A newly proposed propulsion system could theoretically beam a heavy spacecraft to outside the confines 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' propulsion, was awarded
an early-stage US$175,000 NASA grant for further development earlier this year.
To be clear, the concept currently doesn't exist much beyond
calculations on paper, so we can't get too excited just yet.
Still, it's attracted attention not only because of its
potential to get us into interstellar space within a human lifetime – something
that traditional, chemical-fueled rockets can't – but also because it claims it
can do so with much larger crafts.
"This proposal examines a new propulsion architecture
for fast transit of heavy (1 ton and more) payloads across the Solar System and
to interstellar medium," explains the lead researcher behind the proposal,
aerospace engineer Artur Davoyan from the University of California, Los
Angeles.
The pellet-beam concept was partly inspired by the
Breakthrough Starshot initiative, which is working on a 'light-sail' propulsion
system. With the help of millions of lasers, a tiny probe would theoretically
be able to sail to neighboring Proxima Centauri in just 20 years.
The new proposal starts with a similar idea – throw fuel at
a rocket instead of blast it out of one – but it looks at how to shift larger
objects. After all, a small probe isn't necessarily what we need if we want to
one day explore, or colonize, the world’s outside our Solar System ourselves.
To work, the conceptual propulsion system requires two
spacecraft – one that sets off for interstellar space, and one that goes into
orbit around Earth.
The spacecraft orbiting Earth would shoot a beam of tiny
microscopic particles at the interstellar spacecraft.
Those particles would be heated up by lasers, causing part
of them to melt into plasma that accelerates the pellets further, a process
known as laser ablation.
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Illustration of how the pellet-beam propulsion system could work. (Artur Davoyan) |
Those pellets could reach 120 km/second (75 miles/second)
and either hit the sail of the interstellar spacecraft or repel a magnet within
it, helping to propel the spacecraft to huge speeds that would let it whizz out
of our heliosphere – the bubble of solar wind around our Solar System.
"With the pellet-beam, outer planets can be reached in
less than a year, 100 AU [astronomical unit] in about 3 year and solar gravity
lens at 500 AU in about 15 years," says Davoyan.
For context, an AU, which stands for 'astronomical unit', roughly represents the distance between Earth and the Sun, or around 150 million km (93 million miles).
It took the Voyager 1 probe 35 years of travel to cross into
interstellar space back in 2012, at roughly 122 AU away.
According to the current projections, a pellet-beamed
spacecraft weighing 1 ton could do the same in under 5 years.
Davoyan explained to Matt Williams from Universe Today back
in February that his team has taken the pellet approach, rather than simply using
lasers like other sail projects, because the pellets can be propelled by
relatively low-power lasers.
In their current projections, only a 10-megawatt laser beam
could be used.
"Unlike a laser beam, pellets do not diverge as
quickly, allowing us to accelerate a heavier spacecraft," Davoyan told
Williams.
"The pellets, being much heavier than photons, carry
more momentum and can transfer a higher force to a spacecraft."
Of course, all of this is pure speculation for now. But the
Phase I of NASA's Innovative and Advanced Concepts (NIAC) grant will help.
The project was one of 14 that were funded at this early
stage, and the next step will be to show proof of concept using experiments.
"In Phase I effort we will demonstrate feasibility of
the proposed propulsion concept by performing detailed modelling of different
subsystems of the proposed propulsion architecture, and by performing proof of
concept experimental studies," says Davoyan.
We'll be following the progress closely.
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