Electromagnetic Formation Flight (EMFF)
Encyclopedia
Electromagnetic Formation Flight (EMFF) investigates the concept of using electromagnet
s coupled with reaction wheels in place of more traditional propulsion systems to control the positions and attitudes of a number of spacecraft in close proximity. Unlike traditional propulsion systems, which use exhaustible propellants that often limit lifetime, the EMFF system uses solar power to energize a magnetic field. The Massachusetts Institute of Technology
Space Systems Laboratory is exploring this concept by developing dynamics and control models as well as an experimental testbed for their validation.
(TPF) Mission and Space Telescope assembly are just two such types of missions. EMFF provides the foremost advantage of reduced dependence on consumables . In addition, it eliminates thruster plumes and enhances the capability of replacing a failed element more economically.
(HTS) coils. The testbed has demonstrated control of the relative degrees of freedom (DOF) in open loop and closed loop control using linearized controllers and a nonlinear sliding mode controller.
) has been awarded the first Bepi Colombo Prize for a paper on electromagnetic formation flight. According to Aero-Astro Professor Manuel Martinez-Sanchez, who worked with Colombo and was a juror in the competition, "The jury was unanimous in that Ray's paper best represented 'Bepi' Colombo's spirit of innovation and originality, combined with rigor."
Electromagnet
An electromagnet is a type of magnet in which the magnetic field is produced by the flow of electric current. The magnetic field disappears when the current is turned off...
s coupled with reaction wheels in place of more traditional propulsion systems to control the positions and attitudes of a number of spacecraft in close proximity. Unlike traditional propulsion systems, which use exhaustible propellants that often limit lifetime, the EMFF system uses solar power to energize a magnetic field. The Massachusetts Institute of Technology
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
Space Systems Laboratory is exploring this concept by developing dynamics and control models as well as an experimental testbed for their validation.
How it Works
The magnetic fields for EMFF are generated by sending current through coils of wire. The interaction between the magnetic dipoles created is easily understood with a far field approximation where the separation distance between two vehicles is large compared to the physical size of the dipole. By controlling the dipoles on various vehicles, attraction, repulsion, and shear forces can be created. Combined with reaction wheels, any desired maneuver can be performed as long as the formation’s center of mass is not required to change.Applications
The EMFF system is most applicable in cases where multiple spacecraft are free-flying relative to one another and there is no need to control the center of mass of the system. NASA’s Terrestrial Planet FinderTerrestrial Planet Finder
The Terrestrial Planet Finder was a proposed project by NASA to construct a system of telescopes for detecting extrasolar terrestrial planets. TPF was postponed several times and finally cancelled...
(TPF) Mission and Space Telescope assembly are just two such types of missions. EMFF provides the foremost advantage of reduced dependence on consumables . In addition, it eliminates thruster plumes and enhances the capability of replacing a failed element more economically.
Testbed
The MIT-SSL constructed two EMFF testbed vehicles for demonstrating control of 2-D formations on a large flat floor. Vehicles are suspended on a frictionless air carriage and are completely self-contained using RF communications, microprocessors, and a metrology system. Liquid Nitrogen maintains cryogenic temperatures and batteries provide the power to the high-temperature superconductiveHigh-temperature superconductivity
High-temperature superconductors are materials that have a superconducting transition temperature above . From 1960 to 1980, 30 K was thought to be the highest theoretically possible Tc...
(HTS) coils. The testbed has demonstrated control of the relative degrees of freedom (DOF) in open loop and closed loop control using linearized controllers and a nonlinear sliding mode controller.
Awards
Former Space Systems Lab associate director Dr. Raymond Sedwick (now at the University of Maryland, College ParkUniversity of Maryland, College Park
The University of Maryland, College Park is a top-ranked public research university located in the city of College Park in Prince George's County, Maryland, just outside Washington, D.C...
) has been awarded the first Bepi Colombo Prize for a paper on electromagnetic formation flight. According to Aero-Astro Professor Manuel Martinez-Sanchez, who worked with Colombo and was a juror in the competition, "The jury was unanimous in that Ray's paper best represented 'Bepi' Colombo's spirit of innovation and originality, combined with rigor."
Collaborators
Research on Electromagnetic Formation Flight or similar projects is also ongoing at:- The Institute of Space and Astronautical Science / JAXA
- Space Research Centre, Polish Academy of Sciences
- Michigan Technogical University on Colomb Force Spacecraft
Other Journal Articles
- Elias, Laila M., Kwon, Daniel W., Sedwick, Raymond J., and Miller, David W., "Electromagnetic Formation Flight Dynamics including Reaction Wheel Gyroscopic Stiffening Effects" Journal of Guidance, Control, and Dynamics, Vol. 30, No. 2, Mar-Apr. 2007, pp. 499-511.
External links
- SSL's EMFF web page
- Other research at the MIT Space Systems Laboratory MSEMars Surface ExplorationMars Surface Exploration ' is a systems engineering tool for the design of rover missions originally developed in 2003 by the Space Systems Engineering graduate class at MIT. It has since been further enhanced by the MIT Space Systems Laboratory with the support of the Jet Propulsion Laboratory ....
- SPHERESSPHERESThe Synchronized Position Hold, Engage, Reorient Experimental Satellites experiment is a testbed consisting of three miniaturized satellites that can operate in a variety of environments, including inside the International Space Station...