An ion engine able to recover its fuel in the atmosphere now exists: the European Space Agency has indeed built a prototype that can recover the molecules useful for its operation by simply passing through certain layers of the atmosphere. A world first.
Ionic engines do not exist only in science fiction. The space industry is already using it to propel probes or satellites. For example, NASA had made an impression in 1998 by testing this technology for the first time under real conditions, with Deep Space 1. Since then, other powers have rushed in this direction.
Its principle is to ionize the fuel, a gas in this case, instead of burning it. This process results in the release of ions, which are then accelerated using an electric field. At present, it is xenon, a noble gas, which is preferred for supplying ionic engines. This is typically the case in Europe. Whether with the Artemis satellite, designed in partnership with Japan in 2001, or the SMART-1 spacecraft in 2003, the European Space Agency (ESA) ventured into this terrain many years ago. Here, it is a Hall effect booster that served, while NASA installed a grid ion engine for Deep Space 1.
The ion engine has some advantages over a traditional space engine. However, it is dependent on the amount of fuel that is shipped at the start. When all the xenon has been consumed and ionized, its propulsion stops. This is what happened with the European satellite Gravity Field and Steady-State Ocean Circulation Explorer, which had a stock of 40 kg xenon for the whole of its mission.
In the short term, the simplest answer to this problem is to increase the load of xenon. But the higher the mass of the payload, the more it costs money: typically, it may be necessary to use a heavy launcher and burn large amounts of conventional fuel to simply take the machine into space. And this answer can not be used indefinitely.
The ion engine prototype designed by Esa.Credit: ESA / SitaelA world first
That is why the recent progress made in this sector by the European Space Agency is very promising. To put it simply, tests have found an alternative to the use of xenon cylinders for probes and satellites – or at least a complement – which could significantly extend the duration of space missions.
Specifically, Esa has developed an ion engine that is able to collect its own fuel by simply walking through the atmosphere to collect rare gases. "This opens the way for satellites flying in very low orbit for years," observes the agency. And this is true for the Earth's atmosphere as for others, even very tenuous, like the Martian atmosphere.
General operation of the prototype.Credit: ESA-A. Di GiacomoSimulation of altitude
The prototype, which is the first of its kind to exist, indicates the Esa has proven itself in a vacuum chamber. It was to reproduce the same environment found at 200 km altitude. "There are no valves or complex parts – everything works on a simple and passive basis. Just power the coils and electrodes to get an extremely robust drag compensation system, "Esa writes.
The demonstration took place in three stages: first, there was a classic power supply of the ion engine with xenon. Then, it was partially replaced by a mixture of air composed of oxygen and nitrogen. The last phase consisted of cutting the arrival of xenon to only use common molecules of the atmosphere (oxygen and nitrogen make up more than 99%).
Ionic engine off.Credit: ESA
Photo credit of one: ESA