NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Integrated Orbit and Attitude Control for a Nanosatellite with Power ConstraintsHokieSat is a NASA Goddard sponsored spacecraft currently being built by students at Virginia Tech. HokieSat is part of the Ionospheric Observation Nanosatellite Formation (ION-F) project. The project involves spacecraft built by three schools: Virginia Tech (VT), Utah State University (USU), and University of Washington (UW). The three spacecraft are similar in design and will perform formation flying demonstrations, and make ionospheric measurements. HokieSat uses Pulsed Plasma Thrusters (PPTs) to maintain its position in the formation. There are two pairs of PPTs on HokieSat; their position on HokieSat's hexagonal cross-section is shown. Thrusters T(sub 2) and T(sub 3) provide translation control, and Thrusters TI and T4 can provide yaw steering. Any thruster can be fired individually. However because they share a capacitor, thrusters T(sub 1) and T(sub 2) or thrusters T(sub 3) and T(sub 4) cannot be fired simultaneously. Thrusters T(sub 2) T(sub 3) can be fired simultaneously, as well as thrusters T(sub 1) and T(sub 4). Each thruster provides an impulse-bit of 56 micronN-s and fires at a rate of 1 Hz. For translation control thrusters T2 and T3 are fired together providing an impulse-bit of 112 micronN-s. All four thrusters are positioned slightly above the center of mass, and therefore exert a torque on the spacecraft. Because there are no thrusters in the zenith-nadir directions, and the communication system requires that the spacecraft remain nadir-pointing, there is no way to thrust in the radial direction. The attitude of HokieSat is controlled by 3 orthogonal magnetic torque coils. Attitude control is achieved by forcing a current through the torque coils, which interacts with the Earth's magnetic field and creates a torque. Due to magnetic field interactions between the coils and PPTs, the two actuator systems cannot be used simultaneously, and any attitude or orbit control must be performed in a piecewise fashion. Power limitations place an additional constraint on the HokieSat control subsystem. When the spacecraft is in eclipse, the power subsystem can provide only enough power to operate vital spacecraft functions.
Document ID
20030031373
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Berry, Matthew M.
(Virginia Polytechnic Inst. and State Univ. Blacksburg, VA, United States)
Naasz, Bo J.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Kim, Hye-Young
(Virginia Polytechnic Inst. and State Univ. Blacksburg, VA, United States)
Hall, Christopher D.
(Virginia Polytechnic Inst. and State Univ. Blacksburg, VA, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2002
Subject Category
Astronautics (General)
Meeting Information
Meeting: Space Flight Mechanics Meeting
Location: Ponce
Country: Puerto Rico
Start Date: February 9, 2003
End Date: February 12, 2003
Distribution Limits
Public
Copyright
Public Use Permitted.
Document Inquiry

Available Downloads

There are no available downloads for this record.
No Preview Available