Category Archives: Planetary Science

Mars Rover Discovers Chocolate on Mars

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Scientists at the National Air and Space Museum’s Center for Earth and Planetary Studies announced an astounding discovery at a press conference this morning: the NASA Mars rover Curiosity has found chocolate on Mars.*

“Definitely more than just a trace,” said CEPS spokesperson Dr. John Grant. “More than a trace, less than a Snickers. But there could be more.”

“We were completely blindsided by this,” he said. “The Gale Crater area of Mars is about the last place you’d look for chocolate if you were looking for chocolate on Mars, which we weren’t.”

Mars

This color panorama shows a 360-degree view of the landing site of NASA’s Curiosity rover, including the highest part of Mount Sharp visible to the rover. That part of Mount Sharp is approximately 12 miles (20 kilometers) away from the rover.

 

“Here we were, searching for evidence of whether Mars was ever habitable, and we found this. Complete surprise. Curiosity was scraping away some surface materials and unearthed this small, dark, irregularly shaped mass,” Grant said, showing a sharp, close-up photo of the find, which looked vaguely like a Hershey’s bar left out on the beach.

“The initial chemical analysis was perplexing. We were prepared for the possible discovery of organic substances of some sort, but nothing like this. We ran the numbers and scratched our heads, then suddenly realized, ‘Whoa! This is, like, 90 percent cocoa, at least. Maybe more!’ Very pure stuff. Very exciting.”

The discovery begs the obvious question, where did the chocolate come from? Could it be a contaminant introduced by Curiosity itself? Perhaps a smudge left on the rover by a sloppy technician with sticky hands? “No way,” Grant asserted. “the rover is extremely clean and virtually sterile at launch. And because of the nature of the deposition, we don’t think it was a candy bar accidentally dropped by a passing alien or something. It’s a mystery.”

Curiosity

Artist concept of rover Curiosity on Mars.

When asked about the prospect of beds of chocolate on Mars that could perhaps be mined and used to sustain future explorers on the Red Planet, Grant laughed. “That’s just science fiction,” he said. “For now anyway. We don’t even know how much there is, but we’re certainly going to try and find out.”

The discovery clearly has profound implications for science and for humanity. It presents many consequential questions that scientists and others will now begin to grapple with. Of most immediate importance? Grant says: “Is it edible?”

David Romanowski is a writer and editor in the Exhibitions Department of the National Air and Space Museum.

*April Fools!

 

An Artistic Search for Pluto

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How do you illustrate a non-fiction book for kids based on the former ninth planet? Some people still have some pretty strong feelings about Pluto’s demotion: protest signs, student protest speeches, public demonstrations. Cries of unfairness could be heard when news of poor Pluto’s removal from the planetary ranks occurred. It is the intention of this new children’s book to set the story straight or at least attempt to share “Pluto’s side of the story.”

I‘ve worked in the children’s book market as a freelance illustrator for several years in addition to my full-time job with the Museum’s Early Childhood program. My latest book assignment from Abrams Books for Young Readers, Pluto’s Secret: an Icy World’s Tale of Discovery, connected my job as an artist and an educator.

Pluto's Secreet

Pluto’s Secret, An Icy World’s Tale of Discovery, by Margaret A. Weitekamp and David DeVorkin. Illustrated by Diane Kidd.

In publishing, typically the illustrator and the author never meet or exchange ideas. In some cases the author might live across the state or in another country. The approved manuscript is sent to the artist from the publisher. It is then up to the artist to find the visual voice of the text. Fortunately, for this project the authors Margaret Weitekamp and David DeVorkin were my Museum colleagues. In my first sketch, for example, I used my daughter’s old high school algebra homework, which was my interpretation of a possible equation mathematician Percival Lowell might have calculated. David knew right away it was not correct and gave me a copy of an actual Lowell equation which is now in the book. I also needed to re-work my idea of a telescope, which originally looked like one from Dr. Seuss, to one that looked more like Lowell’s telescope.

Telescope

Original draft of the telescope from Pluto’s Secret.

telescope

Revised draft of the telescope, based on David DeVorkin’s comments.

When I work, I use water jars, brushes, water color pads, and tissue paper. I need good lighting and scads of paper towel, and music really helps the flow. Next I usually consider color and composition. In this case, “What color should I make Pluto? Hmmm… Purple? Blue? Meatball brown? Red is taken by Mars.” There is also a lot of activity in space. Things crash into each other, explosions and collisions happen, surfaces have been impacted by objects bumping into them.  Maybe Pluto might have a somewhat bumpy surface with a few craters. What does dirty methane gas look like? An icy world might have a few patches of surface ice. What might life in a Kuiper belt be like? No one really knows exactly, so imagination holds the paint brush.

Pluto

Color sample for Pluto’s Secret, by Diane Kidd

First I sketched out my ideas then sent them to the editor for review and critique, and to Margaret and David for review. Later the publisher sent corrections back marked in red.  The corrected sketches were re-drawn and then re-submitted  to the publisher. Once all the corrected sketches were approved, I worked on re-drawing and painting each image by hand on watercolor paper.

In the past, the procedure of mailing sketches back and forth between the publisher and artist often took weeks to complete. Today sketches can be scanned and sent out and corrections returned within a few days. Once the designer receives the corrected art, he/she can lay out the text copy with finished art work and get a pretty good idea of what the final product will look like. No more mailing tubes or runs to the copy shop in the middle of the night, or trips to the local post office trying to make a deadline.

Nevertheless, I still waited with baited breath for comments from the art editor/publisher/authors as they reviewed the final art work. Did they like it? Did I get the right look? Did they notice that smudge? For me, this is one of the hardest parts of the process, the waiting. Finally, a thumbs up. Everything was approved. It’s a go.

My hope is that young readers and adults alike will have as much fun as I did learning why Pluto is no longer considered a planet and how “he” really feels about it. And I hope you like the book as much as I liked creating the art!

Diane Kidd is manager of the National Air and Space Museum’s Early Childhood Program.

Join us this Friday, March 15, at the Museum in Washington, DC to learn more about Pluto with the authors of Pluto’s Secret. Children can participate in educational activities, and purchase a signed copy of the book.

Scratching Beneath the Surface

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What’s inside a planet? What instruments do scientists use to figure it out? And what clues does a planet’s surface give us?

On Saturday, April 21, Lisa Walsh and I, scientists from the Museum’s Center for Earth and Planetary Studies, invited visitors to the National Air and Space Museum’s Explore the Universe Family Day to think about these questions, through two hands-on activities relating to our research into tectonics on Mercury. As the MESSENGER (Mercury Surface, Space ENvironment, Geochemistry, and Ranging) spacecraft starts its second Earth year in orbit around Mercury, we interacted with approximately 900 kids and kids-at-heart, asking them to figure out what was inside balloons by using tools analogous to those used in planetary science (scales, magnets, and, slightly less analogously, a good hard shake), and to piece together a puzzle made from images of Mercury’s surface.

Evidently you can’t just do one piece of the puzzle, because often people stuck around until the whole thing was put together, talking with Lisa about MESSENGER results and her own research.

 

explore the universe

Lisa Walsh talks with young visitors about her research during the Explore the Universe Family Day at the National Air and Space Museum in Washington, DC on April 21, 2012.

Lisa studies wrinkle ridges, which form on the surface of a planet when rock layers are crunched in from the sides, like scuffing in the edge of a rug with your shoe. This causes the layers to fault and fold, leaving ‘wrinkles’ in the surface. Wrinkle ridges are found throughout the inner Solar System, and have been mapped in greater detail on Mercury during the last year than was possible before the arrival of MESSENGER. Lisa wants to understand why wrinkle ridges on Mercury are so much larger than those on the Earth’s Moon, and what they look like beneath the surface on both planetary bodies.

The balloons were seemingly irresistible, since holding one out to any passing kid and asking them if they wanted to figure out “What’s Inside?” usually resulted in them spending the time to figure out all six, whether with a cohort of siblings or fellow boy scouts, or with a parent as engaged as they were. The balloons separately contained sand, iron filings, yarn, a magnet, a marble, and beads, with the iron filings being the most popular for further investigation. As the afternoon progressed, I frequently interacted again with previous visitors to the table, when they brought back friends or family to check it out.

 

michelle selvans

Dr. Michelle Selvans helps young investigators as they determine the interior materials of balloons, using scales, magnets, and a good shake.

Every participant left the table with something in hand (sticker, button, poster, or a model of MESSENGER to put together at home). But even more gratifying was seeing everyone leave with an appreciation for who studies the planets in our Solar System (we do!), how they’re studied (for example, through missions like MESSENGER, using instruments like the multi-spectral and multi-resolution camera we depend on for our research), and why they’re studied.

Why do we as a species study our neighbors in space? Why do we look for Earth-like planets around neighboring stars (the ongoing Kepler mission)? Why even study our own planet, its life and climate and geology?

If you ask ten people these same questions, you could very well get ten different answers. We all have our own reasons for being interested in the world around us. Maybe we’re concerned about how to protect people from natural hazards like hurricanes or earthquakes. Maybe we want to know if we are ‘alone’ in the universe, or whether life in any form exists elsewhere. Maybe we are awed by the beauty, intricacy, and divinity of the physical universe and just want to commune with it more intimately. Maybe, like for myself, practical, personal, and spiritual reasons all factor in.

 

Mercury

Mosaic of high-resolution MESSENGER images taken at dawn, showing several newly-identified tectonic features (arrows). Made by Dr. Michelle Selvans.

 

I study large faults on Mercury, which cast long shadows at dawn and dusk, so they’re easy to see when we take pictures at those times of (Mercury) day. They’ve been mapped previously all across the surface (using images from before MESSENGER went into orbit), and appear to be placed in a pattern that suggests global-scale stresses. As we collect pictures at dawn and dusk, I am mapping the greater number of scarps that are being revealed, to see if the pattern holds. I also use the elevation maps that other MESSENGER Science Team members are producing, in order to understand the shapes of the most intriguing faults (measured across the scarp). Those shapes will help me model the fault structure below the surface, in order to understand the shallow structure of Mercury’s crust.

That’s a little bit of what I do here in the Center for Earth and Planetary Studies. What would you want to know about Mercury if you were in my place? Or about any other planet in our Solar System, or beyond? Why are you interested in those questions? And how could we go about figuring out the answers?

We would like to thank everyone who participated in the April 21 Family Day fun, as well as the MESSENGER spacecraft Education Team for developing the puzzle, and the Lunar and Planetary Institute Education Team for the inspiration behind the balloon activity (the Investigating the Insides module, on their Explore! website).

Dr. Michelle Selvans is a planetary geophysicist in the Center for Earth and Planetary Studies at the National Air and Space Museum.

Climate Change in the Solar System

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We are all familiar with the climate on Earth: the seasons, the range of surface temperatures that are just right for being a water world, the oxygen we breathe, the ozone layer that protects us from UV radiation. In short: habitable.

So what other bodies in the Solar System might be (or might have been) habitable, and why aren’t they today?

Mars probably comes to mind, and for good reason. Mars has the most similar climate to our own, with water ice caps at the poles, seasonal snow, and dust storms. This is because Mars has a similar axial tilt as the Earth, which creates similar seasonal temperature variations. However, the colder average temperatures and the thin atmosphere mean liquid water can only exist on the surface around midsummer and at the lowest elevations (where the atmospheric pressure is greatest). The thin atmosphere also means the surface is exposed to intense UV radiation. Mars may not be habitable today (for life on the surface), but climates change.

 

Mars

Hubble image of Mars engulfed in a global dust storm, with its polar caps peeking through. Image courtesy of NASA.

Several lines of evidence point to Mars being wet and warm early in its history. Water-carved channels, minerals formed by interaction with groundwater (like gypsum), river delta deposits, and what may be a shoreline all the way around the northern lowlands (which would have been a giant ocean) all point to lots of liquid water on the surface sometime in the distant past.

So why was Mars so much warmer and wetter than it is today, and why did it change? These are fundamental questions about climate change that have yet to be fully answered.

Early Mars likely had a thicker atmosphere, made of mostly CO2 like it is today, which would have warmed the surface through the greenhouse effect. One way to understand the climate early in Mars history is to study the oldest rocks and landforms. Another is to look at more recent climate changes, which are likely preserved in the polar ice caps.

Just as ice cores on Earth provide a record of annual changes in climate, the thick stacks of polar ice on Mars have internal layering that suggests they were built up one layer at a time, for millions if not billions of years. (Some of the research I do here at the Museum is directly related to the internal structure of these ice caps, which I mapped out using orbital radar data. I am currently working to understand smaller-scale features buried in the ice.)

So if one of our neighbors may have been habitable in the past, what about our nearest neighbor, Venus?

Venus is almost the same size as Earth, and only slightly closer to the Sun. However, its axis does not tilt relative to the Sun, so it has no seasons like Earth and Mars. We know less about ancient Venus than we do about Mars, because the surface of Venus is relatively young (~1 billion years old). However, we think the atmosphere is much older than the surface, made up of mostly CO2 (like Mars, and like early Earth). With 100 times the atmosphere of Earth, its runaway greenhouse effect long ago boiled all the water off the surface. Some of that water is bound to sulfur and makes up the sulfuric acid clouds that circle the planet, but much of it was broken down in the atmosphere and removed by the solar wind. Venus is dry and hot, despite its clouds reflecting 80% of the sunlight that arrives, since it very effectively traps the remaining 20%.

 

Venus

Clouds swirl around the south pole of Venus, imaged in UV by Venus Express. Image courtesy of the European Space Agency.

So was Venus ever more like Earth?

Being so similar to Earth, Venus likely formed from the same material. The key to their different climates today may be in part due to Earth having plate tectonics, which buries carbon-rich sedimentary rocks (taking CO2 out of the atmosphere). Venus instead keeps all of its CO2 in the atmosphere. The clues to climate change on Venus will probably be found in the composition of its atmosphere, with isotopic ratios of elements like carbon and hydrogen pointing the way to understanding when and why it became so hot and dry.

Only those three inner planets in our Solar System have atmospheres thick enough and persistent enough to have climates that change over time. However, one moon in our Solar System, more massive than the planet Mercury, has an atmosphere. In fact, Titan, a moon of Saturn, was once thought to be the largest moon in the Solar System precisely because its atmosphere is so thick (1.5 times the atmosphere of Earth).

 

Titan

Titan is the only moon in the Solar System with a thick atmosphere, imaged by Cassini. Image courtesy of NASA.

Titan is particularly interesting because its atmosphere is made up mostly of nitrogen, just like the Earth. The remainder is mostly methane, which breaks down easily in the atmosphere and has to be replenished every ~50 million years; this implies some unknown but ongoing process. Titan gets 100 times less sunlight than the Earth, so its surface is frigid, cold enough that water ice is as hard as rock. So while Titan is not currently habitable for life as we know it on Earth, it is the only other place in the Solar System with rain (made of methane and ethane). However, in another 5 billion year the Sun will become a red giant star, and Titan probably will be warm enough to have liquid water on its surface, making it habitable at last.

For the time being, understanding the methane cycle on Titan (perhaps analogous to the water cycle on Earth) will help us understand climate change on Titan, and may give us insight into the behavior of climate on early Earth.

Titan, Venus, and Mars all have something to teach us about the possibilities for climate change and habitability on Earth. While nothing as dramatic as the changes experienced by Mars or Venus is likely to happen anytime soon on Earth, we do know that smaller changes in climate have had big effects on life, and vice versa.

When photosynthesis appeared on Earth ~2.5 billion years ago, it put oxygen into the atmosphere for the first time. When the “snowball Earth” episode ended ~500 million years ago, the warmer and friendlier climate produced macroscopic life for the first time. When extensive volcanism occurred ~250 million years ago, ~95% of life on Earth was wiped out. When the aftermath of a large impact cooled the climate ~65 million years ago, the dinosaurs died off. In the last million years, according to ice core records from Greenland and Antarctica,  recurring periods of warming and cooling (correlated with increasing and decreasing amounts of CO2 in the atmosphere) have caused repeated ice ages and interglacial periods; during the most recent interglacial period (from ~10,000 years ago to today), humanity has thrived.

 

Earth

The one climate in our Solar System that is "just right" for life, imaged by Apollo 17. Image courtesy of NASA.

Currently we are blessed with a friendly climate. What will help us best understand it? What more might we want to know about changes in other climates? What is the role of humanity in the future climate of Earth?

Michelle Selvans is a planetary geophysicist in the Center for Earth and Planetary Studies at the National Air and Space Museum.

Was Mars Ever Habitable?

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If all goes according to plan, on November 25th the Mars Science Laboratory (MSL) rover Curiosity will leave the Earth and begin its journey to Mars. Any delays due to weather or other factors should be accommodated by a launch window that extends until December 18th. The spacecraft will use a new landing system to arrive at its landing site on Mars in August, 2012, and the rover carries an impressive array of scientific instruments. The rover is about twice as large as the Mars Exploration Rovers Spirit and Opportunity, thereby enabling it to navigate terrain characterized by larger obstacles (such as rocks) as it travels up to about 200 meters (219 yards) per Martian day.

 

Curiosity

This artist concept features NASA's Mars Science Laboratory Curiosity rover, a mobile robot for investigating Mars' past or present ability to sustain microbial life.

The new landing system for the Mars Science Laboratory replaces the airbag system utilized by the Pathfinder and Mars Exploration Rovers during landing. The new landing system enables much larger rovers and science instrument payloads to be delivered to the surface of Mars than was previously possible and opens the door for future missions geared towards the eventual return of samples for the Red Planet. Upon entering the Martian atmosphere, the MSL spacecraft will first steer itself through the upper atmosphere before deploying a parachute and then using rockets and a tether to lower the Curiosity rover to the surface.

Curiosity’s mission is geared towards understanding whether Mars is or ever could have been habitable. Recent data from NASA’s orbiting spacecraft (Odyssey and the Mars Reconnaissance Orbiter) and the Mars Exploration Rovers suggests the planet has had a long and complicated history of changing environmental conditions and landscapes. Curiosity will follow those missions by deploying a diverse complement of instruments to interrogate the rocks and soils in the vicinity of the landing site. The “next generation” of instruments carried by Curiosity comprises a “mobile laboratory” and should lead to a quantum leap in our understanding of Mars’ potential habitability and how the surface of Mars evolved over time.

landing site

Images of Gale Crater, the selected landing site for the Mars Science Laboratory. The first image shows the regional context of Gale Crater (labeled on the left and discussed above) with colors representing the elevation of the land surface (purple lowest and red highest). The second image shows an example of high priority science targets for exploration near the ellipse (yellow box in first image shows the location) and the last image shows science targets within the target landing ellipse (white box in the first image shows the location).

Advances in landing precision enable consideration of smaller landing sites than was possible during prior missions and made it possible to access the selected landing site within Gale crater. Gale crater is attractive to scientists because there is a five kilometer (three mile)-thick section of layered rocks deemed likely to enable study of changing conditions on Mars over a time when the abundance and duration of water on the surface was decreasing over time. As water is an important factor in evaluating potential habitability, the chance to access the rocks that record the changes from relatively wetter to drier present an opportunity to learn a great deal about Mars as a planet and its potential as a possible abode for life.

Curiosity is an important step in the long term study of Mars and sets the stage for future missions that will be focused on whether there is or ever was life on Mars. By helping to understand whether the planet was habitable and, if so, for how long, MSL will help identify the likely environments and potential targets for future sample return and the eventual search for possible life.

The excitement should begin the day after Thanksgiving, so while resting after eating all that turkey, tune in to NASA TV and watch as Curiosity counts down towards lift-off and the start of an exciting new chapter in our understanding Mars and the solar system.

Visitors to our Museum in DC can also watch the launch, targeted for 10:25 am ET Nov 25, on the giant screen in the Moving Beyond Earth gallery.

John Grant is a geologist in the Center for Earth and Planetary Studies at the National Air and Space Museum, and co-led the process for selecting the landing site for the 2011 Mars Science Laboratory rover.