Where’s the Line Between Massive Planet and Brown Dwarf Star?

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 — 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 — 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.

Let the debate begin.

January 24, 2018January 24, 2018 by Evan Gough

Finally! SpaceX’s Falcon Heavy Does its Static Fire Test. Actual Flight Should Be “In A Week Or So”

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

— SpaceX (@SpaceX) January 24, 2018

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 — 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.

January 23, 2018 by Evan Gough

The Solar Eclipse Caused a Bow Wave in Earth’s Atmosphere

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 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.

January 22, 2018 by Evan Gough

A New Kind of Propulsion System That Doesn’t Need Propellant. It Converts Electricity into Thrust and Vice Versa.

The proposed "space-tie" propulsion system being patented by Spanish scientists could be useful on Satellites like the ESA's Sentinel-1, pictured. Image: ESA/ATG

Some of the best things in science are elegant and simple. A new propulsion system being developed in Spain is both those things, and could help solve a growing problem with Earth’s satellites: the proliferation of space junk.

Researchers at Universidad Carlos III de Madrid (UC3M) and the Universidad Politécnica de Madrid (UPM) in Spain are patenting a new kind of propulsion system for orbiting satellites that doesn’t use any propellant or consumables. The system is basically a tether, in the form of an aluminum tape a couple kilometers long and a couple inches wide, that trails out from the satellite. The researchers call it a space tie.

“This is a disruptive technology because it allows one to transform orbital energy into electrical energy and vice versa without using any type of consumable”. – Gonzalo Sánchez Arriaga, UC3M.

The lightweight space tie is rolled up during launch, and once the satellite is in orbit, it’s deployed. Once deployed, the tape can either convert electricity into thrust, or thrust into electricity. The Spanish researchers behind this say that the space-ties will be used in pairs.

The system is based on what is called a “low-work-function” tether. A special coating on the tether has enhanced electron emission properties on receiving sunlight and heat. These special properties allow it to function in two ways. “This is a disruptive technology because it allows one to transform orbital energy into electrical energy and vice versa without using any type of consumable,” said Gonzalo Sánchez Arriaga, Ramón y Cajal researcher at the Bioengineering and Aerospace Engineering Department at UC3M.

As a satellite loses altitude and gets closer to Earth, the tether converts that thrust-caused-by-gravity into electricity for the spacecraft systems to use. When it comes to orbiting facilities like the International Space Station (ISS), this tether system could solve an annoying problem. Every year the ISS has to burn a significant amount of propellant to maintain its orbit. The tether can generate electricity as it moves closer to Earth, and this electricity could replace the propellant. “With a low- work function tether and the energy provided by the solar panel of the ISS, the atmospheric drag could be compensated without the use of propellant”, said Arriaga.

“Unlike current propulsion technologies, the low-work function tether needs no propellant and it uses natural resources from the space environment such as the geomagnetic field, the ionospheric plasma and the solar radiation.” – Gonzalo Sánchez Arriaga, UC3M.

For satellites with ample on-board power, the tether would operate in reverse. It would use electricity to provide thrust to the space craft. This is especially useful to satellites near the end of their operational life. Rather than languish in orbit for a long time as space junk, the derelict satellite could be forced to re-enter Earth’s atmosphere where it would burn up harmlessly.

The space-tie system is based on what’s called Lorentz drag. Lorentz drag is an electrodynamic effect. (Electrodynamics enthusiasts can read all about it here.) I won’t go too deeply into it because I’m not a physicist, but the Spanish researchers suggest that the Lorentz drag can be easily observed by watching a magnet fall through a copper tube. Here’s a video.

Space organizations have shown interest in the low-work-function tether, and the Spanish team is getting the word out to experts in the USA, Japan, and Europe. The next step is the manufacture of prototypes. “The biggest challenge is its manufacturing because the tether should gather very specific optical and electron emission properties,” says Sánchez Arriaga.

The Spanish Ministry of Economy, Industry and Competitiveness has awarded the Spanish team a grant to investigate materials for the system. The team has also submitted a proposal to the European Commission’s Future and Emerging Technologies (FET-Open) consortium for funding. “The FET-OPEN project would be foundational because it considers the manufacturing and characterization of the first low-work-function tether and the development of a deorbit kit based on this technology to be tested on a future space mission. If funded, it would be a stepping stone to the future of low-work-function tethers in space” Sanchez Arriaga concluded.

In this video, Gonzalo Sanchez Arriaga explains how the system works. If you don’t speak Spanish, just turn on subtitles.

January 19, 2018 by Evan Gough

Researchers Develop a New Low Cost/Low Weight Method of Searching for Life on Mars

Study co-author I. Altshuler sampling permafrost terrain near the McGill Arctic research station, Canadian high Arctic. Image: Dr. Jacqueline Goordial

Researchers at Canada’s McGill University have shown for the first time how existing technology could be used to directly detect life on Mars and other planets. The team conducted tests in Canada’s high arctic, which is a close analog to Martian conditions. They showed how low-weight, low-cost, low-energy instruments could detect and sequence alien micro-organisms. They presented their results in the journal Frontiers in Microbiology.

Getting samples back to a lab to test is a time consuming process here on Earth. Add in the difficulty of returning samples from Mars, or from Ganymede or other worlds in our Solar System, and the search for life looks like a daunting task. But the search for life elsewhere in our Solar System is a major goal of today’s space science. The team at McGill wanted to show that, conceptually at least, samples could be tested, sequenced, and grown in-situ at Mars or other locations. And it looks like they’ve succeeded.

Recent and current missions to Mars have studied the suitability of Mars for life. But they don’t have the ability to look for life itself. The last time a Mars mission was designed to directly search for life was in the 1970’s, when NASA’s Viking 1 and 2 missions landed on the surface. No life was detected, but decades later people still debate the results of those missions.

The Viking 2 lander captured this image of itself on the Martian surface. The Viking Landers were the last missions to directly look for life on Mars. By NASA - NASA website; description,[1] high resolution image.[2], Public Domain, https://commons.wikimedia.org/w/index.php?curid=17624 — The Viking 2 lander captured this image of itself on the Martian surface. The Viking Landers were the last missions to directly look for life on Mars. By NASA – NASA website; description,[1] high resolution image.[2], Public Domain, https://commons.wikimedia.org/w/index.php?curid=17624

But Mars is heating up, figuratively speaking, and the sophistication of missions to Mars keeps growing. With crewed missions to Mars a likely reality in the not-too-distant future, the team at McGill is looking ahead to develop tools to search for life there. And they focused on miniature, economical, low-energy technology. Much of the current technology is too large or demanding to be useful on missions to Mars, or to places like Enceladus or Europa, both future destinations in the Search for Life.

“To date, these instruments remain high mass, large in size, and have high energy requirements. Such instruments are entirely unsuited for missions to locations such as Europa or Enceladus for which lander packages are likely to be tightly constrained.”

The team of researchers from McGill, which includes Professor Lyle Whyte and Dr. Jacqueline Goordial, have developed what they are calling the ‘Life Detection Platform (LDP).’ The platform is modular, so that different instruments can be swapped out depending on mission requirements, or as better instruments are developed. As it stands, the Life Detection Platform can culture microorganisms from soil samples, assess microbial activity, and sequence DNA and RNA.

There are already instruments available that can do what the LDP can do, but they’re bulky and require more energy to operate. They aren’t suitable for missions to far-flung destinations like Enceladus or Europa, where sub-surface oceans might harbour life. As the authors say in their study, “To date, these instruments remain high mass, large in size, and have high energy requirements. Such instruments are entirely unsuited for missions to locations such as Europa or Enceladus for which lander packages are likely to be tightly constrained.”

A key part of the system is a miniaturized, portable DNA sequencer called the Oxford Nanopore MiniON. The team of researchers behind this study were able to show for the first time that the MiniON can examine samples in extreme and remote environments. They also showed that when combined with other instruments it can detect active microbial life. The researches succeeded in isolatinh microbial extremophiles, detecting microbial activity, and sequencing the DNA. Very impressive indeed.

This image shows the instruments tested in the Life Detection Platform. Image: J. Goordial et. al.

These are early days for the Life Detection Platform. The system required hands-on operation in these tests. But it does show proof of concept, an important stage in any technological development. “Humans were required to carry out much of the experimentation in this study, while life detection missions on other planets will need to be robotic,” says Dr Goordial.

“Humans were required to carry out much of the experimentation in this study, while life detection missions on other planets will need to be robotic.” – Dr. J. Goordial

The system as it stands now is useful here on Earth. The same things that allow it to search for and sequence microorganisms on other worlds make it suitable for the same task here on Earth. “The types of analyses performed by our platform are typically carried out in the laboratory, after shipping samples back from the field,” says Dr. Goordial. This makes the system desirable for studying epidemics in remote areas, or in rapidly changing conditions where transporting samples to distant labs can be problematic.

These are very exciting times in the Search for Life in our Solar System. If, or when, we discover microbial life on Mars, Europa, Enceladus, or some other world, it will likely be done robotically, using equipment similar to the LDP.

December 22, 2017 by Evan Gough

Yes Please! NASA is Considering a Helicopter Mission to Titan

In this illustration, the Dragonfly helicopter drone is descending to the surface of Titan. Image: NASA

The only thing cooler than sending a helicopter drone to explore Titan is sending a nuclear powered one to do the job. Called the “Dragonfly” spacecraft, this helicopter drone mission has been selected as one of two finalists for NASA’s robotic exploration missions planned for the mid 2020’s. NASA selected the Dragonfly mission from 12 proposals they were considering under their New Horizons program.

Titan is Saturn’s largest moon, and is a primary target in the search for life in our Solar System. Titan has liquid hydrocarbon lakes on its surface, a carbon-rich chemistry, and sub-surface oceans. Titan also cycles methane the way Earth cycles water.

This true-color image of Titan, taken by the Cassini spacecraft, shows the moon's thick, hazy atmosphere. Image: By NASA - http://photojournal.jpl.nasa.gov/catalog/PIA14602, Public Domain, https://commons.wikimedia.org/w/index.php?curid=44822294 — This true-color image of Titan, taken by the Cassini spacecraft, shows the moon’s thick, hazy atmosphere. Image: By NASA – http://photojournal.jpl.nasa.gov/catalog/PIA14602, Public Domain, https://commons.wikimedia.org/w/index.php?curid=44822294

Dragonfly would fulfill its mission by hopping around on the surface of Titan. Once an initial landing site is selected on Titan, Dragonfly will land there with the assistance of a ‘chute. Dragonfly will spend periods of time on the ground, where it will charge its batteries with its radioisotope thermoelectric generator. Once charged, it would then fly for hours at time, travelling tens of kilometers during each flight. Titan’s dense atmosphere and low gravity (compared to Earth) allows for this type of mission.

During these individual flights, potential landing sites would be identified for further scientific work. Dragonfly will return to its initial landing site, and only visit other sites once they have been verified as safe.

Dragonfly is being developed at the Johns Hopkins Applied Physics Laboratory (JHAPL.) It has a preliminary design weight of 450 kg. It’s a double quad-copter design, with four sets of dual rotors.

“Titan is a fascinating ocean world,” said APL’s Elizabeth Turtle, principal investigator for Dragonfly. “It’s the only moon in the solar system with a dense atmosphere, weather, clouds, rain, and liquid lakes and seas—and those liquids are ethane and methane. There’s so much amazing science and discovery to be done on Titan, and the entire Dragonfly team and our partners are thrilled to begin the next phase of concept development.”

The science objectives of the Dragonfly mission center around prebiotic organic chemistry and habitability on Titan. It will likely have four instruments:

Mass Spectrometer
Gamma-Ray Spectrometer
Atmospheric and Geophysical Sensors
Cameras

Being chosen as a finalist has the team behind Dragonfly excited for the project. “This brings us one step closer to launching a bold and very exciting space exploration mission to Titan,” said APL Director Ralph Semmel. “We are grateful for the opportunity to further develop our New Frontiers proposals and excited about the impact these NASA missions will have for the world.”

Exploring Titan holds a daunting set of challenges. But as we’ve seen in recent years, NASA and its partners have the capability to meet those challenges. The JHAPL team behind Dragonfly also designed and built the New Horizons mission to Pluto and the Kuiper Belt object 2014 MU69. Their track record of success has everyone excited about the Dragonfly mission.

The Dragonfly mission, and the other finalist—the Comet Astrobiology Exploration Sample Return being developed by Cornell University and the Goddard Space Flight Center—will each receive funding through the end of 2018 to work on the concepts. In the Spring of 2019, NASA will select one of them and will fund its continued development.

Dragonfly is part of NASA’s New Frontiers program. New Frontiers missions are planetary science missions with a cap of approximately $850 million. New Frontiers missions include the Juno mission to Jupiter, the Osiris-REx asteroid sample-return missions, and the aforementioned New Horizons mission to Pluto.

They Just Began Casting the Giant Magellan Telescope’s 5th Mirror. What a Monster Job.

The fifth mirror for the GMT's 7 segment primary mirror is being cast at the Richard F. Caris Mirror Laboratory at the University of Arizona. In this image, a worker at the lab places the last piece of glass for mirror 5. Image: Giant Magellan Telescope Organization

The fifth mirror for the Giant Magellan Telescope (GMT) is now being cast, according to an announcement from the Giant Magellan Telescope Organization (GMTO), the body behind the project. The GMT is a ground-breaking segmented telescope consisting of 7 gigantic mirrors, and is being built at the Las Campanas Observatory, in Atacama, Chile.

The mirrors for the GMT are being cast at the Richard F. Caris Mirror Laboratory, at the University of Arizona. This lab is the world centre when it comes to building large mirrors for telescopes. But in a lab known for ground-breaking, precision manufacturing, the GMT’s mirrors are pushing the engineering to its limits.

This illustration shows what the Giant Magellan Telescope will look like when it comes online. The fifth of its seven mirror segments is being cast now. Each of the segments is a 20 ton piece of glass. Image: Giant Magellan Telescope – GMTO Corporation

Seven separate mirrors, each the same size (8.4 meters,) will make up the GMT’s primary mirror. One mirror will be in the centre, and six will be arranged in a circle around it. Each one of these mirrors is a 20 ton glass behemoth, and each one is cast separately. Once the seven are manufactured (and one extra, just in case) they will be assembled at the observatory site.

The result will be an optical, light-gathering surface almost 24.5 meters (80 ft.) in diameter. That is an enormous telescope, and it’s taking extremely precise engineering and manufacturing to build these mirrors.

The glass for the mirrors is custom-manufactured, low-expansion glass from Japan. This glass comes as blocks, and each mirror requires exactly 17,481 kg of these glass blocks. A custom built furnace and mold heats the glass to 1165°C (2129°F) for several hours. The glass liquefies and flows into the mold. During this time, the mold is rotated at up to 5 rpm. Then the rotation is slowed, and for several months the glass cools in the mold.

After lengthy cooling, the glass can be polished. The tolerances for the mirrors, and the final shape they must take, requires very careful, extremely accurate polishing. The first mirror was cast in 2005, and in 2011 it was still being polished.

The mirrors for the GMT are not flat; they’re described as “potato chips.” They’re aspherical and parabaloidal. They have to be surface polished to an accuracy of 25 nanometers, which is a fraction of the wavelength of light.

Precision manufacturing is at the heart of the Giant Magellan Telescope. The surface of each mirror must be polished to within a fraction of the wavelength of light. Image: Giant Magellan Telescope Organization

“Casting the mirrors for the Giant Magellan Telescope is a huge undertaking, and we are very proud of the UA’s leading role creating this new resource for scientific discovery. The GMT partnership and Caris Mirror Lab are outstanding examples of how we can tackle complex challenges with innovative solutions,” said UA President Robert C. Robbins. “The University of Arizona has such an amazing tradition of excellence in space exploration, and I have been constantly impressed by the things our faculty, staff, and students in astronomy and space sciences can accomplish.”

Mirror construction for the GMT is a multi-stage process. The first mirror was completed several years ago and is in storage. Three others are in various stages of grinding and polishing. The glass for mirror 6 is in storage awaiting casting, and the glass for mirror 7 is on order from Japan.

Once completed, the GMT will be situated in Atacama, at the Las Campanas Observatory, where high-elevation and clear skies make for excellent seeing conditions. First light is planned for the mid 2020’s.

When the mirrors for the GMT are completed, they are transported in a special container with shock absorbers and insulation. In this image, the first completed mirror is moved from the Caris Mirror Lab to storage several miles away. Image: GMTO Corp.

The GMT will be largest telescope in existence, at least until the Thirty Meter Telescope and the European Extremely Large Telescope supersede it.

“Creating the largest telescope in history is a monumental endeavor, and the GMT will be among the largest privately-funded scientific initiatives to date,” said Taft Armandroff, Professor of Astronomy and Director of the McDonald Observatory at The University of Texas at Austin, and Vice-Chair of the GMTO Corporation Board of Directors. “With this next milestone, and with the leadership, technical, financial and scientific prowess of the members of the GMTO partnership, we continue on the path to the completion of this great observatory.”

The power of the GMT will allow it to directly image extra-solar planets. That alone is enough to get anyone excited. But the GMT will also study things like the formation of stars, planets, and disks; the assembly and evolution of galaxies; fundamental physics; and first light and re-ionization.

The Giant Magellan Telescope is one of the world’s Super Telescopes that we covered in this series of articles. The Super Telescopes include the:

Giant Magellan Telescope
James Webb Space Telescope
Thirty Meter Telescope
European Extremely Large Telescope
Large Synoptic Survey Telescope
Wide Field Infrared Survey Telescope

You can also watch our videos on the Super Telescopes: Part 1: Ground Telescopes, and Part 2: Space Telescopes.

June 9, 2017 by Evan Gough

What Made this Mysterious Pit on Mars? Impact Crater or Natural Collapse?

The HiRISE camera on NASA's Mars Reconnaissance Orbiter captured this unusual crater or pit on the surface of Mars. Frozen carbon dioxide gives the region its unique "Swiss cheese" like appearance. Image:NASA/JPL/University of Arizona

During late summer in the Southern hemisphere on Mars, the angle of the sunlight as it strikes the surface brings out some subtle details on the planet’s surface.

In this image, the HiRISE camera on board NASA’s Mars Reconnaissance Orbiter (MRO) captured an area of frozen carbon dioxide on the surface. Some of the carbon dioxide ice has melted, giving it a swiss-cheese appearance. But there is also an unusual hole or crater on the right side of the image, with some of the carbon dioxide ice clearly visible in the bottom of the pit.

NASA scientists are uncertain what exactly caused the unusual pit. It could be an impact crater, or it could be a collapsed pit caused by melting or sublimation of sub-surface carbon dioxide ice.

MRO has been in orbit around Mars for over 10 years, and has completed over 50,000 orbits. The MRO has two cameras. The CTX camera is lower resolution, and has imaged over 99% of the Martian surface. HiRISE is the high-resolution camera that is used to closely examine areas and objects of interest, like the unusual surface pit in this image.

At the Largest Scales, Our Milky Way Galaxy is in the Middle of Nowhere

The Millenium Simulation created this image of the large-scale structure of the Universe, showing filaments and voids within the cosmic structure. According to a new study from the University of Wisconsin, our Milky Way is situated in a huge void in the cosmic structure. The Millennium Simulation is a project of the Max Planck Supercomputing Center in Germany. Image: Millennium Simulation Project — Image of the large-scale structure of the Universe, showing filaments and voids within the cosmic structure. Who knows how many other civilizations might be out there? Credit: Millennium Simulation Project

Ever since Galileo pointed his telescope at Jupiter and saw moons in orbit around that planet, we began to realize we don’t occupy a central, important place in the Universe. In 2013, a study showed that we may be further out in the boondocks than we imagined. Now, a new study confirms it: we live in a void in the filamental structure of the Universe, a void that is bigger than we thought.

In 2013, a study by University of Wisconsin–Madison astronomer Amy Barger and her student Ryan Keenan showed that our Milky Way galaxy is situated in a large void in the cosmic structure. The void contains far fewer galaxies, stars, and planets than we thought. Now, a new study from University of Wisconsin student Ben Hoscheit confirms it, and at the same time eases some of the tension between different measurements of the Hubble Constant.

The void has a name; it’s called the KBC void for Keenan, Barger and the University of Hawaii’s Lennox Cowie. With a radius of about 1 billion light years, the KBC void is seven times larger than the average void, and it is the largest void we know of.

The large-scale structure of the Universe consists of filaments and clusters of normal matter separated by voids, where there is very little matter. It’s been described as “Swiss cheese-like.” The filaments themselves are made up of galaxy clusters and super-clusters, which are themselves made up of stars, gas, dust and planets. Finding out that we live in a void is interesting on its own, but its the implications it has for Hubble’s Constant that are even more interesting.

Hubble’s Constant is the rate at which objects move away from each other due to the expansion of the Universe. Dr. Brian Cox explains it in this short video.

The problem with Hubble’s Constant, is that you get a different result depending on how you measure it. Obviously, this is a problem. “No matter what technique you use, you should get the same value for the expansion rate of the universe today,” explains Ben Hoscheit, the Wisconsin student who presented his analysis of the KBC void on June 6th at a meeting of the American Astronomical Society. “Fortunately, living in a void helps resolve this tension.”

There are a couple ways of measuring the expansion rate of the Universe, known as Hubble’s Constant. One way is to use what are known as “standard candles.” Supernovae are used as standard candles because their luminosity is so well-understood. By measuring their luminosity, we can determine how far away the galaxy they reside in is.

Another way is by measuring the CMB, the Cosmic Microwave Background. The CMB is the left over energy imprint from the Big Bang, and studying it tells us the state of expansion in the Universe.

This is a map of the observable Universe from the Sloan Digital Sky Survey. Orange areas show higher density of galaxy clusters and filaments. Image: Sloan Digital Sky Survey.

The two methods can be compared. The standard candle approach measures more local distances, while the CMB approach measures large-scale distances. So how does living in a void help resolve the two?

Measurements from inside a void will be affected by the much larger amount of matter outside the void. The gravitational pull of all that matter will affect the measurements taken with the standard candle method. But that same matter, and its gravitational pull, will have no effect on the CMB method of measurement.

“One always wants to find consistency, or else there is a problem somewhere that needs to be resolved.” – Amy Barger, University of Hawaii, Dept. of Physics and Astronomy

Hoscheit’s new analysis, according to Barger, the author of the 2013 study, shows that Keenan’s first estimations of the KBC void, which is shaped like a sphere with a shell of increasing thickness made up of galaxies, stars and other matter, are not ruled out by other observational constraints.

“It is often really hard to find consistent solutions between many different observations,” says Barger, an observational cosmologist who also holds an affiliate graduate appointment at the University of Hawaii’s Department of Physics and Astronomy. “What Ben has shown is that the density profile that Keenan measured is consistent with cosmological observables. One always wants to find consistency, or else there is a problem somewhere that needs to be resolved.”

June 7, 2017June 7, 2017 by Evan Gough

Mars Had Way More Water on its Surface Than We Thought

The image on the left is what Mars looks like today. On the right is what Mars would look like according to a new study. Image Credit: Wei Luo, Northern Illinois University.

Mars has an extensive network of ancient valleys that were likely carved out by water over geologic time periods. Now a new study suggests that Mars had much more water than previously thought, and the key behind calculating that amount of water is in the valleys themselves.

The issue of exactly how much liquid water Mars had on its surface has been a hotly debated topic. There’s ample evidence that there was liquid water there. Orbiters and rovers have provided most of that evidence. Sedimentary rock, hydrated minerals that only form in the presence of water, and the obvious valleys, lake basins, and deltas all show that Mars was once a world with large quantities liquid water.

This false-color composite image was taken by the Mars rover Opportunity. It shows rocks termed "blueberries" which are geologic concretions that form in the presence of water. It also shows sedimentary rock which forms in the presence of water. Image credit: NASA/JPL/Cornell — This false-color composite image was taken by the Mars rover Opportunity. It shows rocks termed “blueberries” which are geologic concretions that form in the presence of water. It also shows sedimentary rock which forms in the presence of water. Image credit: NASA/JPL/Cornell

But to find out how much water there was in Mars’ past, we have to go beyond what we can see with our orbiters and rovers and construct models. That’s exactly what Northern Illinois University geography professor Wei Luo and his colleagues Xuezhi Cang & Alan D. Howard did. To do this, they relied on what previous studies have found, what we know about erosion and water cycles here on Earth, and on an innovative new algorithm that calculated the volume of Mars’ valleys, and how much water would be required to excavate them.

“Our most conservative estimates of the global volume of the Martian valley networks and the cumulative amount of water needed to carve those valleys are at least 10 times greater than most previous estimates,” Luo said.

Their new estimate of Martian water volume is 4,000 times the volume of the valley cavities on Mars. This means that Mars would have had an active water cycle much like Earth does. Water would have moved from the lakes and oceans through the atmosphere and over the surface via evaporation and precipitation.

“That means water must have recycled through the valley systems on Mars many times, and a large open body of water or ocean is needed to facilitate such active cycling,” Luo said. “I would imagine early Mars as being similar to what we have on Earth–with an ocean, lakes, running rivers and rainfall.”

The Eberswalde delta near Holden Crater on Mars is considered the 'smoking gun' for evidence of liquid water on Mars. By NASA/JPL/Malin Space Science Systems — The Eberswalde delta near Holden Crater on Mars is considered the ‘smoking gun’ for evidence of liquid water on Mars. By NASA/JPL/Malin Space Science Systems

However, as the authors acknowledge, the results of this study are difficult to reconcile with our understanding of the Martian climate. Mars’ paleoclimate was likely never warm enough to support the kind of active hydrologic cycle required for their study to be accurate. “Mars is much farther way from the sun than Earth, and when the sun was younger, it was not as bright as it is today,” Luo said. “So there’s still a lot to work out in trying to reconcile the evidence for more water.”

As the authors write in their paper, “Without an ocean-sized open body of water, it would be hard to imagine the high rate of water cycling suggested by our new estimates.” So where does that leave us?

Some of the largest features on Mars, like the huge Valles Marineris, might have formed as a tectonic crack, which was then further enlarged by erosion. For other valleys, a lot of other causes have been proposed for their formation, including glaciation, and erosion by CO2, lava, and even wind.

This topographic map of the Valles Marineris region on Mars shows clearly visible outflow channels. This is image is from NASA's Mars Global Surveyor. By NASA / JPL-Caltech / Arizona State University — This topographic map of the Valles Marineris region on Mars shows clearly visible outflow channels. This is image is from NASA’s Mars Global Surveyor. By NASA / JPL-Caltech / Arizona State University

It’s clear that at some point in the past, Mars had liquid water. How much water exactly is a hotly-debated topic, and this study won’t end that debate. But this study used much higher-resolution techniques, perfected in terrestrial uses, to arrive at its estimates. This study was also conducted globally on Mars, rather than by sampling individual locations. It will affect the debate in some way.

As they say in their paper, “There is no ground truth to assess the real accuracy of our estimation.” There’s really no way for scientists to reach a conclusion yet about the size of Martian oceans in the past, and on how active the hydrological cycle might have been on that planet.

For now, we can let the debate continue.