From MIT News and Kavli MIT Institute For Astrophysics and Space Research: “This is how a “fuzzy” universe may have looked”

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Kavli MIT Institute of Astrophysics and Space Research

Kavli MIT Institute For Astrophysics and Space Research

October 3, 2019
Jennifer Chu

1
A simulation of early galaxy formation under three dark matter scenarios. In a universe filled with cold dark matter, early galaxies would first form in bright halos (far left). If dark matter is instead warm, galaxies would form first in long, tail-like filaments (center). Fuzzy dark matter would produce similar filaments, though striated (far right), like the strings of a harp. Image courtesy of the researchers.

Scientists simulate early galaxy formation in a universe of dark matter that is ultralight, or “fuzzy,” rather than cold or warm.

Dark matter was likely the starting ingredient for brewing up the very first galaxies in the universe. Shortly after the Big Bang, particles of dark matter would have clumped together in gravitational “halos,” pulling surrounding gas into their cores, which over time cooled and condensed into the first galaxies.

Dark matter halo. Image credit: Virgo consortium / A. Amblard / ESA

Although dark matter is considered the backbone to the structure of the universe, scientists know very little about its nature, as the particles have so far evaded detection.

Now scientists at MIT, Princeton University, and Cambridge University have found that the early universe, and the very first galaxies, would have looked very different depending on the nature of dark matter. For the first time, the team has simulated what early galaxy formation would have looked like if dark matter were “fuzzy,” rather than cold or warm.

In the most widely accepted scenario, dark matter is cold, made up of slow-moving particles that, aside from gravitational effects, have no interaction with ordinary matter. Warm dark matter is thought to be a slightly lighter and faster version of cold dark matter. And fuzzy dark matter, a relatively new concept, is something entirely different, consisting of ultralight particles, each about 1 octillionth (10-27) the mass of an electron (a cold dark matter particle is far heavier — about 105 times more massive than an electron).

In their simulations, the researchers found that if dark matter is cold, then galaxies in the early universe would have formed in nearly spherical halos. But if the nature of dark matter is fuzzy or warm, the early universe would have looked very different, with galaxies forming first in extended, tail-like filaments. In a fuzzy universe, these filaments would have appeared striated, like star-lit strings on a harp.

As new telescopes come online, with the ability to see further back into the early universe, scientists may be able to deduce, from the pattern of galaxy formation, whether the nature of dark matter, which today makes up nearly 85 percent of the matter in the universe, is fuzzy as opposed to cold or warm.

“The first galaxies in the early universe may illuminate what type of dark matter we have today,” says Mark Vogelsberger, associate professor of physics in MIT’s Kavli Institute for Astrophysics and Space Research. “Either we see this filament pattern, and fuzzy dark matter is plausible, or we don’t, and we can rule that model out. We now have a blueprint for how to do this.”

Vogelsberger is a co-author of a paper appearing today in Physical Review Letters, along with the paper’s lead author, Philip Mocz of Princeton University, and Anastasia Fialkov of Cambridge University and previously the University of Sussex.

Fuzzy waves

While dark matter has yet to be directly detected, the hypothesis that describes dark matter as cold has proven successful at describing the large-scale structure of the observable universe. As a result, models of galaxy formation are based on the assumption that dark matter is cold.

Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex Mittelmann Cold creation

“The problem is, there are some discrepancies between observations and predictions of cold dark matter,” Vogelsberger points out. “For example, if you look at very small galaxies, the inferred distribution of dark matter within these galaxies doesn’t perfectly agree with what theoretical models predict. So there is tension there.”

Enter, then, alternative theories for dark matter, including warm, and fuzzy, which researchers have proposed in recent years.

“The nature of dark matter is still a mystery,” Fialkov says. “Fuzzy dark matter is motivated by fundamental physics, for instance, string theory, and thus is an interesting dark matter candidate. Cosmic structures hold the key to validating or ruling out such dark matter modles.”

Fuzzy dark matter is made up of particles that are so light that they act in a quantum, wave-like fashion, rather than as individual particles. This quantum, fuzzy nature, Mocz says, could have produced early galaxies that look entirely different from what standard models predict for cold dark matter.

“Even though in the late universe these different dark matter scenarios may predict similar shapes for galaxies, the first galaxies would be strikingly different, which will give us a clue about what dark matter is,” Mocz says.

To see how different a cold and a fuzzy early universe could be, the researchers simulated a small, cubic space of the early universe, measuring about 3 million light years across, and ran it forward in time to see how galaxies would form given one of the three dark matter scenarios: cold, warm, and fuzzy.

The team began each simulation by assuming a certain distribution of dark matter, which scientists have some idea of, based on measurements of the cosmic microwave background — “relic radiation” that was emitted by, and was detected just 400,000 years after, the Big Bang.

“Dark matter doesn’t have a constant density, even at these early times,” Vogelsberger says. “There are tiny perturbations on top of a constant density field.”

The researchers were able to use existing algorithms to simulate galaxy formation under scenarios of cold and warm dark matter. But to simulate fuzzy dark matter, with its quantum nature, they needed a new approach.

A map of harp strings

The researchers modified their simulation of cold dark matter, enabling it to solve two extra equations in order to simulate galaxy formation in a fuzzy dark matter universe. The first, Schrödinger’s equation, describes how a quantum particle acts as a wave, while the second, Poisson’s equation, describes how that wave generates a density field, or distribution of dark matter, and how that distribution leads to gravity — the force that eventually pulls in matter to form galaxies. They then coupled this simulation to a model that describes the behavior of gas in the universe, and the way it condenses into galaxies in response to gravitational effects.

In all three scenarios, galaxies formed wherever there were over-densities, or large concentrations of gravitationally collapsed dark matter. The pattern of this dark matter, however, was different, depending on whether it was cold, warm, or fuzzy.

In a scenario of cold dark matter, galaxies formed in spherical halos, as well as smaller subhalos. Warm dark matter produced first galaxies in tail-like filaments, and no subhalos. This may be due to warm dark matter’s lighter, faster nature, making particles less likely to stick around in smaller, subhalo clumps.

Similar to warm dark matter, fuzzy dark matter formed stars along filaments. But then quantum wave effects took over in shaping the galaxies, which formed more striated filaments, like strings on an invisible harp. Vogelsberger says this striated pattern is due to interference, an effect that occurs when two waves overlap. When this occurs, for instance in waves of light, the points where the crests and troughs of each wave align form darker spots, creating an alternating pattern of bright and dark regions.

In the case of fuzzy dark matter, instead of bright and dark points, it generates an alternating pattern of over-dense and under-dense concentrations of dark matter.

“You would get a lot of gravitational pull at these over-densities, and the gas would follow, and at some point would form galaxies along those over-densities, and not the under-densities,” Vogelsberger explains. “This picture would be replicated throughout the early universe.”

The team is developing more detailed predictions of what early galaxies may have looked like in a universe dominated by fuzzy dark matter. Their goal is to provide a map for upcoming telescopes, such as the James Webb Space Telescope, that may be able to look far enough back in time to spot the earliest galaxies. If they see filamentary galaxies such as those simulated by Mocz, Fialkov, Vogelsberger, and their colleagues, it could be the first signs that dark matter’s nature is fuzzy.

“It’s this observational test we can provide for the nature of dark matter, based on observations of the early universe, which will become feasible in the next couple of years,” Vogelsberger says.

This research was supported, in part, by NASA.

See the full article here .


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Mission Statement

The mission of the MIT Kavli Institute (MKI) for Astrophysics and Space Research is to facilitate and carry out the research programs of faculty and research staff whose interests lie in the broadly defined area of astrophysics and space research. Specifically, the MKI will

Provide an intellectual home for faculty, research staff, and students engaged in space- and ground-based astrophysics
Develop and operate space- and ground-based instrumentation for astrophysics
Engage in technology development
Maintain an engineering and technical core capability for enabling and supporting innovative research
Communicate to students, educators, and the public an understanding of and an appreciation for the goals, techniques and results of MKI’s research.

The Kavli Foundation, based in Oxnard, California, is dedicated to the goals of advancing science for the benefit of humanity and promoting increased public understanding and support for scientists and their work.

The Foundation’s mission is implemented through an international program of research institutes, professorships, and symposia in the fields of astrophysics, nanoscience, neuroscience, and theoretical physics as well as prizes in the fields of astrophysics, nanoscience, and neuroscience.

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The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

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From MIT News: Women in STEM “3 Questions: Lisa Barsotti on the new and improved LIGO”

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From MIT News

April 1, 2019
Jennifer Chu

1
LIGO laboratory detection site near Hanford in eastern Washington. Image: Caltech/MIT/LIGO Laboratory

“If we are very lucky, we might observe something new … or maybe even something totally unexpected.”

The search for infinitely faint ripples in space-time is back in full swing. Today, LIGO, the Laser Interferometer Gravitational-wave Observatory, operated jointly by Caltech and MIT, resumes its hunt for gravitational waves and the immense cosmic phenomena from which they emanate.

Over the past several months, LIGO’s twin detectors, in Washington and Lousiana, have been offline, undergoing upgrades to their lasers, mirrors, and other components, which will enable the detectors to listen for gravitational waves over a far greater range, out to about 550 million light-years away — around 190 million light-years farther out than before.

As the LIGO detectors turn back on, they will be joined by Virgo, the European-based counterpart based in Italy, which also turns on today after undergoing upgrades that doubled its sensitivity. With both LIGO and Virgo back online, scientists anticipate that detections of gravitational waves from the farthest reaches of the universe may be a regular occurrence.

MIT News spoke with LIGO member Lisa Barsotti, principal research scientist at MIT’s Kavli Institute for Astrophysics and Space Research, about the potential discoveries that lie ahead.

Kavli MIT Institute For Astrophysics and Space Research

Q: Give us a sense of the new capabilities that the LIGO detectors now have. What sort of upgrades were made?

A: Both LIGO detectors are coming back online more sensitive than ever before, thanks to a wide range of improvements. In particular, we more than doubled the laser power in the interferometers to reduce one of the LIGO fundamental noise sources — quantum “shot noise,” caused by the uncertainty of the arrival time of photons onto the main photodetector. We also deployed a new technology, “squeezed” light, that uses quantum optics to further reduce shot noise.

Combined with other upgrades to mitigate technical noises (for example noises introduced by the control scheme or from stray light) we improved the sensitivity to binary neutron stars by 40 percent in each detector, with respect to the past observing run.

Q: What do these new capabilities mean for you, as a researcher who will be looking through the data from these upgraded detectors?

A: I am personally very excited to see the LIGO detectors operating with squeezed light! This new technology has been developed here at MIT after many years of research to make it compatible with the very stringent LIGO requirements, and our graduate students have been leading the commissioning of this new system at the observatories. It is particularly rewarding to see that we succeeded in making LIGO better.

Also, operation at high laser power has been enabled by another upgrade developed and built here at MIT — an “acoustic mode damper” glued to the main LIGO optics that mitigates instabilities originating with high laser power. We are looking forward to seeing many years of work in our labs pay off in this observing run!

Q: What new phenomena are you hoping to detect, and how soon could you detect them, with these new capabilities?

A: We hope to detect more binary neutron star systems (so far only one has been detected), and thanks to the improved LIGO sensitivity, we should be able to observe them with high signal-to-noise ratio. And more black holes, obviously! The more sources we detect, the more we can learn about the way these systems form and evolve.

If we are very lucky, we might observe something new, like a neutron star-black hole system, or maybe even something totally unexpected. Not only are the LIGO detectors better than before — the Virgo detector in Italy more than doubled its sensitivity with respect to the last observing run, and this will improve our ability to localize sources in the sky, facilitating the follow-up of telescopes at multiple wavelengths.

VIRGO Gravitational Wave interferometer, near Pisa, Italy

So, if the last observing run, “O2,” will be remembered as the one that started multimessenger astronomy, I hope the upcoming one, “O3,” will be the one in which multimessenger astronomy becomes the new normal!

See the full article here .


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The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

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From Kavli MIT Institute For Astrophysics and Space Research: “NASA’s TESS Spacecraft Starts Science Operations”

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Kavli MIT Institute of Astrophysics and Space Research

From Kavli MIT Institute For Astrophysics and Space Research

July 27, 2018

NASA/MIT TESS

NASA’s Transiting Exoplanet Survey Satellite has started its search for planets around nearby stars, officially beginning science operations on July 25, 2018. TESS is expected to transmit its first series of science data back to Earth in August, and thereafter periodically every 13.5 days, once per orbit, as the spacecraft makes it closest approach to Earth. The TESS Science Team will begin searching the data for new planets immediately after the first series arrives.

“I’m thrilled that our planet hunter is ready to start combing the backyard of our solar system for new worlds,” said Paul Hertz, NASA Astrophysics division director at Headquarters, Washington. “With possibly more planets than stars in our universe, I look forward to the strange, fantastic worlds we’re bound to discover.”

TESS is NASA’s latest satellite to search for planets outside our solar system, known as exoplanets. The mission will spend the next two years monitoring the nearest and brightest stars for periodic dips in their light. These events, called transits, suggest that a planet may be passing in front of its star. TESS is expected to find thousands of planets using this method, some of which could potentially support life.

TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Dr. George Ricker of MIT’s Kavli Institute for Astrophysics and Space Research serves as principal investigator for the mission. Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASA’s Ames Research Center in California’s Silicon Valley; the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts; MIT’s Lincoln Laboratory in Lexington, Massachusetts; and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes and observatories worldwide are participants in the mission.
For the latest updates on TESS, visit nasa.gov/tess and tess.mit.edu

See the full article here .


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Please help promote STEM in your local schools.

Stem Education Coalition

Mission Statement

The mission of the MIT Kavli Institute (MKI) for Astrophysics and Space Research is to facilitate and carry out the research programs of faculty and research staff whose interests lie in the broadly defined area of astrophysics and space research. Specifically, the MKI will

Provide an intellectual home for faculty, research staff, and students engaged in space- and ground-based astrophysics
Develop and operate space- and ground-based instrumentation for astrophysics
Engage in technology development
Maintain an engineering and technical core capability for enabling and supporting innovative research
Communicate to students, educators, and the public an understanding of and an appreciation for the goals, techniques and results of MKI’s research.

The Kavli Foundation, based in Oxnard, California, is dedicated to the goals of advancing science for the benefit of humanity and promoting increased public understanding and support for scientists and their work.

The Foundation’s mission is implemented through an international program of research institutes, professorships, and symposia in the fields of astrophysics, nanoscience, neuroscience, and theoretical physics as well as prizes in the fields of astrophysics, nanoscience, and neuroscience.

#astronomy, #astrophysics, #basic-research, #cosmology, #kavli-mit-institute-for-astrophysics-and-space-research, #nasa-mit-tess, #nasas-tess-spacecraft-starts-science-operations

From Kavli MIT Institute For Astrophysics and Space Research: “Could gravitational waves reveal how fast our universe is expanding?”

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http://www.kavlifoundation.org/institutes

Kavli MIT Institute of Astrophysics and Space Research

From Kavli MIT Institute For Astrophysics and Space Research

Signals from rare black hole-neutron star pairs could pinpoint rate at which universe is growing, researchers say.

July 11, 2018
Jennifer Chu

Since it first exploded into existence 13.8 billion years ago, the universe has been expanding, dragging along with it hundreds of billions of galaxies and stars, much like raisins in a rapidly rising dough.

Astronomers have pointed telescopes to certain stars and other cosmic sources to measure their distance from Earth and how fast they are moving away from us — two parameters that are essential to estimating the Hubble constant, a unit of measurement that describes the rate at which the universe is expanding.

But to date, the most precise efforts have landed on very different values of the Hubble constant, offering no definitive resolution to exactly how fast the universe is growing. This information, scientists believe, could shed light on the universe’s origins, as well as its fate, and whether the cosmos will expand indefinitely or ultimately collapse.

Now scientists from MIT and Harvard University have proposed a more accurate and independent way to measure the Hubble constant, using gravitational waves emitted by a relatively rare system: a black hole-neutron star binary, a hugely energetic pairing of a spiraling black hole and a neutron star. As these objects circle in toward each other, they should produce space-shaking gravitational waves and a flash of light when they ultimately collide.

In a paper to be published July 12th in Physical Review Letters, the researchers report that the flash of light would give scientists an estimate of the system’s velocity, or how fast it is moving away from the Earth. The emitted gravitational waves, if detected on Earth, should provide an independent and precise measurement of the system’s distance. Even though black hole-neutron star binaries are incredibly rare, the researchers calculate that detecting even a few should yield the most accurate value yet for the Hubble constant and the rate of the expanding universe.

“Black hole-neutron star binaries are very complicated systems, which we know very little about,” says Salvatore Vitale, assistant professor of physics at MIT and lead author of the paper. “If we detect one, the prize is that they can potentially give a dramatic contribution to our understanding of the universe.”

Vitale’s co-author is Hsin-Yu Chen of Harvard.

Competing constants

Two independent measurements of the Hubble constant were made recently, one using NASA’s Hubble Space Telescope and another using the European Space Agency’s Planck satellite.

NASA/ESA Hubble Telescope

ESA/Planck 2009 to 2013

The Hubble Space Telescope’s measurement is based on observations of a type of star known as a Cepheid variable, as well as on observations of supernovae. Both of these objects are considered “standard candles,” for their predictable pattern of brightness, which scientists can use to estimate the star’s distance and velocity.

The other type of estimate is based on observations of the fluctuations in the cosmic microwave background [CMB] — the electromagnetic radiation that was left over in the immediate aftermath of the Big Bang, when the universe was still in its infancy. While the observations by both probes are extremely precise, their estimates of the Hubble constant disagree significantly.

CMB per ESA/Planck

“That’s where LIGO comes into the game,” Vitale says.

LIGO, or the Laser Interferometry Gravitational-Wave Observatory, detects gravitational waves — ripples in the Jell-O of space-time, produced by cataclysmic astrophysical phenomena.


Caltech/MIT Advanced aLigo Hanford, WA, USA installation


Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project


Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

ESA/eLISA the future of gravitational wave research

“Gravitational waves provide a very direct and easy way of measuring the distances of their sources,” Vitale says. “What we detect with LIGO is a direct imprint of the distance to the source, without any extra analysis.”

In 2017, scientists got their first chance at estimating the Hubble constant from a gravitational-wave source, when LIGO and its Italian counterpart Virgo detected a pair of colliding neutron stars for the first time. The collision released a huge amount of gravitational waves, which researchers measured to determine the distance of the system from Earth. The merger also released a flash of light, which astronomers focused on with ground and space telescopes to determine the system’s velocity.

With both measurements, scientists calculated a new value for the Hubble constant. However, the estimate came with a relatively large uncertainty of 14 percent, much more uncertain than the values calculated using the Hubble Space Telescope and the Planck satellite.

Vitale says much of the uncertainty stems from the fact that it can be challenging to interpret a neutron star binary’s distance from Earth using the gravitational waves that this particular system gives off.

“We measure distance by looking at how ‘loud’ the gravitational wave is, meaning how clear it is in our data,” Vitale says. “If it’s very clear, you can see how loud it is, and that gives the distance. But that’s only partially true for neutron star binaries.”

That’s because these systems, which create a whirling disc of energy as two neutron stars spiral in toward each other, emit gravitational waves in an uneven fashion. The majority of gravitational waves shoot straight out from the center of the disc, while a much smaller fraction escapes out the edges. If scientists detect a “loud” gravitational wave signal, it could indicate one of two scenarios: the detected waves stemmed from the edge of a system that is very close to Earth, or the waves emanated from the center of a much further system.

“With neutron star binaries, it’s very hard to distinguish between these two situations,” Vitale says.

A new wave

In 2014, before LIGO made the first detection of gravitational waves, Vitale and his colleagues observed that a binary system composed of a black hole and a neutron star could give a more accurate distance measurement, compared with neutron star binaries. The team was investigating how accurately one could measure a black hole’s spin, given that the objects are known to spin on their axes, similarly to Earth but much more quickly.

The researchers simulated a variety of systems with black holes, including black hole-neutron star binaries and neutron star binaries. As a byproduct of this effort, the team noticed that they were able to more accurately determine the distance of black hole-neutron star binaries, compared to neutron star binaries. Vitale says this is due to the spin of the black hole around the neutron star, which can help scientists better pinpoint from where in the system the gravitational waves are emanating.

“Because of this better distance measurement, I thought that black hole-neutron star binaries could be a competitive probe for measuring the Hubble constant,” Vitale says. “Since then, a lot has happened with LIGO and the discovery of gravitational waves, and all this was put on the back burner.”

Vitale recently circled back to his original observation, and in this new paper, he set out to answer a theoretical question:

“Is the fact that every black hole-neutron star binary will give me a better distance going to compensate for the fact that potentially, there are far fewer of them in the universe than neutron star binaries?” Vitale says.

To answer this question, the team ran simulations to predict the occurrence of both types of binary systems in the universe, as well as the accuracy of their distance measurements. From their calculations, they concluded that, even if neutron binary systems outnumbered black hole-neutron star systems by 50-1, the latter would yield a Hubble constant similar in accuracy to the former.

More optimistically, if black hole-neutron star binaries were slightly more common, but still rarer than neutron star binaries, the former would produce a Hubble constant that is four times as accurate.

“So far, people have focused on binary neutron stars as a way of measuring the Hubble constant with gravitational waves,” Vitale says. “We’ve shown there is another type of gravitational wave source which so far has not been exploited as much: black holes and neutron stars spiraling together,” Vitale says. “LIGO will start taking data again in January 2019, and it will be much more sensitive, meaning we’ll be able to see objects farther away. So LIGO should see at least one black hole-neutron star binary, and as many as 25, which will help resolve the existing tension in the measurement of the Hubble constant, hopefully in the next few years.”

This research was supported, in part, by the National Science Foundation and the LIGO Laboratory.

See the full article here .


five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

Mission Statement

The mission of the MIT Kavli Institute (MKI) for Astrophysics and Space Research is to facilitate and carry out the research programs of faculty and research staff whose interests lie in the broadly defined area of astrophysics and space research. Specifically, the MKI will

Provide an intellectual home for faculty, research staff, and students engaged in space- and ground-based astrophysics
Develop and operate space- and ground-based instrumentation for astrophysics
Engage in technology development
Maintain an engineering and technical core capability for enabling and supporting innovative research
Communicate to students, educators, and the public an understanding of and an appreciation for the goals, techniques and results of MKI’s research.

The Kavli Foundation, based in Oxnard, California, is dedicated to the goals of advancing science for the benefit of humanity and promoting increased public understanding and support for scientists and their work.

The Foundation’s mission is implemented through an international program of research institutes, professorships, and symposia in the fields of astrophysics, nanoscience, neuroscience, and theoretical physics as well as prizes in the fields of astrophysics, nanoscience, and neuroscience.

#astronomy, #astrophysics, #basic-research, #cosmology, #hubble-constant, #kavli-mit-institute-for-astrophysics-and-space-research, #using-gravitational-waves-emitted-by-a-relatively-rare-system-a-black-hole-neutron-star-binary-to-measure-how-fast-our-universe-is-expanding

From Kavli MIT Institute For Astrophysics and Space Research: “To Seek Out New Life: How the TESS Mission Will Accelerate the Hunt for Livable Alien Worlds”

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http://www.kavlifoundation.org/institutes

Kavli MIT Institute of Astrophysics and Space Research

From Kavli MIT Institute For Astrophysics and Space Research

May 17, 2018

Adam Hadhazy
Spring 2018

The just-launched Transiting Exoplanet Survey Satellite (TESS) could soon provide the breakthrough
identification of dozens of potentially habitable exoplanets right in our cosmic backyard.

NASA/TESS

A NEW ERA IN THE SEARCH FOR EXOPLANETS—and the alien life they might host—has begun. Aboard a SpaceX rocket, the Transiting Exoplanet Survey Satellite (TESS) launched on April 18, 2018, at 6:51 PM EDT. The TESS mission, developed with support from The Kavli Foundation, is led by the Massachusetts Institute of Technology (MIT) and the MIT Kavli Institute for Astrophysics and Space Research.

Over the next two years, TESS will scan the 200,000 or so nearest and brightest stars to Earth for telltale dimming caused when exoplanets cross their stars’ faces. Among the thousands of new worlds TESS is expected to discover should be hundreds ranging in size from about one to two times Earth. These small, mostly rocky planets will serve as prime targets for detailed follow-up observations by other telescopes in space and on the ground.

The goal for those telescopes will be to characterize the newfound exoplanets’ atmospheres. The particular mixtures of gases in an atmosphere will reveal key clues about a world’s climate, history, and if it might even be hospitable to life.

The Kavli Foundation spoke with two scientists on the TESS mission to get an inside look at its development and revolutionary science aim of finding the first “Earth twin” in the universe.

The participants were:

GREG BERTHIAUME – is the Instrument Manager for the TESS mission, in charge of ensuring the spacecraft’s cameras and other equipment will perform their science tasks. Berthiaume is based at the Massachusetts Institute of Technology’s (MIT) Lincoln Laboratory and he is also a member of the MIT Kavli Institute for Astrophysics and Space Research.

DIANA DRAGOMIR – is an observational astronomer whose focus is on small exoplanets. Dragomir is a Hubble Postdoctoral Fellow at the MIT Kavli Institute for Astrophysics and Space Research.

The following is an edited transcript of their roundtable discussion. The participants have been provided the opportunity to amend or edit their remarks.

THE KAVLI FOUNDATION: Starting with the big picture, why is TESS important?

DIANA DRAGOMIR: TESS is going to find thousands of exoplanets, which might not sound like a big deal, because we already know of nearly 4,000. But most of those discovered planets are too far away for us to do anything more than just know their size and that they are there. The difference is that TESS will be looking for planets around stars very close to us. When stars are closer to us, they’re also brighter from our point of view, and that helps us discover and study the planets around them much more easily.

GREG BERTHIAUME: One of the things TESS is doing is helping to answer the fundamental question, “Is there other life in the universe?” People have been wondering that for thousands of years. Now TESS won’t answer that question directly, but it’s a step, just like Diana mentioned, on the path to getting us the data to see where there might be other life out there. That’s something we’ve been struggling with and questioning since we were able to come up with questions.

TKF: What exactly do you expect TESS to find?

Diana DragomirDiana Dragomir is an observational astronomer whose research focus is on small exoplanets. She is a Hubble Postdoctoral Fellow at the MIT Kavli Institute for Astrophysics and Space Research.

DRAGOMIR: TESS will probably find 100 to 200 approximately Earth-size worlds, as well as thousands of more exoplanets all the way up to Jupiter in size.

BERTHIAUME: We’re trying to find planets that are Earth analogs, meaning they’ll be Earth-like in their characteristics, such as size, mass, and so on. That means we want to find planets with atmospheres, with gravity similar to Earth’s. We want to find planets that are cool enough so water can be liquid on their surfaces, and not so cold that the water is frozen all the time. We call these “Goldilocks” planets, located in a star’s “habitable zone.” That’s really our target.

DRAGOMIR: Exactly right. We want to find the first “Earth twin.” TESS will mainly find planets in the habitable zone of red dwarfs. These are stars a bit smaller and cooler than the Sun. A planet around a red dwarf can be located in an orbit closer to its star than it could be with a hotter star like our Sun and still maintain that nice, Goldilocks temperature. Closer orbits translate to more transits, or star crossings, which makes these red dwarf planets easier to find and study than planets around Sun-like stars.

Astronomers are working hard on ways that we might push the TESS data and find some planets in the habitable zone of Sun-like stars, too. It’s challenging because those planets have longer orbital periods—years, that is—than close-in planets. That means we need a lot more observation time in order to detect enough transits of the planets across their stars to say we’ve definitely detected a planet. But we’re hopeful, so stay tuned!

TKF: What do you need to see in order to deem any of the planets discovered by TESS as potentially habitable?

DRAGOMIR: We want a planet to be close to Earth in size for all the reasons we just gave, but there’s a small problem with that. Those sorts of planets will probably have pretty small atmospheres, compared to how much rock makes up their bulk. And for most telescopes to be able to look at an atmosphere in detail, we actually need the planet to have a substantial atmosphere.

This is because of a technique we use called transmission spectroscopy. It gathers the light from the star that has gone through the atmosphere of the planet when the planet is crossing the star. That light comes to us with a spectrum of the planet’s atmosphere imprinted on it, which we can analyze to identify the composition of the atmosphere. The more atmosphere there is, the more material there is that can imprint on the spectrum, giving us a bigger signal.

If the light from the star is going through very little atmosphere, though, like we’d be looking at with an Earth twin, the signal would be very small. Based on what TESS finds, we’re therefore going to be starting with bigger planets that have a lot of atmosphere, and as we get better instruments, we’re going to move towards smaller and smaller planets with less atmosphere. It’s those latter planets which will more likely be habitable.

BERTHIAUME: What we’re going to look for in the atmosphere are things like water vapor, oxygen, carbon dioxide—the standard gases we see in our atmosphere that life needs and life produces. We’re also going to try and measure the nasty things that aren’t compatible with life as we know it on Earth. For instance, it would be a bad thing for biology if there were too much ammonia in a world’s atmosphere. Hydrocarbons, like methane, would also be problematic in too high an abundance.

TKF: Diana, your specialty is exoplanets smaller than Neptune—a planet four times bigger than Earth. What is our general knowledge about those kinds of worlds and how will TESS help with your research?

DRAGOMIR: One thing we know about these planets is that they are extremely common compared to planets larger than Neptune. So that’s good. We therefore expect TESS to find lots and lots of planets smaller than Neptune for us to look at.

Although small is bad for getting those atmospheric imprints we just talked about, if the stars are nearby and bright, we might still be able to get enough light for doing good studies. I’m hoping that we’ll get enough below Neptune-size that we’ll start looking at the atmospheres of “super-Earths,” which are planets twice the size of Earth or so. We don’t have any super-Earths in our solar system, so we’d love to get a closer look at one of these kinds of worlds. And just maybe, if we find a really, really good planetary candidate, we may be able to start looking at the atmosphere of an Earth-sized planet.

With my research, one more thing TESS could really help with is figuring out the boundary between a very gassy planet like Neptune and a very rocky planet like Earth. We believe it’s mostly a matter of mass; have too much mass, and the planet stars to hold into a thick atmosphere. Right now, we’re not sure where that threshold is. And that matters so we know when a planet is rocky and potentially habitable, or gassy and not habitable.

TKF: Greg, as the TESS Instrument Manager, a lot rides on your shoulders for the mission’s success. Can you tell us a bit about your job?

BERTHIAUME: My job as instrument manager is different from a science job, for sure. My job was to make sure that all of the pieces, all the parts that go into the four flight cameras and the image processing hardware all play and work together and give us the great data that we need for Diana to go and continue to explore exoplanets. My personal role on the mission actually ends shortly after launch. Once we’ve demonstrated that the satellite provides the data that we expect, and we deal with any surprises that may come up, then I move on and data goes off to the science community.

I definitely feel responsible for getting the quality of the data as high as it possibly can be. A lot of people worked really hard for years to build the cameras that are flying on TESS and it’s been great to be part of that team.

TKF: New exoplanet missions like the European Space Agency’s Ariel and Plato satellites are slated to begin in the late 2020s. How might these future spacecraft complement and build on TESS’ body of work?

DRAGOMIR: The great thing about TESS is that it’s going to give us a lot to choose from in terms of the best options for planets we’ll want to study. In that way, TESS will set the stage for Ariel’s mission, which is to deeply study the atmospheres of a select group of exoplanets.

The Plato mission will be looking for planets that are habitable, but around bigger stars like the Sun, whereas TESS will focus on looking for habitable planets around smaller stars. I’m happy with that because I don’t want us to put all of our eggs in one basket by only looking at red dwarf stars with TESS. Planets around these red dwarfs are very exciting right now because they’re easier to study and they transit their stars more often, making them easier to find. But at the same time, red dwarfs tend to be much more active than the Sun. When a star is active, that means it often expels bursts of radiation called flares. These flares could be very damaging to a planet’s atmosphere and make the world uninhabitable.

In the end, we of course live around a Sun-like star, and so far, we are the only “we” we know of in the universe. So for those reasons, it’s great to have Plato complementarily come along and find those planets around suns that TESS will probably not be able to find.

TKF: When do you expect TESS’ first discoveries of brand new worlds to be reported?

BERTHIAUME: First, it’s going to take a while to get TESS into its unique orbit. It’s the first time we’re putting a spacecraft in a new kind of far-ranging, highly elliptical orbit, where the gravity from the Earth and the Moon will keep TESS very stable, both from an orbit perspective and from a thermal perspective. So a big part of what’s going to happen over the first six weeks is just achieving that final orbit.

Then there’s a period of time where there’ll be data collected to make sure the instruments are working as expected, as well as getting our data processing pipeline tuned up. I think we’ll start to see interesting results come out sometime this summer.

TKF: Besides new worlds, what else might TESS reveal about the universe?

2
A set of flight camera electronics on one of the TESS cameras, developed by the MIT Kavli Institute for Astrophysics and Space Research (MKI). (Image: MIT Kavli Institute)

DRAGOMIR: Because TESS is observing so much of the sky, it’s going to see lots of things that are happening in real-time, not just exoplanets crossing stars. As for those stars, we can learn a lot about their properties and even measure their masses quite precisely by doing asteroseismology with TESS. This technique involves tracking brightness changes as sound waves move through the interiors of stars—just like how seismic waves pass through the Earth’s rock and molten insides during earthquakes.

We’ll also be studying the flaring activity of the stars, which as we spoke about earlier might make close-in, temperate planets around red dwarf stars uninhabitable.

Moving up in size, scientists will want to search the TESS data for evidence of small black holes. These extreme objects, formed when colossal stars explode, can orbit normal stars that are still “alive,” so to speak. These systems will help us better understand how those black holes form and how they interact with companion stars.

And then finally, going even bigger, TESS will look at galaxies called quasars. These ultra-bright galaxies are powered by supermassive black holes in their cores. TESS will help us monitor how quasars’ brightness changes, which we can link back to the dynamics of their black holes.

TKF: The James Webb Space Telescope, hailed as the successor to the Hubble Space Telescope, has long been talked about as a primary instrument for doing the detailed follow-up observations on promising exoplanets found by TESS. However, James Webb’s launch, already delayed multiple times, just got pushed out yet another year, to 2020. How will the ongoing James Webb delays affect the TESS mission?

DRAGOMIR: The James Webb delay is not so much of a problem because it actually gives us more time to collect great target planets with TESS. Before we can use James Webb to really observe candidate exoplanets and study their atmospheres, we first need to confirm the planets are real—that what we think are planets are not false positives caused, for instance, by stellar activity. That confirmation process takes weeks, using support observations from ground-based telescopes. It will then also take weeks to months to obtain the mass of the planets. We measure that by registering how much planets cause their host stars to experience slight “wobbles” in their motion over time, owing to the planets’ gravities, which are determined by their mass.

Once you have that mass, plus the size of an exoplanet based on how much starlight it blocks during a TESS detection, you can measure its density and determine if it’s rocky or gaseous. With this information, it is then easier to decide which planets we want to prioritize, and the more we can make sense out of what James Webb will tell us about their atmospheres.

TKF: Spacecraft sometimes have humorous or even profound extra elements built into them. One example: the “Golden Records” on the twin Voyager spacecraft, which contain images and sounds of life and civilization on Earth, including the Taj Mahal and birdsong. Are there any such items included on TESS? Any subtle maker’s marks or messages?

BERTHIAUME: One of the things that’s flying along with TESS is a metal plaque that has the signatures of many of the people who worked on developing and building the spacecraft. That was an exciting thing for us.

DRAGOMIR: That’s cool. I didn’t know that!

BERTHIAUME: Also, NASA ran an international contest inviting people from around the world to submit drawings of what they thought exoplanets might look like. I know many children participated. All of those drawings were scanned onto a thumb drive and they’re flying along with TESS. The spacecraft’s orbit is stable for a century at least, so the plaque and the drawings will be in space for a long time!

See the full article here .

Please help promote STEM in your local schools.

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Stem Education Coalition

Mission Statement

The mission of the MIT Kavli Institute (MKI) for Astrophysics and Space Research is to facilitate and carry out the research programs of faculty and research staff whose interests lie in the broadly defined area of astrophysics and space research. Specifically, the MKI will

Provide an intellectual home for faculty, research staff, and students engaged in space- and ground-based astrophysics
Develop and operate space- and ground-based instrumentation for astrophysics
Engage in technology development
Maintain an engineering and technical core capability for enabling and supporting innovative research
Communicate to students, educators, and the public an understanding of and an appreciation for the goals, techniques and results of MKI’s research.

The Kavli Foundation, based in Oxnard, California, is dedicated to the goals of advancing science for the benefit of humanity and promoting increased public understanding and support for scientists and their work.

The Foundation’s mission is implemented through an international program of research institutes, professorships, and symposia in the fields of astrophysics, nanoscience, neuroscience, and theoretical physics as well as prizes in the fields of astrophysics, nanoscience, and neuroscience.

#astronomy, #astrophysics, #basic-research, #cosmology, #kavli-mit-institute-for-astrophysics-and-space-research, #nasa-tess, #the-future-for-tess-an-interview

From Kavli MIT Institute For Astrophysics and Space Research: Women in STEM -“Planets Aplenty with the TESS Mission: An Interview with the Director of the Kavli Institute for Astrophysics and Space Research

KavliFoundation

http://www.kavlifoundation.org/institutes

Kavli MIT Institute of Astrophysics and Space Research

Kavli MIT Institute For Astrophysics and Space Research

Adam Hadhazy, Spring 2018

Jacqueline Hewitt discusses how the TESS exoplanet mission has already changed the institute she directs and will bring about further evolution in the years to come.

Jacqueline Hewitt is the Director of the MIT Kavli Institute (MKI), a lead institution behind the TESS mission.(Credit: MKI)

The Transiting Exoplanet Survey Satellite (TESS) has begun its mission to discover thousands of new exoplanets right in our cosmic background.

NASA/TESS

The lead organization behind TESS is the Massachusetts Institute of Technology, where members of its Kavli Institute for Astrophysics and Space Research (MKI) spearheaded the mission’s development and are serving in prominent science roles today.

Nurturing TESS from an idea to the drawing board, and then from the fabrication lab into the final frontier has churned up a whirlwind of activity at MKI for a decade. The director of MKI, Jacqueline Hewitt, has been there for all of it. She pushed to get TESS approved by NASA, oversaw its instrument development, and will also oversee its science operations over the next two years in the hunt for Earth-like planets that could conceivably host alien life.

For a perspective on the impact TESS has already had and will have on MKI, The Kavli Foundation spoke with Hewitt shortly after TESS’ launched on April 18, 2018. In this candid conversation, Hewitt describes the successes and challenges in making TESS a reality, as well as the excitement she and her colleagues feel serving in the vanguard of advancing our understanding of the broader universe.

The following is an edited transcript of the discussion. The participant has been provided the opportunity to amend or edit her remarks.

___________________________________________________________

THE KAVLI FOUNDATION: How did the idea for TESS first emerge at MIT?

JACQUELINE HEWITT: It was 12 years ago and the field of exoplanets was still in its relative infancy. We did not know yet if exoplanets were these rare things or quite common in the galaxy. Astronomers were talking about the measurements we needed in order to find more planets and to study them. It’s a really difficult problem because exoplanets are, of course, so far away and so tiny and faint from a cosmic perspective.

Back then, George Ricker, a Senior Research Scientist here at MIT and MKI, had finished up his work on the satellite HETE-2.

MIT HETE 2 NASA

This mission looked for sudden brightening events out in the universe, called transients, caused by the explosions of stars and other phenomena. TESS grew out of HETE-2. George and his colleagues had the realization that going to space would give them the ability to accurately gather enough light to find exoplanets when they cross their host stars, causing just a slight dimming, and also to be able to scan a big portion of the sky to find lots of these planets.

So, I remember George walked into my office and said he had this idea for this mission. In your job as director of a place like MKI, you have to figure out how to put scarce resources into different things. A lot of people will walk into my office with ideas, and to be honest, oftentimes they’re not very good ideas. But this idea for TESS, as soon as I heard it, I thought: “Wow—this is timely, the technology is up to it, this is something we’d be able to do now.” I went into high gear at that point, trying to raise money and develop a consensus within our astronomical community that TESS would be a good thing to do.

George had to do some technology development to make this work, to get it funded. NASA tends to avoid risk in these space missions because they’re so expensive. If you’re going to spend millions sending something in orbit, you want it to work, you know? We put quite a bit of money and time into developing a prototype camera. The whole time, George has really been the champion of TESS. He’s someone who has a real talent for designing instruments to meet a particular scientific problem.

All the hard work paid off and NASA greenlit the mission, with George serving as the TESS Principal Investigator.

I feel very lucky being here at MIT because we’re able to gather together the resources needed, in terms of funding and intellectual people power. The Kavli Foundation played a big and direct role, too. TESS development began shortly after we’d received our Kavli endowment, so that helped us be in a position to have resources that we could spend on things like TESS. Also, during a period when significant funding was critically needed to support research staff, the Foundation encouraged us to redirect some funds toward TESS, making sure the program stayed strong and kept moving forward.

So, all these things have had to come together. It’s been incredible. And sort of crazy at times. [Laughter]

_____________________________________________________
3
To Seek Out New Life: How the TESS Mission Will Accelerate the Hunt for Livable Alien Worlds

The just-launched Transiting Exoplanet Survey Satellite (TESS) could soon provide the breakthrough identification of dozens of potentially habitable exoplanets right in our cosmic backyard. Two TESS scientists—Greg Berthiaume and Diana Dragomir—provide an inside look at the mission’s development and revolutionary science.

Read the Kavli Spotlight
_____________________________________________________

TKF: Historically, the Institute has had a very broad astrophysics and cosmology portfolio. Could it develop more of a specialty in exoplanets in the years ahead as TESS begins delivering its bounty?

HEWITT: I’d say in the next five years, exoplanets are definitely going to be a big part of our portfolio. Since we started doing TESS, I’ve had a number of people say to me, “Oh, MIT is the best place to be for exoplanets now.” Which we certainly weren’t 12 years ago! I’m not even sure that’s true now—there are a lot of really good places—but at least we’re in the running. We have new faculty and a lot of postdocs have shown up over the last couple of years because of TESS.

TKF: How else has MKI evolved as a result of pursuing the TESS mission?

HEWITT: I told you about our evolution scientifically, but another way we’ve evolved is in engineering and project management. One thing that’s very hard for a university to do is to maintain the staff needed to do space missions, or even ground-based instruments, because you need mechanical engineers and other specialized staff long term. You need to keep these people employed in between missions so you don’t have to go through the process of staffing up again. Fortunately, TESS was a nice, long sustained mission to develop. We were able to maintain some staff and they’ve been working on other projects as well as TESS. So that’s strengthened our capability moving forward.

The TESS mission also deepened the ties between MKI and MIT’s Lincoln Laboratory, which is a federally funded research and development center that built TESS’ cameras. The engineers at Lincoln have been developing the detectors for x-ray missions for us for decades. But TESS certainly was the biggest thing we’ve ever done with Lincoln. We’ve really built a relationship between our people and those out at Lincoln, about 20 miles away, where they maintain a very deep expertise in engineering that we just cannot.

TKF: I understand the TESS mission has physically changed MKI’s office space, too. Isn’t there now a science operations center in your building on MIT’s campus in Cambridge, Massachusetts?

HEWITT: That’s right. We’ll actually be running the science payload—those cameras and related equipment—on TESS, and that’ll be really cool. We’ll be doing that from a sort of a war room, where we have a bunch of computer screens on the wall. We’ll be getting the data from NASA’s Deep Space Network of radio dishes worldwide, and we’ll be sending out the commands for TESS’ observing sequence.

NASA Canberra, AU, Deep Space Network

NASA Deep Space Network

Now, we’re not actually running the TESS spacecraft itself, mind you; a company called Orbital ATK is doing that. They won’t let us touch the spacecraft. They don’t want a bunch of astronomers running the spacecraft! [Laughter]

TKF: With a major mission like TESS under its belt, do you foresee MIT and MKI making additional forays into primary mission development and operation?

HEWITT: We are having discussions about that. We are presently doing development studies on two other instruments that see the universe in x-rays. One is called Arcus, which will let us study hot gas throughout the universe that we haven’t really been able to see before. The other mission concept is called ISS-TAO, for Transient Astrophysics Observer on the International Space Station, and it will capture transients, such as gamma-ray bursts, and help us better understand them. Those transients include follow-up of the gravitational-wave events detected by the Laser Interferometer Gravitational-Wave Observatory, or LIGO, which is co-led by MIT; and one its founders Rai Weiss, is an MKI member and a Kavli Prize in Astrophysics- and Nobel Prize in Physics-winner.

We have some ideas, too, about putting radio arrays in space or on the moon, and that’s something very challenging that I feel more confident about even trying to do now that we have the TESS experience behind us. We kind of have a feeling for what’s involved.

TKF: TESS is the first NASA mission sent to space aboard a rocket from the commercial company SpaceX, which offers less costly rides off-Earth than legacy rockets. What is the significance of this milestone?

HEWITT: I’m a big fan of SpaceX. I still set my alarm for three o’clock in the morning when they have a launch and I watch it on TV and then go back to bed. [Laughter]

It was just so exciting that TESS got launched in this way, but it’s always a little scary for any spacecraft come launch time. You spend 12 years working on this remarkable machine, and then we put it on top of a column of rocket fuel. I mean, how crazy is that? [Laughter]

This milestone really could be a gamechanger in the science we can do. With it not being so monstrously expensive to put something into space anymore, that might get us to start doing missions that are a little bit riskier and bleeding-edge in terms of technology, but which could potentially have big science rewards.

See the full article here .

Please help promote STEM in your local schools.

STEM Icon

Stem Education Coalition

Mission Statement

The mission of the MIT Kavli Institute (MKI) for Astrophysics and Space Research is to facilitate and carry out the research programs of faculty and research staff whose interests lie in the broadly defined area of astrophysics and space research. Specifically, the MKI will

Provide an intellectual home for faculty, research staff, and students engaged in space- and ground-based astrophysics
Develop and operate space- and ground-based instrumentation for astrophysics
Engage in technology development
Maintain an engineering and technical core capability for enabling and supporting innovative research
Communicate to students, educators, and the public an understanding of and an appreciation for the goals, techniques and results of MKI’s research.

The Kavli Foundation, based in Oxnard, California, is dedicated to the goals of advancing science for the benefit of humanity and promoting increased public understanding and support for scientists and their work.

The Foundation’s mission is implemented through an international program of research institutes, professorships, and symposia in the fields of astrophysics, nanoscience, neuroscience, and theoretical physics as well as prizes in the fields of astrophysics, nanoscience, and neuroscience.

#astronomy, #astrophysics, #basic-research, #cosmology, #jacqueline-hewitt-director-mit-kavli-institute, #kavli-mit-institute-for-astrophysics-and-space-research, #nasa-tess

From Kavli MIT Institute of Astrophysics and Space Research: “To Seek Out New Life: How the TESS Mission Will Accelerate the Hunt for Livable Alien Worlds’

KavliFoundation

http://www.kavlifoundation.org/institutes

Kavli MIT Institute of Astrophysics and Space Research

Kavli MIT Institute For Astrophysics and Space Research

The just-launched Transiting Exoplanet Survey Satellite (TESS) could soon provide the breakthrough identification of dozens of potentially habitable exoplanets
right in our cosmic backyard.

NASA/TESS

A NEW ERA IN THE SEARCH FOR EXOPLANETS—and the alien life they might host—has begun. Aboard a SpaceX rocket, the Transiting Exoplanet Survey Satellite (TESS) launched on April 18, 2018, at 6:51 PM EDT. The TESS mission, developed with support from The Kavli Foundation, is led by the Massachusetts Institute of Technology (MIT) and the MIT Kavli Institute for Astrophysics and Space Research.

Over the next two years, TESS will scan the 200,000 or so nearest and brightest stars to Earth for telltale dimming caused when exoplanets cross their stars’ faces. Among the thousands of new worlds TESS is expected to discover should be hundreds ranging in size from about one to two times Earth. These small, mostly rocky planets will serve as prime targets for detailed follow-up observations by other telescopes in space and on the ground.

The goal for those telescopes will be to characterize the newfound exoplanets’ atmospheres. The particular mixtures of gases in an atmosphere will reveal key clues about a world’s climate, history, and if it might even be hospitable to life.

The Kavli Foundation spoke with two scientists on the TESS mission to get an inside look at its development and revolutionary science aim of finding the first “Earth twin” in the universe.

The participants were:

GREG BERTHIAUME – is the Instrument Manager for the TESS mission, in charge of ensuring the spacecraft’s cameras and other equipment will perform their science tasks. Berthiaume is based at the Massachusetts Institute of Technology’s (MIT) Lincoln Laboratory and he is also a member of the MIT Kavli Institute for Astrophysics and Space Research.

DIANA DRAGOMIR – is an observational astronomer whose focus is on small exoplanets. Dragomir is a Hubble Postdoctoral Fellow at the MIT Kavli Institute for Astrophysics and Space Research.

THE KAVLI FOUNDATION: Starting with the big picture, why is TESS important?

DIANA DRAGOMIR: TESS is going to find thousands of exoplanets, which might not sound like a big deal, because we already know of nearly 4,000. But most of those discovered planets are too far away for us to do anything more than just know their size and that they are there. The difference is that TESS will be looking for planets around stars very close to us. When stars are closer to us, they’re also brighter from our point of view, and that helps us discover and study the planets around them much more easily.

GREG BERTHIAUME: One of the things TESS is doing is helping to answer the fundamental question, “Is there other life in the universe?” People have been wondering that for thousands of years. Now TESS won’t answer that question directly, but it’s a step, just like Diana mentioned, on the path to getting us the data to see where there might be other life out there. That’s something we’ve been struggling with and questioning since we were able to come up with questions.

TKF: What exactly do you expect TESS to find?

DRAGOMIR: TESS will probably find 100 to 200 approximately Earth-size worlds, as well as thousands of more exoplanets all the way up to Jupiter in size.

BERTHIAUME: We’re trying to find planets that are Earth analogs, meaning they’ll be Earth-like in their characteristics, such as size, mass, and so on. That means we want to find planets with atmospheres, with gravity similar to Earth’s. We want to find planets that are cool enough so water can be liquid on their surfaces, and not so cold that the water is frozen all the time. We call these “Goldilocks” planets, located in a star’s “habitable zone.” That’s really our target.

DRAGOMIR: Exactly right. We want to find the first “Earth twin.” TESS will mainly find planets in the habitable zone of red dwarfs. These are stars a bit smaller and cooler than the Sun. A planet around a red dwarf can be located in an orbit closer to its star than it could be with a hotter star like our Sun and still maintain that nice, Goldilocks temperature. Closer orbits translate to more transits, or star crossings, which makes these red dwarf planets easier to find and study than planets around Sun-like stars.

Astronomers are working hard on ways that we might push the TESS data and find some planets in the habitable zone of Sun-like stars, too. It’s challenging because those planets have longer orbital periods—years, that is—than close-in planets. That means we need a lot more observation time in order to detect enough transits of the planets across their stars to say we’ve definitely detected a planet. But we’re hopeful, so stay tuned!

TKF: What do you need to see in order to deem any of the planets discovered by TESS as potentially habitable?

DRAGOMIR: We want a planet to be close to Earth in size for all the reasons we just gave, but there’s a small problem with that. Those sorts of planets will probably have pretty small atmospheres, compared to how much rock makes up their bulk. And for most telescopes to be able to look at an atmosphere in detail, we actually need the planet to have a substantial atmosphere.

This is because of a technique we use called transmission spectroscopy. It gathers the light from the star that has gone through the atmosphere of the planet when the planet is crossing the star. That light comes to us with a spectrum of the planet’s atmosphere imprinted on it, which we can analyze to identify the composition of the atmosphere. The more atmosphere there is, the more material there is that can imprint on the spectrum, giving us a bigger signal.

If the light from the star is going through very little atmosphere, though, like we’d be looking at with an Earth twin, the signal would be very small. Based on what TESS finds, we’re therefore going to be starting with bigger planets that have a lot of atmosphere, and as we get better instruments, we’re going to move towards smaller and smaller planets with less atmosphere. It’s those latter planets which will more likely be habitable.

BERTHIAUME: What we’re going to look for in the atmosphere are things like water vapor, oxygen, carbon dioxide—the standard gases we see in our atmosphere that life needs and life produces. We’re also going to try and measure the nasty things that aren’t compatible with life as we know it on Earth. For instance, it would be a bad thing for biology if there were too much ammonia in a world’s atmosphere. Hydrocarbons, like methane, would also be problematic in too high an abundance.

TKF: Diana, your specialty is exoplanets smaller than Neptune—a planet four times bigger than Earth. What is our general knowledge about those kinds of worlds and how will TESS help with your research?

DRAGOMIR: One thing we know about these planets is that they are extremely common compared to planets larger than Neptune. So that’s good. We therefore expect TESS to find lots and lots of planets smaller than Neptune for us to look at.

Although small is bad for getting those atmospheric imprints we just talked about, if the stars are nearby and bright, we might still be able to get enough light for doing good studies. I’m hoping that we’ll get enough below Neptune-size that we’ll start looking at the atmospheres of “super-Earths,” which are planets twice the size of Earth or so. We don’t have any super-Earths in our solar system, so we’d love to get a closer look at one of these kinds of worlds. And just maybe, if we find a really, really good planetary candidate, we may be able to start looking at the atmosphere of an Earth-sized planet.

With my research, one more thing TESS could really help with is figuring out the boundary between a very gassy planet like Neptune and a very rocky planet like Earth. We believe it’s mostly a matter of mass; have too much mass, and the planet stars to hold into a thick atmosphere. Right now, we’re not sure where that threshold is. And that matters so we know when a planet is rocky and potentially habitable, or gassy and not habitable.

TKF: Greg, as the TESS Instrument Manager, a lot rides on your shoulders for the mission’s success. Can you tell us a bit about your job?

BERTHIAUME: My job as instrument manager is different from a science job, for sure. My job was to make sure that all of the pieces, all the parts that go into the four flight cameras and the image processing hardware all play and work together and give us the great data that we need for Diana to go and continue to explore exoplanets. My personal role on the mission actually ends shortly after launch. Once we’ve demonstrated that the satellite provides the data that we expect, and we deal with any surprises that may come up, then I move on and data goes off to the science community.

I definitely feel responsible for getting the quality of the data as high as it possibly can be. A lot of people worked really hard for years to build the cameras that are flying on TESS and it’s been great to be part of that team.

TKF: New exoplanet missions like the European Space Agency’s Ariel and Plato satellites are slated to begin in the late 2020s. How might these future spacecraft complement and build on TESS’ body of work?

DRAGOMIR: The great thing about TESS is that it’s going to give us a lot to choose from in terms of the best options for planets we’ll want to study. In that way, TESS will set the stage for Ariel’s mission, which is to deeply study the atmospheres of a select group of exoplanets.

The Plato mission will be looking for planets that are habitable, but around bigger stars like the Sun, whereas TESS will focus on looking for habitable planets around smaller stars. I’m happy with that because I don’t want us to put all of our eggs in one basket by only looking at red dwarf stars with TESS. Planets around these red dwarfs are very exciting right now because they’re easier to study and they transit their stars more often, making them easier to find. But at the same time, red dwarfs tend to be much more active than the Sun. When a star is active, that means it often expels bursts of radiation called flares. These flares could be very damaging to a planet’s atmosphere and make the world uninhabitable.

In the end, we of course live around a Sun-like star, and so far, we are the only “we” we know of in the universe. So for those reasons, it’s great to have Plato complementarily come along and find those planets around suns that TESS will probably not be able to find.

TKF: When do you expect TESS’ first discoveries of brand new worlds to be reported?

BERTHIAUME: First, it’s going to take a while to get TESS into its unique orbit. It’s the first time we’re putting a spacecraft in a new kind of far-ranging, highly elliptical orbit, where the gravity from the Earth and the Moon will keep TESS very stable, both from an orbit perspective and from a thermal perspective. So a big part of what’s going to happen over the first six weeks is just achieving that final orbit.

Then there’s a period of time where there’ll be data collected to make sure the instruments are working as expected, as well as getting our data processing pipeline tuned up. I think we’ll start to see interesting results come out sometime this summer.

TKF: Besides new worlds, what else might TESS reveal about the universe?

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A set of flight camera electronics on one of the TESS cameras, developed by the MIT Kavli Institute for Astrophysics and Space Research (MKI). (Image: MIT Kavli Institute)

DRAGOMIR: Because TESS is observing so much of the sky, it’s going to see lots of things that are happening in real-time, not just exoplanets crossing stars. As for those stars, we can learn a lot about their properties and even measure their masses quite precisely by doing asteroseismology with TESS. This technique involves tracking brightness changes as sound waves move through the interiors of stars—just like how seismic waves pass through the Earth’s rock and molten insides during earthquakes.

We’ll also be studying the flaring activity of the stars, which as we spoke about earlier might make close-in, temperate planets around red dwarf stars uninhabitable.

Moving up in size, scientists will want to search the TESS data for evidence of small black holes. These extreme objects, formed when colossal stars explode, can orbit normal stars that are still “alive,” so to speak. These systems will help us better understand how those black holes form and how they interact with companion stars.

And then finally, going even bigger, TESS will look at galaxies called quasars. These ultra-bright galaxies are powered by supermassive black holes in their cores. TESS will help us monitor how quasars’ brightness changes, which we can link back to the dynamics of their black holes.

TKF: The James Webb Space Telescope, hailed as the successor to the Hubble Space Telescope, has long been talked about as a primary instrument for doing the detailed follow-up observations on promising exoplanets found by TESS. However, James Webb’s launch, already delayed multiple times, just got pushed out yet another year, to 2020. How will the ongoing James Webb delays affect the TESS mission?

DRAGOMIR: The James Webb delay is not so much of a problem because it actually gives us more time to collect great target planets with TESS. Before we can use James Webb to really observe candidate exoplanets and study their atmospheres, we first need to confirm the planets are real—that what we think are planets are not false positives caused, for instance, by stellar activity. That confirmation process takes weeks, using support observations from ground-based telescopes. It will then also take weeks to months to obtain the mass of the planets. We measure that by registering how much planets cause their host stars to experience slight “wobbles” in their motion over time, owing to the planets’ gravities, which are determined by their mass.

Once you have that mass, plus the size of an exoplanet based on how much starlight it blocks during a TESS detection, you can measure its density and determine if it’s rocky or gaseous. With this information, it is then easier to decide which planets we want to prioritize, and the more we can make sense out of what James Webb will tell us about their atmospheres.

TKF: Spacecraft sometimes have humorous or even profound extra elements built into them. One example: the “Golden Records” on the twin Voyager spacecraft, which contain images and sounds of life and civilization on Earth, including the Taj Mahal and birdsong. Are there any such items included on TESS? Any subtle maker’s marks or messages?

BERTHIAUME: One of the things that’s flying along with TESS is a metal plaque that has the signatures of many of the people who worked on developing and building the spacecraft. That was an exciting thing for us.

DRAGOMIR: That’s cool. I didn’t know that!

BERTHIAUME: Also, NASA ran an international contest inviting people from around the world to submit drawings of what they thought exoplanets might look like. I know many children participated. All of those drawings were scanned onto a thumb drive and they’re flying along with TESS. The spacecraft’s orbit is stable for a century at least, so the plaque and the drawings will be in space for a long time!

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The Kavli Foundation, based in Oxnard, California, is dedicated to the goals of advancing science for the benefit of humanity and promoting increased public understanding and support for scientists and their work.

The Foundation’s mission is implemented through an international program of research institutes, professorships, and symposia in the fields of astrophysics, nanoscience, neuroscience, and theoretical physics as well as prizes in the fields of astrophysics, nanoscience, and neuroscience.

Mission Statement

The mission of the MIT Kavli Institute (MKI) for Astrophysics and Space Research is to facilitate and carry out the research programs of faculty and research staff whose interests lie in the broadly defined area of astrophysics and space research. Specifically, the MKI will

Provide an intellectual home for faculty, research staff, and students engaged in space- and ground-based astrophysics
Develop and operate space- and ground-based instrumentation for astrophysics
Engage in technology development
Maintain an engineering and technical core capability for enabling and supporting innovative research
Communicate to students, educators, and the public an understanding of and an appreciation for the goals, techniques and results of MKI’s research.

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