Philanthropic Space Science: The Breakthrough Initiatives

Introduction

In the past few years, we have seen increasing discussions of privately funded space exploration efforts. Elon Musk, via SpaceX, has committed to human settlement of Mars, and Jeff Bezos, via Blue Origin, to large-scale space industrialization and human settlements on the moon. These are exciting enterprises with great potential for extending our civilization into the solar system. However, there remains another arm of space activity: scientific space exploration. Until recently, scientific pursuits using space-based instruments have been the exclusive domain of publicly funded space agencies of nation states. This too is changing.

In the United States, space research has a long history. From the earliest days of the Republic, the study of outer space from the ground was of public interest but, for the most part, relied on private effort. The sixth U.S. President, John Quincy Adams, was an avid proponent of astronomy and tried on numerous occasions to get an observatory publicly funded—indeed, in his first State of the Union speech before congress in 1825 he stated:

Connected with the establishment of an university, or separate from it, might be undertaken the erection of an astronomical observatory, with provision for the support of an astronomer, to be in constant attendance of observation upon the phenomena of the heavens, and for the periodical publication of his observances. It is with no feeling of pride as an American that the remark may be made that on the comparatively small territorial surface of Europe there are existing upward of 130 of these light-houses of the skies, while throughout the whole American hemisphere there is not one. If we reflect a moment upon the discoveries which in the last four centuries have been made in the physical constitution of the universe by the means of these buildings and of observers stationed in them, shall we doubt of their usefulness to every nation? And while scarcely a year passes over our heads without bringing some new astronomical discovery to light, which we must fain receive at second hand from Europe, are we not cutting ourselves off from the means of returning light for light while we have neither observatory nor observer upon our half of the globe and the earth revolves in perpetual darkness to our unsearching eyes? ¹

Largely thwarted in his quest for public funds, President Adams was instrumental in getting the privately funded Harvard College Observatory started in 1839. Moreover, the dominant historic trend of U.S. funding for large telescopes came from private sources. For an outstanding review of this history, see the work of Alexander MacDonald. ²

Despite the long history of private funding for ground-based space sciences—John Quincy Adams's “light-houses of the skies”—little private support has focused on space-based space sciences, via space-based telescopes (e.g., Hubble Space Telescope) or other in situ instruments. This is now changing for several reasons. First, lower cost space technologies coupled with cheaper access to space via launch services has made world-class space science possible at traditional philanthropic funding levels—a few million to a several hundred million U.S. dollars (USD). Second, government science funding, while still significant, does not necessarily keep pace with inflation; private fortunes do. Finally, due to recent scientific discoveries, we are at the verge of answering one of humankind's oldest scientific questions—are we alone in the universe?

In this article, we discuss one of these new philanthropic science organizations, devoted to answering questions about life in the universe—the “Breakthrough Initiatives.” But first we turn to the parent entity, which pre-dated the Initiatives, the “Breakthrough Prize Foundation” with its “Breakthrough Prize.”

The Breakthrough Prize Foundation and the Breakthrough Prize

The Breakthrough Prize Foundation is a U.S. nonprofit foundation established in 2012 with the launch of the “Breakthrough Prize in Fundamental Physics.” Since its founding, additional prizes have been added: the “Breakthrough Prize in Life Sciences” (2013) and the “Breakthrough Prize in Mathematics” (2015). Founded by Internet entrepreneur and former physicist Yuri Milner and his wife Julia Milner, alongside founding sponsors Sergey Brin, Priscilla Chan, Mark Zuckerberg, Ma Huateng, and Anne Wojcicki, the prizes serve to recognize individuals who have made profound contributions to human knowledge. With a USD 3 million prize value, they are the world's largest science prizes. Since 2013, the annual prize ceremonies have been held on the campus of NASA Ames Research Center in Silicon Valley, California. ^* First author of this article, Simon P. Worden, was formerly the Center Director of NASA Ames and became acquainted with Yuri Milner in 2014. In 2015, Simon P. Worden retired from NASA and became Chairman of the Breakthrough Prize Foundation. On July 20, 2015, alongside Stephen Hawking at the Royal Society in London, Yuri Milner announced the Breakthrough Initiatives—a series of scientific investigations focused on the questions surrounding Life in the Universe. ³ Simon P. Worden became Executive Director of the Breakthrough Initiatives.

Breakthrough Initiatives—Breakthrough Listen

The Breakthrough Initiatives are a suite of scientific space exploration programs in search of the origin, extent, and nature of life in the Universe. Founded in 2015, the first Breakthrough Initiative was announced on July 20, 2015, the 46th anniversary of 1969 Apollo Moon Landing—humanity's first step on another world. Yuri Milner pledged $100M USD for a 10-year renewed search for extraterrestrial intelligence (SETI).

SETI research began in earnest in the early 1960s. A seminal article by Giuseppe Cocconi and Philip Morrison ⁴ described the methods to “listen” for signs of technological life, and famed astronomer Frank Drake began conducting his pioneering searches. ⁵ Cocconi and Morrison ⁴ suggested that the 21 cm atomic hydrogen emission frequency of 1.42 GHz was ideal for SETI signals. Most searches since that time have centered on this and nearby frequencies using radio telescopes. ⁶

NASA involvement came in the 1970s with funded definition studies on SETI. Furthermore, in a brief moment of excitement on Columbus Day 1992, NASA announced a radio astronomy program called SETI/HRMS, a 10-year $100 million program. Before the program could ever see any light, the program was canceled by the U.S. Congress a year later in 1993, and SETI/HRMS was carried forth in reduced scope and with private funding via Project Phoenix. ⁷ Since the early 1990s, most SETI projects were sponsored by private funds. Co-founder of Microsoft Paul Allen has, via his private foundation, contributed approximately $29 million to the SETI Institute. The SETI Institute developed the 42-radio antenna system known as the Allen Telescope Array. The effort is likely the single largest investment in advanced technosignature research up until 2015. Other private donors have also contributed to the effort, such as Franklin Antonio, co-founder of Qualcomm. The Breakthrough Listen project proposed a significant expansion of these measurements with access to the world's largest radio telescopes, very high frequency resolution (∼Hz), broad spectral coverage 0.1–100 GHz, and an optical component searching for extraterrestrial lasers. To date, significant radio observations have been made using the Green Bank 100-m telescope in Green Bank, West Virginia, USA, and the Parkes 64-m telescope in Parkes, New South Wales, Australia. Additional agreements are in place to use the new MeerKAT Square Kilometer Array precursor in South Africa, the Jodrell Bank 74-m Lovell Telescope, and other facilities of the Jodrell Bank Observatory in the United Kingdom and the new 500-m Five-hundred-meter Aperture Spherical radio Telescope in China.

The objective of Breakthrough Listen is to search in depth for technosignatures from the nearest stars and the nearest 100 galaxies and to conduct a survey over the entire galactic plane. In addition, surveying one million stars—most of the stars within 300 parsecs—for evidence of radio emission in the classically identified low-noise part of the radio spectrum. The latter survey requires an array telescope that can have multiple phased-array beams electronically pointed in order for it to be accomplished in the next few years. This will be the primary objective of the MeerKAT/SKA Breakthrough Listen program.

The approach with radio telescopes is to install sophisticated digital instrumentation at radio observatories to look for spectral and temporal signatures that would not be expected from natural astrophysical mechanisms.^8,9 For example, known astrophysical processes all have spectral extent broader than 500 Hz. For the Listen survey, the program archives data at multiple time/frequency resolutions—with the highest spectral resolution of 3 Hz and time resolution of 18 s—two other modes have lower spectral resolution (300 and 3 KHz, respectively) but higher temporal resolution (300 μs and 1 s, respectively). Correlated signals above a certain threshold are recorded and made available to the scientific community. In addition, the program has begun a full scan of the galactic plane using the multibeam receiver on the Parkes Radio Telescope, ^† supplemented by the Green Bank Telescope for positions not visible from the southern hemisphere. For this program, all the raw voltage signals are periodically recorded to ensure that SETI researchers can have access to unprocessed data. This results in a massive data set of several petabytes—thus, this is an occasional scan conducted approximately once per year. Breakthrough Listen is partnering with a national supercomputing facility in Western Australia, the Pawsey Center, for this effort.

Noting that our own civilization increasingly uses optical (laser) communications, the program began a search for optical laser signals from a selected sample of several hundred nearby stars, using the Lick Observatory Automated Planet Finder 2.4-m telescope. ¹⁰ Other optical and near-infrared SETI searches are planned as well as low–mid frequency radio surveys. ¹¹

Breakthrough Watch

While Breakthrough Listen hopes to find evidence for an alien technosignature within the next decade, a more fundamental question is whether there is any life at all beyond our planet. Most searches for extraterrestrial life have focused on Mars. Indeed, there is tantalizing evidence for extent life there, probably underground, based on the recently reported evidence for complex organic molecules and variable methane, a gas that may be biogenerated.^12,13 However, finding life on or underground on Mars—or even evidence of past life—would be inconclusive of life beyond earth as the terrestrial planets have exchanged substantial material, which could have transported life between these worlds.

A set of perhaps more interesting places to look for unique-origin life in our solar system are the “ocean-world” moons of the outer planets. In particular, Saturn's inner moon, Enceladus, and Jupiter's moon, Europa. Space probes have shown that these moons have a substantial ice-covered ocean in contact with a volcanically active rocky crust. This may mimic conditions that gave rise to life on earth billions of years ago. Both Enceladus ¹⁴ and Europa ¹⁵ are observed to eject water geysers into space. The Cassini mission showed that Enceladus' plumes contain simple organic molecules. As this water, at least in Enceladus' case, contains organic molecules and is accessible via fly-by space probes, it may be possible to conduct near-term low-cost missions to look for more definitive signatures of life. Considering the cost of NASA's Discovery Program, which was in the hundreds of millions, a life signature mission is not out of scope for private entities. The Breakthrough Initiatives have been conducting studies to assess such missions, although no decision has been made on conducting such missions as of yet.

When this article's first author (S.P. Worden) went to graduate school in the 1970s, no exoplanets were known—indeed, many planetary formation models suggested that planetary systems could be rare. That all changed in the 1990s when several exoplanets were detected by observing the radial velocity reflex motion of their primary star. ¹⁶ Several exoplanet detection methods have been used since, but the most productive approach to date has been NASA's Kepler mission—which detects planets by observing the very small light-level decreases from a planetary transit across the disk of the parent star. Kepler's data showed that most stars in the galaxy have a planetary system and about a quarter of solar-type stars have an earth-sized planet orbiting in the habitable zone (defined where the planet's equilibrium temperature would allow liquid water to exist on the surface). ¹⁷

This large number of potential “earths” raises the possibility of there being a nearby life-bearing planet similar to our own—and harboring life of some form. On January 9, 2017, at the European Southern Observatory in Santiago Chile, Simon P. Worden (first author) announced, “Breakthrough Watch,” designed to detect and ultimately investigate the possible presence of life on these planets.

Breakthrough Watch has focused its attention on the nearest star system, Alpha Centauri—officially known as “Rigel Kentaurus” at 4.37 light years (1.34 parsec). This system consists of two solar-type stars (Alpha Centauri A and Alpha Centauri B) orbiting each other with about an 80-year eccentric orbit (e = 0.52). The third star, a red dwarf star known as Proxima Centauri, orbits at a distance of 13,000 AU from the two other stars and is actually the closest star to our sun at 4.24 light years. In 2016, it was reported from radial velocity measurements that Proxima Centauri has an earth-sized planet orbiting in the star's habitable zone (11-day period). ¹⁸

Alpha Centauri A and Alpha Centauri B have been carefully observed to detect planets. There are considerable differences of opinion over whether planets are more easily formed in a binary system, such as Alpha Centauri—dynamical calculations show that earth-sized planets in the habitable zones of both stars could have stable orbits for billions of years. Some observations based on radial velocity measurements have suggested that Alpha Centauri B has one or more planets. ¹⁹ However, these observations have since been disputed. ²⁰

Direct imaging of planets in the Alpha Centauri system is the best way to resolve whether either large star has earth-like planets. A space-based small optical coronagraph attached to a half-meter-class telescope designed to block the light of the primary stars could directly detect earth-sized planets via reflected starlight. ²¹

The Breakthrough Initiatives have looked at various direct detection methods. While reflected optical starlight is one way to detect a planet, the contrast between the parent star and planet is ∼10⁻¹⁰, whereas in the thermal IR, where the planet's thermal emission peaks, at around 10 μ, the contrast is equal to just the geometrical difference between the star and planet, 10⁻⁶. With potential habitable zone planets orbiting within 0.5–2 arcsec around the two stars, a properly constructed IR coronagraph on an existing 8-m class telescope could directly image an earth-sized planet. Correspondingly, the Breakthrough Initiatives have begun construction of an IR coronagraph for the European Southern Observatory's 8-m Very Large Telescope mid-IR Imager (VISIR) in Chile to begin observations in early 2019. ²² Similar instruments on other telescopes are also under consideration.

In addition to detecting planets in the Alpha Centauri system, Breakthrough Watch seeks to characterize their mass and ultimately atmospheric composition. From the latter, it may be possible to infer the presence of life—probably through the detection of water and presence of a nonequilibrium chemical environment. ²³ The next generation of ground-based telescopes, the “Extremely Large Telescopes” or ELTs, with 30-m class apertures are planned to be equipped with a spectroscopic capability to perform these observations within the next decade. ²⁴

In addition, one would like to render the mass of any detected planet—from which key parameters such as internal composition may be deduced. To obtain such data, the space motion of the primary star, which will “wobble” slightly due the gravity of the orbiting planet, is needed. Precise astrometric positions referenced to background stars are the traditional approach. However, since nearby background stars are much fainter than the Alpha Centauri stars, and optical systems all have aberrations and other errors that are difficult to calibrate for, conventional astrometry of this type is insufficiently accurate to obtain masses for earth-sized planets—even for the nearby Alpha Centauri System. Fortunately, a novel approach where one star is referenced to the other has been developed. ²⁵ The Breakthrough Initiatives program commissioned a study to determine if a small space-based astrometric instrument, dubbed “Toliman” (the Arabic name for Alpha Centauri), might be able to make this measurement. This study concluded that a 10–20 cm class optical small satellite, possibly even a CubeSat, could make the necessary observations. The Breakthrough Initiatives are currently considering such a mission.

Breakthrough Starshot

The origin of sailing on light can perhaps be traced back to an open letter Johannes Kepler sent to Galileo Galilei on April 19, 1610, in the Conversation with Star Messenger:

But as soon as somebody demonstrates the art of flying, settlers from our species of man will not be lacking. Who would once have thought that the crossing of the wide ocean was calmer and safer than of the narrow Adriatic Sea, Baltic Sea, or English Channel? Given ships or sails adapted to the breezes of heaven, there will be those who will not shrink from even that vast expanse. Therefore, for the sake of those who, as it were, will presently be on hand to attempt this voyage, let us establish the astronomy, Galileo, you of Jupiter, and me of the moon. ²⁶

In 2015, at the initiation of the Breakthrough Initiatives, the sponsor Yuri Milner asked whether it was plausible to send probes to the nearest star system within a generation. To achieve a transit time comparable to current long-term space exploration missions to the other solar system, the mission would need to last a few decades at most. This requires a probe to travel about 1,000 times faster than currently possible—or about 20% light speed. At 60,000 km/s, it would take just over 20 years to reach the Alpha Centauri system at 4.3 light years distance.

A distinguished panel was assembled with Avi Loeb of the Harvard University as chair. ^‡ Avi Loeb chairs the Astronomy Department at the Harvard University and serves as the director of the Institute for Theory and Computation and the founding director of the Black Hole Initiative there. His team looked at dozens of past proposals for interstellar travel—even those based on uncertain physics.

It was immediately apparent that using a conventional rocket carrying the propellant with it required orders of magnitude more efficient propulsion than any currently in use. Indeed, the propellant would need to have a specific impulse, I_sp, of 10⁶ or higher to allow a rocket system to reach 20% light speed in a reasonable cost and with a reasonable mass. Today, chemical systems have I_sp of a few hundred—even electric systems are less than a few thousand. The “magic million” for practical interstellar flight requires a propulsion system 1,000 times better than today's. While nuclear fission and fusion systems might achieve I_sp of hundreds of thousands, those systems face significant technical challenges. The most efficient reaction possible—a matter–antimatter annihilation reaction could have I_sp of several million—however, the global manufacture of antimatter would need to be increased by at least 15 orders of magnitude. This is currently impossible. A look toward other alternatives was needed. The main limitation of rocket propulsion stems from the need to carry the fuel with the spacecraft. This limits the attainable speeds to a logarithmic factor times the gas speed at the exhaust of the rocket, which is dictated by the energy released per unit mass by the fuel and is much smaller than the speed of light for chemical or even nuclear propulsion. Leaving the fuel behind and using a remote propulsion method would be a better approach for reaching the speed of light.

It turns out that Johannes Kepler had it right—sailing on the “winds of space” turns out to be a feasible method. Sunlight-propelled light sails have been demonstrated by the Planetary Society in 2015 with the lightsail-1 spacecraft ²⁷ and the Japanese Space Agency on its IKAROS probe launched in 2010. ²⁸ Unfortunately, sunlight alone is not sufficient for high-speed subrelativistic flight. The use of directed energy devices, lasers and masers, coupled with a lightsail for interstellar flight were proposed in the 1960s to 1980s by Robert Forward. ²⁹ More recently in 2015, Philip Lubin published an extensive laser light sail study funded by NASA's Innovative and Advanced Concepts (NIAC ^§ ) program. ³⁰ Lubin concluded that advances in satellite miniaturization would soon make it possible to construct a robust spacecraft suitable for an interstellar mission. Avi Loeb's group reviewed Lubin's concept and concluded that it was a viable approach. In late 2015, the Breakthrough Initiatives, in concert with Avi Loeb's and Philip Lubin's research groups at the Harvard University and the University of California, Santa Barbara, respectively, did an in-depth design study to assess the viability of a laser-propelled light sail probe to Alpha Centauri. The team studied whether a system could be built within a few decades for a cost consistent with large science experiments, such as the James Webb Space Telescope and CERN's Large Hadron Collider (about $10B USD). The target velocity was 60,000 km/s (20% of light speed) so that the transit time would be just slightly more than 20 years.

Two key developments make an interstellar laser-driven nanocraft feasible in the next few decades. First, is a rapidly increasing ability in microelectronics to construct a gram-class spacecraft—dubbed “nanocraft.” Indeed, in 2017, the Breakthrough Initiatives collaborated with space company OHB System AG ^** systems to successfully test on-orbit, for the first-time a gram-class spacecraft. ³¹ The second breakthrough is the rapidly decreasing cost of laser technology and increased laser power. Laser costs and capability have been on a “Moore's Law” curve for the past decade. This trend is continuing, and one can expect within the next decades that it might be feasible to gang-together millions of diodes or fiber lasers at about a 1-μm wavelength. This could enable a km-square class, 100 GW class ground-based laser, within target costs.

There are a myriad of major technical challenges, including potential hazards with interstellar space travel, especially impacts by dust particles and interstellar atoms. In addition, there are policy challenges to ensure a laser of this power may be safely utilized without hazarding other space operations. However, the program has identified three key technical challenges that need to be addressed before continuing to the next phase of development. First, it must be demonstrated that millions of lasers can be phased over kilometer scales for the “photon-engine”—and that the cost is within general constraints. Second, demonstrate that materials for the light sail possessing high reflectivity and more importantly, extremely low absorption are possible. And three, that one can communicate key science results, especially high-resolution planetary images of the target planet, back to Earth.

The Breakthrough Starshot initiative was announced atop the One World Trade Center in New York on April 20, 2016, “Breakthrough Starshot.” The program seeks to launch interstellar probes to the Alpha Centauri system and has three phases. In the first phase, an estimated $100M USD over 5–7 years to address the three key technical challenges aforementioned. Pending successful completion of this research phase, a second phase, lasting up to 10 years will entail building a scaled prototype system. The estimate of such a phase is $500M to $1B USD. Both of the initial phases are anticipated to be privately funded. The final phase, a full-scale system may take 10 years and cost approximately $10B USD. One could expect such a phase to be a funded as a public–private partnership.

The final system will consist of a ground-based kilometer scale 100 GW photon engine located in the southern hemisphere [Alpha Centauri, at −61° (S) declination is only accessible from southern latitudes]. A space-based mother ship in a highly elliptical orbit, with an apogee of 60,000 km aimed in the direction of the target stars, will carry thousands of starchip/sail nanocraft. About one nanocraft will be launched per day. The ground-based laser would use its directed energy beam for up to 10 min focused on the lightsail to accelerate it to 60,000 km/s. The laser beam can be focused in an annular beam pattern to keep the nanocraft centered in the beam and directed toward the target star within an arcsecond. Small photonic thrusters on the nanocraft can fire continuously to provide course correction of up to an astronomical unit during its cruise phase. The current system concept envisages a spherical light sail. The spacecraft components will likely be distributed in multiple copies and embedded in the sail to provide redundancy. After acceleration, the nanocraft would coast for 20-plus years toward its target. Small maneuvers to stay on course and fine-tune the trajectory will be possible with small on-board laser photon thrusters.

The nanocraft will fly within a few million kilometers of the target planet obtaining image data. To get high special resolution, an optical system of several tens of centimeters aperture is needed. An analysis is being undertaken to see if the lightsail itself, or a deployed optical system, could better serve this function. After flying by the target system, the nanocraft will lock on to the sun—offset to the earth's predicted position and begin transmitting the imagery (hopefully over 100 images for each successful nanocraft—one could expect to send hundreds) data back to earth using a small watt-class pulsed-laser. At interstellar distances, calculations show that a very large optical receiving aperture will be needed to obtain even a few hundred bits per second. ³⁰ The program currently envisages the kilometer-scale transmit photon engine array to do double service by acting as a receiver. In essence, it is an optical phased array transceiver.

The initial research phase is beginning this year (2018) with several dozen $100K research and analysis contracts covering each of the three key challenges being awarded. In 2019, a down-select will occur to a few laboratory development projects of a few million dollars for each area. Finally, field demonstrations will begin in a few years to validate key conclusions.

No doubt this program is ambitious. It will take decades to come to fruition, if ever. But one is reminded and encouraged by the recent success of the Laser Interferometer Gravitational-Wave Observatory Gravitational Wave discoveries. A century ago, Albert Einstein himself, formulator of gravitational wave physics, thought detecting them was impossible. ³² A few decades ago, a small team began developing the necessary technology—with the spectacular results of 2 years ago to show. One can envision the same success can be reached in the decades ahead with humanity's first foray into the Galaxy!

Breakthrough Discuss and Committees

In 2016, the Breakthrough Initiatives announced “Breakthrough Discuss,” ^†† an annual academic conference focused on the search for life in the Universe and novel ideas for space exploration. The conference provides a forum of discourse and debate among the scientific community who are at the leading edge of their respective fields. The event is streamed live and available on YouTube as archived talks. It also worth noting that every initiative has an advisory committee affixed to it. There are ∼20–35 members in each, and they convene in-person annually during the Breakthrough Discuss conference.

Summary

With lowering costs of space access, enabling technologies and changing government priorities, private space endeavors are coming to the fore. This is not wholly new. Private actors have a rich history in the origins of space exploration, taking on projects deemed too exotic and risky for public funding. Whether the future will follow such a trend, or if private funding can act as a supplement for the shortfall in public space science budgets, is debatable. Perhaps the model of public–private partnerships espoused by contemporary space agencies leverage the latter.

Already, access to space via privately funded companies, SpaceX (Elon Musk), Blue Origin (Jeff Bezos), Virgin Orbit (Richard Branson), and Stratolaunch (Paul Allen), have taken center stage. Private interests in large-scale space industry and settlement underlie much of this effort. However, philanthropic trends bear watching. The Breakthrough Initiatives, focused on the scientific questions of life in the universe, are well underway via Breakthrough Listen, Watch, Starshot, and Discuss. Philanthropic space-based missions are within reach and the shape of space exploration to come promise to usher in an exciting new era.

The Breakthrough Initiatives are managed by the Breakthrough Prize Foundation: Breakthroughinitiatives.org