Micro Ion Thrusters: The newest little idea for nanosat micro rockets

L. Brad King's prototype of a ferrofluid ion thruster. When subjected to voltage, the points of the crown arise from a ring-shaped trench circling a one-inch block of aluminum. 

Credit: L. Brad King

Nanosatellites are smartphone-sized gadgets that can perform simple, yet valuable, space missions.

Dozens of these little spacecraft are now tirelessly orbiting the earth performing valuable missions for NASA, the Department of Defense and even private companies.

Nano-satellites borrow many of their components from terrestrial gadgets: miniaturized cameras, wireless radios and GPS receivers that have been perfected for hand-held devices are also perfect for spacecraft.

However, according to Michigan Technological University's Lyon Brad King, there is at least one technology need that is unique to space: "Even the best smartphones don't have miniaturized rocket engines, so we need to develop them from scratch."

Miniature rockets aren't needed to launch a nano-satellite from Earth. The small vehicles can hitchhike with a regular rocket that is going that way anyway.

But because they are hitchhikers, these nano-satellites don't always get dropped off in their preferred location.

Once in space, a nano-satellite might need some type of propulsion to move it from its drop-off point into its desired orbit. This is where the micro rocket engine comes in.

For the last few years, researchers around the world have been trying to build such rockets using microscopic hollow needles to electrically spray thin jets of fluid, which push the spacecraft in the opposite direction.

The fluid propellant is a special chemical known as an ionic liquid. A single thruster needle is finer than a human hair, less than one millimeter long and produces a thrust force equivalent to the weight of a few grains of sand.

A few hundred of these needles fit in a postage-stamp-size package and produce enough thrust to maneuver a nano-satellite.

Lyon Brad King

These new electrospray thrusters face some design challenges, however. "Because they are so small and intricate, they are expensive to make, and the needles are fragile," says King, the 'Ron and Elaine Starr' Professor of Mechanical Engineering-Engineering Mechanics.

"They are easily destroyed either by a careless bump or an electrical arc when they're running."

To get around the problem, King and his team have developed an elegant strategy: eliminate the expensive and tedious micro-fabrication required to make the needles by letting Mother Nature take care of the assembly.

"We're working with a unique type of liquid called a ferro-fluid that naturally forms a stationary pattern of sharp tips in the liquid surface," he says.

"Each tip in this self-assembling structure can spray a jet of fluid just like a micro-needle, so we don't actually have to make any needles."

Ferro-fluids have been around since the 1960s. They are made of tiny magnetic particles suspended in a solvent that moves when magnetic force is applied.

King illustrates with a tiny container holding a ferro-fluid made of kerosene and iron dust. The fluid lies flat until he puts a magnet beneath it.

Then suddenly, the liquid forms a regular series of peaks reminiscent of a mountain range.

These peaks remain perfectly stable despite vigorous shaking and even turning the container upside down. It is, nonetheless, completely liquid, as a finger-tip touch proves undeniably.

When the magnet is removed, the liquid relaxes to a perfectly flat surface.

King's team was trying to make an ionic liquid that behaved like a ferro-fluid when they learned about a research team at the University of Sydney that was already making these substances.

The Sydney team was using magnetic nanoparticles made by the life-sciences company Sirtex, which are used to treat liver cancer. "They sent us a sample, and we've used it to develop a thruster," King said.

"Now we have a nice collaboration going. It's amazing that the same technology used to treat cancer can also function as a micro rocket for spacecraft."

King's first thruster is made of a one-inch block of aluminum containing a small ring of the special fluid. When a magnet is placed beneath the block, the liquid forms a tiny, five-tipped crown.

Their thruster isn't ready to push a satellite around in orbit just yet. "First we have to really understand what is happening on a microscopic level, and then develop a larger prototype based on what we learn," King said.

"We're not quite there yet; we can't build a person out of liquid, like the notorious villain from the Terminator movies. But we're pretty sure we can build a rocket engine."

NASA: Nuclear Fusion Rockets for Future Space Exploration

A concept image of a spacecraft powered by a fusion-driven rocket. 

In this image, the crew would be in the forward-most chamber. 

Solar panels on the sides would collect energy to initiate the process that creates fusion.

CREDIT: University of Washington, MSNW

Rockets that harness the power of nuclear fusion may provide the next big leap in humanity's quest to explore the final frontier, NASA's science chief says.

Nuclear fusion rockets could slash travel times through deep space dramatically, potentially opening up vast swathes of the solar system to human exploration, said John Grunsfeld, associate administrator for NASA's Science Mission Directorate.

John Grunsfeld

"It's transformative," Grunsfeld said last month after his presentation at Maker Faire Bay Area in San Mateo, Calif., a two-day celebration of DIY science, technology and engineering.

"You could get to Saturn in a couple of months. How fantastic would that be?"

For a little perspective: NASA's robotic Cassini spacecraft blasted off in October 1997 and didn't enter Saturn orbit until July 2004.



Traditional chemical propulsion systems can get humans to destinations in deep space, but with a lot of travel time.

For example, a roundtrip manned mission to the vicinity of Mars, which NASA aims to execute by the mid-2030s, would require about 500 days of spaceflight.

Speeding up the trip to Mars, or anywhere else, is desirable for a number of reasons — to minimize the radiation dose astronauts receive during the journey, for example, and to save money on consumables such as food and water.

So NASA and researchers around the world have been investigating advanced propulsion technologies, including space-bending "warp drives," enormous solar sails and matter-antimatter engines.

Nuclear fusion is perhaps the most promising of these possibilities, at least in the relatively near term, proponents say.

Fusion rockets would harness the energy released when the nuclei of two or more atoms combine.

Our sun and other stars are fusion-powered, converting this energy to light; the same principle also gives hydrogen bombs their immense destructive power.

NASA has funded several early-stage fusion ideas recently via a program called NIAC (NASA Institute for Advanced Concepts).

One of these groups, led by scientists at the University of Washington, recently calculated that a fusion rocket could make it possible to get astronauts to Mars in as little as 30 days.

NASA Orion Spacecraft: ESA ATV Providing the Driving Force

ESA is making a major cotribution to the NASA Orion Spacecraft program.

Both agencies continue with the confident spirit of international cooperation that forms the foundation of the International Space Station.

ESA has agreed with NASA to contribute the driving force for the Orion spacecraft, planned for launch in 2017.

Ultimately, Orion will carry astronauts further into space than ever before using a module based on Europe's Automated Transfer Vehicle technology.

Automated Transfer Vehicles (ATVs) have been successfully resupplying the International Space Station since 2008.

The fourth in the series, ATV Albert Einstein, is being readied for launch next year from Kourou, French Guiana.

The ATV-derived service module, sitting directly below Orion's crew capsule, will provide propulsion, power, thermal control, as well as supplying water and gas to the astronauts in the habitable module.

This collaboration between ESA and NASA continues the spirit of international cooperation that forms the foundation of the International Space Station.

ATV is a versatile showcase of European technology performing many functions during a mission to the International Space Station.

The space freighter reboosts the Station and can even push the orbital complex out of the way of space debris.

While docked, ATV becomes an extra module for the astronauts. Lastly, at the end of its mission it leaves the Space Station with waste materials.

"ATV has proven itself on three flawless missions to the Space Station and this agreement is further confirmation that Europe is building advanced, dependable spacecraft," said Nico Dettmann, Head of ATV's production programme.

Thomas Reiter, ESA director of Human Spaceflight and Operations says: "NASA's decision to cooperate with ESA on their exploration programme with ESA delivering a critical element for the mission is a strong sign of trust and confidence in ESA's capabilities, for ESA it is an important contribution to human exploration."

Dan Dumbacher, deputy associate administrator for exploration systems development at NASA headquarters in Washington DC, agrees: "It is a testament to the engineering progress made to date that we are ready to begin integrating designs of an ESA-built service module with Orion."

The first Orion mission will be an unmanned lunar fly-by in 2017, returning to Earth atmosphere at a speed of 11 km/s - the fastest re-entry ever.

USAF Cape Canaveral: First Stage of Atlas V rocket

At Cape Canaveral Air Force Station's Space Launch Complex 41 in Florida, preparations are underway to erect the first stage of the Atlas V rocket that will carry the Tracking and Data Relay Satellite, TDRS-K, into orbit.

TDRS-K is the first of three next-generation communications satellites designed to ensure vital operational continuity for NASA.

The seven TDRS spacecraft currently in orbit provide tracking, telemetry, command and high-bandwidth data return services for numerous science and human exploration missions orbiting Earth.

These include NASA's Hubble Space Telescope and the International Space Station. TDRS-K has a high-performance solar panel designed for more spacecraft power to meet growing S-band communications requirements.

Image Credit: NASA/Ben Smegelsky

The Rimac e-M3: 1984 3 Series with a 600hp electric power

What is the Rimac e-M3 evaluation vehicle?

This emerald green monster is the Rimac e-M3 evaluation vehicle - the technological testbed used to assess the viability for an all-electric supercar, the Rimac Concept One.

The Rimac Concept One

Due to its volt-powered propulsion system, the Concept_One should be pretty efficient, too - Rimac claims a 375-mile range between charges and quotes fuel economy at a conservative estimate of 125mpg electric equivalent.

According to their figures, drive the Concept_One with a feather light right foot and you could see close to 490.

Rimac Concept_One electric supercar offers 1,088hp

NASA - A Summer of Records for J-2X Engine Testing

NASA is setting new records while testing the J-2X powerpack at the Stennis Space Center.

Image Credit: NASA/SSC

The first time was June 8, when engineers went the distance and set the Test Complex A record with a 1,150-second firing of the developmental powerpack assembly.

On July 24, engineers surpassed that record with a 1,350-second test of the engine component on the A-1 Test Stand at Stennis.

The powerpack is a system of components on the top portion of the J-2X engine. On the complete J-2X engine, the powerpack feeds the thrust chamber, which produces the engine fire and thrust.

The advantage of testing the powerpack without the thrust chamber is to operate over a wide range of conditions to understand safe limits.

The July 24 test specifically gathered data on performance of the liquid oxygen and fuel pumps during extreme conditions.

The test data provides critical information for continued development of the turbopump for use on the J-2X engine, the first human-rated liquid oxygen and liquid hydrogen rocket engine to be developed in four decades.

The J-2X is being built by Pratt & Whitney Rocketdyne for NASA’s Marshall Space Flight Center in Huntsville, Ala.

The J-2X engine will power the upper-stage of a planned two-stage Space Launch System (SLS). The SLS will launch NASA's Orion spacecraft and other payloads, and provide an entirely new capability for human exploration beyond low Earth orbit.

Designed to be safe, affordable and flexible for crew and cargo missions, the SLS will continue America's journey of discovery and exploration to destinations including nearby asteroids, Lagrange points, the moon and ultimately, Mars.

Alternative Energy Sources: Surfactant driven propulsion

A small autonomous boat powered by a volatile surfactant has been developed by scientists in Finland and Israel.

The surfactant modifies the surface tension of the liquid it floats on to create a surface tension gradient that propels the boat forward.

Propulsion induced by a surface tension gradient is known as Marangoni propulsion. It’s used in nature by small creatures such as Microvelia (small aquatic insects) to give a burst of speed to escape predators.

In man-made devices, the Marangoni effect has been used to power small ‘camphor boats’ and ‘soap boats’; however, these systems normally offer only short term propulsion or require the boat to be confined to specific channels.

To develop a longer-term propulsion system, the team led by Robin Ras at Aalto University, Finland, created a boat from a lightweight membrane made from a nano-cellulose aerogel.

The membrane is impermeable to water (and oil) but it allows the gaseous surfactants to pass through it. The team used ethanol as the fuel to power a boat floating on water.

Housed in a reservoir at the rear of the boat, a few drops of ethanol are placed on a tissue. As the ethanol evaporates, it diffuses through the membrane at the rear of the boat and lowers the surface tension of the water.

This creates the surface tension gradient that drives the boat forward. The boat is not steered so it typically travels in a circular route.

Once the boat has passed, the ethanol at the water surface evaporates, returning the surface tension to normal. Modifying the surface tension only requires a small amount of surfactant.

‘The boat ran for over 54 minutes on only 25 microlitres of fuel,’ says Ras. ‘It’s very fuel efficient while cruising at a speed of 2cm s^-1,’ he adds. To demonstrate the generality of their approach, the team showed they could also use pentane to power a boat floating on paraffin oil.

‘This is a beautiful illustration of exciting soft matter research. The researchers combine innovative materials science with fundamental surface science to construct a novel self-propelling floating device that is much more controllable and versatile than any similar device suggested before,’ says Lennart Piculell, an expert in physical chemistry at Lund University, Sweden.

‘I don't see any immediate applications, but the concept is simple and can be applied to even smaller devices.’

NASA ARES: Aerial Regional-scale Environmental Survey Aircraft proposed for MARS

The Aerial Regional-scale Environmental Survey (ARES) was a proposal by NASA's Langley Research Center to build a powered aircraft that would fly on Mars.

The ARES team sought to be selected and funded as a NASA Mars Scout Mission for a 2011 or 2013 launch window. However, the MAVEN mission was chosen instead.




ARES would have travelled to Mars compactly folded into a protective aeroshell; upon entry in the thin atmosphere, the capsule would have deployed a parachute to decelerate, followed by ARES release at altitude.

Among other things, the aircraft would have investigated the atmosphere and weak magnetic field.

Propulsion
Propulsion remained undetermined. The two main criteria used to evaluate the propulsion system were flight range and implementation risk.

Possible propulsion technologies were electrical motors, internal combustion and rocket systems. The aircraft was intended to fly for about one hour.

See also
Mars Scout Program

David Fearn, the father of ION propulsion

David Fearn, who died on August 29 aged 68, was internationally recognised as the father of ion propulsion in spacecraft, which he developed at the Royal Aircraft Establishment, Farnborough (now QinetiQ); his work enables telecommunications satellites to be positioned more accurately and, by saving on heavy rocket fuel, has made feasible missions to deep space that were previously impossible.

Find here a SpaceUK directory of Rocket Propulsion before the ion drive

Until the development of ion propulsion, manoeuvring artificial Earth satellites and deep-space probes was only possible by using conventional rocket thrusters.

Although relatively simple, they were inefficient and required large amounts of fuel.

As the size of Earth satellites has increased, the efficiency of the manoeuvring thrusters has become ever more critical, leading to the need for larger, more costly launch rockets and, ultimately, limiting capabilities.

Many of these limitations have been overcome by ion thrusters, which use the inert and naturally occurring gas xenon.

Physicist David Fearn, who died aged 68 on 29th Sept 2007, was the driving energy behind their development in the UK, and was internationally recognised as a father of spacecraft ion propulsion.

In 1999 two ion thrusters were flown on the European Space Agency Artemis satellite when it was used in the successful spacecraft rescue following the failure of the launch rocket.

Two thrusters are used on the gravity and ocean circulation explorer satellite, which provides a new level of understanding of the planet's composition, climate change and the processes operating below the Earth's crust.

This ground-breaking mission would be impossible without the ion thrusters that compensate for the disturbances the spacecraft experiences as it speeds through the rarefied upper atmosphere five times faster than a rifle bullet.

The level of control is analogous to compensating for the disturbance experienced by a supertanker when a snowflake lands on the deck.

In 2006 ESA used electric propulsion on its Moon mission, SMART-1. Following that event, the European Space Agency (ESA) and the Australian National University (ANU) successfully tested a new design of spacecraft ion engine that dramatically improved performance.  

This new engine was over ten times more fuel efficient than the one used on SMART-1.

Dr Roger Walker of ESA’s Advanced Concepts Team, Research Fellow in Advanced Propulsion and Technical Manager of the project, said at that time: "Using a similar amount of propellant as SMART-1, with the right power supply, a future spacecraft using our new engine design wouldn’t just reach the Moon, it would be able to leave the Solar System entirely"

So, in line with continuing progress on ion drive development, larger thrusters, pioneered by Fearn, will also be used on the 2013 ESA BepiColombo mission to propel a spacecraft to Mercury.

The significance of Fearn's work is illustrated by his extensive list of publications - more than 250 technical papers and scientific articles.

Find here an article written by David Fearn about the Prospero4 /X5 spacecraft

He led teams from a number of UK government, academic and industrial organisations, as well as international collaborative work with the European Space Agency (ESA), United States air force (USAF) and the National Aeronautics and Space Administration (Nasa).

A recent ESA accolade described him as "the father of electric propulsion in the UK and one of the most influential and inspirational figures in the field of European spacecraft propulsion".

He was awarded a visiting chair at Surrey University and often acted as an external supervisor for postgraduate students. His enthusiastic and approachable manner was an inspiration to generations of young scientists.

Jetpacks fly in London

A man takes to the skies of London in Trafalgar Square with a jetpack to celebrate the launch of the game Halo: Reach

What is Solar Sailing?

Solar sail propulsion is simple in concept. Light photons bounce onto a mirror-like aluminized Mylar sail. As each photon hits, its momentum is transmitted to the spacecraft.

Photons have no mass but lots of energy, so a solar sail space probe requires no onboard fuel. The force acts continuously, meaning a solar sail can eventually reach speeds five to ten times greater than any chemical rocket.

Russia, the U.S. and the European Space Agency all started solar sail missions and technology programs but cut them back when money got tight. Japan, we are happy to say, is now moving ahead to develop an innovative solar sail and solar-powered ion drive hybrid.

Yet solar sail propulsion remains largely neglected. That's why the Society has long championed efforts to prove its value. We partnered with Cosmos Studios on the far-sighted Cosmos 1 solar sail project. But technology has advanced enormously since then. We can do more in a fraction of the size, with a fraction of the weight and at a fraction of the cost. This has led us to re-think everything…and what we've arrived at is far more advanced, and ultimately far more valuable.

This technology also opens up many new possibilities for piggyback launching into Earth orbit, which is desperately needed since launch vehicles have been a hindrance preventing solar sail flight. We're considering several launch possibilities and will select the most reliable one that matches our schedule and final orbit choice best.