Mars Exploration by Humans

Want to go to Mars? So do about 200,000 other people who responded to the first calls for Mars explorers by the Mars One team last year. It reminded me of S. R. Hadden in the movie Contact, showing Dr. Arroway his secretly built launch complex and asking her, “Wanna take a ride???”

In this case, a LOT of people wanna.  And, I don’t blame them. Mars is a new frontier, it represents a huge challenge, and there’s this romantic SF-ized idea that going to Mars will allow us a new start on a new planet. Not an unfamiliar concept to humanity: don’t like it where you are? Go somewhere else and colonize. That’s part of our history.

Make no mistake about it, however, going to Mars isn’t going to be a walk in the park. The applicants for the Mars One mission will be facing an entirely different kind of climate, gravity, and magnetic field environment on Mars from what they’re used to on Earth. Just the 210-day trip to get there once they leave Earth is going to be a psychological and physical challenge. They’re going to be in space, in weightlessness for much of that time, and then land on a planet that has gravity they’ll have to adapt to. Granted, it’s a lower gravitational pull than Earth’s, but it will still be a change.

The Mars One team has outlined a pretty ambitious time line for exploration that looks like we could have people on Mars in about 11 years from now. That’s very interesting, because I’ve been saying for a long time that the first Marsnauts will be our kids, or maybe our grandkids. That’s changed now. They could be our neighbors, our friends, ourselves. Before they leave on this one-way trip to Mars (and yes, it is one-way, for now), they will have trained for eight years to become proficient in living in the hostile conditions of the Red Planet. They’ll be ready to do whatever work they need to do on Mars to continue the explorations our rovers and mappers have begun for us over the past few decades. Mars is worthy of exploration, and in the long run, it may well prove to be a second home for humanity. The scientific payback could be huge, particularly in planetary science, where researchers will have at least two (three, if you count the Moon) sources of data about how rocky planets work, how they formed, how they evolve, and what ongoing processes change them.

The main points of the Mars One mission are familiar to most of us who have followed plans for taking people to the Red Planet over the years. Some years ago I was part of the original Mars Underground, a group of people who continued to plan Mars missions after NASA’s focus on human missions slewed to the Space Station and Shuttles. We had meetings every so often, and focused on such issues as timelines to Mars, practice runs on Earth and the Moon to train for Mars, propulsion systems, human health and medicine, the sociology of going to Mars, utilizing resources ON Mars to survive there, precursor missions to locate those resources (water, etc.) as well as appropriate places to land, and the psychological issues that could arise during such a mission. I see much of the same kind of enthusiasm and planning in the Mars One mission guidelines, and even more important — appropriate business decisions about how to fund such a mission. It’s not a single nation’s ride anymore. It’s multinational, something we knew back in the days of the Underground.

So, it’s all good. I like where Mars One is going. Maybe someday I’ll sign up (they do signups every so often to keep the astronaut pool replenished). For now, I’m following their progress with great interest. Very soon they’ll be building simulation habitats here on Earth to use in training the first crews. They have a business model in place, they’re partnering with organizations like Uwingu and others to raise funds, they’re inviting supporters to join and make community decisions about the eventual missions. They’re moving forward. I like that. I envy the first mission folk — they’ll have a helluva ride in front of them, and they’ll be paving the way for the rest of us who want to set foot on Mars in our lifetimes.

Enceladus Has a Watery Ocean

Back when we knew much less about the solar system than we do now (and I’m talking maybe the middle of the last century), people who studied the solar system thought that Earth was about the largest primary source of water in the solar system. Oh, they knew about comets and their watery makeup, but for the most part, it seemed like Earth had the corner on the water market.

It turns out, Earth is not quite the oasis in a water-poor solar system we once thought. Water is everywhere, we just have to use the right tools to find it. Today, astronomers on the Cassini Solstice Mission, which operates at Saturn, have gathered more evidence to confirm that the icy moon Enceladus (which is small — about 500 kilometers across) has a subsurface ocean of liquid water. Enceladus is one of Saturn’s moons and is best known for its geysers of particles streaming out from cracks in its surface, which scientists long suspected was coming from some body of water beneath this moon’s frozen crust.

What evidence helped to confirm that Enceladus has an ocean? Sami Asmar of NASA’s Jet Propulsion Laboratory explained that it was a combination of Cassini observations and measurements of signals received from the spacecraft by the Deep Space Network. That’s right, it was deduced by using radio signals and how they’re affected  by gravity.

“The way we deduce gravity variations is a concept in physics called the Doppler Effect”, he said. “It’s the same principle used with a speed-measuring radar gun. As the spacecraft flies by Enceladus, its velocity is perturbed by an amount that depends on variations in the gravity field that we’re trying to measure. We see the change in velocity as a change in radio frequency, received at our ground stations here all the way across the solar system.”

In layman-speak, the Cassini spacecraft “feels” the gravitational tug of Enceladus, and that tug changes depending on what part of Enceladus the spacecraft is closest to. The changing tugs slow down or speed up its orbital velocity just a tiny amount. That change in speed also changes the frequency of the radio transmissions from Cassini. When the ground stations receive the signal, scientists analyze the signals and can tease out the Doppler effect. That gives them a clue as to the gravitational tug the spacecraft feels as it goes past Enceladus. The gravitational tug of a region full of water is different than the tug of a region that is mostly ice.

The gravity measurements independently suggest a large, possibly regional, ocean about 10 kilometers) deep, beneath the thin icy shell that makes up Enceladus’s surface. That shell is probably around 30-40 kilometers thick in places.

So, is there life on Enceladus?

What does this confirmation of a watery on Enceladus mean for the search for life on other worlds? For one thing, it adds to the list of places where water exists in the solar system. We know there was lots of water on Mars in the past and there is still some there today. How much, we don’t know yet. We also know there’s water at the Moon, but the amount of it (particularly water “encased” in rock) is still under debate. Jupiter’s moon Europa has long been suggested as another place for water, and its frigid surface is made largely of water ice. It’s likely there’s a water ocean under that surface, as well. Of course, the comet reservoir out in the Oort Cloud is known as a “sink” for water ice, given that so many comets show water in their chemical signatures. So, water isn’t an unknown thing beyond Earth anymore.

The first thing that comes to mind when you think about water somewhere on a planet or moon (or even a comet) is life. If there’s water there, could there be life? That’s a reasonable question to ask, actually. Water is always touted as one of the Big Three Ingredients for Life, along with food and heat (energy). We know life happened here on Earth, where there’s lots of water, so it’s logical to assume that it could happen in other wet places. You just need to look for warmth and something for the life to munch on.

At Enceladus, the existence of a subsurface ocean puts it on a short list of places in our solar system that could host microbial life. Couple that evidence with the very obvious gushers of water coming from fractures that planetary scientists have been seeing for some years now, and you have a place that could be hospitable to life. That’s IF it has a source of warmth for microbial life. The food comes along in the form of organic materials that have been detected in the salty spray erupting from beneath the Enceladus surface.

There’s no evidence (yet) that life exists in the Enceladan ocean. That’s a story that requires more data, more study, and more analysis. The big news here is that we’re adding yet another watery place to our list of solar system places where life could exist, given the right conditions.

Thanks to Cassini Director of flight operations Carolyn Porco, who is also the mission Imaging Lead for clarifying the nature of this amazing work!