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] Sending the lightweight spacecraft involves a square-kilometer with 10 kW lasers, operating as a phased array. This is needed for the spot size to fit the sail size at long range, so that the duration of the push is sufficiently long to reach these velocities. Getting sufficiently large effective aperture with one big laser would be impractical.

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 the project's executive director.[9]

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.[10] 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.[11][12]

In January 2017, Breakthrough Initiatives and the European Southern Observatory (ESO) entered a collaboration[13][14] to enable and implement a search for habitable planets 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 (VLT) in Chile. This upgrade will greatly increase the likelihood of planet detection in the system.

In August 2016, the European Southern Observatory announced the detection of a planet orbiting the third star in the Alpha Centauri system, Proxima Centauri.[15][16] The planet, called Proxima Centauri b, could be a potential target for one of the projects of Breakthrough Initiatives.

Breakthrough Starshot[17] is a proof of concept mission to send a fleet of ultra-fast light-driven nanocraft to explore the Alpha Centauri star system, which could pave the way for a first launch within the next generation. An objective of the mission would be to make a fly-by of and possibly photograph any Earth-like worlds that might exist in the system.

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. The phased array of ground-based lasers would then focus a light beam on the crafts' solar 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, 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.[18][19]

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.[20]

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.[21][22] 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.[21][22] A swarm of about 1000 units would compensate for the losses caused by interstellar dust collisions en route to the target.[21][23] 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.[24]

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.[22] 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.[22][25] All components must be engineered to endure extreme acceleration, cold, vacuum, and protons.[23] 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.[22][26] 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.[22]

StarChip

StarChip is the name used by Breakthrough Initiatives for a very small, centimeter-sized, gram-scale, interstellar spacecraft envisioned for the Breakthrough Starshot program,[1][27] a proposed mission to propel a fleet of a thousand StarChips on a journey to the Alpha Centauri star system, the nearest extrasolar stars, about 4.37 light-years from Earth.[28][3][29][2][30][31] The journey may include a flyby of Proxima Centauri b, an Earth-sized exoplanet that is in the habitable zone of its host star.[6] The ultra-light StarChip robotic nanocrafts, fitted with lightsails, are planned to travel at speeds of 20%[1][3][29][2] and 15%[2] of the speed of light, taking between 20 and 30 years to reach the star system, respectively, and about 4 years to notify Earth of a successful arrival.[3] The conceptual principles to enable practical interstellar travel were described in "A Roadmap to Interstellar Flight", by Philip Lubin of UC Santa Barbara,[7] who is an advisor for the Starshot project.

In July 2017, scientists announced that precursors to StarChip, named Sprites, were successfully launched and flown.[32]

Components

Each StarChip 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 lightsail, made of lightweight materials, with a gram-scale mass.[1][27][28][3][30][31][33][34]

Cameras

Four sub-gram scale digital cameras, each with a minimum 2-megapixels resolution, are envisioned.[1][35]

Processors

Four sub-gram scale processors are planned.[30][36]

Photon thrusters

Four sub-gram scale photon thrusters, each minimally capable of performing at a 1W diode laser level, are planned.[27][37][38]

Battery

A 150 mg atomic battery, powered by plutonium-238 or americium-241, is planned.[3][31][39]

Protective coating

A coating, possibly made of beryllium copper, is planned to protect the nanocraft from dust collisions and atomic particle erosion.[31][40]

Lightsail

The lightsail is envisioned to be no larger than 4 by 4 meters (13 by 13 feet),[1][41] possibly of composite graphene-based material.[1][28][3][31][34][42] The material would have to be very thin and, somehow, be able to reflect the laser beam without absorbing any of its thermal energy, or it will vaporize the sail.[1][3][43]

Reference interstellar travel catalog to use photogravitational assists for a full stop.

Name Travel time
(yr)		 Distance
(ly)		 Luminosity
(L☉)
Sirius A 68.90 8.58 24.20
α Centauri A 101.25 4.36 1.52
α Centauri B 147.58 4.36 0.50
Procyon A 154.06 11.44 6.94
Vega 167.39 25.02 50.05
Altair 176.67 16.69 10.70
Fomalhaut A 221.33 25.13 16.67
Denebola 325.56 35.78 14.66
Castor A 341.35 50.98 49.85
Epsilon Eridani 363.35 10.50 0.50

. Ref:[44]

See also

References

  1. 1 2 3 4 5 6 7 8 9 Gilster, Paul (12 April 2016). "Breakthrough Starshot: Mission to Alpha Centauri". Centauri Dreams. Retrieved 14 April 2016.
  2. 1 2 3 4 Staff (12 April 2016). "Breakthrough Starshot". Breakthrough Initiatives. Retrieved 12 April 2016.
  3. 1 2 3 4 5 6 7 8 9 Overbye, Dennis (12 April 2016). "Reaching for the Stars, Across 4.37 Light-Years; A Visionary Project Aims for Alpha Centauri, a Star 4.37 Light-Years Away". New York Times. Retrieved 12 April 2016.
  4. ↑ Stone, Maddie (April 12, 2016). "Stephen Hawking and a Russian Billionaire Want to Build an Interstellar Starship". Gizmodo. Retrieved 12 April 2016.
  5. ↑ Staff (12 April 2016). "Breakthrough Initiatives - Breakthrough Starshot". Breakthrough Initiatives. Retrieved 14 April 2016.
  6. 1 2 Chang, Kenneth (24 August 2016). "One Star Over, a Planet That Might Be Another Earth". New York Times. Retrieved 24 August 2016.
  7. 1 2 Lubin, Philip (April 2015). "A Roadmap to Interstellar Flight" (PDF). University of California, Santa Barbara. Retrieved 16 April 2016.
  8. ↑ Hall, Loura (May 7, 2015). "DEEP IN Directed Energy Propulsion for Interstellar Exploration". NASA News. Retrieved 2016-04-22. NASA is pleased to hear that Professor Lubin has received external funding to continue the work started in his NIAC study.
  9. ↑ Emspak, Jesse (2016-04-15). "No Breakthrough Yet: Stephen Hawking's Interstellar 'Starshot' Faces Challenges". Space.com. Retrieved 2017-05-22.
  10. ↑ Scharf, Caleb A. "Can Starshot Work?". scientificamerican.com. Retrieved 25 August 2016.
  11. ↑ Claudius Gros: Developing Ecospheres on Transiently Habitable Planets: The Genesis Project, Astrophysics and Space Science, Vol. 361, pp 1-14 (2016).
  12. ↑ Jessica Boddy: Q&A: Should we seed life on alien worlds?, Science, 9. September 2016.
  13. ↑ "VLT to Search for Planets in Alpha Centauri System - ESO Signs Agreement with Breakthrough Initiatives". www.eso.org. Retrieved 10 January 2017.
  14. ↑ "Breakthrough Initiatives". breakthroughinitiatives.org. Retrieved 10 January 2017.
  15. ↑ "Planet Found in Habitable Zone Around Nearest Star - Pale Red Dot campaign reveals Earth-mass world in orbit around Proxima Centauri". www.eso.org. Retrieved 10 January 2017.
  16. ↑ Witze, Alexandra (25 August 2016). "Earth-sized planet around nearby star is astronomy dream come true". Nature. pp. 381–382. doi:10.1038/nature.2016.20445. Retrieved 10 January 2017.
  17. ↑ "Breakthrough Initiatives". breakthroughinitiatives.org. Retrieved 10 January 2017.
  18. ↑ Lightsail, Integrity under thrust.
  19. ↑ Lightsail | Stability on the beam.
  20. ↑ "Breakthrough Initiatives". breakthroughinitiatives.org. Retrieved 25 August 2016.
  21. 1 2 3 "Breakthrough Starshot: Concept". 12 April 2016. Retrieved 14 April 2016.
  22. 1 2 3 4 5 6 "A new plan to send spacecraft to the stars: replace rockets with lasers". The Economist. 12 April 2016. Retrieved 13 April 2016.
  23. 1 2 Emspak, Jesse (15 April 2016). "No Breakthrough Yet: Stephen Hawking's Interstellar 'Starshot' Faces Challenges". Space. Retrieved 15 April 2016.
  24. ↑ Timmer, John (24 August 2016). "Just how dangerous is it to travel at 20% the speed of light?". Science. Ars Technica. Retrieved 2016-08-28.
  25. ↑ "Potential Challenges for Starshot". Breakthrough Initiatives. Retrieved 14 April 2016.
  26. ↑ "Interstellar Dust". Breakthrough Initiatives. Retrieved 15 April 2016.
  27. 1 2 3 Greene, Kate (13 April 2016). "What Will Make Interstellar Travel a Reality?". Slate (magazine). Retrieved 16 April 2016.
  28. 1 2 3 Clery, Daniel (12 April 2016). "Russian billionaire unveils big plan to build tiny interstellar spacecraft". Science (journal). doi:10.1126/science.aaf4115. Retrieved 15 April 2016.
  29. 1 2 Stone, Maddie (12 April 2016). "Stephen Hawking and a Russian Billionaire Want to Build an Interstellar Starship". Gizmodo. Retrieved 12 April 2016.
  30. 1 2 3 Domonoske, Camila (12 April 2016). "Forget Starships: New Proposal Would Use 'Starchips' To Visit Alpha Centauri". NPR. Retrieved 15 April 2016.
  31. 1 2 3 4 5 Emspak, Jesse (15 April 2016). "No Breakthrough Yet: Stephen Hawking's Interstellar 'Starshot' Faces Challenges". Space.com. Retrieved 15 April 2016.
  32. ↑ Staff (26 July 2017). "In Quest To Reach Alpha Centauri, BreakThrough Starshot Launches World's Smallest Spacecraft - First Prototype ‘Sprites’ – Precursors to Eventual ‘StarChip’ Probes – Achieve Low Earth Orbit". BreakThroughInitiatives.org. Retrieved 28 July 2017.
  33. ↑ Staff (12 April 2016). "Breakthrough Starshot: Potential Challenges". Breakthrough Initiatives. Retrieved 14 April 2016.
  34. 1 2 Staff (16 April 2016). "Starship enterprise". The Economist. Retrieved 15 April 2016.
  35. ↑ Staff (12 April 2016). "Breakthrouth Starshot: Gram-Scale Starchip Components - 4 Cameras". Breakthrough Initiatives. Retrieved 15 April 2016.
  36. ↑ Staff (12 April 2016). "Breakthrouth Starshot: Gram-Scale Starchip Components - 4 Processors". Breakthrough Initiatives. Retrieved 15 April 2016.
  37. ↑ Staff (12 April 2016). "Breakthrouth Starshot: Gram-Scale Starchip Components - 4 Photon Thrusters". Breakthrough Initiatives. Retrieved 15 April 2016.
  38. ↑ Gilster, Paul (21 October 2013). "Laser Travel by Photonic Thruster". Centauri Dreams. Retrieved 16 April 2016.
  39. ↑ Staff (12 April 2016). "Breakthrouth Starshot: Gram-Scale Starchip Components - Battery". Breakthrough Initiatives. Retrieved 15 April 2016.
  40. ↑ Staff (12 April 2016). "Breakthrouth Starshot: Gram-Scale Starchip Components - Protective Coating". Breakthrough Initiatives. Retrieved 15 April 2016.
  41. ↑ Staff (12 April 2016). "Breakthrough Starshot: Lightsail, Integrity under thrust". Breakthrough Initiatives. Retrieved 16 April 2016.
  42. ↑ Staff (12 April 2016). "Breakthrouth Starshot: Gram-Scale Starchip Components - Lightsail - Structure". Breakthrough Initiatives. Retrieved 15 April 2016.
  43. ↑ Patel, Neel V. (15 April 2016). "The Starshot Breakthrough Light Beam Is Really a Million Lasers, Which Is Insane". Inverse. Retrieved 16 April 2016.
  44. ↑ https://arxiv.org/pdf/1704.03871.pdf OPTIMIZED TRAJECTORIES TO THE NEAREST STARS USING LIGHTWEIGHT HIGH-VELOCITY PHOTON SAILS
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