All things in the cosmos have a lifespan, from the smallest particles to the most ancient suns. Everything has its season. Every season must come to an end.

And this episode marks the end of Orbital Path.

So, for the last transit of our podcast, Dr. Michelle Thaller and producer David Schulman join NASA astrobiologist Dr. Jen Eigenbrode on a site visit to one of Michelle’s very favorite places at Goddard Space Flight Center. It’s building 29, where NASA builds and tests spacecraft in some of the most extreme conditions found anywhere on earth. 

Orbital Path is produced by David Schulman.  
 Our editor is Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Hosted by Michelle Thaller. 
 Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance.

Image credit: NASA

Asteroids, as the dinosaurs found out, can have big effects on life on Earth. 

Sixty-five million years ago, an asteroid crashed into the Yucatán. The impact caused apocalyptic tsunamis and volcanic eruptions. Grit and ash blotted out the sun. It wiped out species that had roamed the Earth for millions of years.

Yet asteroid hits also were critical to the origins of life on Earth. Asteroids may well have been the bringers of water, of carbon, even of amino acids — the building blocks of life.

That’s a big reason why NASA is on a mission to Bennu. This asteroid is like an ancient fossil of our solar system — largely unchanged since the time the planets formed.

In December, after a billion-mile journey, NASA’s Osiris-Rex mission arrives at Bennu. And, for the first time, a spacecraft will try to actually bring back an asteroid sample to Earth.

On this episode of Orbital Path, Dr. Michelle Thaller sits down with Dr. Amy Simon — a senior scientist at NASA’s Goddard Space Flight Center, and a key player on the Osiris-Rex mission. Michelle and Amy talk about the mission, Amy’s work to probe the origins of the solar system, and one other thing: 

The remote chance that Bennu, someday, could collide with Earth.

Orbital Path is produced by David Schulman. 

Our editor is Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler.

Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance.

Image credit: NASA/Goddard/University of Arizona.

To make a black hole, you need to think big. Really big.

Start with a star much bigger than the sun — the bigger the better. Then settle in, and wait a few million years for your star to die.

That should do the trick, if you want to get yourself a garden-variety black hole. But there’s another kind of black hole. They are mind-boggling in size. And deeply mysterious:

Super-massive black holes.

Last year, in the journal Nature, a team of astronomers reported finding one with the mass of 800 million suns. It’s the most distant black hole in the known universe. And it’s so ancient, it dates to a time when it seems light itself was only just beginning to move.

On this episode of Orbital Path, Dr. Michelle Thaller talks with astrophysicist Chiara Mingarelli — Flatiron Research Fellow at the Center for Computational Astrophysics in New York. Using a special gravitational wave observatory, Dr. Mingarelli is part of a cadre of astronomers hoping ancient super-massive black holes will soon reveal mysteries dating to the dawn of our universe.

Orbital Path is produced by David Schulman. Our editor is Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler.

Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance.

Image credit: NASA artist’s rendering of a super-massive black hole.

On September 15, 2018, the last Delta II rocket lifted off from Vandenberg Air Force base, in California. It carried into orbit IceSat-2 — a satellite equipped with perhaps the most sophisticated space laser ever built.   NASA didn’t put it up there to shoot down rogue asteroids. Instead, it’s taking aim — with exquisite precision — at Earth.   On this episode of Orbital Path, Dr. Michelle Thaller talks with Tom Wagner. He’s been looking forward to the launch of IceSat-2 for a decade. Officially, Wagner is NASA’s Program Scientist for the Cryosphere. That means he studies the frozen regions of the Earth: Antarctica. The Arctic Ocean. The glaciers of Greenland. All places critical to understanding our planet’s changing climate.   From 300 miles above, the six laser beams of IceSat-2 won’t harm even the most light-sensitive earthling, Wagner says. But, as he describes it, the satellite will allow scientists to precisely map the retreat of ice at the poles. And that promises to teach us a great deal about how Earth’s climate will change in the years to come.

Orbital Path is produced by David Schulman. Our editor is Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler.

Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance.

Image credit: NASA

We live our lives in three dimensions. But we also walk those three dimensions along a fourth dimension: time.



Our world makes sense thanks to mathematics. Math lets us count our livestock, it lets us navigate our journeys. Mathematics has also proved an uncanny, stunningly accurate guide to what Brian Greene calls “the dark corners of reality.”



But what happens when math takes us far, far beyond what we — as humans — are equipped to perceive with our senses? What does it mean when mathematics tells us, in no uncertain terms, that the world exists not in three, not in four — but in no fewer than 11 dimensions?



In this encore episode of Orbital Path (previously heard in October 2017), Brian Greene, a celebrated explainer of how our universe operates and the director of the Center for Theoretical Physics at Columbia University, sits down to talk with Dr. Michelle Thaller. 

Together they dig into the question of how we — as three-dimensional creatures — can come to terms with all those extra dimensions all around us. 


Orbital Path is produced by David Schulman. Our editor is Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler.

Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance.

Image by: World Science Festival / Greg Kessler

To hear Leonard Susskind tell it, we are living in a golden age of quantum physics.

And he should know.

Susskind is a grandee of theoretical physics. In the 1960s, he was one of the discoverers of String Theory. His friends and collaborators over the years include the likes of Nobel Prize winners Gerard ‘t Hooft and Richard Feynman.

And, for more than a decade, Susskind engaged in an intellectual clash of the Titans with Stephen Hawking — and came out on top.

On this episode of Orbital Path, Dr. Michelle Thaller talks with Susskind about his extraordinary life in physics. And Susskind offers a tantalizing glimpse into his recent work on the holographic principle, which suggests our universe may be a far, far stranger place than humans have yet imagined.

Orbital Path is produced by David Schulman. Our editor is Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler.

Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance.

Image credit: Linda Cicero / Stanford News Service

For a long time, probably as long as we have been gazing up at the night sky, people have been asking ourselves: Are we alone? Is there life out there, anywhere else in the universe?

For modern Earthlings, our fascination with extraterrestrial life has focussed on one place in particular:

Mars.

The planet today is a forbidding, arid place. But billions of years ago, Mars may have had a gigantic ocean. It was, like Earth, just the kind of place you’d think life could get started.

Earlier this month, in the journal Science, NASA astrobiologist Dr. Jen Eigenbrode and her team published a stunning discovery. The Curiosity rover on Mars had found rocks that contain organic molecules — the building blocks of life.

On this episode of Orbital Path, Dr. Michelle Thaller sits down with Eigenbrode to understand what this discovery really says about the possibility of life on Mars.

This episode of Orbital Path was produced by David Schulman. Our editor is Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler.

Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance.

Image credit: NASA

Zoe is in 8th grade. She’s a student in Mr. Andersen’s Earth science class at a public school in Brooklyn.

Lately, she’s been concerned about the future of the planet.

Specifically, Zoe has been learning about the phenomenon of planetary dehydration — and she wanted to ask Dr. Michelle Thaller what would happen if Earth lost its water.

It’s part of a new Orbital Path project called “Telescope,” where Dr. Michelle Thaller fields astronomy questions from public school students.

Michelle says dehydration isn’t anything we’ll have to worry about in our lifetimes. But in 200 million years — not all that long, in astronomical terms — our planet could resemble the desert world of Frank Herbert’s “Dune.”

Orbital Path is produced by David Schulman. The program is edited by Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Hosted by Dr. Michelle Thaller.

The music heard in this episode is “Austin 1” by Manwomanchild.

Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance.

Mars image credit: NASA

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Secrets of the universe? A glimpse of the whiteboard in the office of Nobel Prize-winning astrophysicist Adam Riess.

Adam Riess was only 41 when he was named a Nobel Prize winner. The Johns Hopkins distinguished professor of astronomy shared in the award for his work on something called “dark energy” — a discovery that over the past 20 years has profoundly shifted our understanding of the universe.

Riess made news again recently when he and colleagues working with the Hubble Space Telescope announced new findings about the rate at which the universe is expanding — findings which simply cannot be explained by physics as we know it.

It’s weird and profound stuff. Our story begins a century ago, with a riddle posed by a curious part of Einstein’s Theory of General Relativity — something called the “Cosmological Constant.” The fate of the universe just may hang in the balance.

This episode of Orbital Path was produced by David Schulman. Our editor is Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler.

Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance.

Image credit: David Schulman

Instead of grappling with the big, cosmic questions that preoccupy adults, this week on Orbital Path we’re doing something different.

We’re grappling with the big, cosmic questions that preoccupy kids.

It’s part of a new project called “Telescope,” where Dr. Michelle Thaller takes on the really big questions in astronomy—from public school students.

In this episode, Michelle fields questions from Mr. Andersen’s Earth Science class at MS 442, a public school in Brooklyn.

Sarah Cole asks about creating artificial gravity on spacecraft. And Carter Nyhan wonders whether the stars guiding mariners ancient and modern, were, by the time their light reached the earth, completely kaput. Is the twinkling night sky actually a graveyard of dead stars?

Orbital Path is produced by David Schulman. The program is edited by Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Hosted by Dr. Michelle Thaller.

Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance.

Image credit: NASA image of the International Space Station, where gravity does, in fact, still apply.