Latest Posts

Lighting effects

ESP_034922_1385_1.0xA piece of Mars: It’s winter in the southern hemisphere, and dunes like these are covered in bright white CO2 frost. The sun is near the horizon (shining from the top of the image), so it creates stark shadows. That can make doing science tough, but it’s the best way to show off the beauty of the dunes. Can you tell which way is up here, which way is down, and when you’re looking at a inherent change in the surface color vs. sun and shadows? (ESP_034922_1385, NASA/JPL/Univ. of Arizona)


ESP_034909_1755_0.5xA piece of Mars: What is this big swoosh? It’s a big dark dune. The dark/light striping across it is found in all of the dunes in this area, but what is it? We’re probably seeing the inside of the dune: the wind may so strong here that it erodes the highest point of the dune, showing off the interior structure. (HiRISE ESP_034909_1744, NASA/JPL/Univ. of Arizona)

There’s ripples and then there’s ripples

ESP_034801_1300_1.0xA piece of Mars: On the floor of a crater in the southern midlatitudes, there’s a field of ripples. But wait, there are big ones that are very sinuous and small ones that are not. Why? Both are ripples, but they’re different kinds of ripples. The smaller ones (~3 m, or ~10 ft) are probably made entirely of sand, while the larger ones (~15 m, or 50 ft) are older and they’re probably made of a mixture of different grain sizes. (ESP_034801_1300, NASA/JPL/Univ. of Arizona).

Guest blog for The Planetary Society


See my guest blog for The Planetary Society on the difference between ripples and dunes.

HiRISE image caption for Curiosity

A piece of Mars: Last week I wrote an image caption for Curiosity, showing both the HiRISE perspective and Curiosity’s image of the ripple crossing Dingo Gap. Read more on the HiRISE image page.

Peering at Planets

Astronomers and engineers recently completed building the Gemini Planet Imager (GPI) to study distant solar systems. GPI will obtain high-resolution images of extrasolar planets by blocking the light of stars and detecting the faint thermal glow of orbiting planets.

Near-infrared image of Beta Pictoris b, an extrasolar planet approximately 60 light years away. The light of the host star, Beta Pictoris, is blocked in this image to reveal the much fainter light of the planet. Image processing by Christian Marois, NRC Canada.


Director of the Carl Sagan Center of the SETI Institute publishes a Carl Sagan Biographical Memoir

David Morrison, director of the Carl Sagan Center of the SETI Institute, has written a biographical memoir of Carl Sagan (1934-1996), founder of the modern disciplines of planetary science and exobiology.

Carl Sagan (third from left) with three of his former students: David Morrison, Joseph Veverka, and James Pollack. Photo by David Morrison

Carl Sagan (third from left) with three of his former students: David Morrison, Joseph Veverka, and James Pollack. Photo by David Morrison


My New Book, Life Beyond Earth: The Search for Habitable Worlds in the Universe

By A. Coustenis and Th. Encrenaz
Cambridge University Press

lbeIt all started with Therese and I getting interested in exoplanets, the (still) new field in astronomy dealing with the planets discovered (about 1000 by now) around other stars than our Sun. And also my long-lived passion for Astrobiology, the study of habitable worlds in our solar system and beyond. Looking at how life might have emerged on other planets, seeking to evaluate to potential for hosting life and supporting its development under the surfaces of outer plant satellites in deep oceans of liquid water, and trying to define what makes an environment potentially habitable are some things I have been working on ever since my interest in Saturn’s moons Titan and Enceladus and in some of the Galilean satellites like Europa and Ganymede. Satellites turn out to be great places for looking for habitable conditions (liquid water, organic chemistry, energy sources, etc)

So, we decided to look at the problem from a different perspective: from that of astronomers, planetologists, who don’t know much about biology but would like to share their understanding of where life could possibly emerge and be able to survive.

If you want to know more, attached to this entry are some of the current reviews by Journals and Magazines.

We hope the book and its different point of view will add something to the current available literature which abounds since Astrobiology and Exoplanetology are relatively new interdisciplinary fields but vey attractive ones for all kinds of experts: biologists, geologists, atmospheric physicists, astronomers, climatologists, etc…

Links about the book Life Beyond Earth:
Cambridge University Press
Cambridge University Press, Blog
Times Higher Education
The Guardian





GRAVITY : The Journey To And From Earth

I’m sure you’ve all seen the movie GRAVITY, otherwise you’re not really so interest in space or such rocket-freaks as I am. If you haven’t, what follows includes spoilers…
Some of my friends who saw it said it was excellent but hated the suspense. Others the ending, my friend Isabelle hated the disappearance of Clooney so soon, but then again Isabelle so looooooves Clooney (which is why she and I are still good friends, I’m simply craaaaaazy about Pitt and Cruise…)
But I digress…

The movie moved me (sorry about the pun) a lot, and apologies to all, I loved it all – start, middle and ending. Also Sandra Bullock is a favorite of mine and she’s so real and such a great actress (how does she manage to keep so fit?). So, first of all, after having endured the suspense (congrats to the authors for managing to keep us interested with basically only one actor and void throughout the film… I wasn’t bored one second…) it’s always nice to have a happy ending. And what ending ! Coming out of the water, learning to walk… what a great analogy with humankind’s first steps, emerging from the oceans, learning to breathe and slowly rising on their two legs and learning how to use them… Never mind how she managed to land on one small tiny little bit of water pond…

Even a scientist like me can ignore some of the possible strays from real facts because the purpose here is to show than humans can survive anywhere : In space and on all kinds of extreme environments on Earth. See my recent book with Therese Encrenaz, published by Cambridge University Press, in which we discuss “Life Beyond Earth: the search for habitable worlds in the Universe”. And maybe the reason why we look for them is not only about finding other life forms, but also about discovering other places where humanity could move and inhabit when our Sun turns into a Red Giant and other places that could teach us how life emerged and how to survive in strange environments.

And even if the Clooney ghost and lost little girl melodrama do not add to the facts, I cried my eyes out with them which proves it’s a good movie, a healthy movie because humans like to get emotional in space, I know I would if I had a chance to fly out there, but I won’t – short-sighted you see… Although, in a Radio show recently someone asked me if I’d like to go to space and the same answer came out again, the one I don’t have to think about : “yes, I’d like to go, but only if I were sure not to return”. Returning takes up so much of your energy that it seems to me you won’t be able to appreciate the trip. I’d like to just sit back in a cabin and spend hours reading and contemplating the wonders in our Solar System, not having to worry about oxygen supply and lift-off and re-entry and landing and all of those things that make a space mission so cumbersome and impossible in some cases. But perhaps I’d do that only after I’m 90 or so, I’d like to take advantage of life on Earth and my family in the meantime. But maybe they won’t take me in NASA when I’m old and decrepit – I’ll have to get Sandra to give some hints about keeping fit…
But I digress again…

I’m sure we’ll land on Mars some day and we may be capable of exploring or even terraforming other planets or satellites – that’s why I got so interested in Titan in the first place : can it be a different kind of Earth that could teach us so much about our planet and life occurrence just by changing perspectives? But the most important thing, as Ulysses (Odysseus in reality) would put it, is the journey – the journey to Ithaca, the journey from Earth to planets (and back for some). Humans can do it  !

Listen to C. Kavafis : Enjoy the journey !

by Constantine P. Kavafis (1911)

When you set out on your journey to Ithaca,
pray that the road is long,
full of adventure, full of knowledge.
The Lestrygonians and the Cyclops,
the angry Poseidon — do not fear them:
You will never find such as these on your path,
if your thoughts remain lofty, if a fine
emotion touches your spirit and your body.
The Lestrygonians and the Cyclops,
the fierce Poseidon you will never encounter,
if you do not carry them within your soul,
if your soul does not set them up before you.

Pray that the road is long.
That the summer mornings are many, when,
with such pleasure, with such joy
you will enter ports seen for the first time;
stop at Phoenician markets,
and purchase fine merchandise,
mother-of-pearl and coral, amber and ebony,
and sensual perfumes of all kinds,
as many sensual perfumes as you can;
visit many Egyptian cities,
to learn and learn from scholars.

Always keep Ithaca in your mind.
To arrive there is your ultimate goal.
But do not hurry the voyage at all.
It is better to let it last for many years;
and to anchor at the island when you are old,
rich with all you have gained on the way,
not expecting that Ithaca will offer you riches.

Ithaca has given you the beautiful voyage.
Without her you would have never set out on the road.
She has nothing more to give you.

And if you find her poor, Ithaca has not deceived you.
Wise as you have become, with so much experience,
you must already have understood what Ithacas mean.”

Yes, this is a bit of windy Mars. Really.

ESP_034234_1255_1.0xA piece of Mars: Yep, this is really Mars. It’s a tiny bit (600×450 m) of the southwestern side of a large dune in the southern midlatitudes. The dark lines are furrows that are thought to be carved by blocks of CO2 ice that slide down in the spring. The tiny stripes are ~4m wavelength windblown ripples that are just starting to get covered in seasonal frost. Both the furrows and ripples are likely to be active today. (ESP_034234_1255, NASA/JPL/Univ. of Arizona)