Electric Sails Could Ride Solar Wind to Deep Space in the Next Ten Years

Monday, 09 November 2015 - 2:01PM
NASA
Technology
Monday, 09 November 2015 - 2:01PM
Electric Sails Could Ride Solar Wind to Deep Space in the Next Ten Years
We may be able to explore the furthest reaches of space by 2025, as researchers are attempting to build electric sails that can ride solar wind to the outskirts of the solar system.

The Heliopause Electrostatic Rapid Transit System (HERTS) project, which has received two rounds of funding from NASA, has spent the last few years developing "e-sails," which uses solar wind as a propulsion system to reach the heliopause, the outermost edge of the heliosphere, or the bubble-like region of space that lies far beyond the orbit of Pluto.

"It looks really, really promising for ultra-deep-space exploration," said Les Johnson of NASA's Marshall Space Flight Center at the 100-Year Starship Symposium on October 30 (via Space.com).

The e-sails would consist of a collection of wires that are extremely thin- approximately half the thickness of a human hair- attached to a spacecraft that turns slowly, keeping the wires taut. The electric charge on the wires would propel the spacecraft away from the sun, allowing the probe to move at unprecedented speeds.

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"A high-voltage, positive bias on the wires, which are oriented normal to the solar wind flow, deflects the streaming protons, resulting in a reaction force on the wires - also directed radially away from the sun," the HERTS team wrote in their project description. "Over periods of months, this small force can accelerate the spacecraft to enormous speeds - on the order of 100-150 km/s (~ 20 to 30 AU/year)."
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One AU, or astronomical unit, is the distance between the Earth and the Sun. As a comparison, the most distant spacecraft from Earth, Voyager One, has traveled 134 AU since 1977. It took 35 years to enter interstellar space, but these electric sails could allow a spacecraft to reach the same distance in a fraction of that time.

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"The proposed HERTS can provide the unique ability to explore the heliopause and the extreme outer solar system on timescales of less than a decade," HERTS team members wrote on the NIAC page. "It is significantly more effective than any other near-to-mid-term propulsion system for deep-space missions, meshes well with heliospheric science payloads, and could be implemented in the 2025-2030 timeframe."
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There are several logistical kinks to work out; the probe would likely need to be equipped with some kind of electron gun in order to maintain its charge, and the research team doesn't know whether the amount of energy required to keep an electron gun running on a spacecraft would be feasible. But if the scientists can work out these obstacles, e-sails could usher in a whole new era of space exploration.

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"The Heliopause Electrostatic Rapid Transit System (HERTS) fully supports NASA's vision to 'lead advances in space' by providing a revolutionary, in-space propulsion system that can open the frontier of Heliophysics to new discovery. With the performance and benefits of a HERTS mission, the Heliospheric physics community will have at its disposal the ability to carry out Heliophysics missions with one-way Earth to Heliopause trip times of less than 10 years. This study is a necessary step between a scientific dream and engineering development."
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