Breakthrough Starshot

On 24 August 2016, ESO hosted a press conference to discuss the announcement of exoplanet Proxima b at its headquarters in Germany. In this picture, Pete Worden giving a speech.

Breakthrough Starshot is a research and engineering project by Breakthrough Initiatives to develop a proof-of-concept fleet of light sail spacecraft, named StarChip,^[1] capable of making the journey to the Alpha Centauri star system, 4.37 light-years away, at speeds between 15% and 20% of the speed of light,^[2][3][4][5] taking between 30 and 20 years to get there, respectively, and about 4 years to notify Earth of a successful arrival. The journey may include a flyby of Proxima Centauri b, an Earth-sized exoplanet that is in the habitable zone of its host star in the Alpha Centauri system.^[6] The conceptual principles to enable this interstellar travel project were described in "A Roadmap to Interstellar Flight", by Philip Lubin of UC Santa Barbara.^[7][8]

The project was announced on 12 April 2016 in an event held in New York City by physicist and venture capitalist Yuri Milner and cosmologist Stephen Hawking who is serving as board member of the initiatives. Other board members include Facebook CEO Mark Zuckerberg. The project has an initial funding of US$100 million to start research. Milner places the final mission cost at $5–10 billion, and estimates the first craft could launch around 2036.^[3] Pete Worden is tasked to run the Breakthrough Initiatives,^[9] of which this is the third.^[10]

Objectives

Breakthrough Starshot aims to demonstrate proof of concept for ultra-fast light-driven nano-spacecraft, and lay the foundations for a first launch to Alpha Centauri within the next generation. Secondary goals are Solar System exploration and detection of Earth-crossing asteroids.^[11] The German physicist Claudius Gros has proposed, that the technology of the Breakthrough Starshot initiative may be utilized in a second step to establish a biosphere of unicellular microbes on otherwise only transiently habitable exoplanets. ^{[12] [13]}

Concept

A solar sail concept.

The Starshot concept envisions launching a "mothership" carrying about a thousand tiny spacecraft (on the scale of centimeters) to a high-altitude orbit and then deploying them. Ground-based lasers would then focus a light beam on the crafts' solar sail to accelerate them one by one to the target speed within 10 minutes, with an average acceleration on the order of 100 km/s², and an illumination energy on the order of 1 TJ delivered to each sail, estimated to have a surface area of 4 m × 4 m.^[14][15]

If an Earth-size planet is orbiting within the Alpha Centauri system habitable zones, Breakthrough Starshot will try to aim its spacecraft within 1 astronomical unit (150 million kilometers or 93 million miles) of it. From this distance, a craft's cameras could potentially capture an image of high enough quality to resolve surface features.^[16]

The fleet would have about 1000 spacecraft, and each one (dubbed a StarChip), would be a very small centimeter-sized vehicle weighing a few grams.^[1] They would be propelled by a square-kilometre array of 10 kW ground-based lasers with a combined output of up to 100 GW.^[17][18] Each spacecraft would transmit data back to Earth using a compact on-board laser communications system using its solar sail as an antenna and the propulsion array as the receiver.^[17][18] A swarm of about 1000 units would compensate for the losses caused by interstellar dust collisions en route to the target.^[17][19] In more recent (albeit preliminary) work, it's suggested that mitigating the collisions with dust, hydrogen and galactic cosmic rays may not be quite as severe an engineering problem as first thought.^[20]

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 of thrust.^[18] The spaceship will compensate for the low thrust by having a mass of only a few grams. The camera, computer, communications laser, a plutonium power source, and the solar sail must be miniaturized to fit within a mass limit.^[18][21] All components must be engineered to endure extreme acceleration, cold, vacuum, and protons.^[19] The spacecraft will have to survive collisions with space dust; 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.^[18][22] Focusing a set of lasers totaling one hundred gigawatts onto the solar sail will be difficult, due to atmospheric turbulence. According to The Economist, at least a dozen off-the-shelf technologies will need to improve by orders of magnitude.^[18]

See also

References

External links

• Breakthrough Initiatives' official website
• Video (00:35) - Launching a StarChip - concept on YouTube
• Video (02:06) - Going interstellar (NASA) on YouTube
• Video (12:16) - Will Starshot's Insterstellar Journey Succeed? (PBS Digital Studios) on YouTube

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