Tag: #Life

Water, weather, new worlds: Cassini mission revealed Saturn’s secrets

Cassini is the most sophisticated space probe ever built. Launched in 1997 as a joint NASA/European Space Agency mission, it took seven years to journey to Saturn. It’s been orbiting the sixth planet from the sun ever since, sending back data of immense scientific value and images of magnificent beauty. The Conversation

Cassini now begins one last campaign. Dubbed the Grand Finale, it will end on Sept. 15, 2017 with the probe plunging into Saturn’s atmosphere, where it will burn up. Although Saturn was visited by three spacecraft in the 1970s and 1980s, my fellow scientists and I couldn’t have imagined what the Cassini space probe would discover during its sojourn at the ringed planet when it launched 20 years ago.

A huge storm churning across the face of Saturn. At the time this image was taken, 12 weeks after the storm began, it had completely wrapped around the planet.
NASA/JPL-Caltech/SSI, CC BY

 

A planet of dynamic change

Massive storms periodically appear in Saturn’s cloud tops, known as Great White Spots, observable by Earthbound telescopes. Cassini has a front-row seat to these events. We have discovered that just like Earth’s thunderstorms, these storms contain lightning and hail.

Cassini has been orbiting Saturn long enough to observe seasonal changes that cause variations in its weather patterns, not unlike the seasons on Earth. Periodic storms often appear in late summer in Saturn’s northern hemisphere.

In 2010, during northern springtime, an unusually early and intense storm appeared in Saturn’s cloud tops. It was a storm of such immensity that it encircled the entire planet and lasted for almost a year. It was not until the storm ate its own tail that it eventually sputtered and faded. Studying storms such as this and comparing them to similar events on other planets (think Jupiter’s Great Red Spot) help scientists better understand weather patterns throughout the solar system, even here on Earth.

Having made hundreds of orbits around Saturn, Cassini was also able to deeply investigate other features only glimpsed from Earth or earlier probes. Close encounters with Saturn’s largest moon, Titan, have allowed navigators to use the moon’s gravity to reorient the probe’s orbit so that it could swing over Saturn’s poles. Because of Saturn’s strong magnetic field, the poles are home to beautiful Aurorae, just like those of Earth and Jupiter.

Saturn’s six-sided vortex at Saturn’s north pole known as ‘the hexagon.’ This is a superposition of images taken with different filters, with different wavelengths of light assigned colors.
NASA/JPL-Caltech/SSI/Hampton University, CC BY

Cassini has also confirmed the existence of a bizarre hexagon-shaped polar vortex originally glimpsed by the Voyager mission in 1981. The vortex, a mass of whirling gas much like a hurricane, is larger than the Earth and has top wind speeds of 220 mph.

Home to dozens of diverse worlds

Cassini discovered that Saturn has 45 more moons than the 17 previously known – placing the total now at 62.

The largest, Titan, is bigger than the planet Mercury. It possesses a dense nitrogen-rich atmosphere with a surface pressure one and a half times that of Earth’s. Cassini was able to probe beneath this moon’s cloud cover, discovering rivers flowing into lakes and seas and being replenished by rain. But in this case, the liquid is not water, but rather liquid methane and ethane.

False-color image of Ligeia Mare, the second largest known body of liquid on Saturn’s moon Titan. It’s filled with liquid hydrocarbons.
NASA/JPL-Caltech/ASI/Cornell, CC BY

That’s not to say that water is not abundant there – but it’s so cold on Titan (with a surface temperature of -180℃) that water behaves like rock and sand. Although it has all the ingredients for life, Titan is essentially a “frozen Earth,” trapped at that moment in time before life could form.

The sixth-largest moon of Saturn, Enceladus, is an icy world about 300 miles in diameter. And for me, it’s the site of the Mission’s most spectacular finding.

The discovery started humbly, with a curious blip in magnetic field readings during the first flyby of Enceladus in 2004. As Cassini passed over the moon’s southern hemisphere, it detected strange fluctuations in Saturn’s magnetic field. From this, the Cassini magnetometer team inferred that Enceladus must be a source of ionized gas.

Intrigued, they instructed the Cassini navigators to make an even closer flyby in 2005. To our amazement, the two instruments designed to determine the composition of the gas that the spacecraft flies through, the Cassini Plasma Spectrometer (CAPS) and the Ion and Neutral Mass Spectrometer (INMS), determined that Cassini was unexpectedly passing through a cloud of ionized water. Emanating from cracks in the ice at Enceladus’ south pole, these water plumes gush into space at speeds up to 800 mph.

I am on the team that made the positive identification of water, and I have to say it was the most thrilling moment in my professional career. As far as Saturn’s moons were concerned, everyone thought all of the action would be at Titan. No one expected small, unassuming Enceladus to harbor any surprises.

Geologic activity happening in real time is quite rare in the solar system. Before Enceladus, the only known active world beyond Earth was Jupiter’s moon Io, which possesses erupting volcanoes. To find something akin to Old Faithful on a moon of Saturn was practically unimaginable. The fact that it all started with someone noticing an odd reading in the magnetic field data is a wonderful example of the serendipitous nature of discovery.

The geyser basin at the south pole of Enceladus, with its water plumes illuminated by scattered sunlight.
NASA/JPL-Caltech/Space Science Institute, CC BY

The story of Enceladus only becomes more extraordinary. In 2009, the plumes were directly imaged for the first time. We now know that water from Enceladus comprises the largest component of Saturn’s magnetosphere (the area of space controlled by Saturn’s magnetic field), and the plumes are responsible for the very existence of Saturn’s vast E-ring, the second outermost ring of the planet.

More amazingly, we now know that beneath the crust of Enceladus is a global ocean of liquid saltwater and organic molecules, all being heated by hydrothermal vents on the seafloor. Detailed analysis of the plumes show they contain hydrocarbons. All this points to the possibility that Enceladus is an ocean world harboring life, right here in our solar system.

NASA at Saturn: Cassini’s Grand Finale.

When Cassini plunges into the cloud tops of Saturn later this year, it will mark the end of one of the most successful missions of discovery ever launched by humanity.

Scientists are now considering targeted missions to Titan, Enceladus or possibly both. One of the most valuable lessons one can take from Cassini is the need to continue exploring. As much as we learned from the first spacecraft to reach Saturn, nothing prepared us for what we would find with Cassini. Who knows what we will find next?

Dan Reisenfeld, Professor of Physics & Astronomy, The University of Montana

Photo Credit: NASA/JPL/Space Science Institute.

You can follow The Systems Scientist on Twitter or Facebook.


Donate to The Systems Scientist

Buy Now Button

This article was originally published on The Conversation. Read the original article.

NASA to Reveal New Discoveries in News Conference on Oceans Beyond Earth

NASA will discuss new results about ocean worlds in our solar system from the agency’s Cassini spacecraft and the Hubble Space Telescope during a news briefing 2 p.m. EDT on Thursday, April 13. The event, to be held at the James Webb Auditorium at NASA Headquarters in Washington, will include remote participation from experts across the country.

The briefing will be broadcast live on NASA Television and the agency’s website.

These new discoveries will help inform future ocean world exploration — including NASA’s upcoming Europa Clipper mission planned for launch in the 2020s — and the broader search for life beyond Earth.

The news briefing participants will be:

  • Thomas Zurbuchen, associate administrator, Science Mission Directorate at NASA Headquarters in Washington
  • Jim Green, director, Planetary Science Division at NASA Headquarters
  • Mary Voytek, astrobiology senior scientist at NASA Headquarters
  • Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California
  • Hunter Waite, Cassini Ion and Neutral Mass Spectrometer team lead at the Southwest Research Institute (SwRI) in San Antonio
  • Chris Glein, Cassini INMS team associate at SwRI
  • William Sparks, astronomer with the Space Telescope Science Institute in Baltimore

A question-and-answer session will take place during the event with reporters on site and by phone. Members of the public also can ask questions during the briefing using #AskNASA.

To participate by phone, reporters must contact Dwayne Brown at 202-358-1726 or dwayne.c.brown@nasa.gov and provide their media affiliation no later than noon April 13.

For NASA TV downlink information, schedules and to view the news briefing, visit:

http://www.nasa.gov/nasatv

For more information on ocean worlds, visit:

https://www.nasa.gov/specials/ocean-worlds

For more information on Cassini, visit:

https://www.nasa.gov/cassini

http://saturn.jpl.nasa.gov

For more information on Hubble, visit:

https://www.nasa.gov/hubble

-end-

Felicia Chou/ Dwayne Brown
Headquarters, Washington
202 358 0257 / 202-358-1077
felicia.chou@nasa.gov / dwayne.c.brown@nasa.gov

Preston Dyches
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-7013
preston.dyches@jpl.nasa.gov

Rob Gutro
Goddard Space Flight Center, Greenbelt, Md.
301-286-4044
robert.j.gutro@nasa.gov

Editor: Katherine Brown

Photo Credit: NASA

You can follow The Systems Scientist on Twitter or Facebook.


Donate to The Systems Scientist

Buy Now Button

How I used math to develop an algorithm to help treat diabetes

When people ask me why I, an applied mathematician, study diabetes, I tell them that I am motivated for both scientific and human reasons.

Type 2 diabetes runs in my family. My grandfather died of complications related to the condition. My mother was diagnosed with the disease when I was 10 years old, and my Aunt Zacharoula suffered from it. I myself am pre-diabetic.

As a teen, I remember being struck by the fact that my mother and her sister received different treatments from their respective doctors. My mother never took insulin, a hormone that regulates blood sugar levels; instead, she ate a limited diet and took other oral drugs. Aunt Zacharoula, on the other hand, took several injections of insulin each day.

Though they had the same heritage, the same parental DNA and the same disease, their medical trajectories diverged. My mother died in 2009 at the age of 75 and my aunt died the same year at the age of 78, but over the course of her life dealt with many more serious side effects.

When they were diagnosed back in the 1970s, there were no data to show which medicine was most effective for a specific patient population.

Today, 29 million Americans are living with diabetes. And now, in an emerging era of precision medicine, things are different.

Increased access to troves of genomic information and the rising use of electronic medical records, combined with new methods of machine learning, allow researchers to process large amounts data. This is accelerating efforts to understand genetic differences within diseases – including diabetes – and to develop treatments for them. The scientist in me feels a powerful desire to take part.

Using big data to optimize treatment

My students and I have developed a data-driven algorithm for personalized diabetes management that we believe has the potential to improve the health of the millions of Americans living with the illness.

It works like this: The algorithm mines patient and drug data, finds what is most relevant to a particular patient based on his or her medical history and then makes a recommendation on whether another treatment or medicine would be more effective. Human expertise provides a critical third piece of the puzzle.

After all, it is the doctors who have the education, skills and relationships with patients who make informed judgments about potential courses of treatment.

We conducted our research through a partnership with Boston Medical Center, the largest safety net hospital in New England that provides care for people of lower income and uninsured people. And we used a data set that involved the electronic medical records from 1999 to 2014 of about 11,000 patients who were anonymous to us.

These patients had three or more glucose level tests on record, a prescription for at least one blood glucose regulation drug, and no recorded diagnosis of type 1 diabetes, which usually begins in childhood. We also had access to each patient’s demographic data, as well their height, weight, body mass index, and prescription drug history.

Next, we developed an algorithm to mark precisely when each line of therapy ended and the next one began, according to when the combination of drugs prescribed to the patients changed in the electronic medical record data. All told, the algorithm considered 13 possible drug regimens.

For each patient, the algorithm processed the menu of available treatment options. This included the patient’s current treatment, as well as the treatment of his or her 30 “nearest neighbors” in terms of the similarity of their demographic and medical history to predict potential effects of each drug regimen. The algorithm assumed the patient would inherit the average outcome of his or her nearest neighbors.

If the algorithm spotted substantial potential for improvement, it offered a change in treatment; if not, the algorithm suggested the patient remain on his or her existing regimen. In two-thirds of the patient sample, the algorithm did not propose a change.

The patients who did receive new treatments as a result of the algorithm saw dramatic results. When the system’s suggestion was different from the standard of care, an average beneficial change in the hemoglobin of 0.44 percent at each doctor’s visit was observed, compared to historical data. This is a meaningful, medically material improvement.

Based on the success of our study, we are organizing a clinical trial with Massachusetts General Hospital. We believe our algorithm could be applicable to other diseases, including cancer, Alzheimer’s, and cardiovascular disease.

It is professionally satisfying and personally gratifying to work on a breakthrough project like this one. By reading a person’s medical history, we are able to tailor specific treatments to specific patients and provide them with more effective therapeutic and preventive strategies. Our goal is to give everyone the greatest possible opportunity for a healthier life.

Best of all, I know my mom would be proud.

Dimitris Bertsimas, Professor of Applied Mathematics, MIT Sloan School of Management

Photo Credit: Shutterstock.com

You can follow The Systems Scientist on Twitter or Facebook.


Donate to The Systems Scientist

Buy Now Button

This article was originally published on The Conversation. Read the original article.

Does empathy have limits?

Is it possible to to run out of empathy?

That’s the question many are asking in the wake of the U.S. presidential election. Thousands have marched on streets and airports to encourage others to expand their empathy for women, minorities, and refugees. Others have argued that liberals lack empathy for the plight of rural Americans.

Against this backdrop, some scholars have recently come out against empathy, saying that it is overhyped, unimportant and, worse, dangerous. They make this recommendation because empathy appears to be limited and biased in ethically problematic ways.

As psychologists who study empathy, we disagree.

Based on advances in the science of empathy, we suggest that limits on empathy are more apparent than real. While empathy appears limited, these limits reflect our own goals, values, and choices; they do not reflect limits to empathy itself.

The ‘dark side’ of empathy

Over the past several years, a number of scholars, including psychologists and philosophers, have made arguments that empathy is morally problematic.

For example, in a recently published and thought-provoking book, “Against Empathy,” psychologist Paul Bloom highlights how empathy, so often touted for its positive outcomes, may have biases and limitations that make it a poor guide for everyday life.

What explains our feelings of empathy toward some and not others?
N i c o l a, CC BY

Bloom claims that empathy is a limited-capacity resource, like a fixed pie or fossil fuel that quickly runs out. He suggests that,

“We are not psychologically constituted to feel toward a stranger as we feel toward someone we love. We are not capable of feeling a million times worse about the suffering of a million than about the suffering of one.”

Such views are echoed by other scholars as well. For example, psychologist Paul Slovic suggests that “we are psychologically wired to help only one person at a time.”

Similarly, philosopher Jesse Prinz has argued that empathy is prejudiced and leads to “moral myopia,” making us act more favorably toward people we have empathy for, even if this is unfair.

For the same reason, psychologist Adam Waytz suggests that empathy can “erode ethics.” Slovic, in fact, suggests that “our capacity to feel sympathy for people in need appears limited, and this form of compassion fatigue can lead to apathy and inaction.”

Are there limits?

The empathy that the scholars above are arguing against is emotional: It’s known scientifically as “experience sharing,” which is defined as feeling the same emotions that other people are feeling.

This emotional empathy is thought to be limited for two main reasons: First, empathy appears to be less sensitive to large numbers of victims, as in genocides and natural disasters. Second, empathy appears to be less sensitive to the suffering of people from different racial or ideological groups than our own.

In other words, in their view, empathy seems to put the spotlight on single victims who look or think like us.

Empathy is a choice

We agree that empathy can often be weaker in response to mass suffering and to people who are dissimilar from us. But the science of empathy actually suggests a different reason for why such deficits emerge.

As a growing body of evidence shows, it’s not that we are unable to feel empathy for mass suffering or people from other groups, but rather that sometimes we “choose” not to. In other words, you choose the expanse of your empathy.

Empathy is a choice.
Riccardo Cuppini, CC BY-NC-ND

There is evidence that we choose where to set the limits of empathy. For example, whereas people usually feel less empathy for multiple victims (versus a single victim), this tendency reverses when you convince people that empathy won’t require costly donations of money or time. Similarly, people show less empathy for mass suffering when they think their helping won’t make any difference or impact, but this pattern goes away when they think they can make a difference.

This tendency also varies depending on an individual’s moral beliefs. For instance, people who live in “collectivist cultures,” such as Bedouin individuals, do not feel less empathy for mass suffering. This is perhaps because people in such cultures value the suffering of the collective.

This can also be changed temporarily, which makes it seem even more like a choice. For example, people who are primed to think about individualistic values show less empathic behaviors for mass suffering, but people who are primed to think about collectivistic values do not.

We argue that if indeed there was a limit on empathy for mass suffering, it should not vary based upon costs, efficacy or values. Instead, it looks like the effect shifts based on what people want to feel. We suggest that the same point applies to the tendency to feel less empathy for people different from us: Whether we extend empathy to people who are dissimilar from us depends on what we want to feel.

In other words, the scope of empathy is flexible. Even people thought to lack empathy, such as psychopaths, appear able to empathize if they want to do so.

Why seeing limits to empathy is problematic

Empathy critics usually do not talk about choice in a logically consistent manner; sometimes they say individuals choose and direct empathy willfully, yet other times say we have no control over the limits of empathy.

These are different claims with different ethical implications.

The problem is that arguments against empathy treat it as a biased emotion. In doing so, these arguments mistake the consequences of our own choices to avoid empathy as something inherently wrong with empathy itself.

We suggest that empathy only appears limited; seeming insensitivity to mass suffering and dissimilar others is not built into empathy, but reflect the choices we make. These limits result from general trade-offs that people make as they balance some goals against others.

We suggest caution in using terms like “limits” and “capacity” when talking about empathy. This rhetoric can create a self-fulfilling prophecy: When people believe that empathy is a depleting resource, they exert less empathic effort and engage in more dehumanization.

So, framing empathy as a fixed pie misses the mark – scientifically and practically.

What are the alternatives?

Even if we accepted that empathy has fixed limits – which we dispute, given the scientific evidence – what other psychological processes could we rely upon to be effective decision-makers?

Is compassion less biased?
Fr Lawrence Lew, O.P., CC BY-NC

Some scholars suggest that compassion is not as costly or biased as empathy, and so should be considered more trustworthy. However, compassion can also be insensitive to mass suffering and people from other groups, just like empathy.

Another candidate is reasoning, which is considered to be free from emotional biases. Perhaps, cold deliberation over costs and benefits, appealing to long-term consequences, may be effective. Yet this view overlooks how emotions can be rational and reasoning can be motivated to support desired conclusions.

We see this in politics, and people use utilitarian principles differently depending on their political beliefs, suggesting principles can be biased too. For example, a study found that conservative participants were more willing to accept consequential trade-offs of civilian lives lost during wartime when they were Iraqi instead of American. Reasoning may not be as objective and unbiased as empathy critics claim.

Whose standard of morality are we using?

Even if reasoning was objective and didn’t play favorites, is this what we want from morality? Research suggests that for many cultures, it can be immoral if you don’t focus on the immediate few who share your beliefs or blood.

For example, some research finds that whereas liberals extend empathy and moral rights to strangers, conservatives are more likely to reserve empathy for their families and friends. Some people think that morality should not play favorites but others think that morality should be applied more strongly to family and friends.

So even if empathy did have fixed limits, it doesn’t follow that this makes it morally problematic. Many view impartiality as the ideal, but many don’t. So, empathy takes on a specific set of goals given a choice of a standard.

By focusing on apparent flaws in empathy and not digging deeper into how they emerge, arguments against empathy end up denouncing the wrong thing. Human reasoning is sometimes flawed and it sometimes leads us off course; this is especially the case when we have skin in the game.

In our view, it is these flaws in human reasoning that are the real culprits here, not empathy, which is a mere output of these more complex computations. Our real focus should be on how people balance competing costs and benefits when deciding whether to feel empathy.

Such an analysis makes being against empathy seem superficial. Arguments against empathy rely on an outdated dualism between biased emotion and objective reason. But the science of empathy suggests that what may matter more is our own values and choices. Empathy may be limited sometimes, but only if you want it to be that way.

C. Daryl Cameron, Assistant Professor of Psychology and Research Associate in the Rock Ethics Institute, Pennsylvania State University; Michael Inzlicht, Professor of Psychology, Management, University of Toronto, and William A. Cunningham, Professor of Psychology, University of Toronto

Photo Credit: Francisco Schmidt

You can follow The Systems Scientist on Twitter or Facebook.

Donate to The Systems Scientist

Buy Now Button

This article was originally published on The Conversation. Read the original article.

How we discovered the world’s oldest fossils

Over 3,770m years ago, the Earth looked very different. There were no plants, no animals, the sky was not blue. The surface would have resembled a bare rocky wasteland. The Conversation

Yet it was around this time that we think the first life appeared, deep in the ocean around hot fissures in the seabed known as hydro-thermal vents. Here, hot fluids circulate through the rocks on the seafloor, carrying iron and other elements out of the rocks and into the surrounding water. The chemicals and energy in these environments make them look like the perfect place for life to start.

To test this theory, my colleagues and I studied an ancient group of rocks in north-east Canada called the Nuvvuagittuq belt, dated to be between 4,280m and 3,770m years old. Preserved within this belt are iron formations formed in settings analogous to hydro-thermal vents today. And in it we found micro-fossils that we believe to be 300m years older than the previous oldest known microfossils from rocks in western Australia dated to be around 3,500m years old. That makes these the oldest known fossils and possibly the oldest known evidence for life on Earth.

Rocks created from hydrothermal vent precipitates on the seafloor. Dominic Papineau

To uncover the fossils, we cut slices of the rocks so thin you could see through them and study them with a microscope. In doing so, we found microscopic filaments and tubes of iron, ranging in size from 5-10 microns in diameter, less than half the width of human hair, and up to half a millimeter in length. The tubes and filaments we saw were very detailed features that shared remarkable similarities with fossils of microbes in younger rocks and also modern microbes.

Features of these ancient filaments, such as their attachment to clumps of iron, are similar to those found in modern microbes, which use these clumps to hold themselves to rocks. These iron-oxidizing microbes trap iron coming out of underwater vents, which they use in a reaction to release chemical energy. They then use this energy to turn carbon dioxide from the surrounding water into organic matter, allowing them to grow.

How did we know they were fossils?

When we found the fossil structures we knew they were very interesting and promising candidates for micro-fossils. But we needed to demonstrate that this is what they really were and that they weren’t a non-biological phenomena. So we assessed all the likely scenarios that could have formed the tubes and filaments, including chemical gradients in iron-rich gels and metamorphic stretching of the rocks. None of the mechanisms fitted with the observations we had made.

We then looked for chemical traces in the rocks that might have been left behind by microorganisms. We found organic matter preserved as graphite in a way that suggested it had been formed by microbes. We also found key minerals that are commonly produced by the decay of biological materials in sediments, such as carbonate and apatite (which contains phosphorus). These minerals also occurred in granule structures that commonly form in sediments around decaying organisms and sometimes preserve micro-fossil structures within them. All of these independent observations provided strong evidence for the micro structures’ biological origin.

Together, this evidence very clearly demonstrates a strong biological presence in the 3,770m- to 4,280m-year-old rocks, pushing back the date of the earliest known micro-fossils by 300m years. To put that timescale into perspective, if we went back in time 300m years from today, the dinosaurs would not yet have even come into existence.

The fact we found these lifeforms in hydro-thermal vent deposits from so early in Earth’s history supports the long-standing theory that life arose in these types of environments. The environment that we found these ancient micro-fossils in, and their similarity to younger fossilized and modern bacteria, suggests that their iron-based metabolisms were among the first ways life sustained itself on Earth.

It’s also worth remembering that this discovery shows us life managed to take hold and rapidly evolve on Earth at a time when Mars had liquid water on its surface. This leaves us with the exciting possibility that if the conditions on the Martian surface and Earth were similar, life should also have begun on Mars over 3,770m years ago. Or else the Earth may have just been a special exception.

Matthew Dodd, PhD candidate, UCL

Photo Credit: Matthew Dodd

You can follow The Systems Scientist on Twitter or Facebook.

Donate to The Systems Scientist

Buy Now Button

 

 

 

 

 

This article was originally published on The Conversation. Read the original article.

Newly discovered planets could have water on their surfaces

An international team of astronomers has found a system of seven potentially habitable planets orbiting a star 39 light years away three of which could have water on their surfaces raising the possibility they could host life. Using ground and space telescopes, the team identified the planets as they passed in front of the ultracool dwarf star known as TRAPPIST-1. The star is around eight per cent of the mass of the Sun and is no bigger than Jupiter.

The team has been using the TRAPPIST–South telescope at the European Space Observatory’s (ESO) La Silla Observatory, the Very Large Telescope (VLT) at Paranal, the NASA Spitzer Space Telescope as well as two other telescopes supported by the UK’s STFC, the William Herschel Telescope and the Liverpool Telescope. All the planets, labelled TRAPPIST-1b, c, d, e, f, g and h in order of increasing distance from their parent star, have sizes comparable to Earth.

The astronomers identified the planets thanks to periodic drops in the brightness of the central star. As the planets passed in front of the star, they cast a shadow, events known as transits, from which the team could measure the planet’s orbital periods and calculate their sizes and masses. They found that the inner six planets were comparable in size, mass and temperature to the Earth raising the possibility that they host liquid water on their surface.

With just 8% the mass of the Sun, TRAPPIST-1 is very small in stellar terms, only marginally bigger than the planet Jupiter — and though nearby in the constellation Aquarius, it is invisible visually with anything less than powerful telescopes. Astronomers expected that such dwarf stars might host many Earth-sized planets in tight orbits, making them promising targets in the hunt for extraterrestrial life. TRAPPIST-1 is the first such system to be discovered.

Co-author Dr Amaury Triaud, of the University of Cambridge’s Institute of Astronomy, explains: “Stars like TRAPPIST-1 belong to the most common type of stars that exist within our Galaxy. The planets that we found are likely representative of the most common sort of planets in the Universe.

“That the planets are so similar to Earth bodes well for the search for life elsewhere. Planets orbiting ultra-cool dwarfs, like TRAPPIST-1, likely represent the largest habitable real estate in the Milky Way!”

The team determined that all the planets in the system were similar in size to Earth and Venus in our Solar System, or slightly smaller. The density measurements suggest that at least the innermost six are probably rocky in composition.

The planetary orbits are not much longer than that of Jupiter’s Galilean moon system, and much smaller than the orbit of Mercury in the Solar System. However, TRAPPIST-1’s small size and low temperature means that the energy input to its planets is similar to that received by the inner planets in our Solar System; TRAPPIST-1c, d and f receive similar energy inputs to Venus, Earth and Mars, respectively.

All seven planets discovered in the system could potentially have liquid water on their surfaces, though their orbital distances make some of them more likely candidates than others. Climate models suggest the innermost planets, TRAPPIST-1b, c and d, are probably too hot to support liquid water, except maybe on a small fraction of their surfaces. The orbital distance of the system’s outermost planet, TRAPPIST-1h, is unconfirmed, though it is likely to be too distant and cold to harbour liquid water — assuming no alternative heating processes are occurring. TRAPPIST-1e, f, and g, however, are of more interest for planet-hunting astronomers, as they orbit in the star’s habitable zone and could host oceans of surface water.

These new discoveries make the TRAPPIST-1 system an even more important target in the search for extra-terrestrial life. Team member Didier Queloz, from the University of Cambridge’s Cavendish Laboratory, is excited about the future possibilities: “Thanks to future facilities like ESO’ Extremely Large Telescope, or NASA/ESA’s soon-to-be-launched James Webb Space telescope, we will be capable to measure the structure of the planets’ atmospheres, as well as their chemical composition. We are about to start the remote exploration of terrestrial climates beyond our Solar system.”

The discovery is described in Nature, which also includes a science fiction short story, written by Laurence Suhner. Amaury Triaud comments: “We were thrilled at the idea of having artists be inspired by our discoveries right away. We hope this helps convey the sense of awe and excitement that we all have within the team about the TRAPPIST-1 system.”

The star draws its name from the TRAPPIST-South telescope, which made the initial discovery. TRAPPIST is the forerunner of a more ambitious facility called “SPECULOOS” that includes Cambridge as core partner, conducted by researchers of the “Cambridge Centre for Exoplanet Research” in the broad research context related to “Universal Life”. SPECULOOS is currently under construction at ESO’ Observatory of Cerro Paranal. SPECULOOS will survey 10 times more stars for planets, than TRAPPIST could do. We expect to detect dozens of additional terrestrial planets.

 

You can follow The Systems Scientist on Twitter or Facebook

Photo credit: European Southern Observatory

Donate to The Systems Scientist

Buy Now Button

 

 

 

 

This article was originally published by the University of Cambridge.

 

Introducing the terrifying mathematics of the Anthropocene

Here are some surprising facts about humans’ effect on planet Earth. We have made enough concrete to create an exact replica of Earth 2mm thick. We have produced enough plastic to wrap Earth in clingfilm. We are creating “technofossils”, a new term for congealed human-made materials – plastics and concretes – that will be around for tens of millions of years.

But it is the scale that humans have altered Earth’s life support system that is the most concerning.

In 2000, Nobel laureate Paul Crutzen and Eugene Stoermer proposed that human impact on the atmosphere, the oceans, the land and ice sheets had reached such a scale that it had pushed Earth into a new epoch. They called it the Anthropocene and argued the current Holocene epoch was over.

The Holocene began 11,700 years ago as we emerged from a deep ice age. Over the past 10,000 years, the defining feature of the Holocene has been a remarkably stable Earth system. This stability has allowed us to develop agriculture and hence villages, towns and eventually cities – human civilization.

We use pretty powerful rhetoric to describe the Anthropocene and current human impact. As The Economist stated in 2011, humanity has “become a force of nature reshaping the planet on a geological scale”. We are like an asteroid strike. We have the impact of an ice age.

But what does this really mean? Does it mean, for example, that we are having as big an impact as these natural forces are having right now, or is it, somehow, more profound?


Humans: the new asteroids.
Steve Jurvetson, CC BY

The maths of the Anthropocene

In our recent study, we wanted to find the simplest way to mathematically describe the Anthropocene and articulate the difference between how the planet once functioned and how it now functions.

Life on Earth, the chemical and physical composition of the atmosphere and oceans, and the size of the ice sheets have changed over time because of slight alterations to Earth’s orbit around the sun, changes to the sun’s energy output or major asteroid impacts like the one that killed the dinosaurs.

Cyanobacteria changed the world; now it’s our turn.
Matthew J Parker, CC BY-SA

They can also change due to geophysical forces: continents collide, cutting off ocean currents so heat is distributed in a new way, upsetting climate and biodiversity.

They also shift due to sheer internal dynamics of the system – new life evolves to drive great planetary shifts, such as the Great Oxidation Event around 2.5 billion years ago when newly evolved cyanobacteria began emitting the deadly poison oxygen that killed all simple life forms it came in touch with. Life had to evolve to tolerate oxygen.

Taking as our starting point a 1999 article by Earth system scientist Hans Joachim Schellnhuber, we can say the rate of change of the Earth system (E) has been driven by three things: astronomical forcings such as those from the sun or asteroids; geophysical forcing, for example changing currents; and internal dynamics, such as the evolution of cyanobacteria. Let’s call them A, G and I.

Mathematically, we can put it like this:

It reads: the rate of change of the Earth system (dE/dt) is a function of astronomical and geophysical forcings and internal dynamics. It is a very simple statement about the main drivers of the system.

This equation has been true for four billion years since the first life evolved. In his article, Schellnhuber argued that people must be added into this mix, but his theory came before the full impact of humanity had been assessed. In the past few decades, this equation has been radically altered.

We are losing biodiversity at rates tens to hundreds of times faster than natural rates. Indeed, we are approaching mass extinction rates. There have been five mass extinctions in the history of life on Earth. The last killed the non-avian dinosaurs 66 million years ago, now humans are causing the sixth.

The rate we are emitting carbon dioxide might be at an all-time high since that time too. Global temperatures are rising at a rate 170 times faster than the Holocene baseline. The global nitrogen cycle is undergoing its largest and most rapid change in possibly 2.5 billion years.

In fact, the rate of change of the Earth system under the human influence in the past four decades is so significant we can now show that the equation has become:

H stands for humanity. In the Anthropocene Equation, the rate of change of the Earth system is a function of humanity.

A, G and I are now approaching zero relative to the other big force – us – they have become essentially negligible. We are now the dominant influence on the stability and resilience of the planet we call home.

This is worth a little reflection. For four billion years, the Earth system changed under the influence of tremendous solar-system wide forces of nature. Now, this no longer holds.


IPCC, 2014: Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. IPCC, Geneva, Switzerland

A new reality

Heavenly bodies of course still exert some force; so does the ground beneath our feet. But the rates at which these forces operate are now negligible compared with the rate at which we are changing the Earth system. In the 1950s or 1960s, our own impact rivaled the great forces of nature. Now it usurps them entirely.

This should come as a shock not only to environmentalists but to everyone on Earth. But our conclusion is arguably a modest addition to the canon of academic literature. The scale and rate of change have already been well established by Earth system scientists over the past two decades.

Recently, Mark Williams and colleagues argued that the Anthropocene represents the third new era in Earth’s biosphere, and astrobiologist David Grinspoon argued that the Anthropocene marks one of the major events in a planet’s “life”, when self-aware cognitive processes become a key part of the way the planet functions.

Still, formalizing the Anthropocene mathematically brings home an entirely new reality.

The drama is heightened when we consider that for much of Earth’s history the planet has been either very hot – a greenhouse world – or very cold – an icehouse world. These appear to be the deeply stable states lasting millions of years and resistant to even quite major shoves from astronomical or geophysical forces.

But the past 2.5 million years have been uncharacteristically unstable, periodically flickering from cold to a gentle warmth.

The consumption vortex

So, who do we mean when we talk of H? Some will argue that we cannot treat humanity as one homogenous whole. We agree.

While all of humanity is now in the Anthropocene, we are not all in it in the same way. Industrialized societies are the reason we have arrived at this place, not Inuits in northern Canada or smallholder farmers in sub-Saharan Africa.

Scientific and technological innovations and economic policies promoting growth at all costs have created a consumption and production vortex on a collision course with the Earth system.

Others may say that natural forces are too important to ignore; for example, the El Niño weather system periodically changes patterns globally and causes Earth to warm for a year or so, and the tides generate more energy than all of humanity. But a warm El Niño is balanced by a cool La Niña. The tides and other great forces of nature are powerful but stable. Overall, they do not affect the rate of change of the Earth system.

Now, only a truly catastrophic volcanic eruption or direct asteroid hit could match us for impact.

So, can the Anthropocene equation be solved? The current rate of change must return to around zero as soon as possible. It cannot continue indefinitely. Either humanity puts on the brakes or it would seem unlikely a global civilization will continue to function on a destabilized planet. The choice is ours.

The Conversation

Owen Gaffney, Anthropocene analyst and communicator. Co-founder Future Earth Media Lab, Director of media (Stockholm Resilience Centre), Stockholm University and Will Steffen, Adjunct Professor, Fenner School of Environment and Society, Australian National University

Photo Credit: Maxpixel

You can follow The Systems Scientist on Twitter or Facebook.

Donate to The Systems Scientist

Buy Now Button

This article was originally published on The Conversation. Read the original article.