One of the most important changeless to NASA for reaching destinations across the solar system such as Mars and asteroids is a viable while cost effective solution. At the same time, NASA is trying to find a method of reducing the time for the development and implementation of transformative technologies. Such technologies will NASA’s capabilities for future missions as well as a variety of commercial spaceflight activities.
NASA’s Solar Electric Propulsion (SEP) project is currently trying to develop serious technologies aimed at extending the time duration as well as capabilities of ambitious exploration missions. Implementation of such alternative propulsion technologies as SEP would provide a cost-effective while secure and safe propulsive power for a variety of future journeys to destinations beyond the Earth’s orbit.
Electric vehicles are the other good option for space missions. While in terms of their use they are not still comparable to traditional chemical spacecraft engines, electric engines are gradually gaining popularity for such missions as scientific spacecraft missions to deep space and of course earth orbiting satellites. As experts indicate, electric engines seem to be a key element in NASA’s near future plans for sending people to Mars.
There are two main ways to power an electric spacecraft engine:
- solar energy absorbed from the sun
- Nuclear fission
While both of the above technologies have successfully passed tests aimed at getting their efficiency and capabilities, solar electric propulsion technology is regarded as the most commonly used.
During the past few decades, Electric spacecraft engines have been into operation and flying in various forms. In the 1970s, the Soviet Union got the upper hand in pioneering Hall thruster technology. This technology is still the most commonly used technology for designing electric engines for the majority of space crafts. Hall thrusters make use of both the electric and magnetic fields in a propellant to convert neutral atoms into charged atoms, called ions. By accelerating ions, it would be possible to produce thrust.
Hall thruster technology
Nathaniel Fisch, head of the Hall Thruster Experiment project at the Princeton Plasma Physics Laboratory in Princeton, N.J. has explained that “You have an electrical grid held at a certain voltage … You form a plasma and accelerate the ions in the plasma. Then the ions would be ejected at the voltage you put between the grid and the plasma.”
Engines made on the basis of Hall thruster technology has proved to be much more fuel-efficient compared to the traditional chemical rocket engines. These engines use the energy created through chemical reactions between the fuel and the oxidizer to create thrust.
Challenges of the Solar Electric Propulsion (SEP) technology for the Human Mars Mission
The disadvantage of this technology is that often the fuel efficiency can be achieved at the expense of thrust power. This means that the acceleration of an electrically propelled spacecraft is slower and therefore it takes a longer time for such a spacecraft to reach the same destination. (They could be designed to produce the same thrust as chemical engines, but would then require more power than current solar arrays are able to provide.)