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THE PLANETARY REPORT DECEMBER SOLSTICE 2019 VOLUME 39, NUMBER 4 planetary.org LOOKING BACK, LOOKING AHEAD WE FOLLOWED WATER FOUND HOT SPRINGS, RIVERS, AND LAKES NEXT, WE SEARCH FOR

SPACE LIFE GOALS C CELEBRATING 40 YEARS C ON SPACE ON EARTH

Deep Freezer Simulating Chemical Processes on Far-Away Worlds

DOCTORAL STUDENT Caitlin Ahrens works in Pluto has a huge variety of surface textures the Pluto lab at the University of Arkansas. The with large, blotchy regions of different kinds of machine can simulate Pluto’s surface tempera- ices. In the Pluto lab, investigating these ices ture (34 to 54 kelvins, or -239 to -219 Celsius, helps to understand how they form crystals or -398 to -362 Fahrenheit) and pressure (14 and how those crystals change with tempera- microbars, or 14 millionths of Earth surface ture and pressure. Spectrometers can see how pressure). It has a separate chamber for mixing light of different wavelengths interacts with carbon monoxide, , and gases the crystals, so Pluto lab experiments will in different proportions before Ahrens intro- help Ahrens and her coworkers to interpret duces them to the Pluto chamber to observe the data from spacecraft and Earth-based tele- how they would behave on Pluto, helping sci- scopes. They can also study how shifts in Pluto’s

entists to interpret ’ observations climate affect its ices. Eventually, the work with University of Arkansas NASA/JPL/Ted Stryk of Pluto’s surface composition. While scientists this Pluto lab will lead to other experiments have studied the behavior of the individual ices investigating how these different ices behave before, how they interact with each other is not as the geologic materials that form Pluto’s well understood. diverse landforms.

2 THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 SNAPSHOTS FROM SPACE Contents DECEMBER SOLSTICE 2019

12 A New Understanding Abigail Fraeman examines how and changed our view of . 12

18 What Comes Next on Mars? Javier Gómez-Elvira anticipates the next phase of the search for life on the Red Planet.

DEPARTMENTS 2 Space on Earth How to study Pluto ices in an Earthly laboratory.

3 Snapshots From Space Triton shines, awaiting future exploration.

4 Your Place in Space Bill Nye revels in 4 decades of bringing space to everyone. NEPTUNE’S TRITON, nearly as large as our own moon, probably began its existence in the Kuiper belt. It’s covered by the same kinds of 5 Your Impact ices as Pluto: solid forms of water, methane, nitrogen, and carbon-rich Celebrating our global membership! gunk. It’s been 30 years since flew past, seeing only its southern hemisphere. If Earth were to begin developing a Neptune orbiter mission 9 Get Involved soon, we could arrive in the 2040s, when the Neptune system would be Do you have any Space Life Goals? near equinox, and the entire surface of the moon would be sunlit over the course of its day. 10 What’s Up? —Emily Stewart Lakdawalla Bruce Betts looks forward to 3 planets dancing together. SEE MORE AMATEUR-PROCESSED SPACE IMAGES PLANETARY.ORG/AMATEUR SEE MORE EVERY DAY! PLANETARY.ORG/BLOGS 10 Where We Are Emily Lakdawalla takes stock of the

University of Arkansas robots exploring beyond Earth . NASA/JPL/Ted Stryk CONTACT US: The Planetary ON THE COVER: The sets below a fan of blue in a brown sky over the mountainous rim of Society, 60 South Los Robles Gusev crater, Mars. The Spirit took this photo on 19 May 2005. Credit: Avenue, Pasadena, CA 91101-2016; NASA/JPL/Cornell/Texas A&M C The Planetary Report (ISSN 0736-3680) is published quarterly General calls: 626-793-5100; Email: at the editorial offices of The Planetary Society, 60 South Los Robles Avenue, Pasadena, CA 23 Why I Explore [email protected]; Internet: planetary.org; 91101-2016, 626-793-5100. It is available to members of The Planetary Society. Annual dues Editor EMILY LAKDAWALLA; are $50 (U.S. dollars) for members in the United States as well as in Canada and other countries. Some wise words from Art Director LOREN A. ROBERTS for Printed in USA. Third-class postage at Pasadena, California and at an additional mailing office. astronomer Franck Marchis. HEARKEN CREATIVE; Canada Post Agreement Number 87424. C Viewpoints expressed in articles and editorials are Copy Editor NICOLE YUGOVICH; those of the authors and do not necessarily represent positions of The Planetary Society, its Technical Editor JAMES D. BURKE; officers, or its advisers. © 2019 by The Planetary Society. All Rights Reserved. The Editor BRUCE BETTS Society and The Planetary Report: Registered Trademarks ® The Planetary Society. Planetfest™ The Planetary Society. YOUR PLACE IN SPACE BILL NYE is chief executive officer of The Planetary Society.

People. Passion. Planets. Celebrating 40 Years of Space for Everyone BILL NYE Chief Executive Officer

JENNIFER VAUGHN LIKE SPACECRAFT, time flies. Forty years ago, We have a new 5-year strategic framework: Chief Operating Officer our founders Carl, Bruce, and Lou had a hypoth- Space for Everyone. We want more people COFOUNDERS CARL SAGAN esis. They believed that public support for space taking action for space, enabling humankind 1934–1996 exploration was strong but was unrecognized to explore worlds, search for life, and defend BRUCE MURRAY 1931–2013 and unfocused. Their idea was to form a grass- Earth from . We aim to increase our LOUIS D. FRIEDMAN Executive Director Emeritus roots organization dedicated to advancing plan- membership to 75,000 and to engage a broader

BOARD OF DIRECTORS etary exploration. community of many millions more around Chairman of the Board DANIEL T. GERACI Carl wrote in the first issue ofThe Planetary the globe. Managing Partner & Director, Cygnus Investment Partners, Inc. Report: “If we are as successful as at least some

President experts think we are likely to be, we may be JAMES BELL Professor, School of Earth about to accomplish not only our initial goal and Space Exploration, of demonstrating a base of popular support for Vice President HEIDI HAMMEL planetary exploration, but also to provide some Executive Vice President, Association of Universities for carefully targeted funds for the stimulation of Research in Astronomy Secretary critical activities.” C. WALLACE HOOSER Associate Professor of Radiology, Over and over again, you have proven that University of Texas Southwestern Medical School the founding hypothesis was correct. Public Treasurer support for space and fascination about space LON LEVIN President and CEO, GEOshare LLC are stronger than ever. People everywhere have BETHANY EHLMANN a renewed interest in exploring Mars, searching Professor, California Institute of Technology; Research Scientist, for life, protecting against an incoming , Jet Propulsion Laboratory JOHN LOGSDON visiting the Moon, and watching what commer- Professor Emeritus, Space Policy Institute, The George cial companies like SpaceX and Blue Origin are You can help. Share the adventure of space Washington University accomplishing. with others. Pass on The Planetary Report, give ROBERT PICARDO Actor Looking back on our 40-year history, it’s clear a gift membership, and share videos, podcasts, BRITNEY SCHMIDT Assistant Professor, that 2019 has been extraordinary. Your very own and stories from our website. School of Earth and Atmospheric Sciences, LightSail 2 spacecraft has proven that a solar You’re reading this because not only do you Georgia Institute of Technology BIJAL “BEE” THAKORE sail can maneuver and raise its altitude in Earth support space exploration but you also take Regional Coordinator for Asia Pacific, Space Generation Advisory Council orbit for one twentieth the cost of a government- action to shape our future in space. Thank FILLMORE WOOD built mission. Your efficient PlanetVac you indeed. Vice President and Regional Counsel, BP, retired sampling system now has a chance to go to the Onward! The best is yet ahead! Antonio Peronace for The Planetary Society ADVISORY COUNCIL

BUZZ ALDRIN Moon. Your advocacy efforts continue to pay off: Navid Baraty for The Planetary Society ROBERT D. BRAUN DAVID BRIN New Horizons maneuvered and flew by another G. SCOTT HUBBARD GARRY E. HUNT fantastically distant Kuiper belt object, BRUCE JAKOSKY RYAN JOHNSON and missions are in development, and BEN LAMM ROSALY LOPES BOB MCDONALD NASA has committed to a new space telescope PETE SLOSBERG TIM SPAHR to help us detect dangerous asteroids. DIPAK SRINIVASAN KEVIN STUBE It’s amazing to see what we can do when we LORNE TROTTIER NEIL DeGRASSE TYSON work together to advance space exploration.

4 THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 YOUR IMPACT

YOUR YEAR ADVANCING SPACE EXPLORATION

1–50 members 50–250 members 250–5,000 members 5,001+ members

Your membership helps sponsor events like the biannual Planetary Defense Conference, which brings together the world’s leading experts in planetary defense. LEFT Members 46,996 celebrate together members in at Kennedy Space Center just before watching the launch of LightSail 2. 107 countries

Global 5,700 Collaboration volunteers in HOW YOU’VE CULTIVATED A GLOBAL VOICE FOR SPACE IN 2019 Antonio Peronace for The Planetary Society The Planetary Society is at its 111

Navid Baraty for The Planetary Society countries core a community. Working together across our pale blue dot, we advance space science and exploration. In 2019, our community grew. ABOVE CEO Bill Nye addresses the attendees 1.5M of the Planetary Defense Conference’s public social media event on 1 May 2019 in Washington, D.C. community

THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 5 Education HOW YOU EXPANDED PUBLIC KNOWLEDGE ABOUT SPACE IN 2019 Thanks to you, millions of people have learned about the importance of space exploration through educational resources, powerful storytelling, and human connection.

RADIO VIDEO WEB

All Aboard the Spacecraft

We believe that the best way to educate people about a space mission is to make them 2.5 million worldwide 60 new videos Planetary.org received a part of it. In 2019, your name Planetary Radio garnered 6.5 million page and those of fellow members listeners tuned in to 3.15 million views views from 2.8 million flew past Kuiper belt object 2014 MU69 aboard New 69 new episodes website visitors Horizons, orbited asteroid Bennu aboard OSIRIS-REx, and landed on asteroid Ryugu as part of . Learn more about the names on these and other missions at planetary.org/membernames. Antonio Peronace for The Planetary Society; Casey chart: Dreier/Loren A. Roberts : JAXA, Chiba Inst. Tech and collaborators; classroom: Jyothsna Palwai

ABOVE On 17 September ABOVE Illinois volunteer 2019, Hayabusa2 dropped Learn, Share, Connect Sathwik Palwai shares a baseball-sized target the LightSail 2 story The Planetary Society’s free online course offerings marker toward asteroid with his community. grew this year, giving you the knowledge you need to Ryugu. Etched onto foil wrapped around the target advocate for space and share your passion with others. marker are names collected Thanks to your support, we also added new online tools by The Planetary Society for community outreach that equipped volunteers to and the Japan Aerospace organize more than 100 events and activities, reaching Exploration Agency in 2013. more than 30,000 people in their communities.

6 THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 YOUR IMPACT

A Day of Action in Washington, D.C.

In February 2019, 100 Planetary Society members from 25 states in the United States came together in Washington, D.C. for the first annual Day of Action. They represented members worldwide in 127 meetings with congressional representatives, advocating for funding for space science and exploration. ABOVE Members listen to a presentation by New Horizons team member and Planetary Society charter member Ralph McNutt during the 2019 Day of Action.

Advocacy $200M HOW YOU SHAPED SPACE POLICY AND NASA’S Near-Earth Object FOUGHT FOR EXPLORATION IN 2019 (NEO) Program Funding $150M Bringing Space Seeing the

Antonio Peronace for The Planetary Society; Casey chart: Dreier/Loren A. Roberts Exploration to Results of

Hayabusa: JAXA, Chiba Inst. Tech and collaborators; classroom: Jyothsna Palwai NEO Observations Capitol Hill Your Work $100M DART (Double Asteroid Redirection Test) This year, your support led to Thanks to your many years the reestablishment of the of advocacy for planetary $50M Planetary Science Caucus in defense (protecting our planet the 116th U.S. Congress. The from asteroid and caucus, which unites members impacts), real is being of Congress from both parties made. NASA has increased $0

who are passionate about its planetary defense budget ‘08 ‘09 ‘10 ‘11 ‘12 ‘13 ‘14 ‘15 ‘16 ‘17 ‘18 ‘19 promoting the scientific by 4,000 percent over the exploration of space, currently past decade. This year, NASA ABOVE The budget for NASA’s Near-Earth Object boasts 20 members and announced that it will build Observations Program (renamed Planetary Defense in continues to grow. an asteroid-hunting space 2019) grew from less than $4 million in fiscal year 2009 to telescope as part of a new, more than $150 million in 2019. It now supports regular multipronged approach planetary defense missions, beginning with the Double to planetary defense. Asteroid Redirection Test (DART), launching in 2021.

THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 7 Innovation HOW YOU’VE INVESTED IN INNOVATIVE SCIENCE AND TECHNOLOGY IN 2019

PlanetVac on Its Way to ABOVE In 2018, The Defending Earth the Moon Planetary Society awarded LightSail 2 its first-ever Shoemaker Thanks to you, the Gene In 2019, NASA selected Mission Success grant to an observatory Shoemaker Near-Earth Object PlanetVac, a streamlined, in Africa, the Morocco (NEO) Grant Program is now less-expensive method for This year, The Planetary Oukaïmeden Sky Survey in its twenty-second year. gathering samples from Society’s LightSail 2 spacecraft (MOSS). In recent years, This year, 696 donors gave planetary surfaces, for its launched into Earth orbit and our asteroid hunters have $76,633 to support work by Commercial Lunar Payload succeeded in its mission to helped NASA confirm amateur and professional Services Program. Your demonstrate controlled solar a rare double asteroid, astronomers that is critical to support funded 2 crucial sailing. With this mission, observed a fast-spinning asteroid that rotates every the defense of our planet. As tests for PlanetVac: lab you showed the world 3.5 minutes, and imaged we go to press, we’re about to testing of PlanetVac in that groundbreaking space the interstellar asteroid announce a new set of winners. 2013 and a field test in the exploration technologies ‘Oumuamua that visited Get the latest information at Mojave desert onboard a can be made possible our in 2017. planetary.org/neogrants. Xodiac rocket in 2018. entirely by crowdfunding.

SHOEMAKER PLANETVAC LIGHTSAIL 2

56 grants awarded in 1,389 members gave LightSail 2 was funded The Planetary Society; NASA; Getty Images 18 countries $124,465 to support by 49,426 donations

on 6 continents the development totaling $7 million MOSS; The Planetary Society of PlanetVac over 10 years

Planetary Society members like you make this work possible. Thank you!

8 THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 GET INVOLVED SOCIETY TRAVEL

YOUR GUIDE TO YEAR-END GIVING FOR SPACE EXPLORATION Planetary Society You can make a difference in our Member Adventures WHAT ARE YOUR mission by making a gift to advance SPACE LIFE GOALS? space science and exploration. Give cash: use your credit or debit In 2020, join us in building the card at planetary.org/donate or mail ultimate list of life goals for space a check in the provided envelope. enthusiasts. Have you ever wit- nessed a rocket launch or observed Corporate gift matching: use ’s through a tele- our lookup tool to see if your scope? If not, do you want to? You company participates. can help give space enthusiasts a Get a tax break: make an IRA- way to track their experiences and qualified charitable distribution. be inspired to share their excite- Give stock: contact ment, whether they’re a lifelong [email protected] for space geek or a newfound fan. instructions for your broker.

IMPORTANT DEADLINES ALASKA AURORA BOREALIS 27 FEBRUARY—4 MARCH 2020 For U.S. tax purposes, gifts must Come see the aurora dance across the night be received on or before the last sky in this perennially favorite expedition! day of the year. Here are some common methods of making a gift ARIZONA SKIES AND NEW DISCOVERIES and their associated deadlines. 19—26 APRIL 2020 Discover the desert and astronomical ONLINE CREDIT CARD wonderland around Tucson and Flagstaff. GIFTS: transaction Annular Eclipse 2020 completed by 11:59 p.m. EST You can see the “ring of fire” of an annular (8:59 p.m. PST), 31 Dec eclipse as the 21 June 2020 eclipse crosses from Ethiopia to Tibet on 2 different expeditions: CHECKS SENT VIA U.S. MAIL: postmarked on or before 31 Dec ETHIOPIA, 9—23 JUNE 2020 Including the source of the Blue Nile CHECKS SENT VIA THIRD- PARTY SHIPPING (SUCH AS TIBET, 10—23 JUNE 2020 What are the greatest space See the eclipse at the “top of the world” FEDEX OR UPS): delivered things you’ve seen and done? on or before 31 Dec What experiences caused your ARGENTINA TOTAL SOLAR ECLIPSE 2020 8—19 DECEMBER 2020 The Planetary Society; NASA; Getty Images CREDIT CARD GIFTS VIA interest in space? What are the With optional Peru or Easter Island absolute must-sees and must-dos U.S. MAIL: received and pretrips, 2–8 December 2020 for a space fan like you? processed on or before 31 Dec MOSS; The Planetary Society ANTARCTICA TOTAL SOLAR ECLIPSE 2021 Between now and 31 January 2020, STOCK TRANSFER: broker- 23 NOV—15 DEC 2021 send us your creative ideas for to-broker instructions issued A once-in-a-lifetime opportunity! ways to experience space. Share in time for completed transfer For detailed brochures, please contact your space life goal suggestions on or before 31 Dec Betchart Expeditions Inc. at 800-252-4910 at planetary.org/spacegoals. or go to betchartexpeditions.com.

THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 9 WHAT’S UP? by Bruce Betts

1 2 PALLAS

200km 10 HYGIEA

4

ABOVE was the first spacecraft to return a ABOVE The Very Large Telescope in Chile has an instrument cometary sample and extraterrestrial material to earth named SPHERE, designed to image extrasolar planets, which from outside the orbit of the Moon. In 2004, Stardust can also resolve details on minor planets within our solar system. made a close of comet 81P/Wild (Wild 2), collecting In October, scientists announced that SPHERE images revealed comet and interstellar dust in a substance called aerogel. fourth-largest asteroid 10 Hygiea to be round, implying that it is a dwarf planet. All 4 images above were taken with SPHERE. IN THE SKY The Quadrantids, an above-average shower, peak on the night of 3 to 4 January. From a dark site, one may see as many as 40 meteors per hour. The best viewing occurs after the Moon sets around midnight. Super-bright dominates the West after sunset. Dimmer Mercury is to its lower right in early February. Reddish Mars Where We Are is in the East before . By February, bright Jupiter and yellowish have joined it to Mars’ lower left. In March, the 3 planets dance An At-A-Glance Spacecraft Locator close together with Mercury to their lower left. On 18 March, the IN THE FIRST QUARTER of 2020, there will be one interplan-

crescent Moon joins Jupiter, Mars, and Saturn in a tight grouping. NASA/JPL; ESO/P. Vernazza et al./MISTRAL algorithm (ONERA/CNRS); Loren A. Roberts for The Planetary Society after a concept by Olaf Frohn etary launch—ESA’s , which is planned to go up on an Atlas 5 rocket from Cape Canaveral on or after 5 February. It RANDOM SPACE FACT will travel close to the Sun to study the inner heliosphere. While The distance from Earth to the Moon is about the same as the it won’t get as close to the Sun as does, Solar distance traveled around Earth 10 times. Orbiter will enjoy an unusual polar orbit. We’ll lose one interplanetary spacecraft this quarter when the TRIVIA CONTEST great Spitzer Space Telescope ends its mission with a planned Our June solstice contest winner is David Lee Summers of shutdown on 30 January. Mesilla Park, New Mexico. Congratulations! The question was: Sadly, the Indian Space Research Organisation (ISRO)’s What was the first spacecraft mission to return samples Vikram crashed on 6 September, but it did successfully from a comet? The answer: The Stardust mission. test a number of new technologies before it tumbled out of

Try to win a copy of Super Cool Space Facts: A Fun, Fact-filled Space control. The Chandrayaan-2 orbiter is operating well and could Book for Kids by Bruce Betts and a Planetary Radio T-shirt by last for as many as 7 years at the Moon, ISRO said. answering this question: Orbiters are sending science data from Venus, the Moon, a near-Earth asteroid, Mars, and Jupiter. There are two active In January 2019, Chang’e-4 became the first Mars landers and two active lunar landers. Hayabusa2 departed spacecraft to soft-land on the far side of the Moon, asteroid Ryugu on 15 November to return its samples to Earth. but what was the first spacecraft to impact on the far Parker Solar Probe flies past Venus on 26 December. BepiCo- side of the Moon? lombo is catching up with Earth on the inside track toward a Email your answer to [email protected] or mail your answer to The Plan- 13 April flyby. etary Report, 60 S. Los Robles Ave., Pasadena, CA 91101. Make sure you include the answer and your name, mailing address, and email address (if you have one). By enter- Back on Earth, space agencies around the world are scram- ing this contest, you are authorizing The Planetary Report to publish your name and hometown. Submissions must be received by 1 March 2020. The winner will be chosen bling to prepare for the opening of the summer 2020 Mars in a random drawing from among all the correct entries received. launch opportunity. Three rovers (NASA’s , ESA’s For a weekly dose of “What’s Up?” complete with humor, a weekly trivia contest, and Rosalind Franklin, and China’s Huoxing-1) are undergoing final a range of significant space and science-fiction guests, listen to Planetary Radio at planetary.org/radio. preparations for launch. Last-minute problems could delay the launch until 2022, so the stakes are high.

10 THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 EMILY STEWART LAKDAWALLA is The Planetary Society’s senior editor On Moon: Earth-Sun L2 and planetary evangelist. Chang’e-3 Chang’e-4 Planets and spacecraft Queqiao Moon positions are shown Chandrayaan-2 for 1 January 2020 or Julian date 2458849.5 Chang’e-5 T1 Julian dates, used by Lunar astronomers, count up the Reconnaissance Earth days since noon Universal Mars year 35/solar longitude 128.8° Orbiter Time on 1 January 4713 BC. Solar longitude measures Mars’ season, with equinoxes and solstices occurring at 0°, 90°, 180°, and 270°. Mars year ACE SOLSTICE (SOUTHERN SUMMER) SOLSTICE (NORTHERN SUMMER) 1 began at northern vernal equinox WIND Mars (solar longitude 0°) on 11 April 1955. EQUINOX Reconnaissance Earth-Sun L1 “STAND” INDICATES SMALL-BODY Orbiter SOHO POSITION ABOVE OR BELOW THE ECLIPTIC

MAVEN ExoMars DSCOVR Mars InSight Express Mars Odyssey Bennu STEREO OSIRIS-REx Ahead Spitzer Parker Venus Solar BepiColombo Probe NASA/JPL; ESO/P. Vernazza et al./MISTRAL algorithm (ONERA/CNRS); Loren A. Roberts for The Planetary Society after a concept by Olaf Frohn Sun Mercury Earth

Hayabusa2

STEREO Ryugu COMING IN 2020 Behind Mars Main  Korea Pathfinder Lunar Orbiter launch Asteroid  Hayabusa2 Earth return Belt  NASA Mars 2020 rover launch  ESA Rosalind Franklin rover launch  UAE Mars Hope orbiter launch  China Huoxing-1 Mars orbiter/rover launch At this scale,  ESA Solar Orbiter launch would be 27.0 centimeters  Chang’e-5 launch/landing or 10.6 inches away from the Sun.

Voyager 1

Neptune New Horizons Uranus

Cold Saturn At this scale, Classical Jupiter Voyager 2 would be Kuiper 22.4 centimeters Belt or 8.8 inches away from the Sun.

Voyager 2

THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 11 ABIGAIL FRAEMAN is a planetary scientist at NASA’s Jet Propulsion Laboratory.

A New Understanding How Spirit and Opportunity Changed Our View of Mars

THE MARS EXPLORATION Rover science strategy for studying Mars was summarized by ABOVE Opportunity’s last Martian field site was team gathered in Pasadena, CA for our final the mantra “follow the water” because liquid valley, a meeting on 11 June 2019, and I wondered if I water is an essential ingredient for life. Today, 200-meter-long channel had ordered enough Thai food. I had been the it may seem like there’s a news story every few that cut into Endeavour deputy project scientist for the Mars Explora- months reporting that water was discovered crater’s rim. Like Earth field tion Rover Opportunity for 3 years, capping on Mars, but things were different 2 decades geologists, the Opportunity team sought out places like 15 years of involvement with the mission as a ago. We had known that Mars had frozen crater rims—and channels cut graduate, an undergraduate, and even a high water ice in its poles and water vapor in its into them—to layered school student. That night, I was responsible atmosphere, but we could only hypothesize bedrock that illuminates for organizing an evening celebration bringing that there had been liquid water on the Mars’ history in this spot. together engineers and scientists to toast the planet in its past. Mars-orbiting spacecraft The exaggerated colors of end of the surface mission. For all of us, the had imaged channels that seemed to have this panorama emphasize the diversity among rocks rovers had been a part of our daily for been carved by water, and they had spotted

and soils that Opportunity years or even decades, and this group was evidence of minerals that could have formed NASA/JPL-Caltech/Cornell/USGS NASA/JPL-Caltech/Cornell/ASU encountered at Endeavour. just a small subset of the thousands of people in water, but we really needed to get down The black-and-white frames who had contributed to making the mission a onto the surface to test these hypotheses. in the lower left are portions reality. It was important that we marked the Geologists had dreamed of roving on Mars Opportunity was still planning to image in color achievement appropriately. ever since images that were returned from the when the mission-ending dust NASA launched the identical rovers Spirit Viking landers in the 1970s showed tantalizing storm hit. and Opportunity in July 2003. At the time, our rocks that were just out of reach of the landers.

12 THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 outcrops and hematite The Jet Propul- “blueberries” in Eagle crater. Not to sion Laboratory has built all of be outdone, Spirit followed suit several NASA’s Mars rovers. In 1997, the Pathfinder years later when it detected minerals that rover had demonstrated that it form in water, including goethite and car- was possible to drive on Mars, and Spirit and bonate, in the Columbia Hills. By mission’s Opportunity were the first mobile rovers with end, the rovers had driven through 5 differ- a fully capable payload. Spirit and Opportuni- ent geologic settings. Four of the 5 settings ty’s instruments were designed to collect clues about how Martian rocks and soils formed LEFT The small spherules and could see if their elements and minerals on the Martian surface in had ever been altered by liquid water. The this close-up image are near Fram Crater, visited by rovers were each designed to drive at least NASA's Mars Exploration 600 meters over 90 Martian days (sols). It Rover Opportunity during was anyone’s guess as to how well the mission April 2004. The area shown would work or if it would even succeed at all. is 1.2 inches (3 centimeters) Of course, most of us know the ending across. The view comes from of the story. By the time NASA Associate the microscopic imager on Opportunity’s robotic arm, Administrator Thomas Zurbuchen declared with color information the mission complete on 13 February 2019, added from the rover’s Spirit had traveled more than 7.73 kilome- panoramic camera. ters (4.80 miles) over 2,208 sols of operation, while Opportunity drove more than 45.16 kilo- meters (28.16 miles) in 5,111 sols. The data the 2 rovers returned from their adventures changed our view of Mars. Spirit and Oppor- preserved evidence of at least a dozen unique tunity not only followed and found evidence times when liquid water had interacted with for liquid water but also discovered that Mars the Martian surface and subsurface (see info- was wet many different times in the past and graphic on page 14).

NASA/JPL-Caltech/Cornell/USGS in many different environments, both on and In the plains of Meridiani Planum, Oppor- NASA/JPL-Caltech/Cornell/ASU beneath its surface. tunity roved atop ancient acidic playas where very salty water had been exposed to the atmo- WATER ON MARS sphere, evaporating to leave its salts behind. Although it landed second, Opportunity was Once dried, the salts had been eroded, trans- the first of the rovers to find evidence of past ported, and deposited into sand that liquid water, locating it in the sedimentary were later cemented into rock when ground-

THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 13 YOUNG SAND ENDEAVOUR RIPPLES EAGLE CRATER ENDURANCE CRATER RIM CRATER SANTA MARIA VICTORIA CRATER CRATER

FRACTURES UNKNOWN OVERPRINTING STRATIGRAPHY

BURNS FORMATION

OLD BASEMENT ROCK Opportunity (ALTERED BY WATER)

HUSBAND HILL

ALTERED BY WATER

HOME PLATE

YOUNG LAVA FLOWS ANCIENT BROKEN BY IMPACT COLUMBIA HILLS ANCIENT HOT SPRINGS POTENTIAL BURIED AND FUMAROLES LAKE SEDIMENTS? INNER Spirit BASIN

DRAWINGS NOT TO SCALE

ABOVE Spirit and water rose from beneath them, dissolving and structures are always associated with biology. Opportunity explored 5 redepositing salts into the pore spaces between Spirit’s findings were so exciting to astrobiolo- major geologic environments. the sand, gluing the grains together. The acidic, gists that the Home Plate site was one of the THE LAVA FIELDS OF GUSEV CRATER, where Spirit salty environment would not have been espe- top 3 finalists for a landing site for a future landed, showed no evidence cially friendly to life, but later in Opportunity’s sample return mission. for water. THE COLUMBIA mission, it found that pH-neutral groundwater Abigail Fraeman, Emily Lakdawalla, and Loren A. Roberts for The Planetary Society HILLS, much older than had flowed many different times through frac- EYES IN THE SKY, HANDS IN THE DIRT the Gusev plains, contained tures in the ancient rocks that made up the rim Spirit and Opportunity conclusively demon- rocks altered by groundwater. of Endeavour crater. strated the value of operating landed missions HOME PLATE, an extinct volcano, had hot springs On the other side of the planet, Spirit found in synergy with science orbiters. For example, and fumaroles. MERIDIANI different kinds of watery environments. At in 2009, the Compact Reconnaissance Imaging PLANUM contained the base of Home Plate within the Columbia Spectrometer for Mars (CRISM) instrument on sedimentary rocks laid down Hills, Spirit roved where ancient fumaroles the Mars Reconnaissance Orbiter discovered in water and later altered by had left thick deposits of silica and sulfate salts that clay minerals were present at several loca- groundwater. ENDEAVOUR centimeters below the surface, and extinct hot tions along the rim of Endeavour crater. On

CRATER RIM had fractures NASA/JPL-Caltech/Cornell/ASU that acted as conduits for springs had left behind finger-shaped nodules Earth, clay minerals most commonly form groundwater multiple times. made of nearly pure silica. On Earth, similar when volcanic minerals are altered by liquid

ABIGAIL FRAEMAN is a planetary scientist at NASA’s Jet Propulsion Laboratory. She was the deputy project scientist for the Mars Exploration Rover mission and one of The Planetary Society’s student astronauts.

14 THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 SPIRIT AND OPPORTUNITY

water. The rover science team directed Oppor- of an ancient Lake Gusev. The science team tunity to the exact CRISM-detected spots. The dubbed the plains of Gusev crater a “basalt journey took more than 3-and-a-half years, prison” out of a mixture of frustration and but it paid off in science. In one spot, the rover affection. It wasn’t until Spirit escaped the discovered clays that formed when there was prison by ascending into the Columbia Hills lots of water flowing through a fracture. In that it found minerals that form in watery another area, Opportunity discovered dif- environments. Spirit’s discoveries at Home ferent clays, also in fractures, that probably Plate could never have been predicted from formed by a very small amount of stagnant orbital data but were just as compelling as an water. Now, geologists can return to the ancient lake would have been in the search for CRISM data set and find spots all over Mars life. The evidence was just below the surface where similar environments probably existed. or too small to be seen by even the highest- Spirit and Opportunity also confirmed to us resolution cameras. Every place we land, we that there are some things you just can’t see are almost certain to learn something new and from orbit and that there’s no substitute for potentially paradigm-shifting. wheels on the ground. For instance, Spirit was sent to Gusev crater because we thought it was THE LEGACY OF SPIRIT an ancient lake based on its shape in orbital AND OPPORTUNITY images, yet the rover landed on top of young The findings from the Mars Exploration lava flows that buried any geologic evidence Rovers allowed the Mars science community

LEFT The light-colored INNER BASIN material in the center of this exaggerated-color image is a vein called “Esperance.” The chemical data Opportunity collected from this target showed that a large amount of nearly neutral-pH groundwater flowed through it in the past, leaving behind aluminum- rich clay minerals. Of all

Abigail Fraeman, Emily Lakdawalla, and Loren A. Roberts for The Planetary Society sites Opportunity visited, this site has the best potential to have supported ancient Martian life. NASA/JPL-Caltech/Cornell/ASU

THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 15 SPIRIT AND OPPORTUNITY

TOP Spirit landed on a field of volcanic rocks at Gusev crater. Scientists had hoped to find evidence of an ancient lake there, but the volcanic materials covered any such evidence. However, the chemical and textural measurements Spirit made here still provided important information about the volcanic of Mars. Many of the rocks in this image have pointy, jagged shapes. The shapes could result from them being broken by impacts or from erosion by Martian winds over billions of years.

BOTTOM A subset of the Mars Exploration Rover science and engineering teams gathered at Caltech for a team meeting in 2015. Over the 30-plus years of the mission’s existence, thousands of people were involved. NASA/JPL-Caltech/Cornell/ASU/Daniel Crotty/Emily Lakdawalla; Keck Institute for Space Sciences/Michele Judd NASA/JPL-Caltech/Cornell/ASU

16 THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 to develop our strategy for Mars exploration big wheel beyond “follow the water” to the more com- prints to fill, plicated question of whether these watery they have also environments were ever habitable. Very opened the loosely defined, a habitable environment is door to dreams one that has the 2 other essential require- of even greater ments in addition to liquid water that are voyages. We’ve needed to support life as we know it: a source demonstrated of carbon and a source of energy. The Mars the power of mobility Science Laboratory mission’s Curiosity rover, on the ground. Now, which landed on Mars in 2012, carried a larger we are looking to the and more complicated payload than the Mars skies of other worlds to Exploration Rovers. Curiosity is capable of travel farther and faster. finding evidence of all 3 of these requirements. A helicopter will ride In fact, it has succeeded: within its landing along with the Mars site at Gale crater, Curiosity found ancient 2020 rover, and NASA river and lake deposits that preserved carbon- recently announced containing compounds as well as evidence for that it will send a drone water chemistry that could power microbial called to soar metabolism. Today, we not only know that above the sand dunes Mars was once wet—it was also habitable. and in Almost 2 decades after Spirit and Oppor- the 2030s. tunity and a decade after Curiosity landed, Spirit and Opportunity showed

NASA/JPL-Caltech/Cornell/ASU/Daniel Crotty/Emily Lakdawalla; Keck Institute for Space Sciences/Michele Judd NASA’s Mars 2020 rover and ESA’s ExoMars us just a small taste of the richness rover are now poised to address the most of Mars’ past. I believe we have challenging question in our search for life on only just begun to understand the Mars when it lands in February 2021: did it full complexity of Martian history exist? The designs of these missions and the and to piece together what Mars’ selections of their landing sites rest on what 3-to-4-billion-year-old rocks can we learned from Spirit and Opportunity. tell us about how planets inside At the Thai-food-fueled, end-of-mission cel- and outside our solar system can ebration, people were in a reflective mood. evolve into habitable worlds. As They told stories about their experiences the mission’s principal investiga- during mission development and reminisced tor Steve Squyres said at the end of the final ABOVE When one of Spirit’s about the escapades that had occurred over science team meeting, “The biggest stuff is front-wheel motors failed, 14 years of operations. For all this looking still ahead, and I think [enabling] that in large the rover had to drive backward and drag along back, there was just as much anticipation of measure may be the greatest legacy that this the stuck wheel, creating the road ahead: “What are you working on project has.”

NASA/JPL-Caltech/Cornell/ASU shallow trenches. Near now?” “Can you tell me more about your new (For those wondering, the Thai food I had Home Plate, the trenches mission concept?” ordered for the celebration exceeded mis- exposed nearly pure silica, a Spirit and Opportunity took humanity on sion-success criteria, like Spirit and Oppor- probable sign of fumaroles and hot springs that could’ve a great adventure and set the bar extremely tunity. We ended up with abundant leftovers been a habitat for life. high for what we can accomplish with robotic that were consumed by eager Caltech grad space exploration. Although the rovers leave students the next day.)

THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 17 JAVIER GÓMEZ-ELVIRA is the principal investigator of the REMS weather sensor instrument on the Curiosity rover and coinvestigator of the similar MEDA instrument on the Mars 2020 rover.

What Comes Next on Mars? Planning the Search for Life on the Red Planet

THE SEARCH FOR LIFE has been a goal of Mars increased the variety of environments we exploration since its beginning. However, thought capable of hosting life and therefore more than 50 years of work have failed to the chances of finding life elsewhere in the answer the basic question: is or was there life solar system. on Mars? The next missions to Mars seek to The Viking lander missions sought to address this question directly. discover in 1976, and their fruitless In the 1950s and 1960s, work by Stanley results had a negative impact on the enthusi- RIGHT ESA’s ExoMars rover, Miller, Joan Oro, and others demonstrated asm for funding Mars missions. Twenty years named Rosalind Franklin, is that the building blocks of life could form later, a new stage of Mars exploration began in final preparations for a July 2020 launch and March through naturally occurring chemical reac- with , which arrived in 2021 landing in Oxia Planum, tions under specific environmental conditions. orbit in 1997. Since then, community interest where Martian rivers once These conditions could have pre- has increased so much that the flowed. Its goal is to search vailed on early Earth. When the number of publications on Mars for signs of ancient life. In solar system was young, Mars has skyrocketed, outnumbering addition to cameras and and Earth would have under- those about all other planetary spectrometers, Rosalind Franklin carries a drill that gone similar evolution. What destinations combined. can penetrate as many as 2 happened on Earth could also have meters beneath the surface to happened on Mars. In the 1990s, THE LIFE GOAL retrieve samples and deliver other researchers identified microor- Since Mars Global Surveyor, the goals of them to analytical laboratory ganisms called that are NASA’s have instruments. In the artwork at right, the cover of the capable of thriving in extreme conditions been constant. There are 4 goals: charac- drill has been removed to of temperature, pressure, salinity, and so terize the climate of Mars, characterize the show its internal workings. on. These resilient life forms substantially geology of Mars, determine whether life ESA/ATG medialab; ESA/DLR/FU Berlin

18 THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 ever arose on Mars, and prepare for human exploration. ESA’s Mars mission goals are similar. The orbiters Mars Global Surveyor, Mars Odyssey, , Mars Reconnaissance Orbiter, MAVEN, Mars Orbiter Mission, and now ExoMars Trace Gas Orbiter have sent to Earth thousands of terabits of information about the surface and atmosphere of Mars. Landed missions , the Mars Exploration Rovers, , Curiosity, and Insight have ground-truthed these measure- ments at landing sites characterized from orbit. We now have a continuous weather record dating back to 1997. We know Mars’ atmo- sphere very well—its composition, pressure, temperature, and how these vary with the seasons. We know the motion of Mars’ winds LEFT While liquid water may and how their flow conforms to Mars’ topog- not have been exposed at the surface of Mars for much of raphy. We are beginning to understand how its 4.5-billion-year history, Mars lost its atmosphere over time. There are evidence from orbiters and open questions, like how dust storms become rovers suggests it has been global and how the atmosphere evolved to available underground for its present state, but we have made great much longer. The channels advances in characterizing the climate of Mars. of the Hephaestus Fossae region within Utopia Planitia We have located volcanoes, impact craters, (top) likely formed when lava flows, deep channels, depositional impacts released subsurface deltas, and vast plains, and we understand by water in massive floods. analogy to Earth how many of these formed. Data from the Mars Express We have mapped the distribution of chemical orbiter provides the basis for this elevation map. Cool elements and minerals like clays, sulfates, colors represent depressions; and carbonates. However, we only know warmer colors are higher the planet’s surface. To understand Earth’s areas. The image is about 55 evolution, geologists explore its interior. We kilometers (35 miles) wide. look for places where its inner layers have been exposed by tectonic movements and employ seismographs to see hidden layering. A deep drill is usually our best option to see into Earth’s geology. It is the same on Mars. In

ESA/ATG medialab; ESA/DLR/FU Berlin some places, erosion has exposed inner layers, but much is hidden. We can say that we have characterized the surface geology of Mars but not its interior. We have not advanced much in determining whether life ever arose on Mars, but we have found that the necessary conditions for life existed in Mars’ past. These conditions include

20km THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 19 ABOVE RIGHT NASA is liquid water, some key elements (carbon, LIFE DETECTION AT MARS SURFACE preparing the Mars 2020 nitrogen, phosphorus, and sulfur), chemical Several missions plan to launch toward for a July 2020 launch gradients (to provide energy for metabolism), in summer 2020. Two in particular seek as well. In this 5 June 2019 and adequate environment (in terms of to advance the search for life by exploring photo, engineers take a selfie after attaching the radiation, temperature, chemical conditions, beneath the surface: Mars 2020 and ESA’s remote sensing mast. Like its and so on). However, we have detected no Rosalind Franklin rover. The design of Mars predecessor Curiosity and . We have found some carbon- 2020 is based on the Curiosity rover, but it its contemporary Rosalind containing molecules, but they could all have has different instruments and an improved Franklin, the Mars 2020 an abiotic origin. (Meteoritic falls deliver 100 capacity to detect organic molecules thanks rover (which will receive a more colloquial name before tons of material to Mars each day, a portion of to its Raman spectrometers. Its goal is to drill launch) is able to drill to which is carbonaceous.) Complex, carbon-rich and collect samples for future Mars sample acquire samples. Unlike the molecules are quite prone to degradation by return. The Rosalind Franklin rover is also other missions, Mars 2020 radiation. Therefore, they can only be found equipped with a Raman spectrometer and has plans to package and drop below the surface. Similarly, for present life, a drill that can collect a sample up to 2-meters those samples for future all evidence suggests that if Mars has stable deep for onboard analysis. retrieval and return to Earth. The work it does on the liquid water, it resides below the surface. The Raman spectrometers are widely used in surface with cameras and Mars community consensus is that we need to Earth laboratories but have never before flown spectrometers will document go beneath the surface in order to progress in to Mars. They can identify the presence of the geologic context of the the search for life. carbon-containing compounds and the kinds samples, making them a rich Robotic missions have taken some steps to of chemical bonds they contain. Mars 2020 prize for future science in Earth laboratories if Earth help prepare for future human exploration by has 2: SHERLOC, which is at the end of the can successfully retrieve them. studying the radiation environment on the robotic arm, and SuperCam, which is in the way to Mars and at the surface. NASA’s Mars rover mast with the cameras. They will be able 2020 rover will perform a first demonstration to operate on hundreds of different targets. In experiment for in-situ resource utilization, Rosalind Franklin, the spectrometer is called generating oxygen from the Martian RLS and is in the rover’s internal sample atmosphere. The biggest contribution to analysis laboratory. future human exploration has involved terrain alone cannot prove mapping and climate characterization. life existed on Mars. It is possible that one

JAVIER GÓMEZ-ELVIRA is director of the Payload and Space Science Department at Spain’s Instituto Getty Images

Nacional de Técnica Aeroespacial (INTA) and former director of its Centro de Astrobiología (CSIC- NASA/JPL INTA). He is the principal investigator of the REMS weather sensor instrument on the Curiosity rover and coinvestigator of the similar MEDA instrument on the Mars 2020 rover.

20 THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 WHAT COMES NEXT ON MARS?

of the rovers could spot a carbon-containing A 3.7-billion-year-old fossil molecule that is a perfect match for a known stromatolite from western compound of biological interest. More likely, Australia preserves some of the they will find evidence that some carbon- oldest evidence for life on Earth. containing compounds are present. In all cases, additional analyses are required to determine the origin of the material. Some rover-based Signs of Life on Mars When we talk about searching for signs of ancient experiments can help to narrow this down, life on Mars, what we are actually looking for is a like the isotopic and chirality (molecule shape) : an object, substance, or pattern that could analyses that Rosalind Franklin could perform. only have been made by life. There are 6 specific kinds Neither of the rovers can produce of biosignatures that we might encounter on Mars: definitive evidence for life on Mars. We will Organic compounds contain carbon and need to do more detailed analyses that the ORGANICS hydrogen and other light elements. All life on Earth is rovers cannot perform, employing more made of organic compounds, but organic compounds powerful spectrometers or bringing new also form in the absence of life. Systematic patterns in techniques like immunoassay detection and the types of could be a biosignature. sample processing to extract and concentrate organics. Raman spectroscopy is a very good ISOTOPES Atoms of one chemical element always technique for selecting samples for further contain the same number of protons but can have differing numbers of . On Earth, biological analysis. We will either need to bring samples processes sometimes prefer one isotope over another, back to Earth or bring a more powerful and that preference can be preserved in rocks. laboratory to the site, perhaps operated by human explorers. MINERALS On Earth, some minerals are uniquely NASA and ESA are now discussing plans associated with life. Discovery of a mineral that for the return of the Mars 2020 rover samples. requires life to form would be a biosignature. A surface-retrieval lander would deploy a CHEMICALS Earth-life metabolic activity often has a sample fetch rover that would spend 6 months chemical signature. Signs of varying pH or oxidation collecting the samples and loading them into a state over very small scales might be the signature of basketball-sized sample canister launched by a microbial metabolism in an ancient environment. rocket from the lander deck. A sample-return SMALL-SCALE STRUCTURES At the microscopic level, it’s orbiter would rendezvous with the canister in possible to spot signs of individual microscopic life forms: Mars orbit and return it to Earth. Each of these fossilized cells, or molds of cells, or casts of cells. 2 missions would have components built by both NASA and ESA. As currently envisioned, LARGE-SCALE STRUCTURES At the the spacecraft would launch in 2026, and the macroscopic level, microbes on Earth build mats, stromatolites, reefs, and other structures. samples would return in 2031. On Earth, geologists look for biosignatures in ancient rocks DIGGING DEEPER to learn when life originated. The record for oldest evidence Many organizations besides NASA and ESA for Earth life is from stromatolites in the Pilbara region are planning future Mars missions launch- of Australia. They show mineral, chemical, and structural ing in 2020, 2022, and 2024. We are now evidence for the presence of life on Earth 3.5 billion years ago.

Getty Images The more different kinds of biosignatures observed, the more

NASA/JPL in a period of discussion and planning for confident we can be in the conclusion that life was present. the following decade’s missions. ESA is cur- rently developing a new, long-term plan of

THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 21 WHAT COMES NEXT ON MARS?

its scientific priorities, called Voyage 2050. In the United States, the National Research Council is soliciting community input for the next Planetary Science Decadal Survey, which will state NASA’s scientific priorities for 2023 to 2032. If our goal is to search for extant life, drilling deep enough to encounter subsurface liquid water looks like the best option. It will take a heavy lander to drill deep enough–tens to hundreds of meters beneath the surface–to encounter stable, habitable environments and to carry a powerful-enough scientific payload to analyze them. This in turn will require new RIGHT Heavy frost deposits landing systems. The same kinds of heavy coat the ground in and landing systems will eventually be required around the 139-kilometer diameter (86-mile diameter) for human missions to Mars. Hooke crater in this Mars Even if we had the technology, we could Express image. The frost not yet drill to water on Mars. Current inter- serves as a reminder that national agreements on Mars still possesses water that prohibit contact with liquid water on other moves dynamically between the atmosphere and the worlds in order to avoid any type of contami- surface, mostly in the form nation from Earth. There is an active discus- of ice and vapor. At present, sion in the community about relaxing these Mars has thick water-ice restrictions. We believe that the highest level polar caps and icy clouds. In of sterilization must be used with the compo- many locations, temperatures nents in contact with water, developing new get low enough overnight for the relative humidity to techniques and protocols if needed. If we wish reach 100 percent, and frost to find current life, we must be able to interact forms on the ground as water with liquid water. vapor condenses. As water Exploration is in the DNA of humankind, has moved around with Mars’ but the immense cost of sending humans shifting climate over its long history, there may have been to Mars requires a motivating reason devel- many periods of wetting and oped through the consensus of international drying all over the planet. space agencies and the scientific commu- nity. A win-win option for searching for life on Mars and advancing human presence in the solar system looks like a combination of robots and astronauts. With robotic reconnais- sance, we can select promising sites where subsurface life could be present. I imagine ESA/DLR/FU Berlin/J. Cowart a scenario in which humans can select drill Photo courtesy of the author sites, highly sterilized robots can drill for and retrieve samples, and humans can perform core analysis in Mars-based laboratories. Soon, we will find out how Earth plans to carry on the search for life on Mars.

22 THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 WHY I EXPLORE

A Life of Learning

PEOPLE OFTEN ASK me why I became an generation of extremely large telescopes that astronomer. I think it started with the science- use AO, and we are even considering bringing fiction books I collected when I was young. AO to space with Project Blue and ambitious They were more than a library. They became concepts like HabEx and LUVOIR. Someday, an obsession when I was a teenager—a way to one of these telescopes will take an image escape the harsh reality of life as a person of of another pale blue dot, which will tell that color in France and in a world that I thought was on the verge of destruction. In books, I could imagine a world that mastered faster-than-light propulsion, explored new planets, started conflicts, created egalitarian societies, found weird life, and communicated with extraterrestrials. I explored within my mind first and then joined the space exploration community. Luckily, I lived in Toulouse, France, the European capital of aerospace, where I met astronomers and astronauts who told me their stories and explained why they explored. Shortly after the discovery of an exoplanet orbiting 51 Peg, I heard about adaptive optics (AO) and how it could help astronomers tap somewhere around a nearby star, there is a the full potential of ground-based telescopes. world like ours—a planet with a liquid ocean, a I quickly decided to dedicate my career to , and perhaps intelligent life. We will FRANCK MARCHIS (above left) is a senior planetary AO. Today, AO has lowered the cost of space learn a lot from studying this planet—about astronomer and science exploration and has enabled new discoveries, the past and future of our Earth, about life, outreach manager of the Carl including moons around asteroids and the and about intelligence. We might find out that Sagan Center of the SETI first picture of a Jupiter-like exoplanet. indeed, we are not alone. Institute and chief scientific Astronomy is far more than a research field. What a feast this will be for astronomers, officer and cofounder at Unistellar. His hobbies It also has a huge impact on our civilization. anthropologists, sociologists, and others! include CrossFit, biking, My generation was motivated by the iconic If these extraterrestrials confronted and video games, and reading. picture of our pale blue dot taken by Voyager 1 overcame the same issues we face today, His favorite quote is from in 1990. It made us realize that the solar system we may find an answer to our problems by Nelson Mandela: “It always is our backyard, and Earth is not the limit. The learning from these older siblings. We may seems impossible until it’s recent flyby of Pluto, once called the ninth also realize that we are not a plague in the done.” His favorite space image is an artwork of the planet, is just one consequence of this image. universe but an inevitable evolution of intel- Patroclus Today, AO is everywhere, including on every ligence. If and when this happens, it will take and Menoetius. “In a few large telescope, but we have only begun to tap me back to stories I read in my science-fiction years, when the mission ESA/DLR/FU Berlin/J. Cowart Photo courtesy of the author its huge potential. We are building another books and my earliest drive to explore. visits the binary system, we will have a real picture of this binary asteroid. I named WHY I EXPLORE Planetary Society members are explorers. We share this common passion, although Menoetius, the smaller we have different stories that drive our passion. We’re curious to know your story. If you’d like to share, component, after publishing we’ve set up a form at planetary.org/whyexplore, where you will also be able to read other “Why I their . I can’t wait to Explore” stories. We’ll also continue to share stories in future issues of The Planetary Report. see real pictures of it.”

THE PLANETARY REPORT C DECEMBER SOLSTICE 2019 23 THE PLANETARY SOCIETY 60 SOUTH LOS ROBLES AVENUE PASADENA CA 91101-2016 USA

astronomical art

Adrianna Allen, Life on Mars: Cave Colonies

The surface of Mars is an extremely hostile environment for life. It experiences radiation by high-energy particles from the Sun and space and is drier than the most arid Earth desert. If life exists on Mars today, it would be better off below ground, sheltered from radiation, where there may be liquid water. Human astronauts may one day look for both shelter and water underground.

Adrianna Allen, a scientific illustrator, envisions future astronauts encountering Mars life. About this digital painting, she writes: “As she descended farther into the cave, what was detected in the initial scans suddenly became obvious to her eyes. There indeed had been water trapped here once. The Red Planet was about to reveal its most wondrous secret.” See more of her work at photonillustration.com.