The Insight lander responds to commands to spread its solar arrays during a January 23, 2018 test at the Lockheed Martin clean room in Littleton, Colorado. Image: Lockheed Martin Space
May 2018 is the launch window for NASA’s next mission to Mars, the InSight Lander. InSight is the next member of what could be called a fleet of human vehicles destined for Mars. But rather than working on the question of Martian habitability or suitability for life, InSight will try to understand the deeper structure of Mars.
InSight stands for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport. InSight will be the first robotic explorer to visit Mars and study the red planet’s deep interior. The work InSight does should answer questions about the formation of Mars, and those answers may apply to the history of the other rocky planets in the Solar System. The lander, (InSight is not a rover) will also measure meteorite impacts and tectonic activity happening on Mars currently.
This video helps explain why Mars is a good candidate to answer questions about how all our rocky planets formed, not just Mars itself.
InSight was conceived as part of NASA’s Discovery Program, which are missions focused on important questions all related to the “content, origin, and evolution of the solar system and the potential for life elsewhere”, according to NASA. Understanding how our Solar System and its planets formed is a key part of the Discovery Program, and is the question InSight was built to answer.
This artist’s illustration of InSight on a photo background of Mars shows the lander fully deployed. The solar arrays are open, and in the foreground two of its instruments are shown. On the left is the SEIS instrument, and on the right is the HP3 probe. Image: NASA/Lockheed Martin
To do its work, InSight will deploy three instruments: SEIS, HP³, and RISE.
SEIS
This is InSight’s seismic instrument, designed to take the Martian pulse. It stands for Seismic Experiment for Internal Structure.
In this image, InSight’s Instrument Deployment Arm is practicing placing SEIS on the surface. Image: NASA/Lockheed Martin
SEIS sits patiently under its dome, which protects it from Martian wind and thermal effects, and waits for something to happen. What’s it waiting for? For seismic waves caused by Marsquakes, meteorite impacts, or by the churning of magma deep in the Martian interior. These waves will help scientists understand the nature of the material that first formed Mars and the other rocky planets.
HP³
HP³ is InSight’s heat probe. It stands for Heat Flow and Physical Properties Probe. Upon deployment on the Martian surface, HP³ will burrow 5 meters (16 ft.) into Mars. No other instrument has ever pierced Mars this deeply. Once there, it will measure the heat flowing deeply within Mars.
In this image, the Heat Flow and Physical Properties Probe is shown inserted into Mars. Image: NASA
Scientists hope that the heat measured by HP³ will help them understand whether or not Mars formed from the same material that Earth and the Moon formed from. It should also help them understand how Mars evolved after it was formed.
RISE
RISE stands for Rotation and Interior Structure Experiment. RISE will measure the Martian wobble as it orbits the Sun, by precisely tracking InSight’s position on the surface. This will tell scientists a lot about the deep inner core of Mars. The idea is to determine the depth at which the Martian core is solid. It will also tell us which elements are present in the core. Basically, RISE will tell us how Mars responds to the Sun’s gravity as it orbits the Sun. RISE consists of two antennae on top of InSight.
The two RISE antennae are shown in this image. RISE will reveal information about the Martian core by tracking InSight’s position while Mars orbits the Sun. Image: NASA/Lockheed Martin
InSight will land at Elysium Planitia which is a flat and smooth plain just north of the Martian equator. This is considered a perfect location or InSight to study the Martian interior. The landing sight is not far from where Curiosity landed at Gale Crater in 2012.
InSight will land at Elysium Planitia, just north of the Martian equator. Image: NASA/JPL-CalTech
InSight will be launched to Mars from Vandenberg Air Force Base in California by an Atlas V-401 rocket. The trip to Mars will take about 6 months. Once on the Martian surface, InSight’s mission will have a duration of about 728 Earth days, or just over 1 Martian year.
InSight won’t be launching alone. The Atlas that launches the lander will also launch another NASA technology experiment. MarCO, or Mars Cube One, is two suitcase-size CubeSats that will travel to Mars behind InSight. Once in orbit around Mars, their job is to relay InSight data as the lander enters the Martian atmosphere and lands. This will be the first time that miniaturized CubeSat technology will be tested at another planet.
One of the MarCO Cubesats that will be launched with InSight. This will be the first time that CubeSat technology will be tested at another planet. Image: NASA/JPL-CalTech
If the MarCO experiment is successful, it could be a new way of relaying mission data to Earth. MarCO will relay news of a successful landing, or of any problems, much sooner. However, the success of the InSight lander is not dependent on a successful MarCO experiment.
Totality! The "Winter Solstice Total Lunar Eclipse" of December, 2010. Dave Dickinson
Totality! Not a “Super Blue Blood Moon Total Lunar Eclipse,” but the “Winter Solstice Total Lunar Eclipse” of December, 2010. Dave Dickinson
Can you feel the tremor in the Force? Early next Wednesday morning internet astro-memes collide, in one of the big ticket sky events of the year, with a total lunar eclipse dubbed as — get ready — a Super Blue Blood Moon total lunar eclipse.
Specifics on the eclipse: That’s a mouthful, for sure. This is the first eclipse of 2018, and only one of two featuring totality, lunar or solar. Wednesday morning’s eclipse favors the region centered on the Pacific Rim, with regions of Asia and Australia seeing the evening eclipse at moonrise, while most of North America will see totality early Wednesday morning at moonset. Only the regions of the Canadian Maritimes and the United States east of the Mississippi misses out on the spectacle’s climax, catching a partially eclipsed Moon setting in the west at sunrise.
The path of the Moon through the Earth’s shadow and the circumstances for the January 31st, super blue blood Moon total lunar eclipse. NASA
2018 features four eclipses overall, two lunar and two solar. Paired with this eclipse is a partial solar eclipse on February 15th favoring the very southern tip of South America, followed by another total lunar eclipse this summer on July 27th. The final eclipse for 2018 is a partial solar eclipse on August 11th, favoring northern Europe and northeastern Asia.
What’s all the fuss about? Let’s dissect the eclipse, meme by meme:
Why it’s Super: Totality for this eclipse lasts 1 hour, 16 minutes and 4 seconds, the longest since April 15th, 2014. Full Moon (and maximum duration for this eclipse) occurs at 13:30 Universal Time (UT), just 27 hours after the Moon reaches perigee the day prior on January 30th at 9:55 UT . Note that this isn’t quite the closest perigee of the year in space and time: the January 1st Full Moon perigee beat it out for that title by 2,429 km (1509 miles) and 23 hours.
Worldwide circumstances for Wednesday’s super blue blood moon total lunar eclipse. NASA
Why it’s Blue: This is the second Full Moon of the month, making this month’s Moon “Blue” in the modern sense of the term. This definition comes down to us thanks to a misinterpretation in the July 1943 issue of Sky & Telescope. The Maine Farmer’s Almanac once used an even more convoluted definition of a Blue Moon as “the third Full Moon in an astronomical season with four,” and legend has it, used blue ink in the almanac printing to denote that extra spurious Moon… anyone have any old Maine Farmer’s Almanacs in the attic to verify the tale?
Note that Blue Moons aren’t all that rare… the month of March 2018 also hosts two Full Moons, while truncated February 2018 contains none, sometimes referred to as a “Black Moon”.
Why All the Blood: The cone of the Earth’s umbra or dark inner shadow isn’t completely devoid of light. Instead, you’re seeing sunlight from all the Earth’s sunrises and sunsets around its limb, filtered into the shadow of the the planet onto the nearside of the Moon. Standing on the Earthward facing side of the Moon, you would witness a solar eclipse as the Earth passed between the Moon and the Sun. Unlike the neat near fit for solar eclipses on the Earth, however, solar eclipses on the Moon can last over an hour, as the Earth appears about three times larger than the disk of the Sun. And although astronauts have witnessed eclipses from space, no human has yet stood on the Moon and witnessed the ring of fire surrounding the Earth during a solar eclipse.
Tales of the Saros: For saros buffs, this eclipse is member 49 of 74 lunar eclipses for lunar saros cycle 124, stretching all the way back to August 17th, 1152. If you caught the total lunar eclipse on January 21st, 2000, you saw the last eclipse in this cycle. Stick around until April 18th, 2144 AD and you can watch the final total lunar eclipse for saros 124.
Unlike total solar eclipses, lunar eclipses are leisurely affairs. The entire penumbral phase of the eclipse lasts for over 5 hours, though you probably won’t notice the subtle shading on the limb of the Moon until its about halfway immersed in the Earth’s penumbral shadow.
Not all total lunar eclipses are the same. Depending on how deep the Moon passes through the Earth’s shadow and the murkiness of the Earth’s atmosphere, the Moon can appear anywhere from a sickly orange, to a deep brick red during totality… for example, the Moon almost disappeared entirely during a total lunar eclipse shortly after the eruption of Mount Pinatubo in the early 1990s!
The color of the Moon during totality is known as its Danjon Number, with 4 being bright with a bluish cast on the outer limb of the Moon, and 0 appearing dark and deep red.
This is also one of the only times you can see that the Earth is indeed round with your own eyes as the curve of the shadow cast by our homeworld falls back across the Moon. This curve is the same, regardless of the angle, and whether the Moon is high above near the zenith, or close to the horizon.
Don’t miss the first eclipse of 2018 and the (deep breath) super blue blood Moon total lunar eclipse!
The ExTrA telescopes are sited at ESO’s La Silla Observatory in Chile. They will be used to search for and study Earth-sized planets orbiting nearby red dwarf stars. Credit: ESO/Emmanuela Rimbaud
Ever since the Kepler space telescope began discovering thousands of exoplanets in our galaxy, astronomers have been eagerly awaiting the day when next-generation missions are deployed. These include the much-anticipated James Webb Space Telescope, which is scheduled to take to space in 2019, but also the many ground-based observatories that are currently being constructed.
One of these is the Exoplanets in Transits and their Atmospheres (ExTrA) project, which is the latest addition to the ESO’s La Silla Observatory in Chile. Using the Transit Method, this facility will rely on three 60-centimeter (23.6 in) telescopes to search for Earth-sized exoplanets around M-type (red dwarf) stars in the Milky Way Galaxy. This week, the facility began by collecting its first light.
The Transit Method (aka. Transit Photometry) consists of monitoring stars for periodic dips in brightness. These dips are caused by planets passing in front of the star (aka. transiting) relative to the observer. In the past, detecting planets around M-type stars using this method has been challenging since red dwarfs are the smallest and dimmest class of star in the known Universe and emit the majority of their light in the near-infrared band.
Artist’s impression of rocky exoplanets orbiting Gliese 832, a red dwarf star just 16 light-years from Earth. Credit: ESO/M. Kornmesser/N. Risinger (skysurvey.org).
However, these stars have also proven to be treasure trove when it comes to rocky, Earth-like exoplanets. In recent years, rocky planets have been discovered around star’s like Proxima Centauri and Ross 128, while TRAPPIST-1 had a system of seven rocky planets. In addition, there have been studies that have indicated that potentially-habitable, rocky planets could be very common around red dwarf stars.
Unlike other facilities, the ExTrA project is well-suited to conduct surveys for planets around red dwrfs because of its location on the outskirts of the Atacama Desert in Chile. As Xavier Bonfils, the project’s lead researcher, explained:
“La Silla was selected as the home of the telescopes because of the site’s excellent atmospheric conditions. The kind of light we are observing – near-infrared – is very easily absorbed by Earth’s atmosphere, so we required the driest and darkest conditions possible. La Silla is a perfect match to our specifications.”
In addition, the ExTrA facility will rely on a novel approach that involves combining optical photometry with spectroscopic information. This consists of its three telescopes collecting light from a target star and four companion stars for comparison. This light is then fed through optical fibers into a multi-object spectrograph in order to analyze it in many different wavelengths.
The ExTrA telescopes are sited at ESO’s La Silla Observatory in Chile. Credit: ESO/Petr Horálek
This approach increases the level of achievable precision and helps mitigate the disruptive effect of Earth’s atmosphere, as well as the potential for error introduced by instruments and detectors. Beyond the goal of simply finding planets transiting in front of their red dwarf stars, the ExTrA telescopes will also study the planets it finds in order to determine their compositions and their atmospheres.
In short, it will help determine whether or not these planets could truly be habitable. As Jose-Manuel Almenara, a member of the ExTrA team, explained:
“With ExTrA, we can also address some fundamental questions about planets in our galaxy. We hope to explore how common these planets are, the behaviour of multi-planet systems, and the sorts of environments that lead to their formation,”
The potential to search for extra-solar planets around red dwarf stars is an immense opportunity for astronomers. Not only are they the most common star in the Universe, accounting for 70% of stars in our galaxy alone, they are also very long-lived. Whereas stars like our Sun have a lifespan of about 10 billion years, red dwarfs are capable of remaining in their main sequence phase for up to 10 trillion years.
Artist’s impression of Proxima b, which was discovered using the Radial Velocity method. Credit: ESO/M. Kornmesser
For these reasons, there are those who think that M-type stars are our best bet for finding habitable planets in the long run. At the same time, there are unresolved questions about whether or not planets that orbit red dwarf stars can stay habitable for long, owing to their variability and tendency to flare up. But with ExTrA and other next-generation instruments entering into service, astronomers may be able to address these burning questions.
“With the next generation of telescopes, such as ESO’s Extremely Large Telescope, we may be able to study the atmospheres of exoplanets found by ExTra to try to assess the viability of these worlds to support life as we know it. The study of exoplanets is bringing what was once science fiction into the world of science fact.”
ExTrA is a French project funded by the European Research Council and the French Agence National de la Recherche and its telescopes will be operated remotely from Grenoble, France. Also, be sure to enjoy this video of the ExTrA going online, courtesy of the ESOcast:
This artist's conception illustrates the brown dwarf named 2MASSJ22282889-431026, observed by NASA's Hubble and Spitzer space telescopes. Brown dwarfs are more massive and hotter than planets but lack the mass required to become stars.
Image credit: NASA
When is a Brown Dwarf star not a star at all, but only a mere Gas Giant? And when is a Gas Giant not a planet, but a celestial object more akin to a Brown Dwarf? These questions have bugged astronomers for years, and they go to the heart of a new definition for the large celestial bodies that populate solar systems.
An astronomer at Johns Hopkins University thinks he has a better way of classifying these objects, and it’s not based only on mass, but on the company the objects keep, and how the objects formed. In a paper published in the Astrophysical Journal, Kevin Schlaufman made his case for a new system of classification that could helps us all get past some of the arguments about which object is a gas giant planet or a brown dwarf. Mass is the easy-to-understand part of this new definition, but it’s not the only factor. How the object formed is also key.
In general, the less massive a star, the cooler it is. Though stars smaller than our Sun can still sustain heat-producing fusion reactions, protostars that are too small cannot. These “failed” stars are commonly known as brown dwarfs, and a new definition puts their range from between 10-75 times the mass of Jupiter. This artist’s concept compares the size of a brown dwarf to that of Earth, Jupiter, a low-mass star, and the Sun. (Credit: NASA/JPL-Caltech/UCB).
Schlaufman is an assistant professor in the Johns Hopkins Department of Physics and Astronomy. He has set a limit for what we should call a planet, and that limit is between 4 and 10 times the mass of our Solar System’s biggest planet, Jupiter. Above that, you’ve got yourself a Brown Dwarf star. (Brown Dwarfs are also called sub-stellar objects, or failed stars, because they never grew massive enough to become stars.)
“An upper boundary on the masses of planets is one of the most prominent details that was missing.” – Kevin Schlaufman, Johns Hopkins University, Dept. of Physics and Astronomy.
Improvements in observing other solar systems have led to this new definition. Where previously we only had our own Solar System as reference, we now can observe other solar systems with increasing effectiveness. Schlaufman observed 146 solar systems, and that allowed him to fill in some of the blanks in our understanding of brown dwarf and planet formation.
An image of Jupiter showing its storm systems. According to a new definition, Jupiter would be considered a brown dwarf if it had grown to over 10 times its mass when it was formed. Image: Gemini
“While we think we know how planets form in a big picture sense, there’s still a lot of detail we need to fill in,” Schlaufman said. “An upper boundary on the masses of planets is one of the most prominent details that was missing.”
Let’s back up a bit and look at how Brown Dwarfs and Gas Giants are related.
Solar systems are formed from clouds of gas and dust. In the early days of a solar system, one or more stars are formed out of this cloud by gravitational collapse. They ignite with fusion and become the stars we see everywhere in the Universe. The leftover gas and dust forms into planets, or brown dwarfs. This is a simplified version of solar system formation, but it serves our purposes.
In our own Solar System, only a single star formed: the Sun. The gas giants Jupiter and Saturn gobbled up most of the rest of the material. Jupiter gobbled up the lion’s share, making it the largest planet. But what if conditions had been different and Jupiter had kept growing? According to Schlaufman, if it had kept growing to over 10 times the size it is now, it would have become a brown dwarf. But that’s not where the new definition ends.
Metallicity and Chemical Makeup
Mass is only part of it. What’s really behind his new classification is the way in which the object formed. This involves the concept of metallicity in stars.
Stars have a metallicity content. In astrophysics, this means the fraction of a star’s mass that is not hydrogen or helium. So any element from lithium on down is considered a metal. These metals are what rocky planets form from. The early Universe had only hydrogen and helium, and almost insignificant amounts of the next two elements, lithium and beryllium. So the first stars had no metallicity, or almost none.
This is an image of M80, an ancient globular cluster of stars. Since these stars formed in the early universe, their metallicity content is very low. This means that gas giants like Jupiter would be rare or non-existent here, while brown dwarfs are likely plentiful. Image: By NASA, The Hubble Heritage Team, STScI, AURA – Great Images in NASA Description, Public Domain, https://commons.wikimedia.org/w/index.php?curid=6449278
But now, 13.5 billion years after the Big Bang, younger stars like our Sun have more metal in them. That’s because generations of stars have lived and died, and created the metals taken up in subsequent star formation. Our own Sun was formed about 5 billion years ago, and it has the metallicity we expect from a star with its birthdate. It’s still overwhelmingly made of hydrogen and helium, but about 2% of its mass is made of other elements, mostly oxygen, carbon, neon, and iron.
This is where Schlaufman’s study comes in. According to him, we can distinguish between gas giants like Jupiter, and brown dwarfs, by the nature of the star they orbit. The types of planets that form around stars mirror the metallicity of the star itself. Gas giants like Jupiter are usually found orbiting stars with metallicity equal to or greater than our Sun. But brown dwarfs aren’t picky; they form around almost any star. Why?
Brown Dwarfs and Planets Form Differently
Planets like Jupiter are formed by accretion. A rocky core forms, then gas collects around it. Once the process is done, you have a gas giant. For this to happen, you need metals. If metals are present for these rocky cores to form, their presence will be reflected in the metallicity of the host star.
But brown dwarfs aren’t formed by accretion like planets are. They’re formed the same way stars are; by gravitational collapse. They don’t form from an initial rocky core, so metallicity isn’t a factor.
This brings us back to Kevin Schlaufman’s study. He wanted to find out the mass at which point an object doesn’t care about the metallicity of the star they orbit. He concluded that objects above 10 times the mass of Jupiter don’t care if the star has rocky elements, because they don’t form from rocky cores. Hence, they’re not planets akin to Jupiter; they’re brown dwarfs that formed by gravitational collapse.
What Does It Matter What We Call Them?
Let’s look at the Pluto controversy to understand why names are important.
The struggle to accurately classify all the objects we see out there in space is ongoing. Who can forget the plight of poor Pluto? In 2006, the International Astronomical Union (IAU) demoted Pluto, and stripped it of its long-standing status as a planet. Why?
Because the new definition of what a planet is relied on these three criteria:
a planet is in orbit around a star.
a planet must have sufficient mass to assume a hydrostatic equilibrium (a nearly round shape.)
a planet has cleared the neighbourhood around its orbit
The more we looked at Pluto with better telescopes, the more we realized that it did not meet the third criteria, so it was demoted to Dwarf Planet. Sorry Pluto.
Pluto was re-classified as a dwarf planet based on our growing understanding of its nature. Will Schlaufman’s new study help us more accurately classify gas giants and brown dwarfs? NASA’s New Horizons spacecraft captured this high-resolution enhanced color view of Pluto on July 14, 2015. Credit: NASA/JHUAPL/SwRI
Our naming conventions for astronomical objects are important, because they help people understand how everything fits together. But sometimes the debate over names can get tiresome. (The Pluto debate is starting to wear out its welcome, which is why some suggest we just call them all “worlds.”)
Though the Pluto debate is getting tiresome, it’s still important. We need some way of understanding what makes objects different, and names that reflect that difference. And the names have to reflect something fundamental about the objects in question. Should Pluto really be considered the same type of object as Jupiter? Are both really planets in the same sense? The IAU says no.
The same principle holds true with brown dwarfs and gas giants. Giving them names based solely on their mass doesn’t really tell us much. Schlaufman aims to change that.
His new definition makes sense because it relies on how and where these objects form, not simply their size. But not everyone will agree, of course.
Peter Beck, founder of Rocket Lab, is shown with the Humanity Star.
Credit: Rocket Lab
This past weekend, the New Zealand-based aerospace company Rocket Lab reached another milestone. On Sunday, January 21st, the company conducted the second launch – the first having taken place this past summer – of its Electron booster. This two-stage, lightweight rocket is central to the company’s vision of reducing the costs of individual launches by sending light payloads to orbit with regular frequency.
This mission was also important because it was the first time that the company sent payloads into orbit. In addition to several commercial payloads, the launch also sent a secret payload into orbit at the behest of the company’s founder (Peter Beck). It is known as the “Humanity Star“, a disco-like geodesic sphere that measures 1 meter (3.3 ft) in diameter and will form a bright spot in the sky that will be visible to people on Earth.
The Humanity Star is central to Beck’s vision of how space travel can improve the lives of people here on Earth. In addition to presenting extensive opportunities for scientific research, there is also the way it fosters a sense of unity between people and nations. This is certainly a defining feature of the modern space age, where cooperation has replaced competition as the main driving force.
The Electron rocket prepping for its second launch last weekend. Credit: Rocket Lab
As Beck explained to ArsTechnica in an interview before the launch:
“The whole point of the program is to get everybody looking up at the star, but also past the star into the Universe, and reflect about the fact that we’re one species, on one planet. This is not necessarily part of the Rocket Lab program; it’s more of a personal program. It’s certainly consistent with our goal of trying to democratize space.”
Like the Electron rocket, the Humanity Sphere is made of carbon fiber materials and it’s surface consists of 65 highly-reflective panels. Once it reaches an orbit of 300 by 500 km (186 by 310 mi), it will spend the next nine months there reflecting the light of the Sun back to Earth. Whether or not it will be visible to the naked eye remains to be seen, but Rocket Lab is confident it will be.
According to Beck, the sphere will be more visible than a Iridium flare, which are easily spotted from the surface. These flares occur when the solar panels or antennae of an Iridium satellite reflect sunlight in orbit. “Most people will be familiar with the Iridium flares, and this has got much, much more surface area than an Iridium flare,” Beck said. “In theory, it will be easy to find.”
The payload will last for about nine months in orbit. Credit: Rocket Lab
Beck got the idea for the project from talking to people about where they live. In his experience, people tend to think of their locality or nationality when they think of home. Whereas many people he had spoken to were aware that they lived on planet Earth, they were oblivious to where the Earth resided in the Solar System or the Universe at large. In this respect, the Humanity Sphere is meant to encourage people to look and think beyond.
As he states on the website the company created for the Humanity Sphere:
“For millennia, humans have focused on their terrestrial lives and issues. Seldom do we as a species stop, look to the stars and realize our position in the universe as an achingly tiny speck of dust in the grandness of it all.
“Humanity is finite, and we won’t be here forever. Yet in the face of this almost inconceivable insignificance, humanity is capable of great and kind things when we recognize we are one species, responsible for the care of each other, and our planet, together. The Humanity Star is to remind us of this.
“No matter where you are in the world, rich or in poverty, in conflict or at peace, everyone will be able to see the bright, blinking Humanity Star orbiting Earth in the night sky. My hope is that everyone looking up at the Humanity Star will look past it to the expanse of the universe, feel a connection to our place in it and think a little differently about their lives, actions and what is important.
“Wait for when the Humanity Star is overhead and take your loved ones outside to look up and reflect. You may just feel a connection to the more than seven billion other people on this planet we share this ride with.”
The Electron rocket launching on Sunday afternoon, 2:42pm, New Zealand time. Credit: Rocket Lab
The Humanity Star can also be tracked via the website. As of the penning of this article, it is moving south of the equator and should be visible to those living along the west coast of South America. So if you live in Colombia, Peru or Chile, look to the western skies and see if you can’t spot this moving star. After passing south over Antarctica, it will reemerge in the night skies over Central Asia.
Without a doubt, the Humanity Sphere is an inspired creation, and one which is in good company. Who can forget the “Blue Marble” picture snapped by the Apollo 17 astronauts, or Voyager 1‘s “pale blue dot” photo? And even for those who are too young to have witnessed it, the images of Neil Armstrong and Buzz Aldrin setting foot on the Moon still serve to remind us of how far we’ve come, and how much still awaits us out there.
This artist’s impression shows the red supergiant star. Using ESO’s Very Large Telescope Interferometer, an international team of astronomers have constructed the most detailed image ever of this, or any star other than the Sun. Credit: ESO/M. Kornmesser
When it comes to looking beyond our Solar System, astronomers are often forced to theorize about what they don’t know based on what they do. In short, they have to rely on what we have learned studying the Sun and the planets from our own Solar System in order to make educated guesses about how other star systems and their respective bodies formed and evolved.
For example, astronomers have learned much from our Sun about how convection plays a major role in the life of stars. Until now, they have not been able to conduct detailed studies of the surfaces of other stars because of their distances and obscuring factors. However, in a historic first, an international team of scientists recently created the first detailed images of the surface of a red giant star located roughly 530 light-years away.
The study recently appeared in the scientific journal Nature under the title “Large Granulation cells on the surface of the giant star Π¹ Gruis“. The study was led by Claudia Paladini of the Université libre de Bruxelles and included members from the European Southern Observatory, the Université de Nice Sophia-Antipolis, Georgia State University, the Université Grenoble Alpes, Uppsala University, the University of Vienna, and the University of Exeter.
The surface of the red giant star Π¹ Gruis from PIONIER on the VLT. Credit: ESO
For the sake of their study, the team used the Precision Integrated-Optics Near-infrared Imaging ExpeRiment (PIONIER) instrument on the ESO’s Very Large Telescope Interferometer (VLTI) to observe the star known as Π¹ Gruis. Located 530 light-years from Earth in the constellation of Grus (The Crane), Π1 Gruis is a cool red giant. While it is the same mass as our Sun, it is 350 times larger and several thousand times as bright.
For decades, astronomers have sought to learn more about the convection properties and evolution of stars by studying red giants. These are what become of main sequence stars once they have exhausted their hydrogen fuel and expand to becomes hundreds of times their normal diameter. Unfortunately, studying the convection properties of most supergiant stars has been challenging because their surfaces are frequently obscured by dust.
After obtaining interferometric data on Π1 Gruis in September of 2014, the team then relied on image reconstruction software and algorithms to compose images of the star’s surface. These allowed the team to determine the convection patterns of the star by picking out its “granules”, the large grainy spots on the surface that indicate the top of a convective cell.
This was the first time that such images have been created, and represent a major breakthrough when it comes to our understanding of how stars age and evolve. As Dr. Fabien Baron, an assistant professor at Georgia State University and a co-author on the study, explained:
“This is the first time that we have such a giant star that is unambiguously imaged with that level of details. The reason is there’s a limit to the details we can see based on the size of the telescope used for the observations. For this paper, we used an interferometer. The light from several telescopes is combined to overcome the limit of each telescope, thus achieving a resolution equivalent to that of a much larger telescope.”
Artist’s impression of the Earth scorched by our Sun as it enters its Red Giant Branch phase. Credit: Wikimedia Commons/Fsgregs
This study is especially significant because Π1 Gruis in the last major phase of life and resembles what our Sun will look like when it is at the end of its lifespan. In other words, when our Sun exhausts its hydrogen fuel in roughly five billion years, it will expand significantly to become a red giant star. At this point, it will be large enough to encompass Mercury, Venus, and maybe even Earth.
As a result, studying this star will give scientists insight into the future activity, characteristics and appearance of our Sun. For instance, our Sun has about two million convective cells that typically measure 2,000 km (1243 mi) in diameter. Based on their study, the team estimates that the surface of Π1 Gruis has a complex convective pattern, with granules measuring about 1.2 x 10^8 km (62,137,119 mi) horizontally or 27 percent of the diameter of the star.
This is consistent with what astronomers have predicted, which was that giant and supergiant stars should only have a few large convective cells because of their low surface gravity. As Baron indicated:
“These images are important because the size and number of granules on the surface actually fit very well with models that predict what we should be seeing. That tells us that our models of stars are not far from reality. We’re probably on the right track to understand these kinds of stars.”
An illustration of the structure of the Sun and a red giant star, showing their convective zones. These are the granular zones in the outer layers of the stars. Credit: ESO
The detailed map also indicated differences in surface temperature, which were apparent from the different colors on the star’s surface. This are also consistent with what we know about stars, where temperature variations are indicative of processes that are taking place inside. As temperatures rise and fall, the hotter, more fluid areas become brighter (appearing white) while the cooler, denser areas become darker (red).
Looking ahead, Paladini and her team want to create even more detailed images of the surface of giant stars. The main aim of this is to be able to follow the evolution of these granules continuously, rather than merely getting snapshots of different points in time.
From these and similar studies, we are not only likely to learn more about the formation and evolution of different types of stars in our Universe; we’re also sure to get a better understanding of what our Solar System is in for.
The Falcon Heavy Rocket being fired up at launch site LC-39A at NASA’s Kennedy Space Center in Cape Canaveral, Florida. Image: SpaceX
The long-awaited Static Fire of SpaceX’s Falcon Heavy rocket has been declared a success by SpaceX founder Elon Musk. After this successful test, the first launch of the Falcon Heavy is imminent, with Musk saying in a Tweet, “Falcon Heavy hold-down firing this morning was good. Generated quite a thunderhead of steam. Launching in a week or so.”
This is a significant milestone for the Falcon Heavy, considering that SpaceX initially thought the Heavy’s first flight would be in 2013. The first launch for the Falcon Heavy has always seemed to be tantalizingly out of reach. If space enthusiasts could’ve willed the thing into space, it would’ve launched years ago. But that’s not how it goes.
The Falcon Heavy generated an enormous amount of steam when it fired all 27 of its engines. Image: SpaceX
Developing rockets like the Falcon Heavy is not a simple matter. Even Musk himself admitted this when he said in July, “At first it sounds real easy: you just stick two first stages on as strap-on boosters. But then everything changes. All the loads change; aerodynamics totally change. You’ve tripled the vibration and acoustics.” So it’s not really a surprise that the Falcon Heavy’s development has seen multiple delays.
After first being announced in 2011, the rocket’s first flight was set for 2013. That date came and went, then in 2015 rocket failures postponed the flight. Failures postponed SpaceX again in 2016. New target dates were set for late 2016, then early 2017, then late 2017. But with this successful test, long-suffering space fans can finally breathe a sigh of relief, and their collective sigh will last about as long as the static fire: only a few seconds.
First static fire test of Falcon Heavy complete—one step closer to first test flight! pic.twitter.com/EZF4JOT8e4
The Falcon Heavy has a total of 27 individual rocket engines, and all 27 of them were fired in this test, though the Heavy never left the launch pad. For those who don’t know, the Falcon Heavy is based on SpaceX’s successful Falcon 9 rocket, a nine-engine machine that made SpaceX the first commercial space company to visit the International Space Station, when the Falcon 9 delivered SpaceX’s Dragon capsule to the ISS in 2012. Since then, the Falcon has a track record of delivering cargo to the ISS and launching satellites into orbit.
The Heavy is like a Falcon 9 with two more 9-engine boosters strapped on. It will be the most powerful rocket in operation, by a large margin. (It won’t be the most powerful rocket in history though. That title still belongs to the Saturn V rocket, last launched in 1973.)
SpaceX Falcon 9 blasts off with KoreaSat-5A comsat from Launch Complex 39A at the Kennedy Space Center, FL, on 30 Oct 2017. The Falcon 9 has one core of 9 Merlin engines. Credit: Jeff Seibert
The Falcon Heavy will create 5 million pounds of thrust at lift-off, and will be able to carry about 140,000 lbs, which is about three times what the Falcon can carry. The Falcon’s engine core is reusable, and returns itself to Earth after detaching from the second stage. The Falcon Heavy will do the same, with all three cores returning to Earth for reuse. The two outer cores will return to the launch pad at Cape Canaveral, and the center core will land on a drone ship in the Atlantic. This is part of the genius behind the SpaceX designs: reusable components keep the cost down.
An artist’s illustration of the Falcon Heavy rocket. The Falcon Heavy has 3 engine cores, each one containing 9 Merlin engines. Image: SpaceX
We aren’t exactly sure when the first launch of the Falcon Heavy will be, and its first launch may be a very short flight. It’s possible that it may only get a few feet off the launch pad. At a conference in July, Musk said, “I hope it makes it far enough beyond the pad so that it does not cause pad damage. I would consider even that a win, to be honest.”
We know a few things about the eventual first launch and flight of the Falcon. There won’t be any scientific or commercial payload on-board. Rather, Musk intends to put his own personal Tesla roadster on-board as payload. If successful, it will be the first car to go on a trip around the Sun. (I call Shotgun!) It’s kind of silly to use a rocket to send a car around the Sun, but it will generate publicity. Not only for SpaceX, but for Tesla too.
If the launch is successful, the Falcon Heavy will be open for business. SpaceX already has some customers lined up for the Falcon Heavy, with a Saudi Arabian communications satellite first in line. After that, its second commercial mission will place several satellites in orbit. The US Air Force will be watching these launches closely, with an eye to using the Falcon Heavy for their own purposes.
But the real strength of the Falcon Heavy is not blasting cars on frivolous trips around the Sun, or placing communications satellites in orbit. Its destination is deep space.
Originally, SpaceX planned to use the Falcon Heavy to send people to Mars in a Dragon capsule. They’ve cancelled that idea, but the Heavy still has the capability to send rovers or other cargo to Mars and beyond. Who knows what uses it will be put to, once it has a track record of success.
We’re all eager to see the successful launch of the Falcon heavy, but while we wait for it, we can enjoy this animation from SpaceX.
Rosetta mission poster showing the deployment of the Philae lander to comet 67P/Churyumov-Gerasimenko.. Credit: ESA/ATG medialab (Rosetta/Philae); ESA/Rosetta/NavCam (comet)
In August of 2014, the ESA’s Rosetta mission made history when it rendezvoused with the Comet 67P/Churyumov–Gerasimenko. For the next two years, the probe flew alongside the comet and conducted detailed studies of it. And in November of 2014, Rosetta deployed its Philae probe onto the comet, which was the first time in history that a lander was deployed to the surface of a comet.
During the course of its mission, Rosetta revealed some truly remarkable things about this comet, including data on its composition, its gaseous halo, and how it interacts with solar wind. In addition, the probe also got a good look at the endless stream of dust grains that were poured from the comet’s surface ice as it approached the Sun. From the images Rosetta captured, which the ESA just released, it looked a lot like driving through a snowstorm!
The image below was taken two years ago (on January 21st, 2016), when Rosetta was at a distance of 79 km from the comet. At the time, Rosetta was moving closer following the comet reaching perihelion, which took place during the previous August. When the comet was at perihelion, it was closer to the Sun and at its most active, which necessitated that Rosetta move farther away for its own protection.
Image of the dust and particles the Rosetta mission was exposed to as it flew alongside Comet 67P/Churyumov–Gerasimenko. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
As you can see from the image, the environment around the comet was extremely chaotic, even though it was five months after the comet was at perihelion. The white streaks reveal the dust grains as they flew in front of Rosetta’s camera over the course of a 146 second exposure. For the science team directing Rosetta, flying the spacecraft through these dust storms was like trying to drive a car through a blizzard.
Those who have tried know just how dangerous this can be! On the one hand, visibility is terrible thanks to all the flurries. On the other, the only way to stay oriented is to keep your eyes pealed for any landmarks or signs. And all the while, there is the danger of losing control and colliding with something. In much the same way, passing through the comet’s dust storms was a serious danger to the spacecraft.
In addition to the danger of collisions, flying through these clouds was also hazardous for the spacecraft’s navigation system. Like many robotic spacecraft, Rosetta relies on star trackers to orient itself – where it recognizes patterns in the field of stars to orient itself with respect to the Sun and Earth. When flying closer to the comet, Rosetta’s star trackers would occasionally become confused by dust grains, causing the craft to temporarily enter safe mode.
Artist’s impression of the Rosetta probe signalling Earth. Credits: ESA-C.Carreau
This occurred on March 28th, 2015 and again on May 30th, 2016, when Rosetta was conducting flybys that brought it to a distance of 14 and 5 km from the comet’s surface, respectively. On both occasions, Rosetta’s navigation system suffered from pointing errors when it began tracking bright dust grains instead of stars. As a result, on these occasions, the mission team lost contact with the probe for 24 hours.
“We lost contact with the spacecraft on Saturday evening for nearly 24 hours. Preliminary analysis by our flight dynamics team suggests that the star trackers locked on to a false star – that is, they were confused by comet dust close to the comet, as has been experienced before in the mission.”
Despite posing a danger to Rosetta’s solar arrays and its navigation system, this dust is also of high scientific interest. During the spacecraft’s flybys, three of its instruments studied tens of thousands of grains, analyzing their composition, mass, momentum and velocity, and also creating 3D profiles of their structure. By studying these tiny grains, scientists were also able to learn more about the bulk composition of comets.
Another snapshot of Comet 67P/Churyumov–Gerasimenko’s dusty emissions, taken on Jan. 21st, 2016. Credit: ESA
Before it reached its grand finale and crashed into the comet’s surface on September 30th, 2016, Rosetta made some unique scientific finds about the comet. These included mapping the comet’s surface features, discerning its overall shape, analyzing the chemical composition of its nucleus and coma, and measuring the ratio of water to heavy water on its surface.
All of these findings helped scientists to learn more about how our Solar System formed and evolved, and shed some light on how water was distributed throughout our Solar System early in its history. For instance, by determining that the ratio of water to heavy water on the comet was much different than that of Earth’s, scientists learned that Earth’s water was not likely to have come from comets like Comet 67P/Churyumov–Gerasimenko.
On top of that, the spacecraft took more than a hundred thousand image of the comet with its high-resolution OSIRIS camera (including the ones shown here) and its navigation camera. These images can be perused by going to the ESA’s image browser archive. I’m sure you’ll agree, they are all as beautiful as they are scientifically relevant!
Images acquired of the Aqua satellite of the sea lanes off the coast of Portugal, taken on January 16th, 2018. Credit: NASA/Jeff Schmaltz, LANCE/EOSDIS Rapid Response
Earth, when viewed from space, is a pretty spectacular thing to behold. From orbit, one can see every continent, landmass, and major feature. Weather patterns are also eerily clear from space, with everything from hurricanes to auroras appearing as a single system. On top of that, it is only from orbit that the full extent of human activity can be truly appreciated.
For instance, when one hemisphere of Earth passes from day into night, one can see the patchwork of urban development by picking out the filamentary structure of lights. And as NASA’s Aqua satellite recently demonstrated with a high-resolution image it captured over the Atlantic Ocean, ships criss-crossing the ocean can also create some beautiful patterns.
As part of the NASA-centered international Earth Observing System (EOS), the Aqua satellite was launched on May 4th, 2002, to collect information on Earth’s water cycle. Using a suite of six Earth-observing instruments, this satellite has gathered global data on ocean evaporation, water vapor in the atmosphere, clouds, precipitation, soil moisture, sea ice, land ice, and snow cover.
NASA’s Aqua Earth-observing satellite. Credit: NASA
The image was acquired on January 16th, 2018, by the Moderate Resolution Imaging Spectroradiometer (MODIS). Pictured in this image are ships off the coast of Portugal and Spain producing cloud trails known as ship tracks. Some of these tracks stretch for hundreds of kilometers and grow broader with distance – i.e. the narrow ends are the youngest while the broader, wavier ends are older.
These clouds form when water vapor condenses around tiny particles of pollution emitted by the ship’s exhaust. This is due to the fact that some particles generated by ships (like sulfates) are soluble in water and seeds clouds. This also causes light hitting these clouds to scatter in many directions, making them appear brighter and thicker than unpolluted maritime clouds (which are seeded by larger particles like sea salt).
As always, seeing things from space provides an incredible sense of perspective. This is especially helpful when attempting to monitor and model something as complex as Earth’s environment and humanity’s impact on it. And of course, it also allows for some breathtaking photos!
This graphic shows atmospheric bow waves forming during the August 2017 eclipse over the continental United States. Image: Shunrong Zhang/Haystack Observatory
It’s long been predicted that a solar eclipse would cause a bow wave in Earth’s ionosphere. The August 2017 eclipse—called the “Great American Eclipse” because it crossed the continental US— gave scientists a chance to test that prediction. Scientists at MIT’s Haystack Observatory used more than 2,000 GNSS (Global Navigation Satellite System) receivers across the continental US to observe this type of bow wave for the first time.
The Great American Eclipse took 90 minutes to cross the US, with totality lasting only a few minutes at any location. As the Moon’s shadow moved across the US at supersonic speeds, it created a rapid temperature drop. After moving on, the temperature rose again. This rapid heating and cooling is what caused the ionospheric bow wave.
The bow wave itself is made up of fluctuations in the electron content of the ionosphere. The GNSS receivers collect very accurate data on the TEC (Total Electron Content) of the ionosphere. This animation shows the bow wave of electron content moving across the US.
The details of this bow wave were published in a paper by Shun-Rong Zhang and colleagues at MIT’s Haystack Observatory, and colleagues at the University of Tromso in Norway. In their paper, they explain it like this: “The eclipse shadow has a supersonic motion which [generates] atmospheric bow waves, similar to a fast-moving river boat, with waves starting in the lower atmosphere and propagating into the ionosphere. Eclipse passage generated clear ionospheric bow waves in electron content disturbances emanating from totality primarily over central/eastern United States. Study of wave characteristics reveals complex interconnections between the sun, moon, and Earth’s neutral atmosphere and ionosphere.”
The ionosphere stretches from about 50 km to 1000 km in altitude during the day. It swells as radiation from the Sun reaches Earth, and subsides at night. Its size is always fluctuating during the day. It’s called the ionosphere because it’s the region where charged particles created by solar radiation reside. The ionosphere is also where auroras occur. But more importantly, it’s where radio waves propagate.
The ionosphere surrounds the Earth, extending from about 80 km to 650 km. Image Credit: NASA’s Goddard Space Flight Center/Duberstein
The ionosphere plays an important role in the modern world. It allows radio waves to travel over the horizon, and also affects satellite communications. This image shows some of the complex ways our communications systems interact with the ionosphere.
This graphic shows some of the effects that the ionosphere has on communications. Image: National Institute of Information and Communications Technology
There’s a lot going on in the ionosphere. There are different types of waves and disturbances besides the bow wave. A better understanding of the ionosphere is important in our modern world, and the August eclipse gave scientists a chance not only to observe the bow wave, but also to study the ionosphere in greater detail.
The GNSS data used to observe the bow wave was key in another study as well. This one was also published in the journal Geophysical Research Letters, and was led by Anthea Coster of the Haystack Observatory. The data from the network of GNSS was used to detect the Total Electron Content (TEC) and the differential TEC. They then analyzed that data for a couple things during the passage of the eclipse: the latitudinal and longitudinal response of the TEC, and the presence of any Travelling Ionospheric Disturbances (TID) to the TEC.
Predictions showed a 35% reduction in TEC, but the team was surprised to find a reduction of up to 60%. They were also surprised to find structures of increased TEC over the Rocky Mountains, though that was never predicted. These structures are probably linked to atmospheric waves created in the lower atmosphere by the Rocky Mountains during the solar eclipse, but their exact nature needs to be investigated.
This image of GNSS data shows the positive Travelling Ionospheric Disturbance (TID) structure in the center of the primary TEC depleted region. The triangles mark cities in or near the Rocky Mountains. Image: Coster et. al.
“… a giant active celestial experiment provided by the sun and moon.” – Phil Erickson, assistant director at Haystack Observatory.
“Since the first days of radio communications more than 100 years ago, eclipses have been known to have large and sometimes unanticipated effects on the ionized part of Earth’s atmosphere and the signals that pass through it,” says Phil Erickson, assistant director at Haystack and lead for the atmospheric and geospace sciences group. “These new results from Haystack-led studies are an excellent example of how much still remains to be learned about our atmosphere and its complex interactions through observing one of nature’s most spectacular sights — a giant active celestial experiment provided by the sun and moon. The power of modern observing methods, including radio remote sensors distributed widely across the United States, was key to revealing these new and fascinating features.”
The Great American Eclipse has come and gone, but the detailed data gathered during that 90 minute “celestial experiment” will be examined by scientists for some time.
