Breakthrough Starshot
The Alpha Centauri star system is 25 trillion miles (4.37 light years) away. With today’s fastest spacecraft, it would take about30, 000 years to get there. Breakthrough Starshot aims to establish whether a gram-scale nanocraft, on a sail pushed by a light beam, can fly over a thousand times faster. It brings the Silicon Valley approach to space travel, capitalizing on exponential advances in certain areas of technology since the beginning of the 21st century.
1. Nanocrafts
Nanocrafts are gram-scale robotic spacecrafts comprising two main parts:
- StarChip: Moore’s law has allowed a dramatic decrease in the size of microelectronic components. This creates the possibility of a gram-scale wafer, carrying cameras, photon thrusters, power supply, navigation and communication equipment, and constituting a fully functional space probe.
- Lightsail: Advances in nanotechnology are producing increasingly thin and light-weight metamaterials, promising to enable the fabrication of meter-scale sails no more than a few hundred atoms thick and at gram-scale mass.
2. Light Beamer
- The rising power and falling cost of lasers, consistent with Moore’s law, lead to significant advances in light beaming technology. Meanwhile, phased arrays of lasers (the ‘light beamer’) could potentially be scaled up to the 100 gigawattlevel.
Breakthrough Starshot aims to bring economies of scale to the astronomical scale. The StarChip can be mass-produced at the cost of an iPhone and be sent on missions in large numbers to provide redundancy and coverage. The light beamer is modular and scalable. Once it is assembled and the technology matures, the cost of each launch is expected to fall to a few hundred thousand dollars.
Path to the stars
The research and engineering phase is expected to last a number of years. Following that, development of the ultimate mission to Alpha Centauri would require a budget comparable to the largest current scientific experiments, and would involve:
- Building a ground-based kilometer-scale light beamer at high altitude in dry conditions
- Generating and storing a few gigawatt hours of energy per launch
- Launching a ‘mothership’ carrying thousands of nanocrafts to a high-altitude orbit
- Taking advantage of adaptive optics technology in real time to compensate for atmospheric effects
- Focusing the light beam on the lightsail to accelerate individual nanocrafts to the target speed within minutes
- Accounting for interstellar dust collisions en route to the target
- Capturing images of a planet, and other scientific data, and transmitting them back to Earth using a compact on-board laser communications system
- Using the same light beamer that launched the nanocrafts to receive data from them over 4 years later.
Clearance for launches would be required from all the appropriate government and international organizations.
Additional opportunities
As the technology required for interstellar travel matures, a number of additional opportunities will emerge, including the following:
- Contribution to solar system exploration.
- Using the light beamer as a kilometer-scale telescope for astronomical observations.
- Detection of Earth-crossing asteroids at large distances.
Potential Planets in the Alpha Centauri system
Astronomers estimate that there is a reasonable chance of an Earth-like planet existing in the ‘habitable zones’ of Alpha Centauri’s three-star system. A number of scientific instruments, ground-based and space-based, are being developed and enhanced, which will soon identify and characterize planets around nearby stars.
