on August 22, 2013 PLANETARY SCIENCE Dodge the bullets. NASA has identifi ed just 1% of the 1 million sizable asteroids thought to swirl close to Earth’s realm. This plot shows the orbits of the The Save-the-World Foundation known Near-Earth Objects more than 140 meters across—those most dangerous should they collide Convinced that NASA will not fi nish the job, a private foundation intends to raise with our planet. www.sciencemag.org $450 million for a space mission to fi nd asteroids that may threaten Earth dation has set its sights on launching a MENLO PARK, CALIFORNIA—In Antoine de a soft spot for Saint-Exupéry and a drive to $450 million mission by July 2018. The infra- Saint-Exupéry’s beloved novella, The Little safeguard fellow citizens have set out to fi nd red telescope, called Sentinel, would spy a Prince, a pilot stranded in the Sahara Desert the rest. half-million NEOs from a vantage point near encounters a being from an asteroid called Planetary scientists agree that a full Venus. B612 has a star-studded team of plan- B-612. “There are also hundreds of others,” inventory of NEOs will require a dedicated etary science veterans and a fi xed-price con- Downloaded from Saint-Exupéry wrote, “some of which are so space observatory—at least a half-billion-dol- tract with Ball Aerospace & Technologies to small that one has a hard time seeing them lar proposition. That’s a stretch for NASA, in build and operate the satellite. through the telescope.” a thin budgetary era when new planetary mis- In the new economy of commercial ven- That figure was far too conserva- sions without “Mars” in the title are rare. Even tures into Earth’s orbit, the B612 Foundation is tive. There may be a million asteroids the agency’s current assignment, a 2005 man- aiming for much farther—into deep space— with masses far greater than ocean liners date from Congress to identify 90% of NEOs propelled by noth- in Earth-approaching orbits, nearly all of at least 140 meters wide, is behind schedule. ing but philanthropic which telescopes have yet to see. Far from More than halfway toward the target date of Online dollars. Although the being benign abodes like the Little Prince’s 2020, NASA has found just 10% of them. sciencemag.org team’s mission design Podcast inter- domain, some of those Near-Earth Objects “I believe the agency has ducked its re- view with Robert has sparked some dis- (NEOs) are potential killers. sponsibility a little bit,” says Lindley Johnson, Irion (http://scim.ag/ sent and the fundrais- Those at least 40 meters across could NASA’s program executive for NEO Observa- pod_6148). ing goal is steep, all wipe out a metropolis; a kilometer-wide tions. “I never dreamed it would take as long as agree that Sentinel’s asteroid could devastate part of a continent it has to develop a robust capacity.” Although dynamic cartography of the swarm of objects and shroud the planet in soot. NASA-spon- it now seems feasible to defl ect an incoming in Earth’s milieu would transform planetary sored searches, mostly from the ground, have asteroid, scientists would need many years of science. Says physicist Mark Boslough, an found most of the kilometer-size, civilization- advance warning to do so—an unlikely cush- impact specialist at Sandia National Labora- threatening asteroids, but only a fraction— ion at current rates of discovery. tories in Albuquerque, New Mexico: “If we’re perhaps 1%—of the smaller, but still men- Into this breach have stepped the astro- going to take the impact threat seriously, we CREDIT: NASA/JPL-CALTECH CREDIT: acing, objects. Two former astronauts with nauts and their B612 Foundation. The foun- have to do something like this.” www.sciencemag.org SCIENCE VOL 341 23 AUGUST 2013 837 Published by AAAS NEWSFOCUS The Mercury 7 mystique You have to bring that back somehow. And tion to Hubbard, they recruited veteran mis- The public faces of B612 are astronauts from that becomes a special responsibility.” sion director Harold Reitsema, retired from two generations: CEO Edward (“Ed”) Lu, 50, Schweickart took a step toward ful- Ball Aerospace; program manager John and Russell (“Rusty”) Schweickart, 77, chair fi lling those words in 1995 by founding the Troeltzsch, also of Ball Aerospace, who also emeritus of the board of directors. Their pas- Association of Space Explorers, a cadre of manages the Kepler planet-hunting telescope; sions and cultural cachet have lifted B612’s former astronauts devoted to public educa- and mission scientist Marc Buie of the South- profile. “The Mercury 7 tion and planetary stew- west Research Institute, an asteroid author- mystique of ‘the best of ardship. Then in 1998, ity. B612 also convened a review team that the best’ still exists,” says he saw Stanford Univer- Troeltzsch calls “a Who’s Who of every deep- Sentinel program architect sity geophysicist Norman space mission fl own in the last 45 years.” Scott Hubbard of Stanford Sleep speak about Earth’s University in Palo Alto, impact history. “The To Venus, and beyond California, and former incredible energies blew Troeltzsch describes Sentinel as a “pinnacle Mars program director for my mind,” he says. mission” for its heritage of proven systems NASA. “They have a spe- Lu and Schweickart from other space probes—notably Kepler, cial place in society.” soon began discussing the infrared Spitzer Space Telescope, and the Lu, an astrophysi- how to prevent such blasts comet-colliding Deep Impact. Ball Aerospace cist and solar scientist, from happening again. played a central role in each one. fl ew on two space shuttle They founded the B612 The contract between Ball and B612 lays missions before spending Foundation in 2002 with out a cost of about $250 million for Sentinel; 6 months on the Interna- astrophysicist Piet Hut of launch, operations, and staffi ng will take about tional Space Station in the Institute for Advanced $200 million more. In his talks, Lu specifi es a 2003, in the wake of the Study in Princeton and launch date of 20 July 2018, the anniversary Columbia shuttle disaster. planetary scientist Clark of Neil Armstrong’s famous step. Plans call He and Russian cosmo- Chapman of the South- for a 6.5-year mission, the time needed to fi nd on August 22, 2013 naut Yuri Malenchenko west Research Institute 90% of the NEOs larger than 140 meters in maintained the station in Boulder. For a decade, diameter and perhaps half of the ones down and ran experiments, but they and colleagues to 40 meters across. Extending the mission to Lu also had time for pho- examined ways to nudge 10 years would sweep up many others. tography, playing a com- an NEO off a collision Sentinel’s half-meter-wide telescope pact electric piano (his course given at least 10 will spot NEOs with new infrared detectors renditions of Beethoven’s years of warning. Lu and sensitive to 10 microns—a long wavelength Moonlight Sonata and fellow astronaut Stanley at which asteroids warmed by the sun pop Linus and Lucy by Vince Love devised the “grav- out against the cold backdrop of space. But www.sciencemag.org Guaraldi are both on You- ity tractor,” a spacecraft the most notable aspect of Sentinel’s design Tube), and Earth-gazing. hovering near an NEO is its planned orbit in a path similar to that of “You see shooting stars Protectors. Former NASA astronauts Ed to alter its orbit a touch. Venus. This perch, Buie says, will allow Sen- below you,” he says. “You Lu (top) and Rusty Schweickart spearhead Another leading concept, tinel a view of fully illuminated asteroids as know where the impact the B612 Foundation. ramming a projectile into it looks out toward Earth’s orbit, away from craters are. It’s a constant an asteroid, would also do the sun. Ball engineers fi rst made a pitch for reminder.” After leaving NASA in 2007, Lu the trick if done far enough in advance, stud- a Venus-like orbit in 2002, Buie recalls: “I Downloaded from worked as program manager for advanced ies showed. said, ‘You guys have got the answer.’ I could projects at Google—but protecting Earth had “We were four guys and a website and see it in an instant.” become an irresistible pull. tens of dollars,” says Lu, who talks about plan- But the choice forces compromises. For That transition took longer for etary cataclysms with next-door-neighbor instance, Sentinel’s remote position means Schweickart, a U.S. Air Force fighter pilot informality. “We came to the conclusion that that it will not detect as many smaller NEOs chosen for NASA’s third class of astronauts in defl ection was doable. Finding the other 99% in the 40-meter range as it might from a closer 1963. He fl ew on Apollo 9 in March 1969, the [of NEOs] is the entire problem.” vantage, says Tim Spahr, director of the Minor fi rst test of the lunar module in orbit—a criti- All along, the team pushed NASA to Planet Center at the Smithsonian Astrophysi- cal step in the sequence leading to the moon ramp up the search for hazardous asteroids cal Observatory in Cambridge, Massachu- landing. During a spacewalk, Schweickart had —often in harsh terms from the character- setts. That’s the suspected size of the object the rare luxury of simply watching Earth pass istically blunt Schweickart. But when Lu that blew up in 1908 over Tunguska, Siberia, under him for 5 minutes as one of his crew- spoke at Google and lamented that the gov- fl attening 2000 square kilometers of forest.