Whew! Egypt = amazing. I can’t even begin to describe the wonder and awe of standing inside a pyramid or walking the Avenue of the Sphinxes or sailing in a felucca on the Nile. It really is something everyone should do at some point in their lives.
The best part is that it seems I bear some resemblance to an Egyptian soap star, and had many requests to have my picture taken with people at the sites we visited. So much for my attempts to blend in to the crowd …
—Photo by Jon Pearse
But enough about moi, it’s Planetology day! The book is now officially released, and lucky me got to chat with the authors, astronaut Tom Jones and planetary geologist Ellen Stofan, about their careers, their passions, and their extensive knowledge of planets.
What follows is a pared-down version of our conversation for your reading pleasure.
And don’t forget, there’s still time to submit a recipe for the solar system cupcake contest. The winner gets their recipe published here and a copy of Planetology sent to them—so get baking!
You note in the introduction that you first met in 1988 and your careers have been intersecting ever since. When did you start collaboration for this book?
Ellen: My best memory of that would be in 1993 or ’94, mostly when he was in training [for his first flight on the space shuttle Endeavour], and I feel like we’ve been talking about the book ever since then.
Tom: I was surprised to see Ellen when I got to [NASA's Jet Propulsion Laboratory] in ’90 or ’91 as an astronaut trainee and she was there on the staff. I think [the book] was always in the cards as a project we’d both be interested in once we realized we’d be working together on the shuttle’s Space Radar Lab missions.
After all, there’s the fact that we were both working on this Earth-observing mission and that [Earth sciences and studies of other planets] are so intricately related. You get the sense that by looking at features of the Earth from the ground and later from the shuttle you can actually transport yourself mentally to the surfaces of other planets.
What is planetology?
Ellen: It’s the study of planets. There are many university departments that are titled “Earth and Planetary Science.” That makes me laugh, because Earth is a planet. We think it’s special because we live here, but it really is one planet among many.
Which of the eight official planets in our solar system—other than Earth—is your favorite, and why?
Ellen: Venus is definitely my favorite. I’ve spent a lot of my career studying it.
One of the most interesting aspects is why Venus is so different from Earth even though it has a lot of the same basic components. It’s as if you bought a mix for lemon cake and baked it in two pans, but the Earth came out as a chocolate cake and Venus came out as a lemon cake. Why did this happen? There are so many questions we have about Venus. But also it’s covered with volcanoes, and I love volcanoes.
Tom: There’s not a planet that’s my favorite, but I really like asteroids … They’re the leftover building blocks of planets preserved. By sampling asteroids with robot or human explorers, we’re actually going to have these early raw ingredients of the planets to study.
When you started writing, was Pluto still a planet? Did you have more information about Pluto worked into the book that later got cut?
Tom: It was, but right now we have very poor images of Pluto—they’re fuzzy, blurry—and because it’s such a small body more akin to asteroids, it’s not central to the story we’re trying to tell in the book. Even some of the moons of Saturn and Jupiter are much more active geologically than Pluto likely is.
Ellen: When it comes to changing Pluto’s status, you have to note that there are asteroids that fit the definition of a planet better than Pluto does, so astronomers have to draw the line somewhere. The great news is that on 14 July, 2015, the New Horizons spacecraft will make its closest approach to Pluto, and then we’ll know a lot more about it, and this argument will become a lot more interesting.
One of my favorite parts of the book is the fieldwork section, in which you describe some of your most memorable moments aboard the shuttle or conducting geology field trips around the globe. Other than Earth orbit [too obvious!] where was your favorite place to visit for fieldwork, and why?
Ellen: It’s always hard for me, because I’m terribly affectionate toward my volcanoes, but one of my favorites is Mount Etna in Sicily—it’s everything you’d want a volcano to be! It’s been erupting for thousands of years, so it’s a great model for long-term studies. My other favorite place is Iceland, which is covered with volcanoes and is extremely beautiful.
Tom: Not a lot of astronauts get to do geological fieldwork, only long-duration crew members get time to look back at Earth with regularity. I got to go to Hawaii and stalk around the lava fields of Kilauea. I got to go as close as arm length to a lava flow and stick a hammer in and pick up a glob of stuff, then watch it cool—it was so hot it almost scorched my eyebrows off!
I also got to go to central Australia to see ancient folded rock formations that are perhaps harboring oil and gas deposits. Another place I thought was really interesting was Death Valley [in the western U.S.]. We saw a variety of sand dune types built by the wind, and these are similar to what we see on other worlds. Titan has sand dunes, Mars has a lot of sand dunes, we’ve even found them on the surface of Venus.
Okay, I have to know: What is it like looking at Earth from the shuttle?
Tom: It’s achingly beautiful to look at a planet from space. Looking at Earth, it’s as if you have the pages of a geology textbook flipping by you as you orbit … When I flew with the Space Radar Lab it was for eleven days at a time. We had to have [optical] cameras at the ready for capturing our science targets and later, back on the ground, we could compare our images to the radar images. Knowing the environmental conditions and the lay of the land, we could better interpret these radar views of Earth. Experiencing the view of our planet offered by the shuttle was one of the highlights of my life.
Now radar imagery is pulling back the curtains on the subsurface of Mars and penetrating the hazy atmosphere of Saturn’s moon Titan—That’s information we would never get with other instruments.
One of the more poignant fieldwork stories is about taking radar imagery from the space shuttle of the Virunga volcanoes, where today political strife is endangering some of the world’s last mountain gorillas. In the image used for the book, what do the false colors tell you about Virunga’s ecosystem?
Ellen: The area is quite mountainous, and where the park is, the area is really cloud covered, so we were pleased to use radar, which can penetrate the clouds. The different colors are different types of vegetation, and we can use that to say these areas are covered by jungle, these by agriculture.
We took those images for people out in the field so they could better delineate wild habitat where gorillas are likely to be. It shows where there are places where changes are made by nature, such as when a volcano erupts, but also places where humans are causing great changes. Being able to pull back the clouds and look at Earth from space, you can see the situation is quite critical.
In the book you mention that Earth is the only planet known to have plate tectonics, so what else is driving geologic events such as earthquakes and volcanoes on other worlds?
Ellen: What drives these processes on the surface is heat from a planet’s interior—you have to have a heat engine within. On Earth, most of that internal heat goes to plate tectonics, and we have a lot of it because there’s a lot of radioactive elements inside Earth that give off heat as they decay. Venus has the same amount of these elements and its about the same size as Earth, so it is likely to still be active. Mars is much smaller, so it’s more likely to be geologically dead. Still, Mars may have had plate tectonics in its past and so may have Venus.
On some of the geologically active moons around the gas giants, something else is causing the interior of the body to heat up. One example is that the gas giants are so big that they tug on the satellites in orbit around them. You get what are called tidal forces that pull on and thus heat up the interiors of these satellites.
Are you pretty much convinced that liquid water existed on early Mars?
Ellen: I think there is absolutely no doubt. There’s debates of over how long it persisted on the surface, but the evidence at this point is that there were probably long periods of time when Mars had liquid water on its surface. In my opinion, water probably was there long enough for life to form, but that’s “belief science,” not “fact science.” I think finding evidence of past life will take astronauts on the surface.
Tom: The Phoenix Mars lander has actually scooped up chucks of ice, so our machines have touched frozen water on the surface of Mars. The next step will be sending craft to the surface where we suspect there’s water near the surface and really digging into the soil to assess whether there’s biological activity.
We know that microorganisms called extremophiles can survive harsh conditions similar to what we’re seeing on other planets in the solar system. If we do find alien extremophiles someday, would they be the most advanced life likely to arise in those environments?
Ellen: For bilions of years Earth was dominated by single cell bacteria, so that’s probably the most likely form of life we’re going to find.
Tom: We find the most adaptable life forms on Earth are the least complex. Those are the ones we’re likely to find hanging on tenaciously on Mars or extrasolar planets.
Have any missions been proposed to send earthly extremophiles to another planet, to see if they’d survive?
Ellen: There’s an international group involved with planetary protection, and there is an extremely strong feeling that if we want to understand how life evolved, we need to be so careful not to contaminate other worlds. We want to make sure if we find it somewhere else, we can really study it in pristine form. Already spacecraft that go to Mars have to go through an elaborate process of being sterilized.
Tom: Recently there were news reports about “water bears” [tardigrades] surviving in space after launch … Those things can survive if they’re accidentally left on the surface of a craft. It shows how determined life is to hang on under extreme conditions.
How long do you think it will be until we put a person on another planet? Who will that person be, and which planet will they first set foot on?
Tom: Technologically we’ll have enough experience and smarts to have humans on Mars by the 2030s. The big unanswered questions revolve around our vulnerability to space radiation exposure and whether humans can tolerate living outside Earth’s geomagnetic field, which shields us from cosmic rays.
We don’t have the answers yet whether people can tolerate the doses they are going to get [from building a base on the moon or Mars]. Short visits of a couple weeks will be fine on the moon, but you still have to watch out for big solar storms.
It turns out water is a pretty good shield against radiation, but it’s heavy. You can only carry enough up there with you to shield a small area for a couple days until the storm dies down, so protection while traveling across the solar system is going to be hard to provide. But figuring it out is going to be necessary to get the answers to questions about life on Mars. We may find that we can launch a hundred years’ worth of robots and still not get the definitive answers until an astronaut field explorer makes the trip.