Flight to alpha Centauri: dreams and reality

Last year, the famous physicist Stephen Hawking and Russian billionaire Yuri Milner announced an ambitious plan to launch a tiny spacecraft to the alpha Centauri system. Of course, such an ambitious plan requires no less ambitious solutions. For example, one unresolved concern is how moving with one-fifth the speed of light, the spacecraft will be able to stop after you reach your destination. Will he even be capable of such a maneuver?

A Pair of European scientists seem to have found the right answer to this question. In a paper published in the journal the Astrophysical Journal Letters, physicist rené Heller of the max Planck Institute and computer specialist Michael Hippke talk about how to slow a spacecraft to use radiation and gravity of the stars in the alpha Centauri system. According to scientists, instead of just zip by, the tiny spacecraft equipped with a light sail, will be able to slow down enough to in detail study of the triple star system, and perhaps even near one of the stars of this system earth-like planet Proxima b.

Recall that the project Breakthrough Initiative Starshot Milner plans to invest $ 100 million in developing ultralight Autonomous spacecraft with a light sail, which will be able to reach 1/5 the speed of light (about 60 000 km/h). Thanks to this robotic probe will be able to reach alpha Centauri – the closest to Earth a star system in just 20 years, not 100,000, as in the case of the use of traditional chemical accelerators.

According to the original plan of Milner and Hawking, a tiny probe will be attached to compact the size of a few meters, the light sail, controlled by a phased array of lasers. Energy produced by these lasers is theoretically sufficient to accelerate a tiny probe to speeds much higher than is capable of showing the fastest at the moment the spacecraft.

Render the proposed technology the light sails

However, this is not the only proposed scheme the implementation of this project. According to the embodiment Heller and Hippke, the use of larger "photon" sails would eliminate the need to use the laser grid. In this case the probe itself is the size of only a few centimetres and weighing just a few grams. To accelerate and exit in interstellar space the unit will be equipped with several large, but at the same time very light, thin and durable sails. On the proposed European scientists scenario in the direction of alpha Centauri probe will push the radiation of our Sun. When you reach the desired level of inertia, the machine will lay down the sails and continue your journey towards the neighboring star system.

Scientists believe that in this case the probe will be able to develop 4.6 percent of the speed of light and about 95 years to reach alpha Centauri. Yes, this is almost five times longer than the original terms of the Milner and Hawking, but in theory it will seriously make it easier to stop the probe in the right place.

"the Interstellar journey to alpha Centauri is expected to occur at speeds that reduce the journey to less than one thousand, and ideally to less than one hundred years. At this speed spacecraft will require an incredibly large amount of energy to slow down and exit on the desired orbit", — said Heller.

"the Use of any kind of fuel will impede the project as a whole. If the ship would require fuel on Board, he in this case will be too heavy, which in turn further increase the need for more fuel".

Given these limitations and the lack of currently viable solution, the researchers suggest that the probe in this case, just pass alpha Centauri, as it was with the spacecraft New horizons, which flew at the time to Pluto. But then again, if we consider the difference of the speed probe, in contrast to the "New horizons" will not be able to provide at least some more or less exact measurement of this star system. Fortunately, two scientists, there is an option that in theory will not only slow the spacecraft to an acceptable speed at the desired point, but also to conduct a detailed study of the system of alpha Centauri.

"We found a method that allows you to slow down the spacecraft with the energy of the star itself. To slow light-sail you can use light particles. In this case, the presence of additional fuel on Board is not required. Yes, and the plan in General fit into the overall concept proposed by the action group Starshot Breakthrough Initiative".

Animation "photogravitational capture" the star alpha Centauri A

For the success of implementation needs to come up with a way in which the apparatus can re-dissolve your sails upon arrival into the system. In this case, coming from the radiation system will create the necessary pressure, which will slow down the probe. Thanks to computer models of Heller and Hippke calculated that with the weight of the probe in 100 grams of area of the sail will be about 100,000 square meters (approximately 14 soccer fields). Upon arrival into the system by the retarding force of radiation from alpha Centauri, acting on the sail will increase. Computer models show that the forces would be enough to effectively slow down the machine. In other words, the same physics, which will be responsible for pushing the probe towards the neighboring systems will also slow down the device upon his arrival to the right place.

During the manoeuvre, the deceleration of the probe must be closer to alpha Centauri A at a distance of five stellar radii (that is, at a distance equivalent to five times the radius of the star), or approximately 4 million miles to be captured in her orbit. From this point the spacecraft will begin slowing to approximately 2.5 percent of the speed of light. However, it is important to note that in case of failure of deceleration from maximum speed (4.6 percent of the speed of light), the probe will be ejected back into interstellar space.

Every successful journey begins with the creation of the map. In this case, shows all the maneuvers of Autonomous space neaparat in his journey to alpha Centauri A, which is the path to alpha Centauri B is only four days. The ultimate goal of the probe can be a 46-year journey to the star Proxima Centauri is the home address of earth-like planets of Proxima b

When they Reached alpha Centauri A, the space probe will be captured by its gravity whose force can be used for further maneuvers. Similar maneuvers, for example, was used to accelerate the probe "Voyager-1 and Voyager-2", when they were still inside the Solar system. Theoretically Autonomous probe can enter the orbit of alpha Centauri A and search for possible exoplanets. Heller and Heppke also developed a plan to launch probes to the systems of other stars – alpha Centauri B (the companion star alpha Centauri A) and Proxima Centauri (the third remote star system located on a 0.22 light-years, or 1.2 trillion kilometers) from the common centers of the masses of stars A and B. Under this plan, for a flight to alpha Centauri will take about A century, then another 4 days will be required for a flight to alpha Centauri B, then 46 years to travel to Proxima Centauri.

And yet additional time, according to scientists, will be able to pay off in full. One of the most memorable discoveries of 2016 was the discovery by astronomers samplemodel planet near the star Proxima Centauri. Ultimately, the ability to "close to" to explore this planet may be one of the (if not the most) significant events in modern astronomy. Shipment data collected about the planet, given the distance to the Ground, is just over 4 years. However, while this is only a dream, because at the moment we have no systems that were compact enough to fit on the nano-probes, and at the same time possessed sufficient power to transmit signals at such distances.

The Absence of a suitable transmitter is not the only problem in that at all costs must be resolved prior to sending a probe towards the neighboring star system. Equally important are finding solutions and the development of suitable power system for the probe. However, the researchers do not intend to lose optimism since science does not stand still. For example, can not but rejoice the fact that laboratories already developed some ultralight materials that will be required for this project.

"On the creation of such an interstellar solar sail could take one or two decades", — says Heller.

The Scientist also adds that the surface of the sails must be done in such a way as to reflect the waves of blue and red ranges of the visible spectrum, and possibly further beyond.

"Such technologies have not yet, but again, over the last few years research laboratories have made great strides, and researchers have found materials that can reflect up to 99.9% of the volume of the world."

Heller and Hippke going to present their detailed concept steering group Starshot Breakthrough Initiative at the forthcoming meeting Discuss the Breakthrough, which will be held in the us city of Palo Alto in April of this year.

"We really want to get their response and to listen to their opinion about...