A newly proposed propulsion system could theoretically beam a heavy spacecraft outside the boundaries of our Solar System in less than 5 years – a feat that took the historic Voyager 1 probe 35 years to achieve.
The concept, known as ‘pellet-beam’ propulsionwas awarded an early stage US$175,000 NASA grant for further development earlier this year.
To be clear, the concept doesn’t currently exist beyond paper calculations, so we can’t get too excited just yet.
However, it is attracting attention not only because of its potential to take us to interstellar space within a human lifetime – something that traditional, chemical-fueled rockets not allowed – but also because it says it can be done on larger crafts.
“This proposal examines a new propulsion architecture for the rapid transfer of heavy (1 ton and more) payloads across the Solar System and the interstellar medium,” explained the lead researcher behind the proposalaerospace engineer Artur Davoyan from the University of California, Los Angeles.
The pellet-beam concept was partly inspired by Rare Starshot initiative, which works on a ‘light-sail’ propulsion system. With the help of millions of lasers, a small probe could theoretically sail to nearby Proxima Centauri in just 20 years.
The new proposal starts with a similar idea — toss fuel into a rocket instead of blasting it off one — but it looks at how to move larger objects. After all, a little probing isn’t necessarily what we need if we want to one day explore, or colonize, worlds outside our own Solar System.
To work, the conceptual propulsion system would require two spacecraft – one heading into interstellar space, and the other heading into orbit around Earth.
The spacecraft orbiting the Earth will shoot a beam of tiny microscopic particles into the interstellar spacecraft.
Those particles will be heated by lasers, which causes part of them to dissolve in the plasma that further accelerates the pellets, a process known as laser ablation.
Those pellets can reach 120 km/second (75 miles/second) and can hit the sail of an interstellar spacecraft or be repelled a magnet inside itwhich helps propel the spacecraft to such high speeds that it allows it to exit our heliosphere – the bubble of solar wind around our Solar System.
“With the pellet-beam, the outer planets can be reached in less than a year, 100 AU [astronomical unit] in about 3 years and solar gravity lens at 500 AU in about 15 years,” said Davoyan.
For context, one AU, which stands for ‘astronomical unit’, roughly represents the distance between the Earth and the Sun, or about 150 million km (93 million miles).
It took the Voyager 1 probe 35 years of travel to cross interstellar space in 2012, at a distance of about 122 AU.
According to current projections, a pellet-beamed spacecraft weighing 1 ton could do the same in under 5 years.
Davoyan explained Matt Williams from Universe Today in February that his team did the pellet approach, instead of just using lasers like other sail projects, because pellets can be propelled by relatively low-power lasers.
In their current projections, only a 10-megawatt laser beam can be used.
“Unlike a laser beam, the pellets do not diverge as quickly, which allows us to accelerate a heavier spacecraft,” Davoyan told Williams.
“Pellets, being heavier than photons, carry more momentum and can transfer a higher force to a spacecraft.”
Of course, this is all pure speculation at the moment. But Phase I of NASA’s Innovative and Advanced Concepts (NIAC) grant will help.
The project is one in 14 funded at this early stage, and the next step is to demonstrate proof of concept using experiments.
“In the Phase I effort we will demonstrate the feasibility of the proposed propulsion concept by conducting detailed modeling of the various subsystems of the proposed propulsion architecture, and by conducting proof of concept experiments -student,” Davaoyan said.
We will monitor progress closely.
