NASA electric sail: first concept check

The Marshall Space Flight Center began testing as part of a project to develop an electric sail, a revolutionary space engine capable of delivering a spacecraft to the solar system at maximum speed and push it out of the heliosphere. The tests will provide data for simulating the Heliopause Electrostatic Rapid Transit System (HERTS) device itself.



Like the solar sail, the electric sail uses the pressure of the solar wind, not photons, but protons. This has its advantages. Photons no longer give the necessary traction at a distance of 5 AU. from the Sun, somewhere around the asteroid belt, but protons are another thing. The electric sail will accelerate even at a distance of 16-20 or even 30 AU. from the sun! According to calculations, by this time it will reach a very high speed. For example, the distance is approximately 100 AU. before heliopause, it will overcome in less than 9.9 years with acceleration from Jupiter or in 11 years without acceleration, three times as fast as Voyager-1 and twice as fast as the apparatus on a solar sail.





NASA engineer Bruce Wigmann leads the development. In his hands is an aluminum cable with a thickness of 1 mm. An electric sail will consist of such cables.

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The device consists of a series of long and thin ropes with a high positive charge and an onboard electron gun directed against the movement of the spacecraft. The flow of electrons from the gun charges the cables, so that a positively charged metal repels the protons of the solar wind and gets a boost. The sun emits protons with speeds from 400 to 750 km / s - the so-called fast and slow solar winds. The concept was proposed in 2006 by the Finnish scientist Pekka Janhunen .



The electric sail of NASA will consist of 10-20 aluminum cables with a diameter of about 1 mm and a length of 20 km each. Thus, the sail forms a circle with a diameter of 40 kilometers. Having taken the initial position, the apparatus will begin to rotate slowly (approximately one revolution per hour), and the cables themselves will stretch their entire length due to centrifugal force.



After that, it will start moving slowly. At a distance of 1 au from the Sun, the estimated thrust is approximately 0.150 mN.



The effective area of ​​the electronic sail HERTS is approximately 600 km ² at a distance of 1 AU. from the Sun and increases to more than 1200 km ² by 5 AU.







Now they are being tested in the High Intensity Solar Environment Test (which is shown below) in the solar wind simulator, where the number of collisions of protons and electrons from the solar wind with a positively charged cable is measured. Engineers deliberately use steel cable instead of aluminum. Although steel is denser than aluminum, it is a stainless material that simulates the stainless properties of aluminum in space and will allow for longer testing.







Sensors measure proton reflections from a charged cable and the number of electrons attracted to it. This information is needed to develop specifications of the electron gun on the device.



At the moment, the HERTS system is at a low stage of technological readiness, recognizes NASA. Even if the results of the tests in the chamber, modeling and testing of the deployment systems of the cables will be successful, and these tests will take two years, there is still a lot of work on the design and manufacture of electric sails. The first spacecraft on this engine, we can only see in ten years.