Kim M. Aaron

A Method for Balloon Trajectory Control

Abstract A balloon trajectory control system is discussed that is under development for use on NASAs Ultra Long Duration Balloon Project. The trajectory control system exploits the natural wind field variation with altitude to generate passive lateral control forces on a balloon using a tether-deployed aerodynamic surface below the balloon. A lifting device, such as a wing on end, is suspended on a tether well beneath the balloon to take advantage of this variation in wind velocity with altitude. The wing generates a horizontal lift force that can be directed over a wide range of angles. This force, transmitted to the balloon by a tether, alters the balloons path providing a bias velocity of a few meters per second to the balloon drift rate. The trajectory control system enables the balloon to avoid hazards, reach targets, steer around avoidance countries and select convenient landing zones. No longer will balloons be totally at the mercy of the winds. Tests in April 1999 of a dynamically-scaled model of the trajectory control system were carried out by Global Aerospace Corporation in ground level winds up to 15 m/s. The size of the scale model was designed to simulate the behavior of the full scale trajectory control system operating at 20 km altitude. The model confirmed many aspects of trajectory control system performance and the results will be incorporated into future development.

Gossamer Orbit Lowering Device (GOLD) for Safe and Efficient De-orbit

An inflatable de-orbit system that accelerates natural orbit decay by orders of magnitude is discussed. Applications of GOLD include de-orbit of antiquated satellites, micro-satellites, spent stages, and derelict satellites. In this patented concept, a relatively large, ultralightweight envelope is stowed in a small package. GOLD can be used in a number of ways. It is most economical to attach it to a spacecraft or upper stage before launch. However, GOLD could be attached to existing large orbital debris objects using, for example, an electrically propelled orbital tender. For large dense objects that could pose a hazard to people or property on the ground during reentry, GOLD can be used to target reentry into an ocean. For most LEO satellites, GOLD is more mass and cost effective than chemical propulsion and can reduce de-orbit time, in some cases from many centuries to just a few months. Risk assessment indicates that GOLD, as compared with competing non-propulsive de-orbit concepts, does not contribute further to the orbital debris problem and has a lower risk to operating satellites.

Aerodynamic and Mission Performance of a Winged Balloon Guidance System

A winged balloon guidance system exploits the natural wind-field variation with the altitude available in planetary atmospheres to generate passive lateral control forces on a balloon using a tether-deployed aerodynamic surface below the balloon. Several balloon guidance system topics are discussed, including development status, physics and aerodynamics, systems performance, concept of operations, and the near-space applications of this technology for scientific, communications, and defense applications.

Global stratospheric balloon constellations

A revolutionary concept is discussed for a global constellation and network of hundreds of stratospheric superpressure balloons that can address major scientific questions relating to Earth science. Global Aerospace Corporation is proposing this role for a new generation of stratospheric platform based on advanced balloon technology, called the StratoSat. StratoSat constellations can address issues of high interest to the Earth science community including global change, especially tropical circulation and radiation balance; global and polar ozone; hurricane forecasting and tracking; global circulation; and global ocean productivity. StratoSat constellations operating at a 35-km altitude and for 5 to 10 years in duration could augment and complement satellite measurements and possibly replace satellites for making some environmental measurements. The keys to this new concept are (a) affordable, long-duration balloon systems, (b) balloon trajectory control capability, and (c) a global communications infrastructure. Technology for these very long-duration and guided stratospheric balloons is summarized, constellation geometry management is discussed, international overflight issues are explored, and the StratoSat system design is described.

Sailing the Planets: Exploring Mars from Guided Balloons

*† ‡ § We present a new concept for a future Mars exploration architecture. At the core of the architecture are the Directed Aerial Robot Explorer (DARE) platforms, which are autonomous balloons with path guidance capabilities that can carry heavy scientific payloads and deploy swarms of miniature robotic probes over multiple target areas. This architecture enables a multitude of observations that are impossible or too expensive to make in any other way. The architecture enables surface imaging, in situ sampling of the atmosphere and surface, radar soundings of the subsurface, magnetic and gravity surveys and other observations at an unprecedented resolution. We present an overview of the concept in the context of Mars exploration.

Mars Exploration with Directed Aerial Robot Explorers

Global Aerospace Corporation (GAC) is developing a revolutionary system architecture for exploration of planetary atmospheres and surfaces from atmospheric altitudes. The work is supported by the NASA Institute for Advanced Concepts (NIAC). The innovative system architecture relies upon the use of Directed Aerial Robot Explorers (DAREs), which essentially are long‐duration‐flight autonomous balloons with trajectory control capabilities that can deploy swarms of miniature probes over multiple target areas. Balloon guidance capabilities will offer unprecedented opportunities in high‐resolution, targeted observations of both atmospheric and surface phenomena. Multifunctional microprobes will be deployed from the balloons when over the target areas, and perform a multitude of functions, such as atmospheric profiling or surface exploration, relaying data back to the balloons or an orbiter. This architecture will enable low‐cost, low‐energy, long‐term global exploration of planetary atmospheres and surfaces. A conceptual analysis of DARE capabilities and science applications for Mars is presented. Initial results of simulations indicate that a relatively small trajectory control wing can significantly change planetary balloon flight paths, especially during summer seasons in Polar Regions. This opens new possibilities for high‐resolution observations of crustal magnetic anomalies, polar layered terrain, polar clouds, dust storms at the edges of the Polar caps and of seasonal variability of volatiles in the atmosphere.

A Dual-Use Lifting Ballute for Orbit Capture and Entry

A lightweight ballute concept for both high-mass Mars orbit capture and entry is presented. This technology innovation could provide significant mass-savings over other candidate systems and be extended for use at Earth and other planets with atmospheres. This lightweight ballute concept will enable high-altitude deceleration and reduce g-loads for both capture and entry phases, minimizing the thermal protection and structural requirements of the deceleration system. Adding lift-control to a toroidal ballute and extending its use from orbit capture to entry could greatly reduce the required initial mass in low Earth orbit and total mission cost.

Biological Analogs and Emergent Intelligence for Control of Stratospheric Balloon Constellations

Global Aerospace Corporation is developing a revolutionary concept for a global constellation and network of hundreds of stratospheric superpressure balloons. Global Aerospace Corporation and Princeton University are studying methods of controlling the geometry of these stratospheric balloon constellations using concepts related to and inspiration derived from biological group behavior such as schooling, flocking, and herding. The method of artificial potentials determines control settings for trajectory control systems in the steady flow regions. Weak Stability Boundary theory is used to (a) determine the interfaces between smooth flow and areas where chaotic conditions exist and (b) calculate control settings in regions of chaotic flow.