A recent article on the NASA website reveals that a revolutionary technology for powering spacecraft by riding the solar wind and propelling themselves to the edge of the solar system in record time. Called the Heliopause Electrostatic Rapid Transit System (HERTS), this amazing technology sounds like something out a science fiction novel, but in fact, modeling and testing of this solar e-sail concept has started at NASA’s Marshall Space Flight Center in Huntsville, Alabama.
The fascinating details of the design and testing of this revolutionary propulsion system are described in a very interesting and detailed article on the NASA website:
The test results will provide modeling data for the Heliopause Electrostatic Rapid Transit System (HERTS). The proposed HERTS E-Sail concept, a propellant-less propulsion system, would harness solar wind to travel into interstellar space.
“The sun releases protons and electrons into the solar wind at very high speeds — 400 to 750 kilometers per second,” said Bruce Wiegmann an engineer in Marshall’s Advanced Concepts Office and the principal investigator for the HERTS E-Sail. “The E-Sail would use these protons to propel the spacecraft.”
Extending outward from the center of the spacecraft, 10 to 20 electrically charged, bare aluminum wires would produce a large, circular E-Sail that would electrostatically repel the fast moving protons of the solar wind. The momentum exchange produced as the protons are repelled by the positively charged wires would create the spacecraft’s thrust. Each tether is extremely thin, only 1 millimeter — the width of a standard paperclip — and very long, nearly 12 and a half miles — almost 219 football fields. As the spacecraft slowly rotates at one revolution per hour, centrifugal forces will stretch the tethers into position.
The testing, which is taking place in the High Intensity Solar Environment Test system, is designed to examine the rate of proton and electron collisions with a positively charged wire. Within a controlled plasma chamber simulating plasma in a space, the team is using a stainless steel wire as an analog for the lightweight aluminum wire. Though denser than aluminum, stainless steel’s non-corrosive properties will mimic that of aluminum in space and allow more testing with no degradation.
Engineers are measuring deflections of protons from the energized charged wire within the chamber to improve modeling data that will be scaled up and applied to future development of E-Sail technology. The tests are also measuring the amount of electrons attracted to the wire. This information will be used to develop the specifications for the required electron gun, or an electron emitter, that will expel excess electrons from the spacecraft to maintain the wire’s positive voltage bias, which is critical to its operation as a propulsion system.
This concept builds upon the electric sail invention of Dr. Pekka Janhunen of the Finnish Meteorological Institute, and the current technologies required for an E-Sail integrated propulsion system are at a low technology readiness level. If the results from plasma testing, modeling, and wire deployer investigations prove promising after the current two-year investigation, there is still a great deal of work necessary to design and build this new type of propulsion system. The earliest actual use of the technology is probably at least a decade away.
NASA scientists believe that this e-sail design could propel a spacecraft to the heliosphere in just a 10-year journey. By comparison, it took the Voyager spacecraft 35 years to travel to the solar system’s edge.
In this video, NASA reveals the general concepts behind the HERTS E-sail:
For more details links to additional resources about the HERTS E-sail, see the fascinating article on the NASA website.
Source: NASA.gov – “NASA Begins Testing of Revolutionary E-Sail Technology”