Decades of research has shown it is theoretically possible to journey beyond our solar system in the hunt for alien life on exoplanets. Putting this theory into practice is a different beast altogether, and one of the greatest challenges is how to slow down any spacecraft we send when it arrives at the far reaches.
In a study published today, astronomers from the Max Planck Institute of Solar Research claim to have not only found an advanced method for sending a probe to our closest exoplanet in Proxima Centauri, crucially they believe they have found a way to set it into orbit once it arrives.
The idea of sending a spaceship to our closest stellar system, Proxima Centauri, is not new. Last year Stephen Hawking’s Breakthrough Starshot project announced $1 billion in funding to go towards building and sending a prototype of a light-propelled spaceship to the region.
But there's a problem; the prototype, which is based on a probe fitted to a light sail, would have no way of slowing down once it reached the system.
An interstellar sail is a lightweight probe traveling to other stars, pushed by the photon pressure of starlight. Like wind on Earth, the photons in space push the sail. The tiny silicon chip spacecraft would travel at one-fifth the speed of light.
“Although such an interstellar probe could reach Proxima 20 years after launch, without propellant to slow it down it would traverse the system within hours," René Heller, from the Max Planck Institute for Solar Research, and colleague Michael Hippke wrote in the Astronomical Journal.
“We propose a sail that would be accelerated by the starlight from our Sun,” Hippke told WIRED. The probe would be accelerated by solar energy and could orbit the planet within 100 years.
“Our sail would break upon arrival and go into orbit around the planet that we know is there.”
Many believe that if alien life exists, this system is our best chance of finding it. Orbiting the nearby star system is a rocky planet, slightly larger than Earth.
The planet, discovered last year and named Proxima b, orbits its host stars in the habitable zone - a region where liquid water could potentially exist on the surface. It is the closest Earth-like exoplanet we have ever discovered, at four light years away.
“If the sail has sensors on board, it could detect life on Proxima b,” Hippke told WIRED. “Sensors could be cameras, spectrometers like other space probes such as Cassini, Voyager and Mars probes.”
Simulations show that the probe could reach the star within 20 years but would take much longer to slow down and enter orbit, estimated at 96 years. “But one would have years or decades of close-up exploration instead of around six seconds,” they said.
The authors do not see their design as an alternative to the Starshot Project. “The fundamental goal of Breakthrough Starshot is a proof of capability for interstellar flight within a human generation,” they said.
“Our new mission format, acting on a time scale of a century rather than decades, would be more plausible as a follow-up on Starshot or as a companion mission.”
Researchers at Nasa and the Korea Institute of Science and Technology (KASIT) are currently working on designing the first Starshot light sail probe.