Scientists have figured out how to create a new ion engine that uses 100 million times less fuel than a chemical rocket.
Though the device is a lot less powerful, it could some day be a cost-effective and efficient alternative to ship supplies or even people to Mars.
NASA has used ion engines for decades, but the current models come with a huge drawback: They burn out after about a year of use.
Ion engines propel a spacecraft one atom at a time. The devices rip electrons off xenon gas to create a stream of charged particles.
Next the ions pass through a magnetic field, which speeds up the particles to about 45,000 mph.
Then a field of electrons neutralizes the particles so they continue shooting out of the engine and create thrust (instead of being attracted back toward the magnetic field).
But in traditional ion engines, sometimes called Hall thrusters, the constant bombardment of energized particles against the back wall of the engine gradually wears it down until the device shorts out — so they can only operate for about 10,000 hours (1.1 year) of spaceflight.
We'd need them to last closer to 50,000 hours (5.7 years) to be useful them for missions to Mars and beyond.
So to prolong the life of an ion engine, the researchers decided to completely take out the wall that gets worn down over time. Now the charging and acceleration of the particles happens entirely outside of the engine cavity.
The image below shows what one of the wall-less engines looks like. The positively charged anode (red) helps charge up the xenon particles (Xe), and the magnetic field lines (purple) accelerate the particles.
The engine design on the left didn't work because the anode was set up in the middle of the magnetic field. The new design keeps the anode clear of the field:
A long-lasting ion engine would be invaluable because the devices could propel spacecraft faster than chemical engines — it just takes them a long time to rev up.
"It's like taking four days to accelerate from 0 to 90 km/hour with a car," Julien Vaudolon, lead researcher of the new study, told Tech Insider in an email.
"But the thruster can be fired for accumulated periods of time much above those of chemical spacecrafts," he wrote. "So in the long term you will exceed the typical velocities attained by regular rockets."
Ion engines come with other bonuses too.
They need far less fuel than chemical engines — about 100 million times less — so they're cheaper to operate. The spacecraft also doesn't have to be loaded up with so much fuel, freeing up extra room for cargo or astronauts. The chance of an explosion is also lower, too, since xenon is inert.
The research team hopes their new design will prolong the life of a plasma engine near or past 50,000 hours, but they haven't done any tests yet.
"Preliminary theoretical investigations indicate that the lifespan may lie around 50,000 hours," Vaudolon said. "But once again, this has not been validated by any test."
If they can accomplish this, then we might be close to figuring out a cost-effective and efficient way to send supplies to Mars and possibly even human colonists (if they don't mind a longer journey, that is).
The research team is already working on new models to test the durability of their ion engine concept.
