What is a “Habitable” Planet, Anyway?

By Corey S. Powell | July 31, 2018 11:45 pm
Exoplanets (planets around other stars) ranked by researchers at the Planetary Habitability Lab at the University of Puerto Rico. Note the abundance of disclaimers; the truth is, we know little about these planets beyond their size and their distance from their stars. (Credit: UPR Arecibo)

Exoplanets (planets around other stars) ranked by researchers at the University of Puerto Rico’s Planetary Habitability Lab. Note the abundance of disclaimers; the truth is, we know little about these worlds besides their size and the distance they orbit from their stars. (Credit: UPR Arecibo)

We are living at the greatest moment in history for finding life beyond Earth. We have robots poking and sniffing around on Mars. We have a space probe in the works that will take a close look at Europa, to examine the likelihood of life on an ice-covered ocean world. Above all, we no longer have to wonder if our solar system is unique: We know of thousands of planets around other stars, and it’s clear that the total number of planets in our galaxy alone must number in the billions, if not the trillions.

But with all these rapid advances have come acute intellectual growing pains. It is only natural that people want to know how many of those distant planets could truly support life–to know whether living worlds like our own are common or rare (or unique). The desire for answers runs far ahead of the ability of science to provide them, unfortunately. And so we end up with whiplash conclusions based on the latest speculative study: Red dwarf stars are great places to find habitable planets…or maybe they are deadly. Earth couldn’t sustain life without the Moon…or maybe the Moon is not necessary at all.

Read More

Here’s the Answer That Will Finally Settle the “Is Pluto a Planet?” Debate for Good (Yeah, Right)

By Corey S. Powell | June 5, 2018 12:43 pm
Pluto is a beautiful world, with ice mountains, nitrogen glaciers, and methane dunes. But that doesn't make it a planet. (Credit: NASA/JHUAPL/SwRI)

Pluto is a beautiful world, with ice mountains, nitrogen glaciers, a haze-layered atmosphere, and methane dunes. But all that complexity does not necessarily make it a “planet.” (Credit: NASA/JHUAPL/SwRI)

I love Pluto. I grew up entranced by this strange little world: What could you be, you rebel that doesn’t seem to follow any of the rules? I even wrote a childhood letter to a local astronomer, offering my homespun hypothesis that Pluto might be a captured fragment of an exploded star. When the New Horizons spacecraft finally revealed the true face of Pluto, I was right there at mission control in Langley, Maryland, to watch the images as they came in.

So I have a lot of sympathy for the Pluto-lovers who were wounded when the International Astronomical Union declared that the 9th planet was not exactly a planet after all, but something called a “dwarf planet.” I also appreciate the sweet irony that the fuss over Pluto’s reclassification stirred up even more interest in the New Horizons encounter. But really, the endless effort to restore Pluto’s planetary status and relegislate the definition of a “planet” is getting tedious. Time to settle this thing.

Read More

665 Days in Space and 47 Minutes on TV: A Conversation with NASA Astronaut Peggy Whitson

By Corey S. Powell | May 28, 2018 12:49 pm
Life outside the bubble: Peggy Whitson took her record-setting 8th spacewalk outside the ISS on March 30, 2017. (Credit; NASA-JSC)

Peggy Whitson took her record-setting 8th spacewalk outside the ISS on March 30, 2017. (Credit: NASA Johnson Space Center)

Life is all about bubbles. Every cell in your body is a bubble, a membrane holding together a miniature world of organelles, ribosomes, and genetic material. Your body itself is another bubble, a skin wrapped around a wet, salty interior that carries a distant memory of the oceans in which our ancestors lived hundreds of millions of years ago. And our entire planet is a bubble, a thin membrane of oxygen-rich air wrapped around a spinning rock warmed by a nearby Sun.

Being able to perceive our reality this way is one of the gifts of spending time with someone like Peggy Whitson, the poetic yet resolutely humble astronaut who has spent 665 days aboard the International Space Station–the longest duration of any American. Her life story is woven into tonight’s final episode of One Strange Rock, an unusual type of nature show that looks back at Earth from the unique perspective of the space explorers who have left it. But what you can see in 47 minutes on screen only scratches the surface of what Whitson has experienced.

Read More

Alan Stern on the Pluto Revolution, the Psychology of Persistence, and “Chasing New Horizons”

By Corey S. Powell | May 4, 2018 3:10 pm
In the 1970s, the original version of the Voyager mission was supposed to include a Pluto flyby--and Alan Stern worked through many failed attempts to launch a Pluto mission in

In the 1970s, the original version of the Voyager mission was supposed to include a Pluto flyby–and Alan Stern worked through many failed attempts to launch a Pluto mission in the decades since. (Graphic: Jason Davis/The Planetary Society)

On July 14, 2015, the New Horizons spacecraft swept past Pluto, returning eye-popping images of the dwarf planet and its huge (relatively speaking) moon, Charon. At the time, the best existing images of Pluto showed nothing more than an enigmatic blur. New Horizons revealed a world of astonishing diversity: organics-coated dark patches, ice mountains, nitrogen glaciers, and methane snows, all in a state of astonishing activity considering the temperatures there are only about 40 degrees above absolute zero.

The scientific bonanza from the Pluto flyby was sweet vindication for Alan Stern, principal investigator on New Horizons. Stern spent decades fighting to make a Pluto mission happen, persisting long after it seemed like a hopeless cause. Teaming up with writer and astrobiologist David Grinspoon, Stern tells the full, thorny story in his engaging new book Chasing New Horizons: Inside the Epic First Mission to Pluto. It’s a a tale about space science, yes, but it’s also a reminder of what can happen when you refuse to let dreams die.

Read More

From the Overview Effect to “One Strange Rock”: A Conversation with Leland Melvin

By Corey S. Powell | April 2, 2018 2:37 pm

Leland Melvin shows the two sides of his passion, with the wonder of the "overview" showing outside his Shuttle window. [Credit: NASA]

Leland Melvin shows the two sides of his passion, with the wonder of the “overview” showing outside his Shuttle window. [Credit: NASA]

It’s hard to think of any modern human activity that has had more of a multiplicative impact on the imagination than space exploration. To date, a grand total of 562 humans have left the Earth—a trivial fraction compared to the 7.6 billion people currently staying put. Yet the images and stories of astronauts voyaging away from their home planet has transformed popular culture, education, even business and politics.

Former NASA astronaut Leland Melvin is a lead agent helping to advance that transformation. In a wide range of appearances, he speaks eloquently about the “overview effect,” the life-changing cognitive shift that comes with seeing Earth from the outside. Most recently, he has participated in the new series One Strange Rock, which embraces that effect by examining the marvels of our world from astronauts’ perspectives.

Read More

Finding Stephen Hawking’s Star—And Finding Your Own

By Corey S. Powell | March 14, 2018 1:21 pm
In 2008, Stephen Hawking delivered a lecture on "why we should go into space" in honor of NASA's 50th anniversary. (Credit: NASA/Paul. E. Alers)

In 2008, Stephen Hawking delivered a lecture on “why we should go into space” in honor of NASA’s 50th anniversary. (Credit: NASA/Paul. E. Alers)

When I look at the night sky, I often view the stars not just in space but also in terms of their places in time. Light moves at a finite speed (299,792 kilometers per second, to be precise), so the journey from star to star is a very long one even for a beam of light. When astronomers talk about light years of distance, they are literally describing the number of years it takes for light to travel from those distant stars to your eyeball.

And so when I heard about the death of Stephen Hawking, I couldn’t help thinking about his place in the stars. At some distance from Earth, there is a star whose light (as seen right now on Earth) started its journey at the time when you were born. You can think of that as your birth star. We all have one. Hawking has one–and you can easily see it. His birth star is shining brightly in the evening tonight.

Read More

Standing on the Shore, Grasping for the Stars

By Corey S. Powell | February 28, 2018 10:58 pm
Pioneer 10 lived up to its name, blazing a trail to the outer solar system and finding that the asteroid belt was no obstacle at all. (Credit: NASA=Ames/Rick Guidice)

The Pioneer 10 spacecraft fully lived up to its name, blazing a trail to the outer solar system and proving that the asteroid belt was no obstacle to space exploration. (Credit: NASA=Ames/Rick Guidice)

This month marks the 45th anniversary of Pioneer 10’s passage through the asteroid belt. It was a key rite of passage in humanity’s journey from this blue planet into the deep reaches of outer space. Unlike the crowded swarms of science-fiction movies, the real asteroid belt is overwhelmingly empty space. Still, nobody knew exactly what to expect. Would Pioneer 10 be pelted with dust-speck micrometeoroids? Was the asteroid belt a serious barrier to exploration?

As it turned out, the dust was even less than expected. Pioneer 10 (and the many other probes that followed) sailed through unscathed. The solar system was wide open, waiting for us.

I was thinking about Pioneer 10 this past week as I contemplated another cosmic frontier. Standing on a beach in the Yucatan, I was far enough south to see the nearest star system, Alpha Centauri, glittering on the horizon. Bright. Beckoning. Waiting for us. Almost impossibly far away–but only almost. It is our human nature to explore, and I believe that it is our human destiny to find a way to the stars.

Read More

Where are You Going in 2018 (Cosmically Speaking)?

By Corey S. Powell | January 24, 2018 12:13 pm
Rotation of the Earth as seen from the DISCOVR spacecraft, 1.6 miles sunward of our planet. (Credit: NASA/NOAA)

Rotation of the Earth as seen from the DSCOVR spacecraft, located 1.5 million kilometers sunward of our planet. (Credit: NASA/NOAA)

A while back, I wrote a column for Discover analyzing your place in space: astronomers’ best look yet at where you fit into the big, crazy, cosmic scheme of things. Any discussion of where you are inevitably brings up the related question of not just where you are, but where you are going. And there’s no better time to think about where you are going that at the beginning of the year–right around the time when you realize that, once again, this isn’t going to be the year you keep all your January 1 resolutions.

How to answer the question Where are you going? depends entirely your reference frame. There is no master set of coordinates for the universe (thanks a lot, Einstein), so you can only answer the question by addressing the subordinate question, In relation to what? Fortunately, that’s exactly when things start to get interesting.

Read More

Could a Lunar Fuel Depot Jump-Start Human Exploration of Deep Space?

By Corey S. Powell | December 29, 2017 9:46 am
Conceptual art for NASA's Deep Space Gateway. Its fate is up in the air due to uncertain funding and mission changes. (Credit: NASA)

Conceptual art for NASA’s Deep Space Gateway. Its fate is up in the air due to uncertain funding and mission changes. (Credit: NASA)

In my previous post I started a conversation with spaceflight entrepreneur Charles Miller, who shared his insights about how NASA’s human spaceflight program got been stuck in low-Earth orbit and how we could enter a new era of deep-space adventure. Part one of the interview focused on the role of private industry in radically lowering the cost of getting back to the Moon. But it left many topics unexplored.

In particular, I wanted to hear more about the economics of what some people are calling “new space”: a more flexible, commercial-oriented approach to exploration. What would the economics look like? What kind of transition would liberate us from the current bureaucratic inertia? It is easy to outline a compelling vision; it’s a lot harder to map out a realistic path to making it happen. Miller had a lot of provocative things to say here, too.

Read More

Back to the Moon for Real: A Conversation with Private-Spaceflight Evangelist Charles Miller

By Corey S. Powell | December 24, 2017 6:56 am
The future that never happened: A bustling Mon base as envisioned by a NASA study in 1986. (Credit: NASA/Dennis M. Davidson)

The future that never happened: A bustling Mon base as envisioned by a NASA study in 1986. (Credit: NASA/Dennis M. Davidson)

NASA’s human spaceflight program has been in a state of uncertainty pretty much from the moment the Apollo 17 crew left the surface of the Moon 45 years ago this month. The Space Shuttle never became the hoped-for workhorse that would makes space access cheap and routine; the International Space Station never became a glorious gateway to deep-space exploration. Now NASA faces yet another U-turn as President Trump has directed the agency’s administrator to send astronauts back to the moon.

One problem: There is no NASA administrator (the Senate hasn’t voted on the nominee, Rep. Jim Bridenstine, so he’ll have to be renominated when congress reconvenes next month). Another problem: There is no budget to support another Apollo-style venture. So where do we go from here? I spoke with Charles Miller — a veteran of both NASA and commercial space ventures, and president of consulting company NexGen Space — to get an insider’s perspective.

Read More

NEW ON DISCOVER
OPEN
CITIZEN SCIENCE
ADVERTISEMENT

Out There

Notes from the far edge of space, astronomy, and physics.
ADVERTISEMENT

See More

ADVERTISEMENT

Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

Collapse bottom bar
+