Nasa wants to send humans to an asteroid by 2025 and Mars in the 2030s.
In a step towards that goal, the space agency is funding plasma engines that could propel astronauts to the red planet on much less fuel.
The tabletop-sized thruster prototype, dubbed the 'X3,' uses a 45,000 mph stream of plasma to push spacecraft forward.
Because its consumes 100 million times less fuel than conventional chemical rockets, the thruster is ideal for exploring Mars, asteroids and the edge of the solar system.
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Nasa wants to send humans to an asteroid by 2025 and Mars in the 2030s In a step towards that goal, the space agency is funding plasma engines that could propel astronauts to the red planet on much less fuel. The tabletop-sized thruster prototype, dubbed the 'X3,' uses a 45,000 mph stream of plasma to push craft forward
The prototypes have been created by engineers from the University of Michigan's Next Space Technologies for Exploration Partnerships (NextSTEP) program.
The engine is part of Aerojet Rocketdyne's XR-100 propulsion system, which could, in the next ten years propel a vessel to Mars.
Nasa awarded $6.5 million over the next three years to Aerojet Rocketdyne for the development of the propulsion system, dubbed the XR-100.
Developed by Professor Alec Gallimore thruster, the X3, is central to this system, and his team will receive $1 million of the award for work on the thruster.
The XR-100 is up against two competing designs.
All three of them rely on ejecting plasma – an energetic state of matter in which electrons and charged atoms called ions coexist – out the back of the thruster.
But the X3 has a bit of a head start. For thrusters of its design power, 200 kilowatts, it is relatively small and light.
And the core technology – the Hall thruster – is already in use for manoeuvring satellites in orbit
'For comparison, the most powerful Hall thruster in orbit right now is 4.5 kilowatts,' said Gallimore.
That's enough to adjust the orbit or orientation of a satellite, but it's too little power to move the massive amounts of cargo needed to support human exploration of deep space.
A Hall thruster works by accelerating the plasma exhaust to extremely high speeds.
The core technology – the Hall thruster (right) – is already in use for manoeuvring satellites in orbit around the Earth. A Hall thruster works by accelerating the plasma exhaust to extremely high speeds
Because its consumes 100 million times less fuel than conventional chemical rockets, the thruster is ideal for exploring Mars, asteroids and the edge of the solar system
The process starts with a current of electrons spiraling through a circular channel.
On their whirlwind journey from the negative electrode at the exhaust end to the positively charged electrode on the inner side of the channel, they run into atoms (typically xenon gas) that are fed into the chamber.
The collisions knock electrons off the xenon atoms and turn the xenon into positively charged ions.
The electrons' spiraling motion also builds a powerful electric field that pulls the gas ions out the exhaust end of the channel.
Just enough electrons leave with the ions to keep the spacecraft from accumulating a charge, which could otherwise cause electrical problems.
'When they're ionized, the xenon atoms can shoot out at up to 30,000 meters per second, which is about 65,000 mph,' said Gallimore.
The X3 contains three of plasma channels, each a few centimeters deep, nested around one another in concentric rings. The nesting is what allows the Hall thruster to operate at 200 kilowatts of power in a relatively small footprint
Nasa is developing the capabilities needed to send humans to an asteroid by 2025 and Mars in the 2030s. Mars is a rich destination for scientific discovery. Its formation and evolution are comparable to Earth, helping us learn more about our own planet’s history and future
The X3 contains three of these channels, each a few centimeters deep, nested around one another in concentric rings.
The nesting is what allows the Hall thruster to operate at 200 kilowatts of power in a relatively small footprint.
Scott Hall, a doctoral student in Professor Gallimore's lab, will use the funding to put the X3 through a battery of tests.
He will first run it up to 60 kilowatts in the Plasmadynamics and Electric Propulsion Lab at U-M and then up to 200 kilowatts at the Nasa Glenn Research Center in Cleveland, Ohio
Meanwhile, another doctoral student, Sarah Cusson, will investigate a tweak that could allow the X3 to remain operational for five to ten times longer than its current lifetime of a little over a year.
'If we do our jobs over the next three years, we can deliver both projects,' said Gallimore.
'If I had to predict, I would say this thruster would be the basis for sending humans to Mars.'
NASA'S 'PHOTONIC PROPULSION' USES LASERS TO PRODUCE THRUST
Hall thrusters aren't the only technology that Nasa is betting on to take humans to Mars.
Technology harnessing the power of light could be the key to cutting down travel times to Mars from years to just a matter of days.
In a separate project, a group of physicists in California is working on probe that could lead to technology to get to Mars at much faster speeds than is currently possible.
The answer to doing this could lie in what's known as photonic propulsion, a technique that uses light from lasers to produce thrust to drive spacecraft.
While the technology the team is creating will be targeted at extremely small probes, someday it could inspire the creation of larger spacecraft that travel rapidly to Mars.
A group of physicists in California is working on spacecraft that could let humans reach the nearest stars in our solar system - a challenge that is not possible with current propulsion technology. The answer could lie in what's known as photonic propulsion, a technique that uses light from lasers to produce thrust (illustrated)
Professor Phillip Lubin and his team from the University of California Santa Barbara are working on the Directed Energy Interstellar Precursors (Deep-In) programme.
The programme aims to create probes capable of reaching relativistic speeds and travelling to the nearest stars.
A relativistic speed is a speed which is a significant proportion of the speed of light.
'We know how to get to relativistic speeds in the lab, we do it all the time,' said Lubin at Nasa's National Innovative Advanced Concepts (Niac) symposium.
'When we go to the macroscopic level, things like aircraft, cars, spacecraft, were pathetically slow.'
Professor Lubin is aiming to bridge the gap between the small and the large, using photonic propulsion technology.
The theory is simple; thrust from photons emitted from a laser array could be used to propel a spacecraft.
All spacecraft operate by firing propellant in the opposite direction to the way they want to travel. Traditionally this propellant is fuel. Photonic propulsion uses an array of lasers instead, which means no fuel needs to be carried on the spacecraft (illustrated)
All spacecrafts operate by firing their propellant in the opposite direction to the way they want to travel.
Traditionally this propellant is fuel and has to be carried on board the spacecraft, making it heavier and slowing it down.
Photonic propulsion uses an array of lasers instead, which adds no mass to the spacecraft other than the laser itself.
This enables it to accelerate for longer and reach higher speeds. n theory, this should help get aircraft to relativistic speeds.
Professor Lubin didn't specify what proportion of the speed of light the technology would reach, although he did say it could be up to a quarter.
The launch into orbit would also be slower at the start and during the descent, for example.
As a result, the professor said: 'We could propel a 100kg aircraft to Mars in a few days. In comparison it would take a shuttle roughly a month to get there,' the researchers said.
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