Breakthrough Starshot is a research and engineering project by the

Breakthrough Initiatives Breakthrough Initiatives is a science-based program founded in 2015 and funded by Julia and Yuri Milner, also of Breakthrough Prize, to search for extraterrestrial intelligence over a span of at least 10 years. The program is divided into multiple ...

to develop a

proof-of-concept Proof of concept (POC or PoC), also known as proof of principle, is a realization of a certain method or idea in order to demonstrate its feasibility, or a demonstration in principle with the aim of verifying that some concept or theory has prac ...

fleet of

light sail Solar sails (also known as light sails and photon sails) are a method of spacecraft propulsion using radiation pressure exerted by sunlight on large mirrors. A number of spaceflight missions to test solar propulsion and navigation have been p ...

interstellar probe An interstellar probe is a space probe that has left—or is expected to leave—the Solar System and enter interstellar space, which is typically defined as the region beyond the heliopause. It also refers to probes capable of reaching other s ...

s named ''Starchip'', to be capable of making the journey to the

Alpha Centauri Alpha Centauri ( Latinized from α Centauri and often abbreviated Alpha Cen or α Cen) is a triple star system in the constellation of Centaurus. It consists of 3 stars: Alpha Centauri A (officially Rigil Kentaurus), Alpha Centaur ...

star system 4.37

light-years A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

away. It was founded in 2016 by

Yuri Milner Yuri Borisovich (Bentsionovich) Milner (russian: Юрий Борисович (Бенционович) Мильнер; born 11 November 1961) is a Soviet-born Israeli entrepreneur, venture capitalist and physicist. He is a cofounder and former c ...

, Stephen Hawking, and

Mark Zuckerberg Mark Elliot Zuckerberg (; born ) is an American business magnate, internet entrepreneur, and philanthropist. He is known for co-founding the social media website Facebook and its parent company Meta Platforms (formerly Facebook, Inc.), o ...

. A flyby mission has been proposed to

Proxima Centauri b Proxima Centauri b (or Proxima b), sometimes referred to as Alpha Centauri Cb, is an exoplanet orbiting in the habitable zone of the red dwarf star Proxima Centauri, which is the closest star to the Sun and part of the triple star system Alpha ...

, an Earth-sized

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

in the

habitable zone In astronomy and astrobiology, the circumstellar habitable zone (CHZ), or simply the habitable zone, is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure.J. F. Kas ...

of its host star,

Proxima Centauri Proxima Centauri is a small, low-mass star located away from the Sun in the southern constellation of Centaurus. Its Latin name means the 'nearest tarof Centaurus'. It was discovered in 1915 by Robert Innes and is the nearest-kno ...

, in the Alpha Centauri system. At a speed between 15% and 20% of the

speed of light The speed of light in vacuum, commonly denoted , is a universal physical constant that is important in many areas of physics. The speed of light is exactly equal to ). According to the special theory of relativity, is the upper limit ...

, it would take between twenty and thirty years to complete the journey, and approximately four years for a return message from the starship to Earth. The conceptual principles to enable this interstellar travel project were described in "A Roadmap to Interstellar Flight", by Philip Lubin of

UC Santa Barbara The University of California, Santa Barbara (UC Santa Barbara or UCSB) is a public land-grant research university in Santa Barbara, California with 23,196 undergraduates and 2,983 graduate students enrolled in 2021–2022. It is part of the Un ...

.(file available at University of California, Santa Barbar
here
Accessed 16 April 2016) Sending the lightweight spacecraft involves a multi-kilometer

phased array In antenna theory, a phased array usually means an electronically scanned array, a computer-controlled array of antennas which creates a beam of radio waves that can be electronically steered to point in different directions without moving th ...

of beam-steerable

laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The fir ...

s with a combined coherent power output of up to 100 GW.

General

The project was announced on 12 April 2016 in an event held in

New York City New York, often called New York City or NYC, is the List of United States cities by population, most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the L ...

by physicist and venture capitalist

, together with cosmologist Stephen Hawking, who was serving as board member of the initiatives. Other board members include

Meta Platforms Meta Platforms, Inc., (file no. 3835815) trade name, doing business as Meta and formerly named Facebook, Inc., and TheFacebook, Inc., is an American multinational technology conglomerate based in Menlo Park, California. The company owns Facebo ...

(then known as Facebook, Inc.) CEO

. The project has an initial funding of US$100 million. Milner places the final mission cost at $5–10 billion, and estimates the first craft could launch by around 2036.

Pete Worden Pete or Petes or ''variation'', may refer to: People * Pete (given name) * Pete (nickname) * Pete (surname) Fictional characters * Pete (Disney), a cartoon character in the ''Mickey Mouse'' universe * Pete the Pup (a.k.a. 'Petey'), a character ...

is the project's executive director and

Harvard Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher le ...

Professor

Avi Loeb Abraham "Avi" Loeb ( he, אברהם (אבי) לייב; born February 26, 1962) is an Israeli-American theoretical physicist who works on astrophysics and cosmology. Loeb is the Frank B. Baird Jr. Professor of Science at Harvard University. He ha ...

chairs the advisory board for the project.

Objectives

The Breakthrough Starshot program aims to demonstrate a proof-of-concept for ultra-fast, light-driven nano-spacecraft, and lay the foundations for a first launch to

within the next generation. The spacecraft would make a flyby, and possibly photograph, of any Earth-like worlds that might exist in the system. Secondary goals are Solar System exploration and detection of Earth-crossing asteroids.

Target planet

The

European Southern Observatory The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental organization, intergovernmental research organisation made up of 16 mem ...

(ESO) announced the detection of a planet orbiting the third star in the Alpha Centauri system,

in August 2016. The planet, called

, orbits within the

of its star. It could be a target for one of the Breakthrough Initiatives' projects. In January 2017, Breakthrough Initiatives and the European Southern Observatory began collaborating to search for

habitable planets Planetary habitability is the measure of a planet's or a natural satellite's potential to develop and maintain environments hospitable to life. Life may be generated directly on a planet or satellite endogenously or be transferred to it from a ...

in the nearby star system Alpha Centauri. The agreement involves Breakthrough Initiatives providing funding for an upgrade to the VISIR (VLT Imager and Spectrometer for mid-Infrared) instrument on ESO's

Very Large Telescope The Very Large Telescope (VLT) is a telescope facility operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. It consists of four individual telescopes, each with a primary mirror 8.2 m across, ...

(VLT) in

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

. This upgrade will increase the likelihood of planet detection in the system.

Concept

A solar sail concept The Starshot concept envisions launching a "

mothership A mother ship, mothership or mother-ship is a large vehicle that leads, serves, or carries other smaller vehicles. A mother ship may be a maritime ship, aircraft, or spacecraft. Examples include bombers converted to carry experimental airc ...

" carrying about a thousand tiny spacecraft (on the scale of centimeters) to a high-altitude Earth orbit for deployment. A

of ground-based lasers would then focus a light beam on the crafts' sails to accelerate them one by one to the target speed within 10 minutes, with an average acceleration on the order of 100 km/s² (10,000 ɡ), and an illumination energy on the order of 1 TJ delivered to each sail. A preliminary sail model is suggested to have a surface area of 4 m × 4 m. An October 2017 presentation of the Starshot system model examined circular sails and finds that the beam director capital cost is minimized by having a sail diameter of 5 meters. The Earth-sized planet Proxima Centauri b is within the Alpha Centauri system's

. Ideally, the Breakthrough Starshot would aim its spacecraft within one

astronomical unit The astronomical unit (symbol: au, or or AU) is a unit of length, roughly the distance from Earth to the Sun and approximately equal to or 8.3 light-minutes. The actual distance from Earth to the Sun varies by about 3% as Earth orbits t ...

(150 million kilometers or 93 million miles) of that world. From this distance, a craft's cameras could capture an image of high enough resolution to resolve surface features. The fleet would have about 1000 spacecraft. Each one, called a StarChip, would be a very small centimeter-sized vehicle weighing a few grams. They would be propelled by a square-kilometre array of 10 kW ground-based

s with a combined output of up to 100 GW. A swarm of about 1000 units would compensate for the losses caused by interstellar dust collisions ''en route'' to the target. In a detailed study in 2016, Thiem Hoang and coauthors found that mitigating the collisions with

dust Dust is made of fine particles of solid matter. On Earth, it generally consists of particles in the atmosphere that come from various sources such as soil lifted by wind (an aeolian process), volcanic eruptions, and pollution. Dust in homes ...

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...

, and

galactic cosmic rays Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own ...

may not be as severe an engineering problem as first thought, although it will likely limit the quality of the sensors on board.

Technical challenges

Light propulsion requires enormous power: a laser with a gigawatt of power (approximately the output of a large nuclear plant) would provide only a few

newtons The newton (symbol: N) is the unit of force in the International System of Units (SI). It is defined as 1 kg⋅m/s, the force which gives a mass of 1 kilogram an acceleration of 1 metre per second per second. It is named after Isaac Newton in r ...

thrust Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that syst ...

. The spaceship will compensate for the low thrust by having a mass of only a few grams. The camera, computer, communications laser, a nuclear power source, and the solar sail must be miniaturized to fit within a mass limit. All components must be engineered to endure extreme

acceleration In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by the ...

, cold, vacuum, and protons. The spacecraft will have to survive collisions with

space dust Cosmic dust, also called extraterrestrial dust, star dust or space dust, is dust which exists in outer space, or has fallen on Earth. Most cosmic dust particles measure between a few molecules and 0.1 mm (100 micrometers). Larger particles are c ...

; Starshot expects each square centimeter of frontal cross-section to collide at high speed with about a thousand particles of size at least 0.1 μm. Focusing a set of lasers totaling one hundred gigawatts onto the solar sail will be difficult due to

atmospheric turbulence An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...

, so there is the suggestion to use space-based laser infrastructure. According to ''

The Economist ''The Economist'' is a British weekly newspaper printed in demitab format and published digitally. It focuses on current affairs, international business, politics, technology, and culture. Based in London, the newspaper is owned by The Econo ...

'', at least a dozen off-the-shelf technologies will need to improve by

orders of magnitude An order of magnitude is an approximation of the logarithm of a value relative to some contextually understood reference value, usually 10, interpreted as the base of the logarithm and the representative of values of magnitude one. Logarithmic dis ...

StarChip

StarChip is the name used by

for a very small, centimeter-sized, gram-scale, interstellar

spacecraft A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, p ...

envisioned for the Breakthrough Starshot program, a proposed mission to propel a fleet of a thousand ''Starchips'' on a journey to

, the nearest

star system A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. A large group of stars bound by gravitation is generally called a '' star cluster'' or '' galaxy'', although, broadly speak ...

, about 4.37

from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

. The journey may include a flyby of

, an Earth-sized

that is in the

of its host star. The ultra-light ''StarChip'' robotic nanocraft, fitted with light sails, are planned to travel at speeds of 20% and 15% of the

, taking between 20 and 30 years to reach the star system, respectively, and about 4 years to notify Earth of a successful arrival. The conceptual principles to enable practical interstellar travel were described in "A Roadmap to Interstellar Flight", by Philip Lubin of

, who is an advisor to the Starshot project. In July 2017, scientists announced that precursors to Spaceprobe, called Sprites, were successfully launched and flown through

Polar Satellite Launch Vehicle The Polar Satellite Launch Vehicle (PSLV) is an expendable medium-lift launch vehicle designed and operated by the Indian Space Research Organisation (ISRO). It was developed to allow India to launch its Indian Remote Sensing (IRS) satellites ...

ISRO The Indian Space Research Organisation (ISRO; ) is the national space agency of India, headquartered in Bengaluru. It operates under the Department of Space (DOS) which is directly overseen by the Prime Minister of India, while the Chairman ...

from

Satish Dhawan Space Centre Satish Dhawan Space Centre - SDSC (formerly Sriharikota Range - SHAR) is a rocket launch centre (spaceport) operated by Indian Space Research Organisation (ISRO). It is located in Sriharikota, Tirupati district of Andhra Pradesh. Sriharikota R ...

. 105 Sprites were also flown to the ISS on the

KickSat KickSat was a satellite dispenser for small-satellite ( femtosatellite) project inaugurated in early October 2011, to launch many very small satellites from a 3U CubeSat. The satellites have been characterized as being the size of a large posta ...

-2 mission that launched on November 17 2018, from where they were deployed on March 18, 2019. They successfully transmitted data before reentering the atmosphere and burning up on March 21.

Components

Each Spaceprobe nanocraft is expected to carry miniaturized cameras, navigation gear, communication equipment, photon thrusters and a power supply. In addition, each nanocraft would be fitted with a meter-scale

, made of lightweight materials, with a gram-scale mass.

Cameras

Five sub-gram scale

digital camera A digital camera is a camera that captures photographs in digital memory. Most cameras produced today are digital, largely replacing those that capture images on photographic film. Digital cameras are now widely incorporated into mobile device ...

s, each with a minimum 2-

megapixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the smal ...

resolution Resolution(s) may refer to: Common meanings * Resolution (debate), the statement which is debated in policy debate * Resolution (law), a written motion adopted by a deliberative body * New Year's resolution, a commitment that an individual mak ...

, are envisioned.

Processors

Four sub-gram scale

processors A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, and ...

are planned.

Photon thrusters

Four sub-gram scale photon thrusters, each minimally capable of performing at a 1W diode

level, are planned.

Battery

A 150 mg

atomic battery An atomic battery, nuclear battery, radioisotope battery or radioisotope generator is a device which uses energy from the decay of a radioactive isotope to generate electricity. Like nuclear reactors, they generate electricity from nuclear ene ...

, powered by

plutonium-238 Plutonium-238 (238Pu or Pu-238) is a fissile, radioactive isotope of plutonium that has a half-life of 87.7 years. Plutonium-238 is a very powerful alpha emitter; as alpha particles are easily blocked, this makes the plutonium-238 isotope suitab ...

americium-241 Americium-241 (, Am-241) is an isotope of americium. Like all isotopes of americium, it is radioactive, with a half-life of . is the most common isotope of americium as well as the most prevalent isotope of americium in nuclear waste. It is com ...

, is planned.

Protective coating

A coating, possibly made of

beryllium copper Beryllium copper (BeCu), also known as copper beryllium (CuBe), beryllium bronze, and spring copper, is a copper alloy with 0.5–3% beryllium but can contain other elements as well. Beryllium copper combines high strength with non- magnetic an ...

, is planned to protect the nanocraft from

collisions and

atomic particle In physical sciences, a subatomic particle is a particle that composes an atom. According to the Standard Model of particle physics, a subatomic particle can be either a composite particle, which is composed of other particles (for example, a pr ...

erosion.

Light sail

The

is envisioned to be no larger than , possibly of composite

graphene Graphene () is an allotrope of carbon consisting of a single layer of atoms arranged in a hexagonal lattice nanostructure.

-based material. The material would have to be very thin and be able to reflect the laser beam while absorbing only a small fraction of the incident energy, or it will vaporize the sail. The light sail may also double as power source during cruise, because collisions with atoms of interstellar medium would deliver 60 watt/m² of power.

Laser data transmitter

A laser communicator, utilizing light sail as the primary reflector, would be capable of data rates 2.6-15

baud In telecommunication and electronics, baud (; symbol: Bd) is a common unit of measurement of symbol rate, which is one of the components that determine the speed of communication over a data channel. It is the unit for symbol rate or modulatio ...

per watt of transmitted power at distance to the Alpha Centauri, assuming 30 m diameter receiving telescope on Earth.

Orbit

The Starshot project is for fly-by missions, which pass the target at high velocity. Heller ''et al.'' proposed that a photo-gravitational assist could be used to slow such a probe and allow it to enter orbit (using photon pressure in maneuvers similar to

aerobraking Aerobraking is a spaceflight maneuver that reduces the high point of an elliptical orbit (apoapsis) by flying the vehicle through the atmosphere at the low point of the orbit (periapsis). The resulting drag slows the spacecraft. Aerobraking is ...

). This requires a sail that is both much lighter and much larger than the proposed Starshot sail. The table below lists possible target stars for photogravitational assist rendezvous. The travel times are the calculated times for an optimized spacecraft to travel to the star and then enter orbit around the star. * Successive assists at α Cen A and B could allow travel times to 75 yr to both stars. * The light sail has a nominal mass-to-surface ratio (σ_nom) of 8.6×10⁻⁴ gram m⁻² for a nominal graphene-class sail. * Area of the light sail, about 10⁵ m² = (316 m)² * Velocity up to 37,300 km s⁻¹ (12.5% c)

Other applications

The German physicist

Claudius Gros Claudius Gros (born 18 February 1961 in Mainz, Germany) is a German physicist. Career Finishing his studies in physics 1985 at the ETH Zürich with a thesis on heavy Fermions, Gros continued for a PhD in theoretical solid-state physics. Usi ...

has proposed that the technology of the Breakthrough Starshot initiative may be used in a second step to establish a

biosphere The biosphere (from Greek βίος ''bíos'' "life" and σφαῖρα ''sphaira'' "sphere"), also known as the ecosphere (from Greek οἶκος ''oîkos'' "environment" and σφαῖρα), is the worldwide sum of all ecosystems. It can also be ...

of unicellular microbes on otherwise only transiently

habitable Habitability refers to the adequacy of an environment for human living. Where housing is concerned, there are generally local ordinances which define habitability. If a residence complies with those laws it is said to be habitable. In extreme e ...

s. A Genesis probe would travel at lower speeds, at a speed 4.6% of the speed of light, which would take at least 90 years to get to Alpha Centauri A. The sail could be configured so that the stellar pressure from Alpha Centauri A brakes and deflects the probe toward Alpha Centauri B, where it would arrive after a few days. The sail would then be slowed again to 0.4% of the speed of light and catapulted towards Proxima Centauri. At that speed it will arrive there after another 46 years — about 140 years after its launch. It could hence be decelerated using a

magnetic sail A magnetic sail is a proposed method of spacecraft propulsion that uses a static magnetic field to deflect a plasma wind of charged particles radiated by the Sun or a Star thereby transferring momentum to accelerate or decelerate a spacecraft. ...

References

External links

* * * * {{Portal bar, Astronomy, Stars, Spaceflight, Outer space, Solar System Alpha Centauri Interstellar travel Proposed space probes Proxima Centauri Projects established in 2016 Yuri Milner Stephen Hawking