INTRODUCTION TO BOLAS MISSION
BOLAS is an experiment designed to exploit a unique set of capabilities in Canada and the United States for novel space science that benefits from recent advances in tether and microsatellite technology. A multi-disciplinary Canada-U.S. team with interests in space plasmas, microsatellites, and tethers is planning a scientific experiment implemented with a low-cost spacecraft comprising two payload packages that are separated by a 100 m tether and in a bolas (cartwheel) rotation in low earth orbit.
The mission definition finalization and preliminary design phase has been funded and is now in progress (first of four phases) for a planned 2001 launch.
The BOLAS experiment is a novel approach to improved understanding of the ionosphere. It uses two payloads separated in space to focus on two major areas of current research, firstly density irregularities that affect radio waves and secondly small-scale instabilities. As well, measurements of the density distribution of the ionosphere will be made in a novel way. All the areas are linked to the dynamics of the auroral plasma. Although other multiple-satellite missions are being operated or proposed abroad, BOLAS will occupy a special niche by virtue of its small payload separation and its relatively low altitude at and just above the ionosphere-magnetosphere interface.
The objectives in basic space science are to improve the understanding of two classes of ionospheric dynamic processes that redistribute plasma energy in its flow from the sun to the low atmosphere. We focus on the class of the fluid processes around the peak of the ionospheric F region that give rise to large-scale density irregularities, such as the gradient-drift instability. Spaceborne BOLAS radio instrumentation will be used to view these irregularities from space and hence allow us to see density structures from a new perspective. The other class of processes is in the realm of microscale plasma instabilities. The simultaneous observation of thermal and suprathermal particles and concomitant waves will lead to improved models of the formation of ion conics, cavitons and other phenomena that must be part of the transport phenomena that control energy and mass flux in the collisionless topside auroral ionosphere.
Our approach is to coordinate the operation of the two-point (bistatic) payload with ground radio-science and other facilities to yield space perspectives on auroral density structures hitherto only observed on the ground. The primary facility for radio-science objectives would be phase coherent receivers on both ends of the tether for measuring the direction of arrival, signal delay and other parameters of the transionospheric waves. Particle detectors on both ends of the 100 m tether will be associated with the receivers in the study of spontaneous auroral processes whose spatial extent approximates the tether length. The bolas rotational motion of the ensemble will allow the double probe to investigate the dependence of measured parameters on the direction with respect to the local magnetic field.
BOLAS will employ established sounding rocket and tether technology as a base, but also will turn the page to new chapters, particularly in tethers, microsats and the use of the Global Positioning System (GPS) in orbit. The Canadian Space Agency (CSA) Space Technology Program and the NASA Marshall Space Flight Center are contributing partners in the project. These organizations will use and extend their expertise in tether technology and in secondary payload integration acquired in the SEDS, PMG and TIPS orbital missions and in the OEDIPUS suborbital flights. The first-time application of GPS technology to instrument time synchronization and to differential determination of the inertial direction of the tether will be new applications of this technology, which also will supply spacecraft ephemeris. The technology demonstrations of this mission have significance to future Canadian microsat and smallsat missions, and to future space station-related and interplanetary missions of NASA.
The BOLAS concept was conceived in response to the Announcement in July 1996 by the Space Science Program of the Canadian Space Agency of Opportunity for small payload experiments. The Mission Team is drawn from various agencies interested in the above topics. We think that we have achieved a balanced mixture of institutional experience in radio science, auroral physics, the space dynamics of tethers, space technology development and space operations. This mixture is the key to achieving an exciting synergism within the tight financial constraints of the participating agencies.