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801 results on '"Johnson, Les"'

60. Near Earth Asteroid Scout Mission Update

Author

Sweetser, Ted, Lantoine, Gregory, Castillo-Rogez, Julie, Seybold, Calina, Marinan, Anne D, Pruitt, Matt, Matus, Joe, and Johnson, Les

Abstract

UNKNOWN

Published
2020

61. Near Earth Asteroid Scout Mission Update

Author

Johnson, Les, Matus, Joe, Pruitt, Matt, Marinan, Anne D, Seybold, Calina, Castillo-Rogez, Julie, Lantoine, Gregory, and Sweetser, Ted

Published
2020

79. Setting Sail for the Sun: The NEA Scout & Solar Cruiser Missions

Author

Johnson, Les

Subjects
Spacecraft Propulsion And Power
Abstract

Join HAL5 as we welcome back Les Johnson, who will talk about his work on developing solar sails at Marshall Space Flight Center and its role in propulsion and exploration of the Sun. With the successful flights of NASA's NanoSail-D and the Planetary Society's LightSail, solar sails are making the transition from an interesting idea to be demonstrated to technology ready for use on space missions. Scientists and engineers here in Huntsville are doing just that with the development of the Near Earth Asteroid Scout's 925 square foot solar sail that will fly in 2020. And that's not all, in August, a team led by NASA MSFC was selected as a finalist to develop an 18,000 square foot solar sail for a project called, Solar Cruiser, that may fly as early as 2024. If you would like to learn the fundamentals of solar sailing and get the scoop on these two innovative and exciting missions, then hang on as we "Set Sail for the Sun!"

Published
2019

80. Electrostatic Solar Sail: A Propellantless Propulsion Concept for an Interstellar Probe Mission

Author

DeStefano, Anthony M, Wiegmann, Bruce M, Bangham, Mike, Bryan, Thomas, Carr, John, Heaton, Andrew, Johnson, Les, Tyler, Daniel, Wright, Kenneth H. Jr, and Stone, Nobie

Subjects
Spacecraft Propulsion And Power
Abstract

The propulsion of an electrostatic solar sail (E Sail) is obtained by extracting momentum from the solar wind through electrostatic repulsion of the positively charged solar wind ions (see Figure 1). The positively charged solar wind protons are deflected by the electric field created around the tethers.This electric field grows in diameter as the spacecraft moves away from the Sun, therefore the E Sail effective area grows. The growth of the E-Sail effective area allows the propulsive force to decrease as 1/r up to distances of 20 AU as it moves away from the Sun, unlike solar sail propulsion whose thrust decreases as 1/r 2 but only to distances of 5AU. This propulsive force is created without using propellant and, therefore, E-sail avoids both the mass and complexity of chemical rockets (that require large amounts of propellant, propellant storage tanks, plumbing, valves, and insulation).

Published
2019

87. Protecting Earth

Author

Johnson, Les, Matloff, Gregory L., Bangs, C, Johnson, Les, Matloff, Gregory L., and Bangs, C

Published
2010
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90. Vanishing Life

Author

Johnson, Les, Matloff, Gregory L., Bangs, C, Johnson, Les, Matloff, Gregory L., and Bangs, C

Published
2010
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93. Climate Change

Author

Johnson, Les, Matloff, Gregory L., Bangs, C, Johnson, Les, Matloff, Gregory L., and Bangs, C

Published
2010
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