Goddard Space Flight Center, Greenbelt, Maryland 20771

ENGINEERING COLLOQUIUM

Monday, May 16, 2005 / 3:30 PM, Building 3 Auditorium

Enrico Lorenzini

"Electrodynamic Tethers in Space and More"

ABSTRACT -- Electrodynamic tethers (EDTs) make possible in-space propulsion in low Earth orbit with negligible propellant consumption. An electrodynamic tether needs a magnetic field and a ionosphere to generate drag or thrust forces without expelling mass. Around Earth, drag forces can be produced at the expense of orbital energy (i.e., without the need for on-board power) while thrust forces require a power source. A number of suborbital missions in the 80s and three orbital missions in the 90s have utilized electrodynamic tethers and demonstrated their basic validity. Intriguing possibilities are offered by EDTs as drag devices to dispose of spacecraft at the end of life and for reboosting the International Space Station through electrodynamic propulsion, thus saving chemical propellant and reducing the number of resupply flights. Around planets such as Jupiter and Saturn, the use of EDTs can be even more intriguing. Thanks to ionospheres that extend beyond the stationary orbits, EDTs can produce thrust and power at the same time above the stationary altitude by stealing the energy from the host planet's rotation. Last but not least, tethers of the non-electrodynamic variety will be an essential component of spinning spacecraft formations for space-based interferometry like the Space Probe of the Evolution of Cosmic Structure (SPECS) being developed at NASA Goddard Space Flight Center.

SPEAKER -- Enrico Lorenzini received a Doctoral Degree in Aeronautics from the University of Pisa in Italy in 1980. After working for aerospace companies, he joined the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts in 1984 where he is presently the Head of the Special Projects Group. His expertise includes orbital dynamics, spacecraft dynamics and control, and mission analysis. His research has focused, among other topics, on tethered satellites and related experiments. He was an investigator in four tethered satellite missions flown by NASA in the 1990s and worked on the development on a number of planned missions involving tether-in-space technology.