Posts Tagged ‘Ion Drives’

Crowdfunded Solar Sail Spacecraft Makes Successful Flight

August 6, 2019

Bit of science news now. Last Friday’s I for 2nd August 2019 reported that a satellite developed by the Planetary Society and funded through internet fundraising had successfully climbed to a higher orbit using a solar sail. This propels spacecraft using only the pressure of light, just like an ordinary sail uses the force given by the window to propel a ship on Earth, or drive a windmill.

The article on this by Joey Roulette on page 23 ran

A small crowdfunded satellite promoted by a TV host in the United States has been propelled into a higher orbit using only the force of sunlight.

The Lightsail 2 spacecraft, which is about the size of a loaf of bread, was launched into orbit in June. 

It then unfurled a tin foil-like solar sail designed to steer and push the spacecraft, using the momentum of tiny particles of light called photons emanating from the Sun – into a higher orbit. The satellite was developed by the California-based research and education group, the Planetary Society, who chief executive is the television personality popularly known as Bill Nye the Science Guy.

The technology could potentially lead to an inexhaustible source of space propulsion as a substitute for finite supplies of rocket fuels that most spacecraft rely on for in-flight manoeuvres.

“We are thrilled to declare mission success for Lightsail 2,” said its programme manager Bruce Betts.

Flight by light, or “sailing on sunbeams”, as Mr Nye called it, could best be used for missions carrying cargo in space.

The technology could also reduce the need for expensive, cumbersome rocket propellants.

“We strongly feel taht missions like Lightsail 2 will democratise space, enable more people send spacecraft to remarkable destinations in the solar system”, Mr Nye said.

This is very optimistic. The momentum given to a spacecraft by the Sun’s light is very small. But, like ion propulsion, it’s constant and so enormous speeds can be built up over time. It may be through solar sail craft that we may one day send probes to some of the extrasolar planets now being discovered by astronomers.

In the 1990s, American scientists designed a solar sail spacecraft, Star Wisp, which would take a 50 kg instrument package to Alpha Centauri. The star’s four light years away. The ship would, however, reach a speed of 1/3 that of light, meaning that, at a very rough calculation, it would reach its destination in 12 years. The journey time for a conventional spacecraft propelled by liquid oxygen and hydrogen is tens of thousands of years.

Although the idea has been around since the 1970s, NASA attempt to launch a solar sail propelled satellite a few years ago failed. If we are ever to reach the stars, it will be through spacecraft and other highly advanced unconventional spacecraft, like interstellar ramjets. So I therefore applaud Nye and the Planetary Society on their great success.

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Scientists Invent Ion-Driven ‘Star Trek’ Plane

November 23, 2018

This is a fascinating piece from yesterday’s I newspaper, for the 22nd November 2018. It reports that Dr. Steven Barrett and his team at MIT have built an airplane that flies through channeling air underneath its wings using electrically charged wires hung below them.

The article, by John von Radowitz, on page 13, reads

A revolutionary electronic aircraft propulsion system inspired by Star Trek has been tested on a working model for the first time.

The five-metre wingspan glider-like plane has no propellers, turbines or any other moving parts, and is completely silent.

Instead, an “ionic wind” of colliding electrically charged air molecules provides the thrust needed to make it fly.

In the tests, the battery-powered unmanned aircraft, that weighs just five pounds, managed sustained flights of 60m at an average height of just 0.47m.

But its inventors believe that, like the early experiments of the Wright brothers more than 100 years ago, such small beginnings will eventually transform the face of aviation.

In the near future, ion wind propulsion could be employed to power quiet drones, the team predicts.

Further down the line, the technology could be paired with more conventional propulsion systems to produce highly fuel-efficient hybrid passenger planes.

Lead researcher Dr. Steven Barret, from Massachusetts Institute of Technology (MIT) in the US, said: “This is the first-ever sustained flight of a plane with no moving parts in the propulsion system.

“This has potentially opened new and unexplored possibilities for aircraft which are quieter, mechanically simpler, and do not emit combustion emissions.”

He revealed that he was partly inspi9red by the TV sci-fi series Star Trek. He was especially impressed by the show’s futuristic shuttle crafts that skimmed through the air producing hardly any noise or exhaust. “This made me think, planes shouldn’t have propellers and turbines,” said Dr. Barrett.
“They should be more like the shuttles in
Star Trek that have just a blue glow and silently glide.

The test aircraft, described in the journal Nature, carries an array of thin wires strung beneath the front end of its wings. A high-voltage current passed through the wires strips negatively charged electrons from surrounding air molecules.

This produces a cloud of positively charged ionized air molecules that are attracted to another set of negatively charged wires at the back of the plane.

As they flow towards the negative charge, the ions collide millions of times with other air molecules, creating the thrust that pushes the aircraft forward.

The article also said that

Test flights were made across the gymnasium at MIT’s duPont Athletic Centre, the largest indoor space the scientists could find.

The article also carried this diagram of the aircraft and its engine.

The illustration is entitled ‘How It Works’, and shows picture of the plane, with an arrow saying ‘Battery in fuselage’. There’s also a diagram of the electrically charged particles and the wires connected to the battery that the plane uses instead of a conventional engine.

The illustration’s notes read

Thin wires are strung under the front of the wing and thicker wires under the rear. When connected to a high voltage battery they act as electrodes. The thin positive electrode takes negatively charged electrons from air molecules, creating positive ions. The ions are attracted to the negative electrode at the rear and, as they flow towards it, they collide with neutral air molecules, creating thrust.

The plane reminds of me of the atmospheric aircraft in one of Alistair Reynold’s SF novels, Revelation Space, which fly through heating up the air below them. The propulsion system’s also related to the nuclear electric propulsion used, or proposed, for some spacecraft. This also uses an electrically charged grating to channel and increase the thrust of charged particles generated by a nuclear reactor. As I understand it, the amount of thrust generated by this type of rocket engine is small, but because it’s constant it can eventually build up over time so that the craft is flying at quite considerable speed.

An ion-driven plane is a fascinating concept, though it won’t be powering passenger craft just yet. But you wonder how many UFO sightings will be generated by the experimental and prototype craft which will be designed and built after this.