First … low Earth orbit. But eventually, these chip-sized spacecraft could explore Proxima Centauri.
Breakthrough Starshot, the $100 million initiative aiming to accelerate small spacecraft to a good fraction of the speed of light to send probes to to nearby stars by the mid-21st century, has achieved what might prove to be a “Sputnik moment” in successfully lofting its first spacecraft—the smallest ever launched and operated in orbit.
In the last decade and a half, rapid technological advances have opened up the possibility of light-powered space travel at a significant fraction of light speed. This involves a ground-based light beamer pushing ultra-light nanocrafts – miniature space probes attached to lightsails – to speeds of up to 100 million miles an hour. Such a system would allow a flyby mission to reach Alpha Centauri in just over 20 years from launch, beaming home images of its recently-discovered planet Proxima b, and any other planets that may lie in the system, as well as collecting other scientific data such as analysis of magnetic fields.
On June 23, Breakthrough Starshot sent not one but six satellites into low-Earth orbit, riding as supplementary payloads on an Indian rocket PSLV-C38 launching two other educational satellites Max Valier and Venta-1 built by the European space company OHB System AG. These six satellites are comparatively dainty, but punch far above their weight. Called “Sprites,” each is a 4-gram flake of circuit-board just 3.5 centimeters on a side, packing solar panels, computers, sensors and communications equipment into an area equal to a U.S. postage stamp. It is now confirm that at least one of the Sprites (probably the one mounted to Venta-1) is transmitting and has been successfully decoded by several ground stations around the world.
The Sprites seemed to be functioning relatively well for an initial flight. They experienced some communications hiccups. But this is just a small hiccup — the Sprites are just prototypes of the “StarChips” that will eventually launch several decades from now. The goal is to strap a microweight space probe onto a star sail, then fire high-powered pulses of photons from a gargantuan ground-based laser array. This will accelerate it to around 20 percent the speed of light. Starshot plans on sending several at a time, increasing the odds that one or more will make it to their final destination in the Alpha Centauri system.
The Sprites are an important first step. The prototype has been built. Now, it’s just time to scale it up so we can head to the stars.
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. Once it is assembled and the technology matures, the cost of each launch is projected to fall to a few hundred thousand dollars.
The program will require:
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 to receive data from nanocrafts over 4 years later.
Some of these requirements represent significant engineering challenges, which the Breakthrough Starship team have begun the process of addressing. The proposed light propulsion system is on a scale significantly exceeding any currently operational analog. The very nature of the project calls for global co-operation and support.
Clearance for launches would be required from all the appropriate government and international organizations.
Source: Scientific American