Saturn’s northern hemisphere prior to one of its 22 Grand Finale dives. Credit: NASA/JPL-Caltech*

Closer to home, the findings could also be significant in the search for life in our own Solar System. “The question is, could it also be happening within other nitrogen-methane atmospheres like at Pluto or Triton, or at exoplanets with similar properties?” asked Desia. And Nicolas Altobelli, the Project Scientist for the Cassini-Huygens mission, added:

“These inspiring results from Cassini show the importance of tracing the journey from small to large chemical species in order to understand how complex organic molecules are produced in an early Earth-like atmosphere. While we haven’t detected life itself, finding complex organics not just at Titan, but also in comets and throughout the interstellar medium, we are certainly coming close to finding its precursors.“

Cassini’s “Grande Finale“, the culmination of its 13-year mission around Saturn and its system of moons, is set to end on September 15th, 2017. In fact, as of the penning of this article, the mission will end in about 1 month, 18 days, 16 hours, and 10 minutes. After making its final pass between Saturn’s rings, the probe will be de-orbited into Saturn’s atmosphere to prevent contamination of the system’s moons.

However, future missions like the James Webb Space Telescope, the ESA’s PLATO mission and ground-based telescopes like ALMA are expected to make some significant exoplanet finds in the coming years. Knowing specifically what kinds of molecules are intrinsic in converting common elements into organic molecules will certainly help narrow down the search for habitable (or even inhabited) planets!

Further Reading: ESA, The Astrophysical Journal Letters

July 27, 2017August 13, 2020 by Matt Williams

Hubble Sees Tiny Phobos Orbiting Mars

While photographing Mars, NASA’s Hubble Space Telescope captured a cameo appearance of the tiny moon Phobos on its trek around the Red Planet. Credit: NASA/Hubble/Goddard

Mars’ moon Phobos is a pretty fascinating customer! Compared to Mars’ other moon Deimos, Phobos (named after the Greek personification of fear) is the larger and innermost satellite of the Red Planet. Due to its rapid orbital speed, the irregularly-shaped moon orbits Mars once every 7 hours, 39 minutes, and 12 seconds. In other words, it completes over three orbits of Mar within a single Earth day.

It’s not too surprising then that during a recent observation of Mars with the Hubble space telescope, Phobos chose to photobomb the picture! It all took place in May of 2016, when while Mars was near opposition and Hubble was trained on the Red Planet to take advantage of it making its closest pass to Earth in over a decade. The well-timed sighting also led to the creation of a time-lapse video that shows the moon’s orbital path.

July 26, 2017July 26, 2017 by Matt Williams

Breakthrough Lofts the Smallest Satellites Ever, not Interstellar Yet, but a Step Forward

Project Starshot, an initiative sponsored by the Breakthrough Foundation, is intended to be humanity's first interstellar voyage. Credit: breakthroughinitiatives.org

In 2015, Russian billionaire Yuri Milner established Breakthrough Initiatives, a non-profit organization dedicated to enhancing the search for extraterrestrial intelligence (SETI). In April of the following year, he and the organization be founded announced the creation of Breakthrough Starshot, a program to create a lightsail-driven “wafercraft” that would make the journey to the nearest star system – Alpha Centauri – within our lifetime.

This past June, the organization took a major step towards achieving this goal. After hitching a ride on some satellites being deployed to Low Earth Orbit (LEO), Breakthrough conducted a successful test flight of its first spacecraft. Known as “Sprites”, these are not only the smallest spacecraft ever launched, but prototypes for the eventual wafercraft Starshot hopes to send to Alpha Centauri.

The concept for a wafercraft is simple. By leveraging recent developments in computing and miniaturization, spacecraft that are the size of a credit card could be created. These would be capable of carrying all the necessary sensors, microprocessors and microthrusters, but would be so small and light that it would take much less energy to accelerate them to relativistic speeds – in the case of Starshot, up to 20% the speed of light.

*Artist’s illustration of a light-sail powered by a laser beam (red) generated on Earth’s surface. Credit: M. Weiss/CfA*

As Pete Worden – Breakthrough Starshot’s executive director and the former director of NASA’s Ames Research Center – said in an interview with Scientific American:

“This is a very early version of what we would send to interstellar distances. In addition, this is another clear demonstration that it is possible for countries to work together to do great things in space. These are European spacecraft with U.S. nanosatellite payloads launching on an Indian booster—you can’t get much more international than that.”

Professor Abraham Loeb also has some choice words to mark this historic occasion. In addition to being the Frank B. Baird Jr. Professor of Science, the Chair of the Astronomy Department and the Director of the Institute for Theory and Computation at Harvard University, Prof. Loeb is also the chairman of the Breakthrough Starshot Advisory Committee. As he told Universe Today via email:

“The launch of the Sprite satellites marks the first demonstration that miniaturized electronics on small chips can be launched without damage, survive the harsh environment of space and communicate successfully with earth. The Starshot Initiative aims to launch similar chips attached to a lightweight sail that it being pushed by a laser beam to a fifth of the speed of light, so that its camera, communication and navigation devices (whose total weight is of order a gram) will reach the nearest planet outside the solar System within our generation.”

*A prototype Sprite nanosatellite, showing its solar panel, microprocessors, sensors and transmitters. Credit: Zac Manchester*

The craft were deployed on June 23rd, piggybacking on two satellites belonging to the multinational technology corporation OHB System AG. Much like the StarChips that Starshot is proposing, the Sprites represent a major step in the evolution of miniature spacecraft that can do the job of larger robotic explorers. They measure just 3.5 by 3.5 cm (1.378 x 1.378 inches) and weight only four grams (0.14 ounces), but still manage to pack solar panels, computers, sensors and radios into their tiny frames.

The Sprite were originally conceived by Zac Manchester, a postdoctorate researcher and aerospace engineer at Cornell University. Back in 2011, he launched a Kickstarter campaign (called “KickSat“) to raise funds to develop the concept, which was his way of bringing down the associated costs of spaceflight. The campaign was a huge success, with Manchester raising a total of $74,586 of his original goal of $30,000.

Now a member of Breakthrough Starshot (where he is in charge of Wafer design and optimization), Manchester oversaw the construction of the Sprites from the Sibley School of Mechanical and Aerospace Engineering at Cornell. As Professor Loeb explained:

“The Sprites project is led by Zac Manchester, a Harvard postdoc who started working on this during his PhD at Cornell. Sprites are chip-size satellites powered by sunlight, intended to be released in space to demonstrate a new technology of lightweight (gram-scale) spacecrafts that can communicated with Earth.”

*Zac Manchester holding a prototype KickSat. Credit: Zac Manchester/kickstarer*

The purpose of this mission was to test how well the Sprites’ electronics systems and radio communications performed in orbit. Upon deployment, the Sprites remained attached to these satellites (known as “Max Valier” and “Venta”) and began transmitting. Communications were then received from ground stations, which demonstrated that the Sprites’ novel radio communication architecture performed exactly as it was designed to.

With this test complete, Starshot now has confirmation that a waferocraft is capable of operating in space and communicating with ground-based controllers. In the coming months and years, the many scientists and engineers that are behind this program will no doubt seek to test other essential systems (such as the craft’s microthrusters and imagers) while also working on the various engineering concerns that an instellar mission would entail.

In the meantime, the Sprites are still transmitting and are in radio contact with ground stations located in California and New York (as well as radio enthusiasts around the world). For those looking to listen in on their communications, Prof. Loeb was kind enough to let us know what frequency they are transmitting on.

“The radio frequency at which the Sprites that were just launched operate is 437.24 MHz, corresponding to a wavelength of roughly 69 cm,” he said. So if you’ve got a ham radio and feel like tuning in, this is where to set your dials!

And be sure to check out Zac Manchester’s Kickstarter video, which showcases the technology and inspiration for the KickSat:

Further: Breakthrough Initiatives

July 26, 2017January 30, 2020 by Matt Williams

Ready to Leave Low Earth Orbit? Prototype Construction Begins for a Deep Space Habitat

Artist illustration of Habitation Module. Credit: Lockheed Martin — Artist illustration of Habitation Module aboard the Deep Space Gateway. Credit: Lockheed Martin

In 2010, NASA announced its commitment to mount a crewed mission to Mars by the third decade of the 21st century. Towards this end, they have working hard to create the necessary technologies – such as the Space Launch System (SLS) rocket and the Orion spacecraft. At the same time, they have partnered with the private sector to develop the necessary components and expertise needed to get crews beyond Earth and the Moon.

To this end, NASA recently awarded a Phase II contract to Lockheed Martin to create a new space habitat that will build on the lessons learned from the International Space Station (ISS). Known as the Deep Space Gateway, this habitat will serve as a spaceport in lunar orbit that will facilitate exploration near the Moon and assist in longer-duration missions that take us far from Earth.

The contract was awarded as part of the Next Space Technologies for Exploration Partnership (NextSTEP) program, which NASA launched in 2014. In April of 2016, as part of the second NextSTEP Broad Agency Announcement (NextSTEP-2) NASA selected six U.S. companies to begin building full-sized ground prototypes and concepts for this deep space habitat.

*Artist’s impression of the Deep Space Gateway, currently under development by Lockheed Martin. Credit: NASA*

Alongside such well-known companies like Bigelow Aerospace, Orbital ATK and Sierra Nevada, Lockheed Martin was charged with investigating habitat designs that would enhance missions in space near the Moon, and also serve as a proving ground for missions to Mars. Intrinsic to this is the creation of something that can take effectively integrate with SLS and the Orion capsule.

In accordance with NASA’s specifications on what constitutes an effective habitat, the design of the Deep Space Gateway must include a pressurized crew module, docking capability, environmental control and life support systems (ECLSS), logistics management, radiation mitigation and monitoring, fire safety technologies, and crew health capabilities.

The design specifications for the Deep Space Gateway also include a power bus, a small habitat to extend crew time, and logistics modules that would be intended for scientific research. The propulsion system on the gateway would rely on high-power electric propulsion to maintain its orbit, and to transfer the station to different orbits in the vicinity of the Moon when required.

With a Phase II contract now in hand, Lockheed Martin will be refining the design concept they developed for Phase I. This will include building a full-scale prototype at the Space Station Processing Facility at NASA’s Kennedy Space Center at Cape Canaveral, Florida, as well as the creation of a next-generation Deep Space Avionics Integration Lab near the Johnson Space Center in Houston.

*Artist’s concept of space habitat operating beyond Earth and the Moon. Credit: NASA*

As Bill Pratt, Lockheed Martin’s NextSTEP program manager, said in a recent press statement:

“It is easy to take things for granted when you are living at home, but the recently selected astronauts will face unique challenges. Something as simple as calling your family is completely different when you are outside of low Earth orbit. While building this habitat, we have to operate in a different mindset that’s more akin to long trips to Mars to ensure we keep them safe, healthy and productive.”

The full-scale prototype will essentially be a refurbished Donatello Multi-Purpose Logistics Module (MPLM), which was one of three large modules that was flown in the Space Shuttle payload bay and used to transfer cargo to the ISS. The team will also be relying on “mixed-reality prototyping”, a process where virtual and augmented reality are used to solve engineering issues in the early design phase.

“We are excited to work with NASA to repurpose a historic piece of flight hardware, originally designed for low Earth orbit exploration, to play a role in humanity’s push into deep space,” said Pratt. “Making use of existing capabilities will be a guiding philosophy for Lockheed Martin to minimize development time and meet NASA’s affordability goals.”

The Deep Space Gateway will also rely on the Orion crew capsule’s advanced capabilities while crews are docked with the habitat. Basically, this will consist of the crew using the Orion as their command deck until a more permanent command module can be built and incorporated into the habitat. This process will allow for an incremental build-up of the habitat and the deep space exploration capabilities of its crews.

As Pratt indicated, when uncrewed, the habitat will rely on systems that Lockheed Martin has incorporated into their Juno and MAVEN spacecraft in the past:

“Because the Deep Space Gateway would be uninhabited for several months at a time, it has to be rugged, reliable and have the robotic capabilities to operate autonomously. Essentially it is a robotic spacecraft that is well-suited for humans when Orion is present. Lockheed Martin’s experience building autonomous planetary spacecraft plays a large role in making that possible.”

The Phase II work will take place over the next 18 months and the results (provided by NASA) are expected to improve our understanding of what is needed to make long-term living in deep space possible. As noted, Lockheed Martin will also be using this time to build their Deep Space Avionics Integration Laboratory, which will serve as an astronaut training module and assist with command and control between the Gateway and the Orion capsule.

Beyond the development of the Deep Space Gateway, NASA is also committed to the creation of a Deep Space Transport – both of which are crucial for NASA’s proposed “Journey to Mars”. Whereas the Gateway is part of the first phase of this plan – the “Earth Reliant” phase, which involves exploration near the Moon using current technologies – the second phase will be focused on developing long-duration capabilities beyond the Moon.

*NASA’s Journey to Mars. NASA is developing the capabilities needed to send humans to an asteroid by 2025 and Mars in the 2030s. Credit: NASA/JPL*

For this purpose, NASA is seeking to create a reusable vehicle specifically designed for crewed missions to Mars and deeper into the Solar System. The Deep Space Transport would rely on a combination of Solar Electric Propulsion (SEP) and chemical propulsion to transport crews to and from the Gateway – which would also serve as a servicing and refueling station for the spacecraft.

This second phase (the “Proving Ground” phase) is expected to culminate at the end of the 2020s, at which time a one-year crewed mission will take place. This mission will consist of a crew being flown to the Deep Space Gateway and back to Earth for the purpose of validating the readiness of the system and its ability to conduct long-duration missions independent of Earth.

This will open the door to Phase Three of the proposed Journey, the so-called “Earth Indepedent” phase. At this juncture, the habitation module and all other necessary mission components (like a Mars Cargo Vehicle) will be transferred to an orbit around Mars. This is expected to take place by the early 2030s, and will be followed (if all goes well) by missions to the Martian surface.

While the proposed crewed mission to Mars is still a ways off, the architecture is gradually taking shape. Between the development of spacecraft that will get the mission components and crew to cislunar space – the SLS and Orion – and the development of space habitats that will house them, we are getting closer to the day when astronauts finally set foot on the Red Planet!

Further Reading: NASA, Lockheed Martin

July 25, 2017 by Matt Williams

Ancient Volcanoes on Mars Could Have Been the Place for Life

The valleys of Coprates Chasma in the east of Valles Marineris. This perspective view was created using stereo image data from DLR’s HRSC (High Resolution Stereo Camera) camera on board ESA’s Mars Express spacecraft Credit: ESA/DLR/FU Berlin

For decades, Mars has been the focal point of intense research. Beginning in the 1960s, literally dozens of robotic spacecraft, orbiters and rovers have explored Mars’ atmosphere and surface, looking for clues to the planet’s past. From this, scientists now know that billions of years ago, Mars was a warmer, wetter place. Not only did liquid water exist on its surface, but it is possible life existed there in some form as well.

Granted, some recent findings have cast some doubt in this, indicating that Mars’ surface may have been hostile to microbes. But a new study from an international team of scientists indicates that evidence life could be found in volcanic deposits. Specifically, they argue that within the massive geological structure known as Valles Marineris, there may be ancient volcanoes that have preserved ancient microbes.

The study, titled “Amazonian Volcanism Inside Valles Marineris on Mars“, recently appeared in the journal Earth and Planetary Science Letters. Led by Petr Brož of the Institute of Geophysics at the Czech Academy of Sciences (AVCR), the team examined Mars’ famous Valles Marineris region – a canyon system stretching for 4000 km (2485.5 mi) – for signs of recent geological activity, which opens up the possibility of there also being fossilized life there.

*Valles Marineris, part of NASA World Wind map of Mars. Credit: NASA*

The team began by examining the Coprates Chasma canyon, one of the lowest points in Valles Marineris, which is home to over 130 volcanoes and solidified lava flows. This consisted of analyzing high-resolution images of the region that were taken by NASA’s Mars Reconnaissance Orbiter (MRO), which revealed cones of basaltic lava (aka. scoria) and ash that measured around 400-meters (1300 ft) high.

After examining the cones’ surface patterns and morphological details, they confirmed that these were indeed the remains of lava volcanoes (and not mud volcanoes, which was another possibility). In addition, they also noted similarities between these cone and others on Mars where mud volcanism is not possible – as well as similarities with volcanic cones here on Earth.

As Ernst Hauber, a researcher from the Institute of Planetary Research at the German Aerospace Center (DLR) and a co-author on the study, explained in a AVCR press release:

“The spatial distribution of the cones also suggests their volcanic origin. They appear to occur more frequently along tectonic fractures that formed the trough in the surface and whose fracture interfaces continue into the subsurface, creating pathways for the magma to ascend.”

Even more surprising was the apparent age of the volcanoes, which was very young. On Mars, the main period of volcanic activity ended during Mars’ Hesperian Period – which ran from 3.7 to approximately 3.0 billion years ago. And while images acquired by the Mars Express mission have shown indications of younger volcanoes (occurring 500 million years ago), these tend to be located in volcanic provinces.

A colorized image of the surface of Mars taken by the Mars Reconnaissance Orbiter. The line of three volcanoes is the Tharsis Montes, with Olympus Mons to the northwest. Valles Marineris is to the east. Image: NASA/JPL-Caltech/ Arizona State University

A good example of this is the Tharsis Bulge, which is located several thousand km from the Coprates Chasma canyon. It is here that the Tharses Montes mountain chain is located, which consists of the shield volcanoes of Ascraeus Mons, Pavonis Mons and Arsia Mons. Olympus Mons, the tallest mountain in the Solar System (with an elevation of 22 km or 13.6 mi), is located at the edge of this region.

In contrast, the volcanic cones spotted in the Coprates Chasma canyon were estimates to be between 200 and 400 million years of age, placing them in the most recent geological period known as the Amazonian (3.0 billion years ago to the present day). This effectively demonstrates that these volcanoes formed late in Mars’ history and far away from volcanic areas like Tharsis and Elysium.

It also demonstrates that these volcanoes were not part of the original formation of Valles Marineris, which is believed to be related to the formation of the Tharsis Bulge. This all took place between the Noachian to Late Hesperian periods of Mars (ca. 3.5 billion years ago), which was the last time Mars experienced widespread geological activity.

Last, but not least, the team used the Compact Reconnaissance Imaging Spectrometer (CRISM) aboard the MRO to learn more about the mineral compositions of the region’s lava and volcanic cones. Once again, their findings proved to be surprising, and could indicate that the Coprates Chasma region is a suitable location to search for evidence of ancient life on Mars.

*Image of young volcanoes at the base of Coprates Chasma on Mars, obtained by the Mars Reconnaissance Orbiter. Credit: NASA/JPL/University of Arizona*

Essentially, the CRISM data indicated the presence of high-silica content minerals in the volcanic rock, which included opaline-like substances at one of the peaks. Opaline silicates, it should be noted, are water-bearing materials that are often produced by hydrothermal processes – where silicate structures form from supersaturated, hot solutions of minerals that cool to become solid.

On Earth, microorganisms are often found within opal deposits since they form in energy and mineral-rich environments, where microbial lifeforms thrive. The presence of these minerals in the Coprates Chasma region could therefore mean that ancient microorganisms once thrived there. Moreover, such organisms could also be fossilized within the mineral-rich lava rock, making it a tempting target for future research.

As Hauber indicated, the appeal of Coprates Chasma doesn’t end there, and future mission will surely want to make exploring this region a priority:

“Coprates Chasma is not just interesting with regard to the question of previous life on Mars. The region would also be an excellent landing site for future Mars Rovers. Here we could investigate many scientifically important and interesting topics. Analyzing samples for their elemental isotopic fractions would allow us to determine with far greater precision when the volcanoes were actually active.

“On the towering, steep walls, the geologic evolution of the Valles Marineris is presented to us almost like a history book – gypsum strata and layers of old, crustal rocks can be observed, as well as indications for liquid water trickling down the slopes even today during the warm season. That is as much Mars geology as you can get!”

*Scientists were able to gauge the rate of water loss on Mars by measuring the ratio of water and HDO from today and 4.3 billion years ago. Credit: Kevin Gill*

In other words, this low-lying region could be central to future studies that attempt to unlock the history and geological evolution of the Red Planet. The payoffs of studying this region not only include determining if Mars had life in the past, but when and how it went from being a warmer, wetter environment to the cold, dessicated landscape we know today.

In the future, NASA, the ESA, the China National Space Agency (CNSA) and Roscosmos all hope to mount additional robotic missions to Mars. In addition, NASA and even SpaceX hope to send crewed missions to the planet in the hopes of learning more about its past – and possibly future – habitability. Between its geological history, greater atmospheric pressure, and the possibility of fossilized life, one or more of these missions may be headed to Valles Marineris to have a look around.

Further Reading: The Czech Academy of Science, Earth and Planetary Science Letters

July 25, 2017 by Matt Williams

Good News for Future Moon Bases. There’s Water Inside the Moon

Evidence from ancient volcanic deposits suggests that lunar magma contained substantial amounts of water, bolstering the idea that the Moon's interior is water-rich. Credit: Olga Prilipko Huber

Since the Apollo program wrapped up in the early 1970s, people all around the world have dreamed of the day when we might return to the Moon, and stay there. And in recent years, however, that actual proposals for a lunar settlement have begun to take shape. As a result, a great deal of attention and research has been focused on whether or not the Moon has indigenous sources of water.

Thanks to missions like Chandrayaan-1 and the Lunar Reconnaissance Orbiter (LRO), scientists know that there are vast amounts of surface ice on the Moon. However, according to a new study, researchers from Brown University have found evidence of widespread water within volcanic deposits on the lunar surface. These findings could indicate that there are also vast sources of water within the Moon’s interior.

For their study – titled “Remote Detection of Widespread Indigenous Water in Lunar Pyroclastic Deposits” – Brown researchers Ralph E. Milliken and Shuai Li combined satellite data with new thermal profiles to search for signs of water away from the polar regions. In so doing, they addressed a long-standing theory about the likelihood of water in the Moon’s interior, as well as the predominant theory of how the Moon formed.

*Lunar Crater as imaged by NASA’s Moon Mineralogy Mapper. Credit: SRO/NASA/JPL-Caltech/USGS/Brown Univ.*

As noted, scientists have known for years that there are large amounts of frozen water in the Moon’s polar regions. At the same time, however, scientists have held that the Moon’s interior must have depleted of water and other volatile compounds billions of years ago. This was based on the widely-accepted hypothesis that the Moon formed after a Mars-sized object (named Theia) collided with Earth and threw up a considerable amount of debris.

Essentially, scientists believed that it was unlikely that any hydrogen – necessary to form water – could have survived the heat of this impact. However, as of a decade ago, new scientific findings began to emerge that cast doubt on this. The first was a 2008 study, where a team of researches (led by Alberto Saal of Brown University) detected trace amounts of water in samples of volcanic glass that were bought back by the Apollo 15 and Apollo 17 missions.

This was followed by a 2011 study (also from Brown University) that indicated how crystalline structures within those beads contained as much water as some basalt mineral deposits here on Earth. These findings were particularly significant, in that they suggested that parts of the Moon’s mantle could contain as much water as Earth’s. The question though was whether these findings represented the norm, or an anomaly.

As Milliken, an associate professor in Brown’s Department of Earth, Environmental, and Planetary Sciences (DEEPS) and the co-author on the paper, summarized in a recent Brown press release:

“The key question is whether those Apollo samples represent the bulk conditions of the lunar interior or instead represent unusual or perhaps anomalous water-rich regions within an otherwise ‘dry’ mantle. By looking at the orbital data, we can examine the large pyroclastic deposits on the Moon that were never sampled by the Apollo or Luna missions. The fact that nearly all of them exhibit signatures of water suggests that the Apollo samples are not anomalous, so it may be that the bulk interior of the Moon is wet.”

*A false colour composite of the distribution of water and hydroxyl molecules over the lunar surface. Credit: ISRO/NASA/JPL-Caltech/Brown Univ/USGS*

To resolve this, Milliken and Li consulted orbital data to examine lunar volcanic deposits for signs of water. Basically, orbiters use spectrometers to bounce light off the surfaces of planets and astronomical bodies to see which wavelengths of light are absorbed and which are reflected. This data is therefore able to determine what compounds and minerals are present based on the absorption lines detected.

Using this technique to look for signs of water in lunar volcanic deposits (aka. pyroclastic deposits), however, was a rather difficult task. During the day, the lunar surface heats up, especially in the latitudes where volcanic deposits are located. As Milliken explained, spectronomers will therefore pick up thermal energy in addition to chemical signatures which this can throw off the readings:

“That thermally emitted radiation happens at the same wavelengths that we need to use to look for water. So in order to say with any confidence that water is present, we first need to account for and remove the thermally emitted component.”

To correct for this, Milliken and Li constructed a detailed temperature profile of the areas of the Moon they were examining. They then examined surface data collected by the Moon Mineralogy Mapper, the spectrographic imager that was part of India’s Chandrayaan-1 mission. They then compared this thermally-corrected surface data to the measurements conducted on the samples returned from the Apollo missions.

*Colored areas indicate elevated water content compared with surrounding terrains. Yellows and reds indicate the richest water content. Credit: Milliken lab/Brown University*

What they found was that areas of the Moon’s surface that had been previously mapped showed evidence of water in nearly all the large pyroclastic deposits. This included the deposits that were near the Apollo 15 and 17 landing sites where the lunar samples were obtained. From this, they determined that these samples were not anomalous in nature, and that water is distributed across the lunar surface.

What’s more, these findings could indicate that the Moon’s mantle is water-rich as well. Beyond being good news for future lunar missions, and the construction of a lunar settlement, these results could lead to a rethinking of how the Moon formed. This research was part of Shuai Li’s – a recent graduate of the University of Brown and the lead author on the study – Ph.D thesis. As he said of the study’s findings:

“The growing evidence for water inside the Moon suggest that water did somehow survive, or that it was brought in shortly after the impact by asteroids or comets before the Moon had completely solidified. The exact origin of water in the lunar interior is still a big question.

What’s more, Li indicated that lunar water that is located in volcanic deposits could be a boon for future lunar missions. “Other studies have suggested the presence of water ice in shadowed regions at the lunar poles, but the pyroclastic deposits are at locations that may be easier to access,” he said. “Anything that helps save future lunar explorers from having to bring lots of water from home is a big step forward, and our results suggest a new alternative.”

*The blue areas show locations on the Moon’s south pole where water ice is likely to exist. Credit: NASA/GSFC*

Between NASA, the ESA, Roscosmos, the ISRO and the China National Space Administration (CNSA), there are no shortage of plans to explore the Moon in the future, not to mention establishing a permanent base there. Knowing there’s abundant surface water (and maybe more in the interior as well) is therefore very good news. This water could be used to create hydrazine fuel, which would significantly reduce the costs of individual missions to the Moon.

It also makes the idea of a stopover base on the Moon, where ships traveling deeper into space could refuel and resupply – a move which would shave billions off of deep-space missions. An abundant source of local water could also ensure a ready supply of drinking and irrigation water for future lunar outposts. This would also reduce costs by ensuring that not all supplies would need to be shipped from Earth.

On top of all that, the ability to conduct experiments into how plants grow in reduced gravity would yield valuable information that could be used for long-term missions to Mars and other Solar bodies. It could therefore be said, without a trace of exaggeration, that water on the Moon is the key to future space missions.

The research was funded by the NASA Lunar Advanced Science and Exploration Research (LASER) program, which seeks to enhance lunar basic science and lunar exploration science.

Further Reading: Brown University

July 24, 2017July 24, 2017 by Matt Williams

What is the Weather Like on Mercury?

With the dawning of the Space Age in the 1950s, human beings were no longer confined to studying the Solar planets and other astronomical bodies with Earth-based instruments alone. Instead crewed missions have gone into orbit and to the Moon while robotic missions have traveled to every corner of the Solar System. And in the process, we have learned some interesting things about the planets, planetoids, and asteroids in our Solar neighborhood.

For example, we have learned that all the Solar planets have their own particular patterns and cycles. For instance, even though Mercury is an airless body, it does have a tenuous exosphere and experiences seasons of a sort. And while it is known for being extremely hot, it also experiences extremes of cold, to the point that ice can exist on its surface. While it is by no means what we are used to here on Earth, Mercury still experiences a kind of “weather”.

Mercury’s Atmosphere:

As noted, Mercury has no atmosphere to speak of, owing to its small size and extremes in temperature. However, it does have a tenuous and variable exosphere that is made up of hydrogen, helium, oxygen, sodium, calcium, potassium and water vapor, with a combined pressure level of about 10^-14 bar (one-quadrillionth of Earth’s atmospheric pressure).

The Fast Imaging Plasma Spectrometer on board MESSENGER has found that the solar wind is able to bear down on Mercury enough to blast particles from its surface into its wispy atmosphere. Shannon Kohlitz, Media Academica, LLC

It is believed this exosphere was formed from particles captured from the Sun (i.e solar wind) as well as volcanic outgassing and debris kicked into orbit by micrometeorite impacts. In any case, Mercury’s lack of a viable atmosphere is the reason why it is unable to retain heat from the Sun, which leads to extreme variations between night and day for the rocky planet.

Orbital Resonance:

Mercury’s temperature variations are also attributed to its orbital eccentricity of 0.2056, which is the most extreme of any planet in the Solar System. Essentially, its distance from the Sun ranges from 46 million km (29 million mi) at its closest (perihelion) to 70 million km (43 million mi) at its farthest (aphelion). As a result, the side facing the Sun reaches temperatures of up to 700 K (427° C), the side in shadow dips down to 100 K (-173° C).

With an average rotational speed of 10.892 km/h (6.768 mph), Mercury also takes 58.646 days to complete a single rotation. This means that Mercury has a spin-orbit resonance of 3:2, where it completes three rotations on its axis for every two rotations completed around the Sun. This does not, however, mean that three days last the same as two years on Mercury.

*The Orbit of Mercury during the year 2006. Credit: Wikipedia Commons/Eurocommuter*

In fact, its high eccentricity and slow rotation mean that it takes 176 Earth days for the Sun to return to the same place in the sky (aka. a solar day). In short, a single day on Mercury is twice as long as a single year! Mercury also has the lowest axial tilt of any planet in the Solar System – approximately 0.027 degrees compared to Jupiter’s 3.1 degrees (the second smallest).

Polar Ice:

This low tilt means that the polar regions are constantly in shadow, which leads to another interesting feature about Mercury. Yes, despite how hot its Sun-facing side can become, the existence of water ice and even organic molecules have been confirmed on Mercury’s surface. But this only true at the poles, where the floors of deep craters are never exposed to direct sunlight, and temperatures within them therefore remain below the planetary average.

These icy regions are believed to contain about 10¹⁴–10¹⁵ kg (1 to 10 billion metric tons, 1.1 to 11 billion US tons) of frozen water, and may be covered by a layer of regolith that inhibits sublimation. The origin of the ice on Mercury is not yet known, but the two most likely sources are from outgassing of water from the planet’s interior or deposition by the impacts of comets.

Mercury transit — *The Big Bear Solar Observatory Captures a high-res image of this week’s transit of Mercury across the face of the Sun. Image credit: NJIT/BBSO*

When one talks about the “weather” on Mercury, they are generally confined to talking about variations between the Sun-facing side and the night side. Over the course of two years, that weather will remain scorching hot or freezing cold. In that respect, we could say that a single season on Mercury lasts a full four years, and includes a “Midnight Sun” that lasts two years, and a “Polar Night” that lasts the same.

Between its rapid and very eccentric orbit, its slow rotation, and its strange diurnal and annual patterns, Mercury is a very extreme planet with a very extreme environment. It only makes sense that its weather would be similarly extreme. Hey, there’s a reason nobody lives there, at least not yet…

We have written many interesting articles about the weather on other planets here at Universe Today. Here’s What is the Weather like on Venus?, What is the Weather Like on Mars?, What is the Weather Like on Jupiter?, What is the Weather Like on Saturn?, What is the Weather Like on Uranus?, and What is the Weather Like on Neptune?

If you’d like more information on Mercury, check out NASA’s Solar System Exploration Guide, and here’s a link to NASA’s MESSENGER Misson Page.

We’ve also recorded an entire episode of Astronomy Cast all about Mercury. Listen here, Episode 49: Mercury.

Sources: