Reuben R. Rohrschneider

Survey of Ballute Technology for Aerocapture

Ballute aerodynamic decelerators have been studied since early in the space age (1960’s), being proposed for aerocapture in the early 1980’s. Significant technology advances in fabric and polymer materials as well as analysis capabilities lend credibility to the potential of ballute aerocapture. The concept of the thin-film ballute for aerocapture shows the potential for large mass savings over propulsive orbit insertion or rigid aeroshell aerocapture. The mass savings of this concept enables a number of high value science missions. Current studies of ballute aerocapture at Titan and Earth may lead to flight test of one or more ballute concepts within the next five years. This paper provides a survey of the literature with application to ballute aerocapture. Special attention is paid to advances in trajectory analysis, hypersonic aerothermodynamics, structural analysis, coupled analysis, and flight tests. Advances anticipated over the next 5 years are summarized.

Entry System Options for Human Return from the Moon and Mars

Earth entry system options for human return missions from the Moon and Mars were analyzed and compared to identify trends among the configurations and trajectory options and to facilitate informed decision making at the exploration architecture level. Entry system options included ballistic, lifting capsule, biconic, and lifting body configurations with direct entry and aerocapture trajectories. For each configuration and trajectory option, the thermal environment, deceleration environment, crossrange and downrange performance, and entry corridor were assessed. In addition, the feasibility of a common vehicle for lunar and Mars return was investigated. The results show that a low lift-to-drag ratio (L/D = 0.3) vehicle provides sufficient performance for both lunar and Mars return missions while providing the following benefits: excellent packaging efficiency, low structural and TPS mass fraction, ease of launch vehicle integration, and system elegance and simplicity. Numerous configuration options exist that achieve this L/D.

Ultra Lightweight Ballutes for Return to Earth from the Moon

47th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference May 2006, Newport, RI.

STATIC AEROELASTIC ANALYSIS OF A THIN-FILM CLAMPED BALLUTE FOR TITAN AEROCAPTURE

Many authors have shown the potential mass savings that a ballute can offer for both aerocapture and entry. This mass savings could enhance or even enable many scientific and human exploration missions. Prior to flight of a ballute several technical issues need to be addressed, including aeroelastic behavior. This paper begins to address the issue of aeroelastic behavior by developing and validating the Ballute Aeroelastic Analysis Tool (BAAT). The validation effort uses wind tunnel tests of clamped ballute models constructed of Kapton supported by a rigid nose and floating aft ring. Good correlation is obtained using modified Newtonian aerodynamics and non-linear structural analysis with temperature dependent material properties and thermal expansion. BAAT is then used to compute the deformed shape of a clamped ballute for Titan aerocapture in both the continuum and transitional regimes using impact method aerodynamics and direct simulation Monte Carlo.

Critical Advancement in Telerobotic Servicing Vision Technology

Future space missions will rely heavily on telerobotic servicing capabilities. One of the most difficult scenarios envisioned for these missions is to provide servicing capabilities beyond low earth orbit. In addition to highly variable lighting and other environmental considerations as well as data latency issues, solutions for these missions must be low mass and low power due to system resource limitations. A key functionality for implementation of these missions is vision systems to provide situational awareness and visual feedback cues to the teleoperator, and to support remote tool selection, dexterous object manipulation and manipulator path planning to the telerobot. Recent advancement in hardware, software and algorithms associated with vision sensors, autonomous feature recognition and high performance processing are critical to mission implementation plans. Critical sensors addressed in this paper include high resolution two dimensional imagers as well as three dimensional vision systems such as flash LIDAR. Both kinds of vision systems benefit from recent technology advances that yield higher resolution images, reduce sensitivity to dynamic lighting variation and are robust to space radiation effects. Real time embedded processing capabilities leverage advances in high throughput processing technology to fuse multiple data sources for the autonomous identification of critical features to support motion and manipulation system operations regardless of communications latency between the servicing system and other critical assets. These high speed processing capabilities also provide near real time visualization for the teleoperator. This paper addresses key development methodologies, results and findings for advancement of these technologies in context of future in-space servicing systems.

An Overview of Ball Flash LIDAR and Related Technology Development

Ball Aerospace has been developing Flash LIDAR systems for more than 7 years, and space qualified their first system on the Sensor Test for Orion Relative-navigation Risk Mitigation (STORRM) mission in May of 2011 on STS-134. The STORRM unit demonstrated the capabilities of the flash LIDAR system for relative navigation, but other applications exist, including science applications, and landing risk mitigation on Earth and other planets. This paper provides an overview of flash LIDAR sensor systems, describes the applications and scenarios where they provide advantages over scanning systems, and provides an overview of related technology development efforts at Ball Aerospace. The current development efforts include relative navigation applications, 6-DOF relative pose determination, landing hazard detection, electronic laser beam steering, and sensor upgrades that include electronic architecture modifications.

Fluid-Structure Analysis of a Clamped Ballute in Titan's atmosphere

This paper presents the ∞uid-structure analysis of a clamped ballute in Titan’s atmosphere. A ballute (balloon + Parachute) is a large in∞atable aerocapture device designed to be used in interplanetary mission. Since a ballute is operated in a high temperature and high altitude environment, such analysis requires a non-equilibrium ∞ow model solver that is coupled with a structure solver that takes into consideration large structure deformation. An unstructured Cartesian grid based ∞ow solver, NASCART-GT, with Titan’s atmospheric composition is used for the ∞ow solver and LS-DYNA is used for the structure solver.

Vision Navigation Sensor (VNS) with Adaptive Electronically Steerable Flash LIDAR (ESFL)

Ball Aerospace has been developing Flash LIDAR systems for more than 7 years, and space qualified their first system on the Sensor Test for Orion Relative-navigation Risk Mitigation (STORRM) mission in May of 2011 on STS-134. The STORRM unit demonstrated the capabilities of the flash LIDAR system for relative navigation, but other applications exist, including science applications, and landing risk mitigation on Earth and other planets. One key technology for making the flash LIDAR a more broadly applicable sensor is the addition of electronically steerable laser projection optics to provide flexibility in operations and to optimize the use of the limited number of photons available. This principle is important in any application where mass and power are limited commodities. The addition of Electronically Steerable Flash LIDAR (ESFL) capability to the VNS enables the system to offer the functionality of both scanning and flash LIDARs simultaneously, without any mechanisms. This paper provides an overview of the Vision Navigation Sensor (VNS) flash LIDAR and the work towards a common navigation sensor that meets NASA’s common specification through the addition of ESFL. Potential mass and volume reductions are also covered to balance the mass and volume required by ESFL. Finally, an overview of a control scheme to maximize the utility of ESFL for earth science applications is presented.

Simulation Results of ISS AR&D Using Only Range Images

NASA’s future plans for space vehicles call for the ability to automatically rendezvous and dock (AR&D) with the International Space Station (ISS) and other targets. This requires sensors and algorithms capable of determining the relative position and orientation (pose) between the target and chase vehicles under the drastically varying lighting conditions of low Earth orbit and beyond. To this end, Ball Aerospace has developed algorithms to produce six degree-of-freedom navigation data from 3D point clouds. The algorithms require a-priori knowledge of the target vehicle geometry and a range image of the target vehicle for in-flight pose determination (no visible or reflective targets are needed). The algorithms have been incorporated into a simulation that includes a flash LIDAR model, orbital dynamics, vehicle thrust control, and a three-dimensional model of the ISS. The flash LIDAR is used as the only relative navigation sensor during AR&D. In this paper we present the results of the docking simulation, including the accuracy of the pose determination algorithms during a successful approach and docking with ISS.

Aeroelastic Design Considerations of a Clamped Ballute for Titan Aerocapture

This research performs aeroelastic analysis of a clamped, thin-film ballute on a Titan aerocapture trajectory of suitable fidelity for conceptual design work. Static deformed shapes and stresses are computed along a Titan Aerocapture trajectory, and an engineering estimate of unsteady hypersonic flow is used to determine if the ballute flutters at the peak dynamic pressure point. Static solutions along a Titan aerocapture trajectory indicate that stress and displacement are correlated to dynamic pressure above 1 Pa. For lower dynamic pressures, the aerodynamic loading is insucient to fully overcome initial material shape, indicating that spacecraft re-contact is possible, and leading to a recommendation to include supports for the torus. Dynamic analysis of the clamped ballute using a first-order engineering estimate of unsteady aerodynamics indicates that flutter will not be a problem at the peak dynamic pressure point on the trajectory.