COMMENT BOOKS & ARTS planet formation. More than 140 Kuiper SATELLITE IMAGING belt objects similar to Pluto have been found, and 45 imaged by Spitzer. The sections dealing with these subjects, and with the outer Solar System Adventures of a space and comets, are the most original; much of the material is relatively new. High points from 2014 to 2017 alone include archaeologist the imaging and mass determination of a near-Earth asteroid, and detection A personal take on panning out to see the past both of an exoplanet by measuring how its grips and frustrates Jo Marchant. gravity affects light from a background star. Werner and Eisenhardt also discuss insights from infrared observations of he ancient city of Tanis was Egypt’s multiple agents and the Milky Way, the close neighbouring capital for more than 350 years before high-profile media galaxies called the Magellanic Clouds, the centre of power shifted, and the appearances. In and others. After a ponderous chapter on Tcity was eventually lost under centuries of Archaeology from infrared galaxy counts come quasars and silt. In 1939, archaeologists working there Space, she sets out the active galactic nuclei, galactic clusters, uncovered temples and tombs containing story of the field for the history of star-formation and, finally, treasures to rival Tutankhamun’s. But Tanis which she is the most Spitzer’s role in estimating the redshifts was largely forgotten amid the horrors of recognizable face. of the most distant galaxies, a remarkable the Second World War, until a fictional Parcak defines achievement for a telescope of its size. version featured in Steven Spielberg’s 1981 space archaeology Archaeology from Werner and Eisenhardt mention, too, film Raiders of the Lost Ark. In one scene, Space: How the (named after a 2008 how NASA devoted a large proportion archaeologist Indiana Jones sneaks into a Future Shapes Our NASA funding pro- of Spitzer’s first-year observation time to map room in which the entire city is laid Past gramme) as using “any six ‘large programmes intended to leave out, and discovers that the Nazis seeking SARAH PARCAK form of air or space- a lasting scientific legacy. These covered a the titular ark are digging in the wrong place. Henry Holt (2019) based data” to look wide range of scientific goals. GLIMPSE, In 2010, space archaeologist Sarah Parcak for ancient features for instance, was a survey of the Milky had her own map-room moment at Tanis. or sites. An early practitioner was Antoine Way, whereas SWIRE, COSMOS and Most of the city remains buried beneath the Poidebard, the ‘Flying Priest’, who spent much GOODS explored the extragalactic desert, a huge area that would take centuries of the 1920s photographing archaeological Universe to various depths. This — in to excavate by conventional means. So, she sites in Syria and Lebanon from a biplane. my view — enlightened approach con- chose two satellite images of the site — one From the 1960s, NASA missions such as the tinued throughout the mission: in the low resolution and multispectral, the other Landsat satellites began to provide a view end, more than 30 legacy programmes higher resolution but black and white — and from orbit, although archaeologists failed were approved. However, there is little combined them. As she writes, “I thought to catch on for two decades. US spy-satellite systematic account of them here. I was hallucinating: an entire ancient city images from the cold war were declassified The book’s title refers to Hamlet’s leapt off the screen.” With details of houses, by then-president Bill Clinton in the 1990s; declaration in William Shakespeare’s streets and suburbs, this was a trove indeed: the field hit “warp speed”, says Parcak, a few eponymous play: “There are more things the layout of the largest, most continuously years later. Today, commercial projects such in heaven and earth, Horatio,/Than are occupied capital city in ancient Egypt. as Google Earth provide space-based images dreamt of in your philosophy.” There are Since then, Parcak has become famous — with ever-higher resolution, and drones scan also more things in the story of infrared winner of a National Geographic Explorer landscapes from closer to Earth. astronomy than appear here. The contri- grant and the US$1-million TED Prize (given Interpreting the resulting flood of data is butions of other missions and ground- for innovative, world-changing ideas), with “part science and part art”, Parcak explains. based efforts tend to be mentioned only in passing. I might have preferred to see a bit more on the theoretical work that makes sense of the Spitzer observations. And the general reader might find the many scientific diagrams perplexing. Spitzer, however, merits a detailed and authoritative account of its successes, and More Things in the Heavens is just that. Eisenhardt was also a member of MELISSA GOLDEN/REDUX/EYEVINE the science team for the WISE mission, launched in December 2009. Werner, by contrast, has devoted his entire scientific career to Spitzer, and deserves to bask in the glow of its success. ■ Michael Rowan-Robinson is emeritus professor of astrophysics at Imperial College London and author of Night Vision: Exploring the Infrared Universe. e-mail: [email protected] Sarah Parcak identifies archaeological sites and monitors looting using aerial and satellite photography. 444 | NATURE | VOL 570 | 27 JUNE 2019 ©2019 Spri nger Nature Li mited. All ri ghts reserved. ©2019 Spri nger Nature Li mited. All ri ghts reserved. A satellite image revealed the houses and streets of Tanis, the capital of ancient Egypt from 1070 to 712 BC. Researchers glean subtle clues about what of Portus, an ancient harbour of imperial such as the 2017 rediscovery of the city of might lie beneath the surface, as well as how Rome, and a failed attempt to find evidence Qalatga Darband in Iraqi Kurdistan, using specific features relate to the landscape. of Vikings in Canada. There is also a long dis- US spy-satellite images and drone data. Different bands in the electromagnetic spec- cussion of Parcak’s specialist area, the process In the final two chapters, Parcak’s vision trum enable researchers to go beyond visual through which, around 2000 bc, Egypt’s Old comes into its own. She describes how, after appearances and detect thermal or chemi- Kingdom gave way to the Middle Kingdom the Egyptian revolution in 2011, she “para- cal cues. Elevation maps identify mounds (complete with fictional interludes). And chuted out of the ivory tower”, pioneering the DIGITALGLOBE/MAXAR VIA GETTY DIGITALGLOBE/MAXAR or ditches that could hide archaeological there is a chapter on her concerns about her use of satellite imagery to monitor the rise in remains. Particularly useful are crop marks, field, from high journal prices charged by thefts from unguarded archaeological sites. small differences in vegetation growth “corporate publishing superpowers” to the Funded by the National Geographic Society, caused by the presence of buried structures. lack of ethnic and gender diversity. she mapped more than 200,000 looting pits This personal approach allows Parcak to across Egypt. The evidence spurred political GLOBAL FRONTIERS recount enchanting details — such as the action against the illegal antiquities trade, as Parcak gives a whirlwind global tour of recent Egyptian goat that ate a third of the team’s well as debunking simplistic explanations findings, from Central America to the Mid- site plans in Sinai, or Newfoundland’s for it. She found that rates of looting actually dle East to Africa (which she calls “the great- ‘wreckhouse winds’, which nearly blew a jumped in 2009, after the financial crash: “It est frontier for archaeological discovery in team member off a cliff as he searched for is not who holds the local political reins, but the world”), and even under water. The sheer Viking remains. We learn, too, what drives the global economy, that does the driving.” scale of what could be found is dizzying: she Parcak: she sees archaeology as “a hope And then there’s that TED Prize. She used estimates that there are more than 50 million machine for humanity”. Ancient Egypt’s the money to raise an “army of global explor- unidentified archaeological sites globally. She repeated reinvention, for instance, reveals ers”. Her team developed an online game also imagines a future in which various types human resilience in the face of adversity. enabling the public to check satellite images of artificial-intelligence-assisted drone, able for signs of looting or archaeological remains. to sequence DNA and virtually unwrap bur- PET PROJECTS Since its 2017 launch, more than 80,000 users ied scrolls, will map, probe and analyse entire At times, however, the book becomes more a from around 100 countries have flagged sites in an hour. Although this might sound list of pet interests than a coherent story. It’s some 19,000 new sites, which specialists are extreme, she bases each aspect on existing a shame that the key topic of remote sensing beginning to confirm on the ground. technologies. Eventually, there might even often fades into the background, with frus- Parcak wants to give citizen scientists the be the potential to extend techniques to tratingly little detail given about some of the gift of wonder. Space archaeology, she says, other planets. If we ever do find remains of imaging technologies. There are mere para- allows us “to see a world without borders, alien civilizations, says Parcak, we’ll need, not graphs on the recent rise of lidar, for exam- full of possibility, past, present and future”. astronauts and engineers, but archaeologists. ple; yet the technology, which takes readings By panning out, we perceive what’s invisible This is a fascinating glimpse into a young by measuring reflected pulses of laser light, on the ground: features that relate not just to field just as its technological possibilities are has peered through Central American and the physical landscape, but to the history of exploding.