October 15, 1997: I am Cassini and today I depart from Earth to begin my journey through space. I fear that I will let my creators down because I am only as good as they have made me. Things in our universe are constantly changing. The prospect of increasing our knowledge of space with this mission is an advancement within itself. I know it will take a long time to arrive at Saturn. All of us will need to be patient. I barely know what I will discover because Saturn and its moons are a mystery to me.
But in this moment, from here, I simply marvel in the beauty of my Earth.
April 25, 1998: My spirits are up because today I conducted my first Venus flyby. A flyby is the word we use to describe the way I fly extremely close to a planet. After my travel around the sun, I was able to fall into line (176 miles away) with Venus in order to gain a speed boost. Back home, the humans are celebrating my first major achievement. It’s a good day.
June 24, 1999: It is the 617th day of my travel, which is strange to me because in space it feels like time stops.
The two flybys and my initial travel away from the Saturn were necessary. Each time I conduct a flyby, it increases the speed at which I travel. If I was to attempt to fly from Earth directly to Saturn, it would take substantially longer than the seven years currently projected.
Nonetheless, today I have completed my second Venus flyby and am going at a faster speed than before. Saturn, here I come…
August 17, 1999: Today I’m flying by Earth. My planet. So close, yet so far. My creators are there somewhere, among the deep blues and greens that can be seen from outside. It’s lonely out here and the reality hits hard that this may be my last time so close to Earth and our moon, which are only 700 miles away from me right now.
Earth gives me yet another speed boost and I continue towards my destination.
December 1999: The first emotion I feel when I see the asteroid belt is fear, but my controllers reassure me that as a spacecraft, I will not be harmed. Passing through the belt however, is different than traveling through space. It’s dusty and to me looks like rocks hanging in the air, suspended in space. It’s kind of cool to actually see it.
July 1, 2004: This is huge. I have reached Saturn and have become the first spacecraft to orbit it. It has taken seven years, but the wait has been worth it. The great mystical planet and its moons are in my grasp, and I am determined to find out as much as I can about them.
January 14, 2005: About a month ago, Huygens, my close friend and fellow probe, detached to fulfill his own destiny to land on Titan. I have just received news that he did and also made incredible observations about the geology on Titan.
Mountainous regions are present on Titan, which leads to the conclusion that there are active tectonic forces that are hidden beneath its surface. It sounds familiar because Earth also has tectonic plates that move and create mountains. This is a definite resemblance to Earth — and I wonder what else about it could be similar.
March 8, 2006: There was always something funny and strange about one of the moons, Enceladus. I could never place it, and neither could the scientists back home. Not only was this spectacular moon covered in ice, I also detected areas of water vapor and varying temperatures. In order to create water vapor, there must be some source of internal heat. On July 13th last year, we found a crack in the crust that supplied this heat; however, it was still mostly undiscovered to us.
Today, I have found evidence of liquid water beneath Enceladus’ icy crust. While this doesn’t sound all that spectacular, the implications of this are immense. Liquid water could mean that Enceladus has conditions that can sustain life, since water is essential for its existence.
Could Enceladus possibly harbor life like that of Earth’s?
December 14, 2008: There is definitely geological activity happening on Enceladus. From space, I can see visible tiger stripes on its surface and plumes of particles and gases. We’ve known that Enceladus was icy but the more I observe, the more we find out about the regions beneath the surface. I guess it aligns with the saying to “never judge a planet by its cover.”
June 21, 2011: This journey has been going on for years now, but with each new discovery, I feel energized and excited. Over the years of examining Enceladus, I’ve observed evidence including ammonia in the plume and the amount of salt in Saturn’s outermost ring that indirectly affects the climates of Enceladus. These all contribute to our claim that Enceladus most likely has a saltwater reservoir of some sort beneath its icy exterior.
March 5, 2013: Today marks my 100th flyby of Titan, the moon of Saturn that most closely resembles the Earth. We’ve found that it has similar geology, seas of methane as well as a hidden ocean comprised of water and ammonia. Ammonia adds to the evidence of liquid water on Titan because it dissolves in water and has antifreeze properties, which allows water to stay liquid at cold temperatures. It makes sense 一 especially because Titan is cold but shows extensive evidence of liquid water.
To imagine that a foreign planet has ammonia (NHз), a compound humans discovered, is mind-boggling. It further compares our very own Earth to a moon almost 1.4 billion kilometers away.
The possibility of life on Titan remains a question. Though there may be water, the surface temperatures are still around minus 290 degrees Fahrenheit. What would life even be like on Titan?
No sky, just an icy layer above. Would there be plants? No photosynthesis. It would be like a completely different kind of world, completely unlike our Earth.
April 12, 2017: Does our world really make sense? I guess that’s what science is for. I’ve found myself wondering about this as I continue to orbit the moons. How were these even created? I guess scientists would say the Big Bang, but before that, was everything just nothingness?
Enceladus is my new favorite moon because each time I flyby it, I discover new things. This time, I’ve found hydrogen in its geysers. Hydrogen, according to the scientists back on Earth, is one of the key elements for life.
April 26, 2017: It’s dawning on me that my expedition is coming to a close and I am running out of fuel. It’s actually lasted so much longer than it was supposed to. My primary mission was only supposed to be four years but because there were so many observations to be made, the mission was extended. I’ve made them proud. Today I embark on my “ring dive,” a literal dive into the gap between Saturn and its rings.
Twenty two. That’s the number of dives I will complete through the gap. It’s amazing; I will be the closest I have ever been to Saturn.
June 29, 2017: Eleven done, eleven more to go. Halfway to the end.
September 15, 2017: The day has finally come. I’m a mix of emotions — but mostly, I’m satisfied. I’ve done my job and what I set out to do, I’ve completed many firsts and most of all, I’m content because I’ve made incredible contributions to the ever-changing world of science. It is time for me to complete my last task — plunging into the atmosphere of Saturn, my second home for the past thirteen years. Thank you Earth and my creators. What a marvelous ride it has been.
https://saturn.jpl.nasa.gov/the-journey/timeline/#launch-from-cape-canaveral (timeline of Cassini’s journey)