Spaceship made of carbon-foam bubbles could zoom from Earth to Alpha Centauri in 185 years, driven only by the power of the sun, finds a new study.
A swarm of these probes can help discover and study mysteries of our solar system Planet Nine, if this hypothetical world exists, scientists added.
Conventional rockets powered by chemical reactions are currently the leading form of space propulsion. However, they are nowhere near efficient enough to reach another star in human life.
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For example, Alpha Centauri, the closest galaxy to Earth, is about 4.37 light-years away – more than 25.6 trillion miles (41.2 trillion kilometers), or about 276,000 times the distance from Earth to the sun. It would take NASAs Voyager 1 spaceship, which launched in 1977 and reached interstellar space in 2012, about 75,000 years to reach Alpha Centauri if the probe went in the right direction (which it is not).
The problem with all conventional spacecraft is that the propellant they use has mass. Long voyages require a lot of propellant, which makes spaceship heavy, which in turn requires more propellant, making them heavier and so on. This problem gets exponentially worse the bigger a spaceship gets.
Earlier research has suggested that “light sailing“Perhaps one of the only technically possible methods to get a probe to another star within a human life. Although light does not exert much pressure, scientists have determined that applying it a little can have a big effect. Indeed, several experiments have shown that “solar seals” can rely on sunlight for propulsion, given a large enough mirror and a spaceship that is light enough.
The $ 100 million Breakthrough Starshot initiative, which was announced in 2016, aims to launch swarms of microchip-sized spaceships to Alpha Centauri, each sporting its extraordinarily thin, incredibly reflective sails. The plan is to fly these “starchips” at up to 20% the speed of light, and reach Alpha Centauri in about 20 years.
A disadvantage of the Starshot project is that it is the most powerful laser array ever needed to send the star chips out. Not only does the technology to build this array not exist at the moment, the estimated total cost of the project could reach $ 5 billion to $ 10 billion.
In the new study, astrophysicists suggested that a cheaper option could involve making carbon foam. Samples could be made from this game interstellar travel faster than any rocket powered by sunlight alone, without the need for a giant laser array, the researchers found.
To develop a way for sunlight to send a light sail to useful interstellar velocities, researchers analyzed previous scientific research in search of strong, light materials. They settled on aerographite, a carbon-based shoe 15,000 times lighter than aluminum.
The scientists calculated that a hollow aerographite sphere about 3.3 feet (1 meter) in diameter with a shell 1 micron thick (about 1% the width of an average human hair) would be exactly five millionths of a pound (2.3 milligrams) weigh.
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If such an atmosphere with 0.035 ounces (1 gram) loadload over one astronomical unit (AU) were released from the sun, sunlight would push it up to a speed of up to 114,000 mph (183,600 km / h) – three times that of Voyager 1. Such an atmosphere would take about 3.9 years to reach orbit Pluto. (One AU is the average distance of Earth-Sun, which is about 93 million miles, or 150 million km.)
If such an atmosphere were released about 0.04 AU from the sun – the closest that NASA’s Parker Solar Probe gets at our star – the intense sunlight would accelerate the spaceship to almost 15.4 million km / h. It could travel 185 light-years between Earth and Proxima Centauri, the closest star to our solar system, in 185 years, the researchers said. The greater the atmosphere, the faster it could go, the more loadload it could carry. (Proxima Centauri is one of three stars in the Alpha Centauri system.)
“What I find amazing about our results is the fact that the power output of a star, in our case the sun, can be used to drive an interstellar probe to the nearest stars without the need for an additional power source on board.” author René Heller, an astrophysicist at the Max Planck Institute for Solar System Research in Göttingen, Germany, told Space.com.
“We don’t need a billion-dollar ground-based laser array to shoot at a sail in space,” Heller said. “Instead, we can use green energy, so to speak.”
The researchers have noted that a few grams of electronics or other loadload is not much to bring on board a mission. However, they claimed that the loadload for this craft would be 10 times the mass of the spacecraft, while the loadload on chemical interstellar rockets would typically be one thousandth the weight of the rocket.
The researchers suggested that this spacecraft could potentially carry a 32-watt laser weighing only two-thousandths of a pound (1 gram). Analyzing possible distortions of this laser beam can help researchers detect gravitational effects, which in turn can help to reveal the presence of worlds otherwise too dark and cold to spot, such as the hypothesis Planet Nine, Said Heller.
The scientists estimated that developing a prototype bubble vessel could cost $ 1 million. They calculate that each foam ship can then be built for about $ 1,000 or less, and a rocket launch to deploy and test this craft could cost $ 10 million.
The biggest caveat of this work at the moment “is that no one has ever built an aerography structure larger than a few centimeters, while we need something that is a few meters in size,” Heller said. However, the researchers are in contact with experiments that suggest that making such large structures is in principle possible, he noted.
Another point of caution about this concept is that there is currently no way to control the trajectory of the spheres once they have been deployed. “To achieve a particular goal, it needs to be corrected,” Heller said.
If on-board electronics and equipment could enable active maneuvering, “then it could potentially transport small masses – 1 to 100 grams – between Earth and Mars within weeks,” Heller said.
The scientists look for conventional rockets that bring the bubble vessel into space and then deploy it for sunlight to launch. It remains unclear how well these bubbles would survive the transport.
“One good thing about aerography is its compressibility,” Heller said. “Even after extreme compression, a sample of aerography can inflate again to its initial state. So if we compress a meter-sized aerography sail in the laboratory, we might be able to send it into space and inflate it there again for the “The question is, what’s going on with the electronics on board?”
The scientists are now conducting experiments to test how well aerographite absorbs and reflects light. See details has the findings online July 7 in the journal Astronomy & Astrophysics.
Follow Charles Q. Choi on Twitter @cqchoi. Follow us on Twitter @Spacedotcom and on Facebook.
