Welcome to the Special Projects Group Web Site



Left Picture: Ground-based observation of SEDS-2 (see more in Missions)

Right picture: TSS-1R from the Shuttle Bay



Tethers-In-Space Research at the Smithsonian Astrophysical Observatory


The Special Projects Group of the Smithsonian Astrophysical Observatory (Cambridge, MA) is where many of the fundamental contributions to space-borne tethered systems (courtesy of NASA) have been made since the early 70's.

Two group members, the late Drs. Giuseppe Colombo and Mario Grossi, jointly held the fundamental patent on the Shuttle-borne orbiting tether (US patent #4,097,010 dated 6/27/78), that was originally conceived by Grossi in the early 70's as a space-borne antenna and a tethered satellite to measure its radiation pattern. Since then, the Group has received many contracts and grants from NASA and aerospace companies for the study of several applications of tethers in space.

The group members, Enrico C. Lorenzini (group's head), Robert D. Estes, Mario L. Cosmo, Gordon E. Gullahorn (associate) and Yakov Alpert (emeritus) have proposed several of the tethers-in-space systems that have been analyzed or flown by NASA during the last two decades.


Our research group has made important contributions to present and past tethered systems, as follows:

  1. Tethers for Electrodynamics and Atmospheric Science;
  2. Tethered Systems for the International Space Station;
  3. Electrodynamic bare tethers for in-space transportation;
  4. Spinning tethers for LEO to GEO orbital transfers;
  5. In-space tethered centrifuges for artificial gravity:
  6. Reentry of drag-decelerated tethered capsules;
  7. Microgravity tethered laboratories attached to the Space Station;
  8. Tethered-satellite-based gravity gradiometers;
  9. Tethered probes for the exploration of the Earth's lower thermosphere;
  10. Tethered probes for Martian aeronomy studies;
  11. Tethered probe for the collection of a sample of Martian atmospheric dust;

Some of the systems above have been originally proposed by group members, such as the electrodynamic bare tethers for space transportation, inclusive of Space Station reboost (in collaboration with Prof. Juan Sanmartin of the Polytechnic University of Madrid and Prof. Manuel Martinez-Sanchez of the Massachusetts Institute of Technology), tethered systems for ionospheric and atmospheric studies, the tethered systems for Martian applications and the drag-decelerated reentry of tethered capsules.

Members of the special projects group were actively involved in six tethered orbital flights.
Click here for a brief description of the missions.

The special projects group has acquired great expertise through two decades of studies and involvement in tethered system flights to become a leader in tethered satellite technology and a driving force behind the next generation of tethered systems such as bare tethers for in-space propulsion (click here for a .pdf copy of our 1995 White Paper) which will be first tested with the flight of ProSEDS in August 2000 from a Delta second stage.

During the last 10 years, members of the group have published more than 100 papers in refereed journals and conference proceedings, and more than 150 NASA reports.
Click here for a list of the Group Publications

If you like to learn more about space tethers download a .pdf version of the Handbook of Tethers in Space edited by SAO in December 1997.

For more information about past and present activities on tethered satellites at the Smithsonian Astrophysical Observatory please contact Enrico Lorenzini at:

e-mail: elorenzini@cfa.harvard.edu
Phone: (617) 495-7211
Fax: (617) 496-7670

Mailing Address:
Harvard-Smithsonian Center for Astrophysics
60 Garden St. Mail Stop 80
Cambridge, MA 02138


Click here for tether related links.





Revised March 30, 1999 by Mario L. Cosmo Harvard-Smithsonian Center For Astrophysics