Carolyn Porco is one of my favourite planetary scientists. In additional to her major roles in my favouirte Voyager and Cassini missions she is a great communicator. Her passion and ability to share amazing concepts and findings is inspiring.
The photo at the start of this post was taken by the Cassini spacecraft in November 2013 looking back at the inner Solar System, as Saturn transited in front of the Sun. It was part of a campaign pioneered by Carolyn Porco as “The Day the Earth Smiled” (aka pale, blue dot 2.0).
Yesterday, Cassini executed its 20th close flyby of the small icy moon, Enceladus, in what was the first of our last three visits to this fantastic world. The close approach altitude was 1,838 kilometers (1,142 miles) over the moon’s high northern latitudes. Our cameras were active during most of this encounter, allowing the imaging team and other remote-sensing instrument teams to observe the Saturn-opposing side of Enceladus on the inbound leg of the encounter, and a narrow, sunlit crescent outbound.
Enceladus fascinates us because of a sub-surface, global ocean, lying a few 10’s of miles beneath its surface, that is actively venting into space. And though this magnificent mission, that left Earth 18 years ago today, is not yet over, we are already looking forward to the time, hopefully not too far in the future, when we can travel back to Enceladus with the express purpose of answering the question that burns in all of us: Could there be life under its cracked and cratered surface?
For now, dwell on these fabulous images from yesterday’s flyby of a moon clear across the solar system. We have another flyby coming up on October 28, and then another in late December.
The last two episodes of Cosmos were glorious and actually made me look at myself differently.
Being more scientist than historian, I never knew of Cecilia Payne. And now I discover she, too, said this:
“The reward of the young scientist is the emotional thrill of being the first person in the history of the world to see something or to understand something. Nothing can compare with that experience… ”
So true, Cecilia. So true.
And I never knew of Marie Tharp, either. It’s telling that I was educated in the Division of Geological and Planetary Sciences at Caltech, had certainly heard in reverent tones the story of Alfred Wegener, but had never even heard the name of Tharp.
Many grateful thanks to Ann Druyan, Steve Soter, Neil deGrasse Tyson, and the Cosmos crew for bringing to light the stories of these women greats of astronomical and geological history.
And to my fellow female scientists, I hope you now see yourselves differently, too. You and I are part of a fine & noble lineage. Walk tall and proud forevermore.
We on Cassini received wonderful news today. In a review this past summer of all the 7 NASA missions seeking to extend their operations for several more years and requesting additional funding to do so, Cassini was the only one of them receiving an unqualified `Excellent’ for its science and future plans. So, we are now gratefully anticipating another 3 years of exploration, with mission operations ending on September 15, 2017 with a dramatic nose-dive into the planet.
How wonderful it is to know that we will live out the full, unabridged promise of this extraordinary mission. For many of us, for the past quarter century, it has been a way of life. For many of us, its end will mirror the end of a major portion of our life’s work.
But this is no time to get sentimental. We now are looking forward to 3 more glorious years of new discoveries and insights, three more close flybys of Enceladus, flights over the Saturn pole and through the rings, and, of course, many more of the most soul-stirring, magnificent vistas there are to be seen anywhere this side of the Oort cloud.
Today, the European Space Agency released an image taken by the Rosetta spacecraft on its very close (8.7 km altitude) flyby of Comet 67P. This mind-blowing scene shows details as small as ¾ meter. You could discern astronauts in an image like this! It reveals a portion of the comet 1.3 km, or ~¾ mile, across….an easy 15 minute walk here on Earth and a trivial (but scary) hop on Comet 67P.
Even as someone who has seen, and even been responsible for, a lot of glorious images of the worlds in our solar system, I am stunned by these pictures. Our pre-exploration imaginings of what the surface of a comet might be like were so lacking.
Now, look at all there is to see and learn in this place where complicated processes have obviously worked the surface. Hats off to the Rosetta folks for a magnificently successful expedition.
I was asked by the National Academy of Science’s Committee on Astrobiology and Planetary Science to present to them the significance of Cassini’s findings at Enceladus, and make the case for a return mission to focus on the search there for evidence of life.
At no other place in the solar system does an extraterrestrial sub-surface ocean of salty, organics-laced liquid water present itself so handsomely, with samples shooting into space, readily accessible to any passing spacecraft.
Earlier this month, I stood before the Committee and made my case (see attached photo).
Fingers crossed that we won’t have to wait too long before we set sail once again for the Saturnian system, this time to probe more deeply and with greater facility the secrets of the ocean we now know lies hidden beneath the surface of the small icy world of Enceladus.
Yesterday a team of us scientists and engineers submitted a proposal to NASA’s Discovery program. The goal: To conduct a mission back to the Saturn system and search for life within its small icy moon, Enceladus! Since all details concerning the mission are still embargoed, and will be until we are selected … if we are selected … I am not free to divulge how we intend to go about this search. But I can say that we will be doing what Cassini cannot, and may in fact be employing diagnostic techniques never used anywhere before in the exploration of the solar system.
I thrill at the thought of it.
When I was a graduate student, moons like Enceladus, and even Titan — both seen in the image here — were mere points of light in the world’s largest telescopes. Forty years later, we’ve been there and know the tantalizing possibilities that are present but hidden and just out of reach.
If our mission is chosen, we may have the chance to make the most intellectually significant and emotionally satisfying discovery humankind has ever made: That a second genesis has occurred in our own backyard and, by inference, that life is not a bug but a feature of the universe in which we live. A look up at the night sky thereafter will never be the same.
One of the many intriguing findings that our Cassini cameras have made at Saturn has been the long, sinuous, finger-like projections emanating from the geysering moon, Enceladus, into the diffuse E ring in which the moon orbits. Now, I’m happy to say that my research colleagues and I have published a paper online, in the Astronomical Journal, reporting the origins of these features in the strongest geysers erupting from the south polar terrain of Enceladus. See for yourself in our new report how well we are able to match the structures of the tendrils with our computer simulations of icy geyser particles leaving the surface of the moon.
This result will ultimately give us a way to estimate the amount of material leaving the ocean of Enceladus and making its way into orbit around Saturn, and from there, just how long-lived the ocean may be.
As you can see, we’re still going strong, and will be til the end! Enjoy!
A Letter to My Friend and Colleague, Carl Sagan, on the Occasion of His 80th Birthday
November 9, 2014
It’s so lovely to be beaming this message to you on your 80th birthday. As you may be aware, the world hasn’t changed much since you left. It’s still a great mess. It’s still looking like we may destroy our civilization after all. Political gridlock is as bad as anyone can remember, and there’s no end yet in sight to the damage we are doing to our environment and our future. Regrettably, in the hallways where power congregates, they are still not listening to you..
But I gotta tell ya… Titan was even more wonderful than even you could have imagined. Seas of liquid hydrocarbons are strewn around the poles. Methane clouds that change seasonally float aloft. And a wide belt of miles and miles and thousands of miles of dunes encircle the globe. Who expected that?! So much like Earth and yet so not.
And you wouldn’t believe what we found on Enceladus! A hundred and one geysers gushing from the surface, laced with organic compounds and erupting from a deep salty sea. It just might be the very place you wished with all your might we could find. Someday, hopefully soon, we may know if…well…you know. Fingers crossed.
And now we’re on the eve of exploring the Kuiper Belt, starting w/ a most historic rendezvous with Pluto, and in only a few days we’ll be landing on a comet. We’ve made great strides in our efforts to know how and where we are. I know all this would have made you smile and would have given you great hope. Just wish you were still here to cheer us on.
Oh, and didn’t Annie do a great job with Cosmos II? You would have been so proud.
Well, wherever you are right now, undoubtedly out there somewhere in the cosmos, having a blast, the happiest of Happy Birthdays to you!
We miss you.
Your friend and colleague, Carolyn
PS. Sending along some pictures from happy days … at Voyager’s encounter with Neptune in 1989, and your 60th birthday party twenty years ago. How time flies.
Today, after more than five years of analysis and thought, our findings resulting from a 6.5-year imaging survey of the south polar basin of Enceladus are finally published online in the Astronomical Journal.
We have found in total 101 distinct geysers, one hundred of which erupt from the four, prominent, now famous `tiger stripe’ fractures crossing the region. In comparing our findings with those of other instruments, and with calculations of the magnitude and orientation of tidal forces that flex the surface on a daily basis, we have arrived at a conclusion that strengthens what we had all, little by little, over time, come to believe. In casting your sights on the geysering glory of Enceladus, you are looking at frozen mist that originates deep within the solar system’s most accessible habitable zone. Not bad for a decade’s work, huh?
As we contemplate the approaching end of Cassini’s travels around Saturn, we dream of the day, hopefully not too far in the future, when we can return to Enceladus to answer the question now uppermost in the mind: Could a second genesis of life have taken hold on this small icy moon of a hundred and one fountains?
For we surely know this: If life is indeed there, it is there for the taking.
Do you relish the notion of being a Saturnian, and gazing out from the lofty heights of Saturn at the same planets we see here from the Earth?
Then check out the image we, the imaging team on Cassini, just released today. Far in the distance, beyond the rings of Saturn, lies the hazy blue orb of Uranus, a planet that was last visited by a spacecraft of our making 28 years ago.
Twenty-five years ago today, Voyager 2 flew within 5,000 km of the cloud tops of Neptune, capping the most glorious and ambitious exploration humankind has ever engineered. We could not claim to know the contents of our cosmic neighborhood without Voyager’s tour through the planetary portion of our solar system. For many of us, including myself, it was a defining, life-shaping experience.
Here are some pictures from that oh-so-memorable time … a time of discovery and peaceful conquest that set the stage for the return expeditions to Jupiter and Saturn, which came to be called Galileo and Cassini. The pictures include artwork, a close-up of the high methane clouds on Neptune, preparations for TV interviews by MacNeil-Lehrer Newshour and CNN, the final press conference in which I gave the summary of our findings on Neptune’s rings, and a pic of Chuck Berry and Carl Sagan, speaking to the Voyager team members already giddy in their celebration of the successful conclusion of Voyager’s historic, 12-year odyssey.
From the finest details ever glimpsed on the surface to a glorious,
dimly lit crescent seen in ‘Farewell!’, here are Cassini’s parting shots
taken of Saturn’s 700-mile-wide moon, Dione, during its final close
flyby four days ago.
Right down to the very last, Cassini has faithfully delivered an extraordinary bounty of riches from this small icy world.